// SPDX-License-Identifier: GPL-3.0-or-later

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.6.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol

pragma solidity ^0.6.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.6.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.6.2;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol

pragma solidity ^0.6.0;

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;
    using Address for address;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

// File: erc20permit/contracts/IERC2612.sol

// Code adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2237/
pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC2612 standard as defined in the EIP.
 *
 * Adds the {permit} method, which can be used to change one's
 * {IERC20-allowance} without having to send a transaction, by signing a
 * message. This allows users to spend tokens without having to hold Ether.
 *
 * See https://eips.ethereum.org/EIPS/eip-2612.
 */
interface IERC2612 {
    /**
     * @dev Sets `amount` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;

    /**
     * @dev Returns the current ERC2612 nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);
}

// File: erc20permit/contracts/ERC20Permit.sol

// Adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/53516bc555a454862470e7860a9b5254db4d00f5/contracts/token/ERC20/ERC20Permit.sol
pragma solidity ^0.6.0;

/**
 * @author Georgios Konstantopoulos
 * @dev Extension of {ERC20} that allows token holders to use their tokens
 * without sending any transactions by setting {IERC20-allowance} with a
 * signature using the {permit} method, and then spend them via
 * {IERC20-transferFrom}.
 *
 * The {permit} signature mechanism conforms to the {IERC2612} interface.
 */
abstract contract ERC20Permit is ERC20, IERC2612 {
    mapping (address => uint256) public override nonces;

    bytes32 public immutable PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public immutable DOMAIN_SEPARATOR;

    constructor(string memory name_, string memory symbol_) internal ERC20(name_, symbol_) {
        uint256 chainId;
        assembly {
            chainId := chainid()
        }

        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                keccak256(bytes(name_)),
                keccak256(bytes("1")),
                chainId,
                address(this)
            )
        );
    }

    /**
     * @dev See {IERC2612-permit}.
     *
     * In cases where the free option is not a concern, deadline can simply be
     * set to uint(-1), so it should be seen as an optional parameter
     */
    function permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public virtual override {
        require(deadline >= block.timestamp, "ERC20Permit: expired deadline");

        bytes32 hashStruct = keccak256(
            abi.encode(
                PERMIT_TYPEHASH,
                owner,
                spender,
                amount,
                nonces[owner]++,
                deadline
            )
        );

        bytes32 hash = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                hashStruct
            )
        );

        address signer = ecrecover(hash, v, r, s);
        require(
            signer != address(0) && signer == owner,
            "ERC20Permit: invalid signature"
        );

        _approve(owner, spender, amount);
    }
}

// File: contracts/IUSM.sol

pragma solidity ^0.6.6;

interface IUSM {
    function mint(address to, uint minUsmOut) external payable returns (uint);
    function burn(address from, address payable to, uint usmToBurn, uint minEthOut) external returns (uint);
    function fund(address to, uint minFumOut) external payable returns (uint);
    function defund(address from, address payable to, uint fumToBurn, uint minEthOut) external returns (uint);
    function defundFromFUM(address from, address payable to, uint fumToBurn, uint minEthOut) external returns (uint);
}

// File: contracts/MinOut.sol

pragma solidity ^0.6.6;

library MinOut {
    function parseMinTokenOut(uint ethIn) internal pure returns (uint minTokenOut) {
        uint minPrice = ethIn % 100000000000;
        if (minPrice != 0 && minPrice < 10000000) {
            minTokenOut = ethIn * minPrice / 100;
        }
    }

    function parseMinEthOut(uint tokenIn) internal pure returns (uint minEthOut) {
        uint maxPrice = tokenIn % 100000000000;
        if (maxPrice != 0 && maxPrice < 10000000) {
            minEthOut = tokenIn * 100 / maxPrice;
        }
    }
}

// File: contracts/FUM.sol

pragma solidity ^0.6.6;

/**
 * @title FUM Token
 * @author Alberto Cuesta Cañada, Jacob Eliosoff, Alex Roan
 *
 * @notice This should be owned by the stablecoin.
 */
contract FUM is ERC20Permit, Ownable {
    IUSM public immutable usm;

    constructor(IUSM usm_) public ERC20Permit("Minimal Funding", "FUM") {
        usm = usm_;
    }

    /**
     * @notice If anyone sends ETH here, assume they intend it as a `fund`.
     * If decimals 8 to 11 (included) of the amount of Ether received are `0000` then the next 7 will
     * be parsed as the minimum Ether price accepted, with 2 digits before and 5 digits after the comma.
     */
    receive() external payable {
        usm.fund{ value: msg.value }(msg.sender, MinOut.parseMinTokenOut(msg.value));
    }

    /**
     * @notice If a user sends FUM tokens directly to this contract (or to the USM contract), assume they intend it as a `defund`.
     * If using `transfer`/`transferFrom` as `defund`, and if decimals 8 to 11 (included) of the amount transferred received
     * are `0000` then the next 7 will be parsed as the maximum FUM price accepted, with 5 digits before and 2 digits after the comma.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal override {
        if (recipient == address(this) || recipient == address(usm) || recipient == address(0)) {
            usm.defundFromFUM(sender, payable(sender), amount, MinOut.parseMinEthOut(amount));
        } else {
            super._transfer(sender, recipient, amount);
        }
    }

    /**
     * @notice Mint new FUM to the _recipient
     *
     * @param _recipient address to mint to
     * @param _amount amount to mint
     */
    function mint(address _recipient, uint _amount) external onlyOwner {
        _mint(_recipient, _amount);
    }

    /**
     * @notice Burn FUM from _holder
     *
     * @param _holder address to burn from
     * @param _amount amount to burn
     */
    function burn(address _holder, uint _amount) external onlyOwner {
        _burn(_holder, _amount);
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.6.2;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.6.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.6.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol

pragma solidity ^0.6.0;


/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;
    using Address for address;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

// File: erc20permit/contracts/IERC2612.sol

// Code adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2237/
pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC2612 standard as defined in the EIP.
 *
 * Adds the {permit} method, which can be used to change one's
 * {IERC20-allowance} without having to send a transaction, by signing a
 * message. This allows users to spend tokens without having to hold Ether.
 *
 * See https://eips.ethereum.org/EIPS/eip-2612.
 */
interface IERC2612 {
    /**
     * @dev Sets `amount` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;

    /**
     * @dev Returns the current ERC2612 nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);
}

// File: erc20permit/contracts/ERC20Permit.sol

// Adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/53516bc555a454862470e7860a9b5254db4d00f5/contracts/token/ERC20/ERC20Permit.sol
pragma solidity ^0.6.0;

/**
 * @author Georgios Konstantopoulos
 * @dev Extension of {ERC20} that allows token holders to use their tokens
 * without sending any transactions by setting {IERC20-allowance} with a
 * signature using the {permit} method, and then spend them via
 * {IERC20-transferFrom}.
 *
 * The {permit} signature mechanism conforms to the {IERC2612} interface.
 */
abstract contract ERC20Permit is ERC20, IERC2612 {
    mapping (address => uint256) public override nonces;

    bytes32 public immutable PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public immutable DOMAIN_SEPARATOR;

    constructor(string memory name_, string memory symbol_) internal ERC20(name_, symbol_) {
        uint256 chainId;
        assembly {
            chainId := chainid()
        }

        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                keccak256(bytes(name_)),
                keccak256(bytes("1")),
                chainId,
                address(this)
            )
        );
    }

    /**
     * @dev See {IERC2612-permit}.
     *
     * In cases where the free option is not a concern, deadline can simply be
     * set to uint(-1), so it should be seen as an optional parameter
     */
    function permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public virtual override {
        require(deadline >= block.timestamp, "ERC20Permit: expired deadline");

        bytes32 hashStruct = keccak256(
            abi.encode(
                PERMIT_TYPEHASH,
                owner,
                spender,
                amount,
                nonces[owner]++,
                deadline
            )
        );

        bytes32 hash = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                hashStruct
            )
        );

        address signer = ecrecover(hash, v, r, s);
        require(
            signer != address(0) && signer == owner,
            "ERC20Permit: invalid signature"
        );

        _approve(owner, spender, amount);
    }
}

// File: contracts/IUSM.sol

pragma solidity ^0.6.6;

interface IUSM {
    function mint(address to, uint minUsmOut) external payable returns (uint);
    function burn(address from, address payable to, uint usmToBurn, uint minEthOut) external returns (uint);
    function fund(address to, uint minFumOut) external payable returns (uint);
    function defund(address from, address payable to, uint fumToBurn, uint minEthOut) external returns (uint);
    function defundFromFUM(address from, address payable to, uint fumToBurn, uint minEthOut) external returns (uint);
}

// File: contracts/Delegable.sol

pragma solidity ^0.6.6;

/// @dev Delegable enables users to delegate their account management to other users.
/// Delegable implements addDelegateBySignature, to add delegates using a signature instead of a separate transaction.
contract Delegable {
    event Delegate(address indexed user, address indexed delegate, bool enabled);

    // keccak256("Signature(address user,address delegate,uint256 nonce,uint256 deadline)");
    bytes32 public immutable SIGNATURE_TYPEHASH = 0x0d077601844dd17f704bafff948229d27f33b57445915754dfe3d095fda2beb7;
    bytes32 public immutable DELEGABLE_DOMAIN;
    mapping(address => uint) public signatureCount;

    mapping(address => mapping(address => bool)) public delegated;

    constructor () public {
        uint256 chainId;
        assembly {
            chainId := chainid()
        }

        DELEGABLE_DOMAIN = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes('USMFUM')),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }

    /// @dev Require that msg.sender is the account holder or a delegate
    modifier onlyHolderOrDelegate(address holder, string memory errorMessage) {
        require(
            msg.sender == holder || delegated[holder][msg.sender],
            errorMessage
        );
        _;
    }

    /// @dev Enable a delegate to act on the behalf of caller
    function addDelegate(address delegate) public {
        _addDelegate(msg.sender, delegate);
    }

    /// @dev Stop a delegate from acting on the behalf of caller
    function revokeDelegate(address delegate) public {
        _revokeDelegate(msg.sender, delegate);
    }

    /// @dev Add a delegate through an encoded signature
    function addDelegateBySignature(address user, address delegate, uint deadline, uint8 v, bytes32 r, bytes32 s) public {
        require(deadline >= block.timestamp, 'Delegable: Signature expired');

        bytes32 hashStruct = keccak256(
            abi.encode(
                SIGNATURE_TYPEHASH,
                user,
                delegate,
                signatureCount[user]++,
                deadline
            )
        );

        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DELEGABLE_DOMAIN,
                hashStruct
            )
        );
        address signer = ecrecover(digest, v, r, s);
        require(
            signer != address(0) && signer == user,
            'Delegable: Invalid signature'
        );

        _addDelegate(user, delegate);
    }

    /// @dev Enable a delegate to act on the behalf of an user
    function _addDelegate(address user, address delegate) internal {
        require(!delegated[user][delegate], "Delegable: Already delegated");
        delegated[user][delegate] = true;
        emit Delegate(user, delegate, true);
    }

    /// @dev Stop a delegate from acting on the behalf of an user
    function _revokeDelegate(address user, address delegate) internal {
        require(delegated[user][delegate], "Delegable: Already undelegated");
        delegated[user][delegate] = false;
        emit Delegate(user, delegate, false);
    }
}

// File: contracts/WadMath.sol

pragma solidity ^0.6.6;

/**
 * @title Fixed point arithmetic library
 * @author Alberto Cuesta Cañada, Jacob Eliosoff, Alex Roan
 */
library WadMath {
    using SafeMath for uint;

    enum Round {Down, Up}

    uint private constant WAD = 10 ** 18;
    uint private constant WAD_MINUS_1 = WAD - 1;
    uint private constant WAD_SQUARED = WAD * WAD;
    uint private constant WAD_SQUARED_MINUS_1 = WAD_SQUARED - 1;
    uint private constant WAD_OVER_10 = WAD / 10;
    uint private constant WAD_OVER_20 = WAD / 20;
    uint private constant HALF_TO_THE_ONE_TENTH = 933032991536807416;
    uint private constant TWO_WAD = 2 * WAD;

    function wadMul(uint x, uint y, Round upOrDown) internal pure returns (uint) {
        return upOrDown == Round.Down ? wadMulDown(x, y) : wadMulUp(x, y);
    }

    function wadMulDown(uint x, uint y) internal pure returns (uint) {
        return x.mul(y) / WAD;
    }

    function wadMulUp(uint x, uint y) internal pure returns (uint) {
        return (x.mul(y)).add(WAD_MINUS_1) / WAD;
    }

    function wadSquaredDown(uint x) internal pure returns (uint) {
        return (x.mul(x)) / WAD;
    }

    function wadSquaredUp(uint x) internal pure returns (uint) {
        return (x.mul(x)).add(WAD_MINUS_1) / WAD;
    }

    function wadCubedDown(uint x) internal pure returns (uint) {
        return (x.mul(x)).mul(x) / WAD_SQUARED;
    }

    function wadCubedUp(uint x) internal pure returns (uint) {
        return ((x.mul(x)).mul(x)).add(WAD_SQUARED_MINUS_1) / WAD_SQUARED;
    }

    function wadDiv(uint x, uint y, Round upOrDown) internal pure returns (uint) {
        return upOrDown == Round.Down ? wadDivDown(x, y) : wadDivUp(x, y);
    }

    function wadDivDown(uint x, uint y) internal pure returns (uint) {
        return (x.mul(WAD)).div(y);
    }

    function wadDivUp(uint x, uint y) internal pure returns (uint) {
        return ((x.mul(WAD)).add(y - 1)).div(y);    // Can use "-" instead of sub() since div(y) will catch y = 0 case anyway
    }

    function wadHalfExp(uint power) internal pure returns (uint) {
        return wadHalfExp(power, uint(-1));
    }

    // Returns a loose but "gas-efficient" approximation of 0.5**power, where power is rounded to the nearest 0.1, and is
    // capped at maxPower.  Note power is WAD-scaled (eg, 2.7364 * WAD), but maxPower is just a plain unscaled uint (eg, 10).
    // Negative powers are not handled (as implied by power being a uint).
    function wadHalfExp(uint power, uint maxPower) internal pure returns (uint) {
        uint powerInTenthsUnscaled = power.add(WAD_OVER_20) / WAD_OVER_10;
        if (powerInTenthsUnscaled / 10 > maxPower) {
            return 0;
        }
        return wadPow(HALF_TO_THE_ONE_TENTH, powerInTenthsUnscaled);
    }

    // Adapted from rpow() in https://github.com/dapphub/ds-math/blob/master/src/math.sol - thank you!
    //
    // This famous algorithm is called "exponentiation by squaring"
    // and calculates x^n with x as fixed-point and n as regular unsigned.
    //
    // It's O(log n), instead of O(n) for naive repeated multiplication.
    //
    // These facts are why it works:
    //
    //  If n is even, then x^n = (x^2)^(n/2).
    //  If n is odd,  then x^n = x * x^(n-1),
    //   and applying the equation for even x gives
    //    x^n = x * (x^2)^((n-1) / 2).
    //
    //  Also, EVM division is flooring and
    //    floor[(n-1) / 2] = floor[n / 2].
    //
    function wadPow(uint x, uint n) internal pure returns (uint z) {
        z = n % 2 != 0 ? x : WAD;

        for (n /= 2; n != 0; n /= 2) {
            x = wadSquaredDown(x);

            if (n % 2 != 0) {
                z = wadMulDown(z, x);
            }
        }
    }

    // Using Newton's method (see eg https://stackoverflow.com/a/8827111/3996653), but with WAD fixed-point math.
    function wadCbrtDown(uint y) internal pure returns (uint root) {
        if (y > 0 ) {
            uint newRoot = y.add(TWO_WAD) / 3;
            uint yTimesWadSquared = y.mul(WAD_SQUARED);
            do {
                root = newRoot;
                newRoot = (root + root + (yTimesWadSquared / (root * root))) / 3;
            } while (newRoot < root);
        }
        //require(root**3 <= y.mul(WAD_SQUARED) && y.mul(WAD_SQUARED) < (root + 1)**3);
    }

    function wadCbrtUp(uint y) internal pure returns (uint root) {
        root = wadCbrtDown(y);
        // The only case where wadCbrtUp(y) *isn't* equal to wadCbrtDown(y) + 1 is when y is a perfect cube; so check for that.
        // These "*"s are safe because: 1. root**3 <= y.mul(WAD_SQUARED), and 2. y.mul(WAD_SQUARED) is calculated (safely) above.
        if (root * root * root != y * WAD_SQUARED ) {
            ++root;
        }
        //require((root - 1)**3 < y.mul(WAD_SQUARED) && y.mul(WAD_SQUARED) <= root**3);
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol

pragma solidity ^0.6.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/MinOut.sol

pragma solidity ^0.6.6;

library MinOut {
    function parseMinTokenOut(uint ethIn) internal pure returns (uint minTokenOut) {
        uint minPrice = ethIn % 100000000000;
        if (minPrice != 0 && minPrice < 10000000) {
            minTokenOut = ethIn * minPrice / 100;
        }
    }

    function parseMinEthOut(uint tokenIn) internal pure returns (uint minEthOut) {
        uint maxPrice = tokenIn % 100000000000;
        if (maxPrice != 0 && maxPrice < 10000000) {
            minEthOut = tokenIn * 100 / maxPrice;
        }
    }
}

// File: contracts/FUM.sol

pragma solidity ^0.6.6;


/**
 * @title FUM Token
 * @author Alberto Cuesta Cañada, Jacob Eliosoff, Alex Roan
 *
 * @notice This should be owned by the stablecoin.
 */
contract FUM is ERC20Permit, Ownable {
    IUSM public immutable usm;

    constructor(IUSM usm_) public ERC20Permit("Minimal Funding", "FUM") {
        usm = usm_;
    }

    /**
     * @notice If anyone sends ETH here, assume they intend it as a `fund`.
     * If decimals 8 to 11 (included) of the amount of Ether received are `0000` then the next 7 will
     * be parsed as the minimum Ether price accepted, with 2 digits before and 5 digits after the comma.
     */
    receive() external payable {
        usm.fund{ value: msg.value }(msg.sender, MinOut.parseMinTokenOut(msg.value));
    }

    /**
     * @notice If a user sends FUM tokens directly to this contract (or to the USM contract), assume they intend it as a `defund`.
     * If using `transfer`/`transferFrom` as `defund`, and if decimals 8 to 11 (included) of the amount transferred received
     * are `0000` then the next 7 will be parsed as the maximum FUM price accepted, with 5 digits before and 2 digits after the comma.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal override {
        if (recipient == address(this) || recipient == address(usm) || recipient == address(0)) {
            usm.defundFromFUM(sender, payable(sender), amount, MinOut.parseMinEthOut(amount));
        } else {
            super._transfer(sender, recipient, amount);
        }
    }

    /**
     * @notice Mint new FUM to the _recipient
     *
     * @param _recipient address to mint to
     * @param _amount amount to mint
     */
    function mint(address _recipient, uint _amount) external onlyOwner {
        _mint(_recipient, _amount);
    }

    /**
     * @notice Burn FUM from _holder
     *
     * @param _holder address to burn from
     * @param _amount amount to burn
     */
    function burn(address _holder, uint _amount) external onlyOwner {
        _burn(_holder, _amount);
    }
}

// File: contracts/oracles/Oracle.sol

pragma solidity ^0.6.6;

abstract contract Oracle {
    function latestPrice() public virtual view returns (uint price);    // Prices must be WAD-scaled - 18 decimal places

    /**
     * @dev This pure virtual implementation, which is intended to be (optionally) overridden by stateful implementations,
     * confuses solhint into giving a "Function state mutability can be restricted to view" warning.  Unfortunately there seems
     * to be no elegant/gas-free workaround as yet: see https://github.com/ethereum/solidity/issues/3529.
     */
    function cacheLatestPrice() public virtual returns (uint price) {
        price = latestPrice();  // Default implementation doesn't do any cacheing, just returns price.  But override as needed
    }
}

// File: contracts/USMTemplate.sol

pragma solidity ^0.6.6;




// import "@nomiclabs/buidler/console.sol";

/**
 * @title USMTemplate
 * @author Alberto Cuesta Cañada, Jacob Eliosoff, Alex Roan
 * @notice Concept by Jacob Eliosoff (@jacob-eliosoff).
 *
 * This abstract USM contract must be inherited by a concrete implementation, that also adds an Oracle implementation - eg, by
 * also inheriting a concrete Oracle implementation.  See USM (and MockUSM) for an example.
 *
 * We use this inheritance-based design (rather than the more natural, and frankly normally more correct, composition-based design
 * of storing the Oracle here as a variable), because inheriting the Oracle makes all the latestPrice() calls *internal* rather
 * than calls to a separate oracle contract (or multiple contracts) - which leads to a significant saving in gas.
 */
abstract contract USMTemplate is IUSM, Oracle, ERC20Permit, Delegable {
    using Address for address payable;
    using SafeMath for uint;
    using WadMath for uint;

    enum Side {Buy, Sell}

    event MinFumBuyPriceChanged(uint previous, uint latest);
    event BuySellAdjustmentChanged(uint previous, uint latest);

    uint public constant WAD = 10 ** 18;
    uint public constant MAX_DEBT_RATIO = WAD * 8 / 10;                 // 80%
    uint public constant MIN_FUM_BUY_PRICE_HALF_LIFE = 1 days;          // Solidity for 1 * 24 * 60 * 60
    uint public constant BUY_SELL_ADJUSTMENT_HALF_LIFE = 1 minutes;     // Solidity for 1 * 60

    FUM public immutable fum;

    uint256 deadline; // Second at which the trial expires and `mint` and `fund` get disabled.

    struct TimedValue {
        uint32 timestamp;
        uint224 value;
    }

    TimedValue public minFumBuyPriceStored;
    TimedValue public buySellAdjustmentStored = TimedValue({ timestamp: 0, value: uint224(WAD) });

    constructor() public ERC20Permit("Minimal USD", "USM")
    {
        fum = new FUM(this);
        deadline = now + (60 * 60 * 24 * 28); // Four weeks into the future
    }

    /** EXTERNAL TRANSACTIONAL FUNCTIONS **/

    /**
     * @notice Mint new USM, sending it to the given address, and only if the amount minted >= minUsmOut.  The amount of ETH is
     * passed in as msg.value.
     * @param to address to send the USM to.
     * @param minUsmOut Minimum accepted USM for a successful mint.
     */
    function mint(address to, uint minUsmOut) external payable override returns (uint usmOut) {
        usmOut = _mintUsm(to, minUsmOut);
    }

    /**
     * @dev Burn USM in exchange for ETH.
     * @param from address to deduct the USM from.
     * @param to address to send the ETH to.
     * @param usmToBurn Amount of USM to burn.
     * @param minEthOut Minimum accepted ETH for a successful burn.
     */
    function burn(address from, address payable to, uint usmToBurn, uint minEthOut)
        external override
        onlyHolderOrDelegate(from, "Only holder or delegate")
        returns (uint ethOut)
    {
        ethOut = _burnUsm(from, to, usmToBurn, minEthOut);
    }

    /**
     * @notice Funds the pool with ETH, minting new FUM and sending it to the given address, but only if the amount minted >=
     * minFumOut.  The amount of ETH is passed in as msg.value.
     * @param to address to send the FUM to.
     * @param minFumOut Minimum accepted FUM for a successful fund.
     */
    function fund(address to, uint minFumOut) external payable override returns (uint fumOut) {
        fumOut = _fundFum(to, minFumOut);
    }

    /**
     * @notice Defunds the pool by redeeming FUM in exchange for equivalent ETH from the pool.
     * @param from address to deduct the FUM from.
     * @param to address to send the ETH to.
     * @param fumToBurn Amount of FUM to burn.
     * @param minEthOut Minimum accepted ETH for a successful defund.
     */
    function defund(address from, address payable to, uint fumToBurn, uint minEthOut)
        external override
        onlyHolderOrDelegate(from, "Only holder or delegate")
        returns (uint ethOut)
    {
        ethOut = _defundFum(from, to, fumToBurn, minEthOut);
    }

    /**
     * @notice Defunds the pool by redeeming FUM from an arbitrary address in exchange for equivalent ETH from the pool.
     * Called only by the FUM contract, when FUM is sent to it.
     * @param from address to deduct the FUM from.
     * @param to address to send the ETH to.
     * @param fumToBurn Amount of FUM to burn.
     * @param minEthOut Minimum accepted ETH for a successful defund.
     */
    function defundFromFUM(address from, address payable to, uint fumToBurn, uint minEthOut)
        external override
        returns (uint ethOut)
    {
        require(msg.sender == address(fum), "Restricted to FUM");
        ethOut = _defundFum(from, to, fumToBurn, minEthOut);
    }

    /**
     * @notice If anyone sends ETH here, assume they intend it as a `mint`.
     * If decimals 8 to 11 (included) of the amount of Ether received are `0000` then the next 7 will
     * be parsed as the minimum Ether price accepted, with 2 digits before and 5 digits after the comma.
     */
    receive() external payable {
        _mintUsm(msg.sender, MinOut.parseMinTokenOut(msg.value));
    }

    /**
     * @notice If a user sends USM tokens directly to this contract (or to the FUM contract), assume they intend it as a `burn`.
     * If using `transfer`/`transferFrom` as `burn`, and if decimals 8 to 11 (included) of the amount transferred received
     * are `0000` then the next 7 will be parsed as the maximum USM price accepted, with 5 digits before and 2 digits after the comma.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal override {
        if (recipient == address(this) || recipient == address(fum) || recipient == address(0)) {
            _burnUsm(sender, payable(sender), amount, MinOut.parseMinEthOut(amount));
        } else {
            super._transfer(sender, recipient, amount);
        }
    }

    /** INTERNAL TRANSACTIONAL FUNCTIONS */

    function _mintUsm(address to, uint minUsmOut) internal returns (uint usmOut)
    {
        // 1. Check that fund() has been called first - no minting before funding:
        uint rawEthInPool = ethPool();
        uint ethInPool = rawEthInPool.sub(msg.value);   // Backing out the ETH just received, which our calculations should ignore
        require(ethInPool > 0, "Fund before minting");

        // 2. Calculate usmOut:
        uint ethUsmPrice = cacheLatestPrice();
        uint usmTotalSupply = totalSupply();
        uint oldDebtRatio = debtRatio(ethUsmPrice, ethInPool, usmTotalSupply);
        usmOut = usmFromMint(ethUsmPrice, msg.value, ethInPool, usmTotalSupply, oldDebtRatio);
        require(usmOut >= minUsmOut, "Limit not reached");

        // 3. Update buySellAdjustmentStored and mint the user's new USM:
        uint newDebtRatio = debtRatio(ethUsmPrice, rawEthInPool, usmTotalSupply.add(usmOut));
        _updateBuySellAdjustment(oldDebtRatio, newDebtRatio, buySellAdjustment());
        _mint(to, usmOut);

        require(now <= deadline, "Trial expired, remove assets");
        require(msg.value <= 1e18, "Capped at 1 ETH per tx");
        require(ethPool() <= 1e20, "Capped at 100 pooled ETH");
    }

    function _burnUsm(address from, address payable to, uint usmToBurn, uint minEthOut) internal returns (uint ethOut)
    {
        // 1. Calculate ethOut:
        uint ethUsmPrice = cacheLatestPrice();
        uint ethInPool = ethPool();
        uint usmTotalSupply = totalSupply();
        uint oldDebtRatio = debtRatio(ethUsmPrice, ethInPool, usmTotalSupply);
        ethOut = ethFromBurn(ethUsmPrice, usmToBurn, ethInPool, usmTotalSupply, oldDebtRatio);
        require(ethOut >= minEthOut, "Limit not reached");

        // 2. Burn the input USM, update buySellAdjustmentStored, and return the user's ETH:
        uint newDebtRatio = debtRatio(ethUsmPrice, ethInPool.sub(ethOut), usmTotalSupply.sub(usmToBurn));
        require(newDebtRatio <= WAD, "Debt ratio > 100%");
        _burn(from, usmToBurn);
        _updateBuySellAdjustment(oldDebtRatio, newDebtRatio, buySellAdjustment());
        to.sendValue(ethOut);
    }

    function _fundFum(address to, uint minFumOut) internal returns (uint fumOut)
    {
        // 1. Refresh mfbp:
        uint ethUsmPrice = cacheLatestPrice();
        uint rawEthInPool = ethPool();
        uint ethInPool = rawEthInPool.sub(msg.value);   // Backing out the ETH just received, which our calculations should ignore
        uint usmTotalSupply = totalSupply();
        uint oldDebtRatio = debtRatio(ethUsmPrice, ethInPool, usmTotalSupply);
        uint fumTotalSupply = fum.totalSupply();
        _updateMinFumBuyPrice(oldDebtRatio, ethInPool, fumTotalSupply);

        // 2. Calculate fumOut:
        uint adjustment = buySellAdjustment();
        fumOut = fumFromFund(ethUsmPrice, msg.value, ethInPool, usmTotalSupply, fumTotalSupply, adjustment);
        require(fumOut >= minFumOut, "Limit not reached");

        // 3. Update buySellAdjustmentStored and mint the user's new FUM:
        uint newDebtRatio = debtRatio(ethUsmPrice, rawEthInPool, usmTotalSupply);
        _updateBuySellAdjustment(oldDebtRatio, newDebtRatio, adjustment);
        fum.mint(to, fumOut);

        require(now <= deadline, "Trial expired, remove assets");
        require(msg.value <= 1e18, "Capped at 1 ETH per tx");
        require(ethPool() <= 1e20, "Capped at 100 pooled ETH");
    }

    function _defundFum(address from, address payable to, uint fumToBurn, uint minEthOut) internal returns (uint ethOut)
    {
        // 1. Calculate ethOut:
        uint ethUsmPrice = cacheLatestPrice();
        uint ethInPool = ethPool();
        uint usmTotalSupply = totalSupply();
        uint oldDebtRatio = debtRatio(ethUsmPrice, ethInPool, usmTotalSupply);
        ethOut = ethFromDefund(ethUsmPrice, fumToBurn, ethInPool, usmTotalSupply);
        require(ethOut >= minEthOut, "Limit not reached");

        // 2. Burn the input FUM, update buySellAdjustmentStored, and return the user's ETH:
        uint newDebtRatio = debtRatio(ethUsmPrice, ethInPool.sub(ethOut), usmTotalSupply);
        require(newDebtRatio <= MAX_DEBT_RATIO, "Debt ratio > max");
        fum.burn(from, fumToBurn);
        _updateBuySellAdjustment(oldDebtRatio, newDebtRatio, buySellAdjustment());
        to.sendValue(ethOut);
    }

    /**
     * @notice Set the min FUM price, based on the current oracle price and debt ratio. Emits a MinFumBuyPriceChanged event.
     * @dev The logic for calculating a new minFumBuyPrice is as follows.  We want to set it to the FUM price, in ETH terms, at
     * which debt ratio was exactly MAX_DEBT_RATIO.  So we can assume:
     *
     *     usmToEth(totalSupply()) / ethPool() = MAX_DEBT_RATIO, or in other words:
     *     usmToEth(totalSupply()) = MAX_DEBT_RATIO * ethPool()
     *
     * And with this assumption, we calculate the FUM price (buffer / FUM qty) like so:
     *
     *     minFumBuyPrice = ethBuffer() / fum.totalSupply()
     *                    = (ethPool() - usmToEth(totalSupply())) / fum.totalSupply()
     *                    = (ethPool() - (MAX_DEBT_RATIO * ethPool())) / fum.totalSupply()
     *                    = (1 - MAX_DEBT_RATIO) * ethPool() / fum.totalSupply()
     */
    function _updateMinFumBuyPrice(uint debtRatio_, uint ethInPool, uint fumTotalSupply) internal {
        uint previous = minFumBuyPriceStored.value;
        if (debtRatio_ <= MAX_DEBT_RATIO) {                 // We've dropped below (or were already below, whatev) max debt ratio
            if (previous != 0) {
                minFumBuyPriceStored.timestamp = 0;         // Clear mfbp
                minFumBuyPriceStored.value = 0;
                emit MinFumBuyPriceChanged(previous, 0);
            }
        } else if (previous == 0) {                         // We were < max debt ratio, but have now crossed above - so set mfbp
            // See reasoning in @dev comment above
            minFumBuyPriceStored.timestamp = uint32(block.timestamp);
            minFumBuyPriceStored.value = uint224((WAD - MAX_DEBT_RATIO).wadMulUp(ethInPool).wadDivUp(fumTotalSupply));
            emit MinFumBuyPriceChanged(previous, minFumBuyPriceStored.value);
        }
    }

    /**
     * @notice Update the buy/sell adjustment factor, as of the current block time, after a price-moving operation.
     * @param oldDebtRatio The debt ratio before the operation (eg, mint()) was done
     * @param newDebtRatio The current, post-op debt ratio
     */
    function _updateBuySellAdjustment(uint oldDebtRatio, uint newDebtRatio, uint oldAdjustment) internal {
        // Skip this if either the old or new debt ratio == 0.  Normally this will only happen on the system's first couple of
        // calls, but in principle it could happen later if every single USM holder burns all their USM.  This seems
        // vanishingly unlikely though if the system gets any uptake at all, and anyway if it does happen it will just mean a
        // couple of skipped updates to the buySellAdjustment - no big deal.
        if (oldDebtRatio != 0 && newDebtRatio != 0) {
            uint previous = buySellAdjustmentStored.value; // Not nec the same as oldAdjustment, because of the time decay!

            // Eg: if a user operation reduced debt ratio from 70% to 50%, it was either a fund() or a burn().  These are both
            // "long-ETH" operations.  So we can take (old / new)**2 = (70% / 50%)**2 = 1.4**2 = 1.96 as the ratio by which to
            // increase buySellAdjustment, which is intended as a measure of "how long-ETH recent user activity has been":
            uint newAdjustment = (oldAdjustment.mul(oldDebtRatio).mul(oldDebtRatio) / newDebtRatio) / newDebtRatio;
            buySellAdjustmentStored.timestamp = uint32(block.timestamp);
            buySellAdjustmentStored.value = uint224(newAdjustment);
            emit BuySellAdjustmentChanged(previous, newAdjustment);
        }
    }

    /** PUBLIC AND INTERNAL VIEW FUNCTIONS **/

    /**
     * @notice Total amount of ETH in the pool (ie, in the contract).
     * @return pool ETH pool
     */
    function ethPool() public view returns (uint pool) {
        pool = address(this).balance;
    }

    /**
     * @notice Calculate the amount of ETH in the buffer.
     * @return buffer ETH buffer
     */
    function ethBuffer(uint ethUsmPrice, uint ethInPool, uint usmTotalSupply, WadMath.Round upOrDown)
        internal pure returns (int buffer)
    {
        // Reverse the input upOrDown, since we're using it for usmToEth(), which will be *subtracted* from ethInPool below:
        WadMath.Round downOrUp = (upOrDown == WadMath.Round.Down ? WadMath.Round.Up : WadMath.Round.Down);
        buffer = int(ethInPool) - int(usmToEth(ethUsmPrice, usmTotalSupply, downOrUp));
        require(buffer <= int(ethInPool), "Underflow error");
    }

    /**
     * @notice Calculate debt ratio for a given eth to USM price: ratio of the outstanding USM (amount of USM in total supply), to
     * the current ETH pool amount.
     * @return ratio Debt ratio
     */
    function debtRatio(uint ethUsmPrice, uint ethInPool, uint usmTotalSupply) internal pure returns (uint ratio) {
        uint ethPoolValueInUsd = ethInPool.wadMulDown(ethUsmPrice);
        ratio = (ethInPool == 0 ? 0 : usmTotalSupply.wadDivUp(ethPoolValueInUsd));
    }

    /**
     * @notice Convert ETH amount to USM using a ETH/USD price.
     * @param ethAmount The amount of ETH to convert
     * @return usmOut The amount of USM
     */
    function ethToUsm(uint ethUsmPrice, uint ethAmount, WadMath.Round upOrDown) internal pure returns (uint usmOut) {
        usmOut = ethAmount.wadMul(ethUsmPrice, upOrDown);
    }

    /**
     * @notice Convert USM amount to ETH using a ETH/USD price.
     * @param usmAmount The amount of USM to convert
     * @return ethOut The amount of ETH
     */
    function usmToEth(uint ethUsmPrice, uint usmAmount, WadMath.Round upOrDown) internal pure returns (uint ethOut) {
        ethOut = usmAmount.wadDiv(ethUsmPrice, upOrDown);
    }

    /**
     * @notice Calculate the *marginal* price of USM (in ETH terms) - that is, of the next unit, before the price start sliding.
     * @return price USM price in ETH terms
     */
    function usmPrice(Side side, uint ethUsmPrice, uint debtRatio_) internal view returns (uint price) {
        WadMath.Round upOrDown = (side == Side.Buy ? WadMath.Round.Up : WadMath.Round.Down);
        price = usmToEth(ethUsmPrice, WAD, upOrDown);

        uint adjustment = buySellAdjustment();
        if (debtRatio_ <= WAD) {
            if ((side == Side.Buy && adjustment < WAD) || (side == Side.Sell && adjustment > WAD)) {
                price = price.wadDiv(adjustment, upOrDown);
            }
        } else {    // See comment at the bottom of usmFromMint() explaining this special case where debtRatio > 100%
            if ((side == Side.Buy && adjustment > WAD) || (side == Side.Sell && adjustment < WAD)) {
                price = price.wadMul(adjustment, upOrDown);
            }
        }
    }

    /**
     * @notice Calculate the *marginal* price of FUM (in ETH terms) - that is, of the next unit, before the price start sliding.
     * @return price FUM price in ETH terms
     */
    function fumPrice(Side side, uint ethUsmPrice, uint ethInPool, uint usmTotalSupply, uint fumTotalSupply, uint adjustment)
        internal view returns (uint price)
    {
        WadMath.Round upOrDown = (side == Side.Buy ? WadMath.Round.Up : WadMath.Round.Down);
        if (fumTotalSupply == 0) {
            return usmToEth(ethUsmPrice, WAD, upOrDown);    // if no FUM issued yet, default fumPrice to 1 USD (in ETH terms)
        }
        int buffer = ethBuffer(ethUsmPrice, ethInPool, usmTotalSupply, upOrDown);
        price = (buffer <= 0 ? 0 : uint(buffer).wadDiv(fumTotalSupply, upOrDown));

        if (side == Side.Buy) {
            if (adjustment > WAD) {
                price = price.wadMulUp(adjustment);
            }
            // Floor the buy price at minFumBuyPrice:
            uint mfbp = minFumBuyPrice();
            if (price < mfbp) {
                price = mfbp;
            }
        } else {
            if (adjustment < WAD) {
                price = price.wadMulDown(adjustment);
            }
        }
    }

    /**
     * @notice How much USM a minter currently gets back for ethIn ETH, accounting for adjustment and sliding prices.
     * @param ethIn The amount of ETH passed to mint()
     * @return usmOut The amount of USM to receive in exchange
     */
    function usmFromMint(uint ethUsmPrice, uint ethIn, uint ethQty0, uint usmQty0, uint debtRatio0)
        internal view returns (uint usmOut)
    {
        uint usmPrice0 = usmPrice(Side.Buy, ethUsmPrice, debtRatio0);
        uint ethQty1 = ethQty0.add(ethIn);
        if (usmQty0 == 0) {
            // No USM in the system, so debtRatio() == 0 which breaks the integral below - skip sliding-prices this time:
            usmOut = ethIn.wadDivDown(usmPrice0);
        } else if (debtRatio0 <= WAD) {
            // Mint USM at a sliding-up USM price (ie, at a sliding-down ETH price).  **BASIC RULE:** anytime debtRatio()
            // changes by factor k (here > 1), ETH price changes by factor 1/k**2 (ie, USM price, in ETH terms, changes by
            // factor k**2).  (Earlier versions of this logic scaled ETH price based on change in ethPool(), or change in
            // ethPool()**2: the latter gives simpler math - no cbrt() - but doesn't let mint/burn offset fund/defund, which
            // debtRatio()**2 nicely does.)

            // Math: this is an integral - sum of all USM minted at a sliding-down ETH price:
            // u - u_0 = ((((e / e_0)**3 - 1) * e_0 / ubp_0 + u_0) * u_0**2)**(1/3) - u_0
            uint integralFirstPart = (ethQty1.wadDivDown(ethQty0).wadCubedDown().sub(WAD)).mul(ethQty0).div(usmPrice0);
            usmOut = (integralFirstPart.add(usmQty0)).wadMulDown(usmQty0.wadSquaredDown()).wadCbrtDown().sub(usmQty0);
        } else {
            // Here we have the special, unusual case where we're minting while debt ratio > 100%.  In this case (only),
            // minting will actually *reduce* debt ratio, whereas normally it increases it.  (In short: minting always pushes
            // debt ratio closer to 100%.)  Because debt ratio is decreasing as we buy, and USM buy price must *increase* as we
            // buy, we need to make USM price grow proportionally to (1 / change in debt ratio)**2, rather than the usual
            // (1 / change in debt ratio)**2 above.  This gives the following different integral:
            // x = e0 * (e - e0) / (u0 * pu0)
            // u - u_0 = u0 * x / (e - x)
            uint integralFirstPart = ethQty0.mul(ethIn).div(usmQty0.wadMulUp(usmPrice0));
            usmOut = usmQty0.mul(integralFirstPart).div(ethQty1.sub(integralFirstPart));
        }
    }

    /**
     * @notice How much ETH a burner currently gets from burning usmIn USM, accounting for adjustment and sliding prices.
     * @param usmIn The amount of USM passed to burn()
     * @return ethOut The amount of ETH to receive in exchange
     */
    function ethFromBurn(uint ethUsmPrice, uint usmIn, uint ethQty0, uint usmQty0, uint debtRatio0)
        internal view returns (uint ethOut)
    {
        // Burn USM at a sliding-down USM price (ie, a sliding-up ETH price):
        uint usmPrice0 = usmPrice(Side.Sell, ethUsmPrice, debtRatio0);
        uint usmQty1 = usmQty0.sub(usmIn);

        // Math: this is an integral - sum of all USM burned at a sliding price.  Follows the same mathematical invariant as
        // above: if debtRatio() *= k (here, k < 1), ETH price *= 1/k**2, ie, USM price in ETH terms *= k**2.
        // e_0 - e = e_0 - (e_0**2 * (e_0 - usp_0 * u_0 * (1 - (u / u_0)**3)))**(1/3)
        uint integralFirstPart = usmPrice0.wadMulDown(usmQty0).wadMulDown(WAD.sub(usmQty1.wadDivUp(usmQty0).wadCubedUp()));
        ethOut = ethQty0.sub(ethQty0.wadSquaredUp().wadMulUp(ethQty0.sub(integralFirstPart)).wadCbrtUp());
    }

    /**
     * @notice How much FUM a funder currently gets back for ethIn ETH, accounting for adjustment and sliding prices.
     * @param ethIn The amount of ETH passed to fund()
     * @return fumOut The amount of FUM to receive in exchange
     */
    function fumFromFund(uint ethUsmPrice, uint ethIn, uint ethQty0, uint usmQty0, uint fumQty0, uint adjustment)
        internal view returns (uint fumOut)
    {
        // Create FUM at a sliding-up FUM price:
        uint fumPrice0 = fumPrice(Side.Buy, ethUsmPrice, ethQty0, usmQty0, fumQty0, adjustment);
        if (usmQty0 == 0) {
            // No USM in the system - skip sliding-prices:
            fumOut = ethIn.wadDivDown(fumPrice0);
        } else {
            // Math: f - f_0 = e_0 * (e - e_0) / (e * fbp_0)
            uint ethQty1 = ethQty0.add(ethIn);
            fumOut = ethQty0.mul(ethIn).div(ethQty1.wadMulUp(fumPrice0));
        }
    }

    /**
     * @notice How much ETH a defunder currently gets back for fumIn FUM, accounting for adjustment and sliding prices.
     * @param fumIn The amount of FUM passed to defund()
     * @return ethOut The amount of ETH to receive in exchange
     */
    function ethFromDefund(uint ethUsmPrice, uint fumIn, uint ethQty0, uint usmQty0)
        internal view returns (uint ethOut)
    {
        // Burn FUM at a sliding-down FUM price:
        uint fumQty0 = fum.totalSupply();
        uint fumPrice0 = fumPrice(Side.Sell, ethUsmPrice, ethQty0, usmQty0, fumQty0, buySellAdjustment());
        if (usmQty0 == 0) {
            // No USM in the system - skip sliding-prices:
            ethOut = fumIn.wadMulDown(fumPrice0);
        } else {
            // Math: e_0 - e = e_0 * (f_0 - f) * fsp_0 / (e_0 + (f_0 - f) * fsp_0)
            ethOut = ethQty0.mul(fumIn.wadMulDown(fumPrice0)).div(ethQty0.add(fumIn.wadMulUp(fumPrice0)));
        }
    }

    /**
     * @notice The current min FUM buy price, equal to the stored value decayed by time since minFumBuyPriceTimestamp.
     * @return mfbp The minFumBuyPrice, in ETH terms
     */
    function minFumBuyPrice() public view returns (uint mfbp) {
        if (minFumBuyPriceStored.value != 0) {
            uint numHalvings = block.timestamp.sub(minFumBuyPriceStored.timestamp).wadDivDown(MIN_FUM_BUY_PRICE_HALF_LIFE);
            uint decayFactor = numHalvings.wadHalfExp();
            mfbp = uint256(minFumBuyPriceStored.value).wadMulUp(decayFactor);
        }   // Otherwise just returns 0
    }

    /**
     * @notice The current buy/sell adjustment, equal to the stored value decayed by time since buySellAdjustmentTimestamp.  This
     * adjustment is intended as a measure of "how long-ETH recent user activity has been", so that we can slide price
     * accordingly: if recent activity was mostly long-ETH (fund() and burn()), raise FUM buy price/reduce USM sell price; if
     * recent activity was short-ETH (defund() and mint()), reduce FUM sell price/raise USM buy price.  We use "it reduced debt
     * ratio" as a rough proxy for "the operation was long-ETH".
     *
     * (There is one odd case: when debt ratio > 100%, a *short*-ETH mint() will actually reduce debt ratio.  This does no real
     * harm except to make fast-succession mint()s and fund()s in such > 100% cases a little more expensive than they would be.)
     *
     * @return adjustment The sliding-price buy/sell adjustment
     */
    function buySellAdjustment() public view returns (uint adjustment) {
        uint numHalvings = block.timestamp.sub(buySellAdjustmentStored.timestamp).wadDivDown(BUY_SELL_ADJUSTMENT_HALF_LIFE);
        uint decayFactor = numHalvings.wadHalfExp(10);
        // Here we use the idea that for any b and 0 <= p <= 1, we can crudely approximate b**p by 1 + (b-1)p = 1 + bp - p.
        // Eg: 0.6**0.5 pulls 0.6 "about halfway" to 1 (0.8); 0.6**0.25 pulls 0.6 "about 3/4 of the way" to 1 (0.9).
        // So b**p =~ b + (1-p)(1-b) = b + 1 - b - p + bp = 1 + bp - p.
        // (Don't calculate it as 1 + (b-1)p because we're using uints, b-1 can be negative!)
        adjustment = WAD.add(uint256(buySellAdjustmentStored.value).wadMulDown(decayFactor)).sub(decayFactor);
    }

    /** EXTERNAL VIEW FUNCTIONS */

    /**
     * @notice Calculate the amount of ETH in the buffer.
     * @return buffer ETH buffer
     */
    function ethBuffer(WadMath.Round upOrDown) external view returns (int buffer) {
        buffer = ethBuffer(latestPrice(), ethPool(), totalSupply(), upOrDown);
    }

    /**
     * @notice Convert ETH amount to USM using the latest oracle ETH/USD price.
     * @param ethAmount The amount of ETH to convert
     * @return usmOut The amount of USM
     */
    function ethToUsm(uint ethAmount, WadMath.Round upOrDown) external view returns (uint usmOut) {
        usmOut = ethToUsm(latestPrice(), ethAmount, upOrDown);
    }

    /**
     * @notice Convert USM amount to ETH using the latest oracle ETH/USD price.
     * @param usmAmount The amount of USM to convert
     * @return ethOut The amount of ETH
     */
    function usmToEth(uint usmAmount, WadMath.Round upOrDown) external view returns (uint ethOut) {
        ethOut = usmToEth(latestPrice(), usmAmount, upOrDown);
    }

    /**
     * @notice Calculate debt ratio.
     * @return ratio Debt ratio
     */
    function debtRatio() external view returns (uint ratio) {
        ratio = debtRatio(latestPrice(), ethPool(), totalSupply());
    }

    /**
     * @notice Calculate the *marginal* price of USM (in ETH terms) - that is, of the next unit, before the price start sliding.
     * @return price USM price in ETH terms
     */
    function usmPrice(Side side) external view returns (uint price) {
        uint ethUsdPrice = latestPrice();
        price = usmPrice(side, ethUsdPrice, debtRatio(ethUsdPrice, ethPool(), totalSupply()));
    }

    /**
     * @notice Calculate the *marginal* price of FUM (in ETH terms) - that is, of the next unit, before the price start sliding.
     * @return price FUM price in ETH terms
     */
    function fumPrice(Side side) external view returns (uint price) {
        price = fumPrice(side, latestPrice(), ethPool(), totalSupply(), fum.totalSupply(), buySellAdjustment());
    }
}

// File: @chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol

pragma solidity >=0.6.0;

interface AggregatorV3Interface {

  function decimals() external view returns (uint8);
  function description() external view returns (string memory);
  function version() external view returns (uint256);

  // getRoundData and latestRoundData should both raise "No data present"
  // if they do not have data to report, instead of returning unset values
  // which could be misinterpreted as actual reported values.
  function getRoundData(uint80 _roundId)
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );
  function latestRoundData()
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );

}

// File: contracts/oracles/ChainlinkOracle.sol

pragma solidity ^0.6.6;


/**
 * @title ChainlinkOracle
 */
contract ChainlinkOracle is Oracle {
    using SafeMath for uint;

    uint private constant SCALE_FACTOR = 10 ** 10;  // Since Chainlink has 8 dec places, and latestPrice() needs 18

    AggregatorV3Interface private aggregator;

    constructor(AggregatorV3Interface aggregator_) public
    {
        aggregator = aggregator_;
    }

    /**
     * @notice Retrieve the latest price of the price oracle.
     * @return price
     */
    function latestPrice() public virtual override view returns (uint price) {
        price = latestChainlinkPrice();
    }

    function latestChainlinkPrice() public view returns (uint price) {
        (, int rawPrice,,,) = aggregator.latestRoundData();
        price = uint(rawPrice).mul(SCALE_FACTOR); // TODO: Cast safely
    }
}

// File: contracts/oracles/CompoundOpenOracle.sol

pragma solidity ^0.6.6;

interface UniswapAnchoredView {
    function price(string calldata symbol) external view returns (uint);
}

/**
 * @title CompoundOpenOracle
 */
contract CompoundOpenOracle is Oracle {
    using SafeMath for uint;

    uint private constant SCALE_FACTOR = 10 ** 12;  // Since Compound has 6 dec places, and latestPrice() needs 18

    UniswapAnchoredView private anchoredView;

    constructor(UniswapAnchoredView anchoredView_) public
    {
        anchoredView = anchoredView_;
    }

    /**
     * @notice Retrieve the latest price of the price oracle.
     * @return price
     */
    function latestPrice() public virtual override view returns (uint price) {
        price = latestCompoundPrice();
    }

    function latestCompoundPrice() public view returns (uint price) {
        price = anchoredView.price("ETH").mul(SCALE_FACTOR);
    }
}

// File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

// File: contracts/oracles/OurUniswapV2TWAPOracle.sol

pragma solidity ^0.6.6;


contract OurUniswapV2TWAPOracle is Oracle {
    using SafeMath for uint;

    /**
     * MIN_TWAP_PERIOD plays two roles:
     *
     * 1. Minimum age of the stored CumulativePrice we calculate our current TWAP vs.  Eg, if one of our stored prices is from
     * 5 secs ago, and the other from 10 min ago, we should calculate TWAP vs the 10-min-old one, since a 5-second TWAP is too
     * short - relatively easy to manipulate.
     *
     * 2. Minimum time gap between stored CumulativePrices.  Eg, if we stored one 5 seconds ago, we don't need to store another
     * one now - and shouldn't, since then if someone else made a TWAP call a few seconds later, both stored prices would be
     * too recent to calculate a robust TWAP.
     *
     * These roles could in principle be separated, eg: "Require the stored price we calculate TWAP from to be >= 2 minutes
     * old, but leave >= 10 minutes before storing a new price."  But for simplicity we keep them the same.
     */
    uint public constant MIN_TWAP_PERIOD = 2 minutes;

    // Uniswap stores its cumulative prices in "FixedPoint.uq112x112" format - 112-bit fixed point:
    uint public constant UNISWAP_CUM_PRICE_SCALE_FACTOR = 2 ** 112;

    uint private constant UINT32_MAX = 2 ** 32 - 1;     // Should really be type(uint32).max, but that needs Solidity 0.6.8...
    uint private constant UINT224_MAX = 2 ** 224 - 1;   // Ditto, type(uint224).max

    IUniswapV2Pair immutable uniswapPair;
    uint immutable token0Decimals;
    uint immutable token1Decimals;
    bool immutable tokensInReverseOrder;
    uint immutable scaleFactor;

    struct CumulativePrice {
        uint32 timestamp;
        uint224 priceSeconds;   // See cumulativePrice() below for an explanation of "priceSeconds"
    }

    /**
     * We store two CumulativePrices, A and B, without specifying which is more recent.  This is so that we only need to do one
     * SSTORE each time we save a new one: we can inspect them later to figure out which is newer - see orderedStoredPrices().
     */
    CumulativePrice private storedPriceA;
    CumulativePrice private storedPriceB;

    /**
     * Example pairs to pass in:
     * ETH/USDT: 0x0d4a11d5eeaac28ec3f61d100daf4d40471f1852, false, 18, 6 (WETH reserve is stored w/ 18 dec places, USDT w/ 18)
     * USDC/ETH: 0xb4e16d0168e52d35cacd2c6185b44281ec28c9dc, true, 6, 18 (USDC reserve is stored w/ 6 dec places, WETH w/ 18)
     * DAI/ETH: 0xa478c2975ab1ea89e8196811f51a7b7ade33eb11, true, 18, 18 (DAI reserve is stored w/ 18 dec places, WETH w/ 18)
     */
    constructor(IUniswapV2Pair uniswapPair_, uint token0Decimals_, uint token1Decimals_, bool tokensInReverseOrder_) public {
        uniswapPair = uniswapPair_;
        token0Decimals = token0Decimals_;
        token1Decimals = token1Decimals_;
        tokensInReverseOrder = tokensInReverseOrder_;

        (uint aDecimals, uint bDecimals) = tokensInReverseOrder_ ?
            (token1Decimals_, token0Decimals_) :
            (token0Decimals_, token1Decimals_);
        scaleFactor = 10 ** aDecimals.add(18).sub(bDecimals);
    }

    function cacheLatestPrice() public virtual override returns (uint price) {
        (CumulativePrice storage olderStoredPrice, CumulativePrice storage newerStoredPrice) = orderedStoredPrices();

        uint timestamp;
        uint priceSeconds;
        (price, timestamp, priceSeconds) = _latestPrice(newerStoredPrice);

        // Store the latest cumulative price, if it's been long enough since the latest stored price:
        if (areNewAndStoredPriceFarEnoughApart(timestamp, newerStoredPrice)) {
            storeCumulativePrice(timestamp, priceSeconds, olderStoredPrice);
        }
    }

    function latestPrice() public virtual override view returns (uint price) {
        price = latestUniswapTWAPPrice();
    }

    function latestUniswapTWAPPrice() public view returns (uint price) {
        (, CumulativePrice storage newerStoredPrice) = orderedStoredPrices();
        (price, , ) = _latestPrice(newerStoredPrice);
    }

    function _latestPrice(CumulativePrice storage newerStoredPrice)
        internal view returns (uint price, uint timestamp, uint priceSeconds)
    {
        (timestamp, priceSeconds) = cumulativePrice();

        // Now that we have the current cum price, subtract-&-divide the stored one, to get the TWAP price:
        CumulativePrice storage refPrice = storedPriceToCompareVs(timestamp, newerStoredPrice);
        price = calculateTWAP(timestamp, priceSeconds, uint(refPrice.timestamp), uint(refPrice.priceSeconds));
    }

    function storeCumulativePrice(uint timestamp, uint priceSeconds, CumulativePrice storage olderStoredPrice) internal
    {
        require(timestamp <= UINT32_MAX, "timestamp overflow");
        require(priceSeconds <= UINT224_MAX, "priceSeconds overflow");
        // (Note: this assignment only stores because olderStoredPrice has modifier "storage" - ie, store by reference!)
        (olderStoredPrice.timestamp, olderStoredPrice.priceSeconds) = (uint32(timestamp), uint224(priceSeconds));
    }

    function storedPriceToCompareVs(uint newTimestamp, CumulativePrice storage newerStoredPrice)
        internal view returns (CumulativePrice storage refPrice)
    {
        bool aAcceptable = areNewAndStoredPriceFarEnoughApart(newTimestamp, storedPriceA);
        bool bAcceptable = areNewAndStoredPriceFarEnoughApart(newTimestamp, storedPriceB);
        if (aAcceptable) {
            if (bAcceptable) {
                refPrice = newerStoredPrice;        // Neither is *too* recent, so return the fresher of the two
            } else {
                refPrice = storedPriceA;            // Only A is acceptable
            }
        } else if (bAcceptable) {
            refPrice = storedPriceB;                // Only B is acceptable
        } else {
            revert("Both stored prices too recent");
        }
    }

    function orderedStoredPrices() internal view
        returns (CumulativePrice storage olderStoredPrice, CumulativePrice storage newerStoredPrice)
    {
        (olderStoredPrice, newerStoredPrice) = storedPriceB.timestamp > storedPriceA.timestamp ?
            (storedPriceA, storedPriceB) : (storedPriceB, storedPriceA);
    }

    function areNewAndStoredPriceFarEnoughApart(uint newTimestamp, CumulativePrice storage storedPrice) internal view
        returns (bool farEnough)
    {
        farEnough = newTimestamp >= storedPrice.timestamp + MIN_TWAP_PERIOD;    // No risk of overflow on a uint32
    }

    /**
     * @return timestamp Timestamp at which Uniswap stored the priceSeconds.
     * @return priceSeconds Our pair's cumulative "price-seconds", using Uniswap's TWAP logic.  Eg, if at time t0
     * priceSeconds = 10,000,000 (returned here as 10,000,000 * 10**18, ie, in WAD fixed-point format), and during the 30
     * seconds between t0 and t1 = t0 + 30, the price is $45.67, then at time t1, priceSeconds = 10,000,000 + 30 * 45.67 =
     * 10,001,370.1 (stored as 10,001,370.1 * 10**18).
     */
    function cumulativePrice()
        private view returns (uint timestamp, uint priceSeconds)
    {
        (, , timestamp) = uniswapPair.getReserves();

        // Retrieve the current Uniswap cumulative price.  Modeled off of Uniswap's own example:
        // https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/examples/ExampleOracleSimple.sol
        uint uniswapCumPrice = tokensInReverseOrder ?
            uniswapPair.price1CumulativeLast() :
            uniswapPair.price0CumulativeLast();
        priceSeconds = uniswapCumPrice.mul(scaleFactor) / UNISWAP_CUM_PRICE_SCALE_FACTOR;
    }

    /**
     * @param newTimestamp in seconds (eg, 1606764888) - not WAD-scaled!
     * @param newPriceSeconds WAD-scaled.
     * @param oldTimestamp in raw seconds again.
     * @param oldPriceSeconds WAD-scaled.
     * @return price WAD-scaled.
     */
    function calculateTWAP(uint newTimestamp, uint newPriceSeconds, uint oldTimestamp, uint oldPriceSeconds)
        private pure returns (uint price)
    {
        price = (newPriceSeconds.sub(oldPriceSeconds)).div(newTimestamp.sub(oldTimestamp));
    }
}

// File: contracts/oracles/MedianOracle.sol

pragma solidity ^0.6.6;


contract MedianOracle is ChainlinkOracle, CompoundOpenOracle, OurUniswapV2TWAPOracle {
    using SafeMath for uint;

    constructor(
        AggregatorV3Interface chainlinkAggregator,
        UniswapAnchoredView compoundView,
        IUniswapV2Pair uniswapPair, uint uniswapToken0Decimals, uint uniswapToken1Decimals, bool uniswapTokensInReverseOrder
    ) public
        ChainlinkOracle(chainlinkAggregator)
        CompoundOpenOracle(compoundView)
        OurUniswapV2TWAPOracle(uniswapPair, uniswapToken0Decimals, uniswapToken1Decimals, uniswapTokensInReverseOrder) {}

    function latestPrice() public override(ChainlinkOracle, CompoundOpenOracle, OurUniswapV2TWAPOracle)
        view returns (uint price)
    {
        price = median(ChainlinkOracle.latestPrice(),
                       CompoundOpenOracle.latestPrice(),
                       OurUniswapV2TWAPOracle.latestPrice());
    }

    function cacheLatestPrice() public virtual override(Oracle, OurUniswapV2TWAPOracle) returns (uint price) {
        price = median(ChainlinkOracle.latestPrice(),              // Not ideal to call latestPrice() on two of these
                       CompoundOpenOracle.latestPrice(),           // and cacheLatestPrice() on one...  But works, and
                       OurUniswapV2TWAPOracle.cacheLatestPrice()); // inheriting them like this saves significant gas
    }

    /**
     * @notice Currently only supports three inputs
     * @return median value
     */
    function median(uint a, uint b, uint c)
        private pure returns (uint)
    {
        bool ab = a > b;
        bool bc = b > c;
        bool ca = c > a;

        return (ca == ab ? a : (ab == bc ? b : c));
    }
}

// File: contracts/USM.sol

pragma solidity ^0.6.6;

contract USM is USMTemplate, MedianOracle {
    constructor(
        AggregatorV3Interface chainlinkAggregator,
        UniswapAnchoredView compoundView,
        IUniswapV2Pair uniswapPair, uint uniswapToken0Decimals, uint uniswapToken1Decimals, bool uniswapTokensInReverseOrder
    ) public
        USMTemplate()
        MedianOracle(chainlinkAggregator, compoundView,
                     uniswapPair, uniswapToken0Decimals, uniswapToken1Decimals, uniswapTokensInReverseOrder) {}

    function cacheLatestPrice() public virtual override(Oracle, MedianOracle) returns (uint price) {
        price = super.cacheLatestPrice();
    }
}

pragma solidity 0.6.6;


/**
 * @title The Owned contract
 * @notice A contract with helpers for basic contract ownership.
 */
contract Owned {

  address payable public owner;
  address private pendingOwner;

  event OwnershipTransferRequested(
    address indexed from,
    address indexed to
  );
  event OwnershipTransferred(
    address indexed from,
    address indexed to
  );

  constructor() public {
    owner = msg.sender;
  }

  /**
   * @dev Allows an owner to begin transferring ownership to a new address,
   * pending.
   */
  function transferOwnership(address _to)
    external
    onlyOwner()
  {
    pendingOwner = _to;

    emit OwnershipTransferRequested(owner, _to);
  }

  /**
   * @dev Allows an ownership transfer to be completed by the recipient.
   */
  function acceptOwnership()
    external
  {
    require(msg.sender == pendingOwner, "Must be proposed owner");

    address oldOwner = owner;
    owner = msg.sender;
    pendingOwner = address(0);

    emit OwnershipTransferred(oldOwner, msg.sender);
  }

  /**
   * @dev Reverts if called by anyone other than the contract owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner, "Only callable by owner");
    _;
  }

}

interface AggregatorInterface {
  function latestAnswer() external view returns (int256);
  function latestTimestamp() external view returns (uint256);
  function latestRound() external view returns (uint256);
  function getAnswer(uint256 roundId) external view returns (int256);
  function getTimestamp(uint256 roundId) external view returns (uint256);

  event AnswerUpdated(int256 indexed current, uint256 indexed roundId, uint256 updatedAt);
  event NewRound(uint256 indexed roundId, address indexed startedBy, uint256 startedAt);
}

interface AggregatorV3Interface {

  function decimals() external view returns (uint8);
  function description() external view returns (string memory);
  function version() external view returns (uint256);

  // getRoundData and latestRoundData should both raise "No data present"
  // if they do not have data to report, instead of returning unset values
  // which could be misinterpreted as actual reported values.
  function getRoundData(uint80 _roundId)
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );
  function latestRoundData()
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );

}

interface AggregatorV2V3Interface is AggregatorInterface, AggregatorV3Interface
{
}

/**
 * @title A trusted proxy for updating where current answers are read from
 * @notice This contract provides a consistent address for the
 * CurrentAnwerInterface but delegates where it reads from to the owner, who is
 * trusted to update it.
 */
contract AggregatorProxy is AggregatorV2V3Interface, Owned {

  struct Phase {
    uint16 id;
    AggregatorV2V3Interface aggregator;
  }
  Phase private currentPhase;
  AggregatorV2V3Interface public proposedAggregator;
  mapping(uint16 => AggregatorV2V3Interface) public phaseAggregators;

  uint256 constant private PHASE_OFFSET = 64;
  uint256 constant private PHASE_SIZE = 16;
  uint256 constant private MAX_ID = 2**(PHASE_OFFSET+PHASE_SIZE) - 1;

  constructor(address _aggregator) public Owned() {
    setAggregator(_aggregator);
  }

  /**
   * @notice Reads the current answer from aggregator delegated to.
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestAnswer()
    public
    view
    virtual
    override
    returns (int256 answer)
  {
    return currentPhase.aggregator.latestAnswer();
  }

  /**
   * @notice Reads the last updated height from aggregator delegated to.
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestTimestamp()
    public
    view
    virtual
    override
    returns (uint256 updatedAt)
  {
    return currentPhase.aggregator.latestTimestamp();
  }

  /**
   * @notice get past rounds answers
   * @param _roundId the answer number to retrieve the answer for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getAnswer(uint256 _roundId)
    public
    view
    virtual
    override
    returns (int256 answer)
  {
    if (_roundId > MAX_ID) return 0;

    (uint16 phaseId, uint64 aggregatorRoundId) = parseIds(_roundId);
    AggregatorV2V3Interface aggregator = phaseAggregators[phaseId];
    if (address(aggregator) == address(0)) return 0;

    return aggregator.getAnswer(aggregatorRoundId);
  }

  /**
   * @notice get block timestamp when an answer was last updated
   * @param _roundId the answer number to retrieve the updated timestamp for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getTimestamp(uint256 _roundId)
    public
    view
    virtual
    override
    returns (uint256 updatedAt)
  {
    if (_roundId > MAX_ID) return 0;

    (uint16 phaseId, uint64 aggregatorRoundId) = parseIds(_roundId);
    AggregatorV2V3Interface aggregator = phaseAggregators[phaseId];
    if (address(aggregator) == address(0)) return 0;

    return aggregator.getTimestamp(aggregatorRoundId);
  }

  /**
   * @notice get the latest completed round where the answer was updated. This
   * ID includes the proxy's phase, to make sure round IDs increase even when
   * switching to a newly deployed aggregator.
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestRound()
    public
    view
    virtual
    override
    returns (uint256 roundId)
  {
    Phase memory phase = currentPhase; // cache storage reads
    return addPhase(phase.id, uint64(phase.aggregator.latestRound()));
  }

  /**
   * @notice get data about a round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * Note that different underlying implementations of AggregatorV3Interface
   * have slightly different semantics for some of the return values. Consumers
   * should determine what implementations they expect to receive
   * data from and validate that they can properly handle return data from all
   * of them.
   * @param _roundId the requested round ID as presented through the proxy, this
   * is made up of the aggregator's round ID with the phase ID encoded in the
   * two highest order bytes
   * @return roundId is the round ID from the aggregator for which the data was
   * retrieved combined with an phase to ensure that round IDs get larger as
   * time moves forward.
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @dev Note that answer and updatedAt may change between queries.
   */
  function getRoundData(uint80 _roundId)
    public
    view
    virtual
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    (uint16 phaseId, uint64 aggregatorRoundId) = parseIds(_roundId);

    (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 ansIn
    ) = phaseAggregators[phaseId].getRoundData(aggregatorRoundId);

    return addPhaseIds(roundId, answer, startedAt, updatedAt, ansIn, phaseId);
  }

  /**
   * @notice get data about the latest round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * Note that different underlying implementations of AggregatorV3Interface
   * have slightly different semantics for some of the return values. Consumers
   * should determine what implementations they expect to receive
   * data from and validate that they can properly handle return data from all
   * of them.
   * @return roundId is the round ID from the aggregator for which the data was
   * retrieved combined with an phase to ensure that round IDs get larger as
   * time moves forward.
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @dev Note that answer and updatedAt may change between queries.
   */
  function latestRoundData()
    public
    view
    virtual
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    Phase memory current = currentPhase; // cache storage reads

    (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 ansIn
    ) = current.aggregator.latestRoundData();

    return addPhaseIds(roundId, answer, startedAt, updatedAt, ansIn, current.id);
  }

  /**
   * @notice Used if an aggregator contract has been proposed.
   * @param _roundId the round ID to retrieve the round data for
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
  */
  function proposedGetRoundData(uint80 _roundId)
    public
    view
    virtual
    hasProposal()
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return proposedAggregator.getRoundData(_roundId);
  }

  /**
   * @notice Used if an aggregator contract has been proposed.
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
  */
  function proposedLatestRoundData()
    public
    view
    virtual
    hasProposal()
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return proposedAggregator.latestRoundData();
  }

  /**
   * @notice returns the current phase's aggregator address.
   */
  function aggregator()
    external
    view
    returns (address)
  {
    return address(currentPhase.aggregator);
  }

  /**
   * @notice returns the current phase's ID.
   */
  function phaseId()
    external
    view
    returns (uint16)
  {
    return currentPhase.id;
  }

  /**
   * @notice represents the number of decimals the aggregator responses represent.
   */
  function decimals()
    external
    view
    override
    returns (uint8)
  {
    return currentPhase.aggregator.decimals();
  }

  /**
   * @notice the version number representing the type of aggregator the proxy
   * points to.
   */
  function version()
    external
    view
    override
    returns (uint256)
  {
    return currentPhase.aggregator.version();
  }

  /**
   * @notice returns the description of the aggregator the proxy points to.
   */
  function description()
    external
    view
    override
    returns (string memory)
  {
    return currentPhase.aggregator.description();
  }

  /**
   * @notice Allows the owner to propose a new address for the aggregator
   * @param _aggregator The new address for the aggregator contract
   */
  function proposeAggregator(address _aggregator)
    external
    onlyOwner()
  {
    proposedAggregator = AggregatorV2V3Interface(_aggregator);
  }

  /**
   * @notice Allows the owner to confirm and change the address
   * to the proposed aggregator
   * @dev Reverts if the given address doesn't match what was previously
   * proposed
   * @param _aggregator The new address for the aggregator contract
   */
  function confirmAggregator(address _aggregator)
    external
    onlyOwner()
  {
    require(_aggregator == address(proposedAggregator), "Invalid proposed aggregator");
    delete proposedAggregator;
    setAggregator(_aggregator);
  }


  /*
   * Internal
   */

  function setAggregator(address _aggregator)
    internal
  {
    uint16 id = currentPhase.id + 1;
    currentPhase = Phase(id, AggregatorV2V3Interface(_aggregator));
    phaseAggregators[id] = AggregatorV2V3Interface(_aggregator);
  }

  function addPhase(
    uint16 _phase,
    uint64 _originalId
  )
    internal
    view
    returns (uint80)
  {
    return uint80(uint256(_phase) << PHASE_OFFSET | _originalId);
  }

  function parseIds(
    uint256 _roundId
  )
    internal
    view
    returns (uint16, uint64)
  {
    uint16 phaseId = uint16(_roundId >> PHASE_OFFSET);
    uint64 aggregatorRoundId = uint64(_roundId);

    return (phaseId, aggregatorRoundId);
  }

  function addPhaseIds(
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound,
      uint16 phaseId
  )
    internal
    view
    returns (uint80, int256, uint256, uint256, uint80)
  {
    return (
      addPhase(phaseId, uint64(roundId)),
      answer,
      startedAt,
      updatedAt,
      addPhase(phaseId, uint64(answeredInRound))
    );
  }

  /*
   * Modifiers
   */

  modifier hasProposal() {
    require(address(proposedAggregator) != address(0), "No proposed aggregator present");
    _;
  }

}

interface AccessControllerInterface {
  function hasAccess(address user, bytes calldata data) external view returns (bool);
}

/**
 * @title External Access Controlled Aggregator Proxy
 * @notice A trusted proxy for updating where current answers are read from
 * @notice This contract provides a consistent address for the
 * Aggregator and AggregatorV3Interface but delegates where it reads from to the owner, who is
 * trusted to update it.
 * @notice Only access enabled addresses are allowed to access getters for
 * aggregated answers and round information.
 */
contract EACAggregatorProxy is AggregatorProxy {

  AccessControllerInterface public accessController;

  constructor(
    address _aggregator,
    address _accessController
  )
    public
    AggregatorProxy(_aggregator)
  {
    setController(_accessController);
  }

  /**
   * @notice Allows the owner to update the accessController contract address.
   * @param _accessController The new address for the accessController contract
   */
  function setController(address _accessController)
    public
    onlyOwner()
  {
    accessController = AccessControllerInterface(_accessController);
  }

  /**
   * @notice Reads the current answer from aggregator delegated to.
   * @dev overridden function to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestAnswer()
    public
    view
    override
    checkAccess()
    returns (int256)
  {
    return super.latestAnswer();
  }

  /**
   * @notice get the latest completed round where the answer was updated. This
   * ID includes the proxy's phase, to make sure round IDs increase even when
   * switching to a newly deployed aggregator.
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestTimestamp()
    public
    view
    override
    checkAccess()
    returns (uint256)
  {
    return super.latestTimestamp();
  }

  /**
   * @notice get past rounds answers
   * @param _roundId the answer number to retrieve the answer for
   * @dev overridden function to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getAnswer(uint256 _roundId)
    public
    view
    override
    checkAccess()
    returns (int256)
  {
    return super.getAnswer(_roundId);
  }

  /**
   * @notice get block timestamp when an answer was last updated
   * @param _roundId the answer number to retrieve the updated timestamp for
   * @dev overridden function to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getTimestamp(uint256 _roundId)
    public
    view
    override
    checkAccess()
    returns (uint256)
  {
    return super.getTimestamp(_roundId);
  }

  /**
   * @notice get the latest completed round where the answer was updated
   * @dev overridden function to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestRound()
    public
    view
    override
    checkAccess()
    returns (uint256)
  {
    return super.latestRound();
  }

  /**
   * @notice get data about a round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * Note that different underlying implementations of AggregatorV3Interface
   * have slightly different semantics for some of the return values. Consumers
   * should determine what implementations they expect to receive
   * data from and validate that they can properly handle return data from all
   * of them.
   * @param _roundId the round ID to retrieve the round data for
   * @return roundId is the round ID from the aggregator for which the data was
   * retrieved combined with a phase to ensure that round IDs get larger as
   * time moves forward.
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @dev Note that answer and updatedAt may change between queries.
   */
  function getRoundData(uint80 _roundId)
    public
    view
    checkAccess()
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return super.getRoundData(_roundId);
  }

  /**
   * @notice get data about the latest round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * Note that different underlying implementations of AggregatorV3Interface
   * have slightly different semantics for some of the return values. Consumers
   * should determine what implementations they expect to receive
   * data from and validate that they can properly handle return data from all
   * of them.
   * @return roundId is the round ID from the aggregator for which the data was
   * retrieved combined with a phase to ensure that round IDs get larger as
   * time moves forward.
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @dev Note that answer and updatedAt may change between queries.
   */
  function latestRoundData()
    public
    view
    checkAccess()
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return super.latestRoundData();
  }

  /**
   * @notice Used if an aggregator contract has been proposed.
   * @param _roundId the round ID to retrieve the round data for
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
  */
  function proposedGetRoundData(uint80 _roundId)
    public
    view
    checkAccess()
    hasProposal()
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return super.proposedGetRoundData(_roundId);
  }

  /**
   * @notice Used if an aggregator contract has been proposed.
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started.
   * (Only some AggregatorV3Interface implementations return meaningful values)
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed.
  */
  function proposedLatestRoundData()
    public
    view
    checkAccess()
    hasProposal()
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return super.proposedLatestRoundData();
  }

  /**
   * @dev reverts if the caller does not have access by the accessController
   * contract or is the contract itself.
   */
  modifier checkAccess() {
    AccessControllerInterface ac = accessController;
    require(address(ac) == address(0) || ac.hasAccess(msg.sender, msg.data), "No access");
    _;
  }
}

pragma solidity 0.6.6;


/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
  /**
    * @dev Returns the addition of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `+` operator.
    *
    * Requirements:
    * - Addition cannot overflow.
    */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a, "SafeMath: addition overflow");

    return c;
  }

  /**
    * @dev Returns the subtraction of two unsigned integers, reverting on
    * overflow (when the result is negative).
    *
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
    * - Subtraction cannot overflow.
    */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a, "SafeMath: subtraction overflow");
    uint256 c = a - b;

    return c;
  }

  /**
    * @dev Returns the multiplication of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
    * - Multiplication cannot overflow.
    */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");

    return c;
  }

  /**
    * @dev Returns the integer division of two unsigned integers. Reverts on
    * division by zero. The result is rounded towards zero.
    *
    * Counterpart to Solidity's `/` operator. Note: this function uses a
    * `revert` opcode (which leaves remaining gas untouched) while Solidity
    * uses an invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // Solidity only automatically asserts when dividing by 0
    require(b > 0, "SafeMath: division by zero");
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
    * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
    * Reverts when dividing by zero.
    *
    * Counterpart to Solidity's `%` operator. This function uses a `revert`
    * opcode (which leaves remaining gas untouched) while Solidity uses an
    * invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0, "SafeMath: modulo by zero");
    return a % b;
  }
}

library SignedSafeMath {
  int256 constant private _INT256_MIN = -2**255;

  /**
   * @dev Multiplies two signed integers, reverts on overflow.
   */
  function mul(int256 a, int256 b) internal pure returns (int256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
    if (a == 0) {
      return 0;
    }

    require(!(a == -1 && b == _INT256_MIN), "SignedSafeMath: multiplication overflow");

    int256 c = a * b;
    require(c / a == b, "SignedSafeMath: multiplication overflow");

    return c;
  }

  /**
   * @dev Integer division of two signed integers truncating the quotient, reverts on division by zero.
   */
  function div(int256 a, int256 b) internal pure returns (int256) {
    require(b != 0, "SignedSafeMath: division by zero");
    require(!(b == -1 && a == _INT256_MIN), "SignedSafeMath: division overflow");

    int256 c = a / b;

    return c;
  }

  /**
   * @dev Subtracts two signed integers, reverts on overflow.
   */
  function sub(int256 a, int256 b) internal pure returns (int256) {
    int256 c = a - b;
    require((b >= 0 && c <= a) || (b < 0 && c > a), "SignedSafeMath: subtraction overflow");

    return c;
  }

  /**
   * @dev Adds two signed integers, reverts on overflow.
   */
  function add(int256 a, int256 b) internal pure returns (int256) {
    int256 c = a + b;
    require((b >= 0 && c >= a) || (b < 0 && c < a), "SignedSafeMath: addition overflow");

    return c;
  }

  /**
   * @notice Computes average of two signed integers, ensuring that the computation
   * doesn't overflow.
   * @dev If the result is not an integer, it is rounded towards zero. For example,
   * avg(-3, -4) = -3
   */
  function avg(int256 _a, int256 _b)
    internal
    pure
    returns (int256)
  {
    if ((_a < 0 && _b > 0) || (_a > 0 && _b < 0)) {
      return add(_a, _b) / 2;
    }
    int256 remainder = (_a % 2 + _b % 2) / 2;
    return add(add(_a / 2, _b / 2), remainder);
  }
}

library Median {
  using SignedSafeMath for int256;

  int256 constant INT_MAX = 2**255-1;

  /**
   * @notice Returns the sorted middle, or the average of the two middle indexed items if the
   * array has an even number of elements.
   * @dev The list passed as an argument isn't modified.
   * @dev This algorithm has expected runtime O(n), but for adversarially chosen inputs
   * the runtime is O(n^2).
   * @param list The list of elements to compare
   */
  function calculate(int256[] memory list)
    internal
    pure
    returns (int256)
  {
    return calculateInplace(copy(list));
  }

  /**
   * @notice See documentation for function calculate.
   * @dev The list passed as an argument may be permuted.
   */
  function calculateInplace(int256[] memory list)
    internal
    pure
    returns (int256)
  {
    require(0 < list.length, "list must not be empty");
    uint256 len = list.length;
    uint256 middleIndex = len / 2;
    if (len % 2 == 0) {
      int256 median1;
      int256 median2;
      (median1, median2) = quickselectTwo(list, 0, len - 1, middleIndex - 1, middleIndex);
      return SignedSafeMath.avg(median1, median2);
    } else {
      return quickselect(list, 0, len - 1, middleIndex);
    }
  }

  /**
   * @notice Maximum length of list that shortSelectTwo can handle
   */
  uint256 constant SHORTSELECTTWO_MAX_LENGTH = 7;

  /**
   * @notice Select the k1-th and k2-th element from list of length at most 7
   * @dev Uses an optimal sorting network
   */
  function shortSelectTwo(
    int256[] memory list,
    uint256 lo,
    uint256 hi,
    uint256 k1,
    uint256 k2
  )
    private
    pure
    returns (int256 k1th, int256 k2th)
  {
    // Uses an optimal sorting network (https://en.wikipedia.org/wiki/Sorting_network)
    // for lists of length 7. Network layout is taken from
    // http://jgamble.ripco.net/cgi-bin/nw.cgi?inputs=7&algorithm=hibbard&output=svg

    uint256 len = hi + 1 - lo;
    int256 x0 = list[lo + 0];
    int256 x1 = 1 < len ? list[lo + 1] : INT_MAX;
    int256 x2 = 2 < len ? list[lo + 2] : INT_MAX;
    int256 x3 = 3 < len ? list[lo + 3] : INT_MAX;
    int256 x4 = 4 < len ? list[lo + 4] : INT_MAX;
    int256 x5 = 5 < len ? list[lo + 5] : INT_MAX;
    int256 x6 = 6 < len ? list[lo + 6] : INT_MAX;

    if (x0 > x1) {(x0, x1) = (x1, x0);}
    if (x2 > x3) {(x2, x3) = (x3, x2);}
    if (x4 > x5) {(x4, x5) = (x5, x4);}
    if (x0 > x2) {(x0, x2) = (x2, x0);}
    if (x1 > x3) {(x1, x3) = (x3, x1);}
    if (x4 > x6) {(x4, x6) = (x6, x4);}
    if (x1 > x2) {(x1, x2) = (x2, x1);}
    if (x5 > x6) {(x5, x6) = (x6, x5);}
    if (x0 > x4) {(x0, x4) = (x4, x0);}
    if (x1 > x5) {(x1, x5) = (x5, x1);}
    if (x2 > x6) {(x2, x6) = (x6, x2);}
    if (x1 > x4) {(x1, x4) = (x4, x1);}
    if (x3 > x6) {(x3, x6) = (x6, x3);}
    if (x2 > x4) {(x2, x4) = (x4, x2);}
    if (x3 > x5) {(x3, x5) = (x5, x3);}
    if (x3 > x4) {(x3, x4) = (x4, x3);}

    uint256 index1 = k1 - lo;
    if (index1 == 0) {k1th = x0;}
    else if (index1 == 1) {k1th = x1;}
    else if (index1 == 2) {k1th = x2;}
    else if (index1 == 3) {k1th = x3;}
    else if (index1 == 4) {k1th = x4;}
    else if (index1 == 5) {k1th = x5;}
    else if (index1 == 6) {k1th = x6;}
    else {revert("k1 out of bounds");}

    uint256 index2 = k2 - lo;
    if (k1 == k2) {return (k1th, k1th);}
    else if (index2 == 0) {return (k1th, x0);}
    else if (index2 == 1) {return (k1th, x1);}
    else if (index2 == 2) {return (k1th, x2);}
    else if (index2 == 3) {return (k1th, x3);}
    else if (index2 == 4) {return (k1th, x4);}
    else if (index2 == 5) {return (k1th, x5);}
    else if (index2 == 6) {return (k1th, x6);}
    else {revert("k2 out of bounds");}
  }

  /**
   * @notice Selects the k-th ranked element from list, looking only at indices between lo and hi
   * (inclusive). Modifies list in-place.
   */
  function quickselect(int256[] memory list, uint256 lo, uint256 hi, uint256 k)
    private
    pure
    returns (int256 kth)
  {
    require(lo <= k);
    require(k <= hi);
    while (lo < hi) {
      if (hi - lo < SHORTSELECTTWO_MAX_LENGTH) {
        int256 ignore;
        (kth, ignore) = shortSelectTwo(list, lo, hi, k, k);
        return kth;
      }
      uint256 pivotIndex = partition(list, lo, hi);
      if (k <= pivotIndex) {
        // since pivotIndex < (original hi passed to partition),
        // termination is guaranteed in this case
        hi = pivotIndex;
      } else {
        // since (original lo passed to partition) <= pivotIndex,
        // termination is guaranteed in this case
        lo = pivotIndex + 1;
      }
    }
    return list[lo];
  }

  /**
   * @notice Selects the k1-th and k2-th ranked elements from list, looking only at indices between
   * lo and hi (inclusive). Modifies list in-place.
   */
  function quickselectTwo(
    int256[] memory list,
    uint256 lo,
    uint256 hi,
    uint256 k1,
    uint256 k2
  )
    internal // for testing
    pure
    returns (int256 k1th, int256 k2th)
  {
    require(k1 < k2);
    require(lo <= k1 && k1 <= hi);
    require(lo <= k2 && k2 <= hi);

    while (true) {
      if (hi - lo < SHORTSELECTTWO_MAX_LENGTH) {
        return shortSelectTwo(list, lo, hi, k1, k2);
      }
      uint256 pivotIdx = partition(list, lo, hi);
      if (k2 <= pivotIdx) {
        hi = pivotIdx;
      } else if (pivotIdx < k1) {
        lo = pivotIdx + 1;
      } else {
        assert(k1 <= pivotIdx && pivotIdx < k2);
        k1th = quickselect(list, lo, pivotIdx, k1);
        k2th = quickselect(list, pivotIdx + 1, hi, k2);
        return (k1th, k2th);
      }
    }
  }

  /**
   * @notice Partitions list in-place using Hoare's partitioning scheme.
   * Only elements of list between indices lo and hi (inclusive) will be modified.
   * Returns an index i, such that:
   * - lo <= i < hi
   * - forall j in [lo, i]. list[j] <= list[i]
   * - forall j in [i, hi]. list[i] <= list[j]
   */
  function partition(int256[] memory list, uint256 lo, uint256 hi)
    private
    pure
    returns (uint256)
  {
    // We don't care about overflow of the addition, because it would require a list
    // larger than any feasible computer's memory.
    int256 pivot = list[(lo + hi) / 2];
    lo -= 1; // this can underflow. that's intentional.
    hi += 1;
    while (true) {
      do {
        lo += 1;
      } while (list[lo] < pivot);
      do {
        hi -= 1;
      } while (list[hi] > pivot);
      if (lo < hi) {
        (list[lo], list[hi]) = (list[hi], list[lo]);
      } else {
        // Let orig_lo and orig_hi be the original values of lo and hi passed to partition.
        // Then, hi < orig_hi, because hi decreases *strictly* monotonically
        // in each loop iteration and
        // - either list[orig_hi] > pivot, in which case the first loop iteration
        //   will achieve hi < orig_hi;
        // - or list[orig_hi] <= pivot, in which case at least two loop iterations are
        //   needed:
        //   - lo will have to stop at least once in the interval
        //     [orig_lo, (orig_lo + orig_hi)/2]
        //   - (orig_lo + orig_hi)/2 < orig_hi
        return hi;
      }
    }
  }

  /**
   * @notice Makes an in-memory copy of the array passed in
   * @param list Reference to the array to be copied
   */
  function copy(int256[] memory list)
    private
    pure
    returns(int256[] memory)
  {
    int256[] memory list2 = new int256[](list.length);
    for (uint256 i = 0; i < list.length; i++) {
      list2[i] = list[i];
    }
    return list2;
  }
}

/**
 * @title The Owned contract
 * @notice A contract with helpers for basic contract ownership.
 */
contract Owned {

  address payable public owner;
  address private pendingOwner;

  event OwnershipTransferRequested(
    address indexed from,
    address indexed to
  );
  event OwnershipTransferred(
    address indexed from,
    address indexed to
  );

  constructor() public {
    owner = msg.sender;
  }

  /**
   * @dev Allows an owner to begin transferring ownership to a new address,
   * pending.
   */
  function transferOwnership(address _to)
    external
    onlyOwner()
  {
    pendingOwner = _to;

    emit OwnershipTransferRequested(owner, _to);
  }

  /**
   * @dev Allows an ownership transfer to be completed by the recipient.
   */
  function acceptOwnership()
    external
  {
    require(msg.sender == pendingOwner, "Must be proposed owner");

    address oldOwner = owner;
    owner = msg.sender;
    pendingOwner = address(0);

    emit OwnershipTransferred(oldOwner, msg.sender);
  }

  /**
   * @dev Reverts if called by anyone other than the contract owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner, "Only callable by owner");
    _;
  }

}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * This library is a version of Open Zeppelin's SafeMath, modified to support
 * unsigned 128 bit integers.
 */
library SafeMath128 {
  /**
    * @dev Returns the addition of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `+` operator.
    *
    * Requirements:
    * - Addition cannot overflow.
    */
  function add(uint128 a, uint128 b) internal pure returns (uint128) {
    uint128 c = a + b;
    require(c >= a, "SafeMath: addition overflow");

    return c;
  }

  /**
    * @dev Returns the subtraction of two unsigned integers, reverting on
    * overflow (when the result is negative).
    *
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
    * - Subtraction cannot overflow.
    */
  function sub(uint128 a, uint128 b) internal pure returns (uint128) {
    require(b <= a, "SafeMath: subtraction overflow");
    uint128 c = a - b;

    return c;
  }

  /**
    * @dev Returns the multiplication of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
    * - Multiplication cannot overflow.
    */
  function mul(uint128 a, uint128 b) internal pure returns (uint128) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint128 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");

    return c;
  }

  /**
    * @dev Returns the integer division of two unsigned integers. Reverts on
    * division by zero. The result is rounded towards zero.
    *
    * Counterpart to Solidity's `/` operator. Note: this function uses a
    * `revert` opcode (which leaves remaining gas untouched) while Solidity
    * uses an invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function div(uint128 a, uint128 b) internal pure returns (uint128) {
    // Solidity only automatically asserts when dividing by 0
    require(b > 0, "SafeMath: division by zero");
    uint128 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
    * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
    * Reverts when dividing by zero.
    *
    * Counterpart to Solidity's `%` operator. This function uses a `revert`
    * opcode (which leaves remaining gas untouched) while Solidity uses an
    * invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function mod(uint128 a, uint128 b) internal pure returns (uint128) {
    require(b != 0, "SafeMath: modulo by zero");
    return a % b;
  }
}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * This library is a version of Open Zeppelin's SafeMath, modified to support
 * unsigned 32 bit integers.
 */
library SafeMath32 {
  /**
    * @dev Returns the addition of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `+` operator.
    *
    * Requirements:
    * - Addition cannot overflow.
    */
  function add(uint32 a, uint32 b) internal pure returns (uint32) {
    uint32 c = a + b;
    require(c >= a, "SafeMath: addition overflow");

    return c;
  }

  /**
    * @dev Returns the subtraction of two unsigned integers, reverting on
    * overflow (when the result is negative).
    *
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
    * - Subtraction cannot overflow.
    */
  function sub(uint32 a, uint32 b) internal pure returns (uint32) {
    require(b <= a, "SafeMath: subtraction overflow");
    uint32 c = a - b;

    return c;
  }

  /**
    * @dev Returns the multiplication of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
    * - Multiplication cannot overflow.
    */
  function mul(uint32 a, uint32 b) internal pure returns (uint32) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint32 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");

    return c;
  }

  /**
    * @dev Returns the integer division of two unsigned integers. Reverts on
    * division by zero. The result is rounded towards zero.
    *
    * Counterpart to Solidity's `/` operator. Note: this function uses a
    * `revert` opcode (which leaves remaining gas untouched) while Solidity
    * uses an invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function div(uint32 a, uint32 b) internal pure returns (uint32) {
    // Solidity only automatically asserts when dividing by 0
    require(b > 0, "SafeMath: division by zero");
    uint32 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
    * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
    * Reverts when dividing by zero.
    *
    * Counterpart to Solidity's `%` operator. This function uses a `revert`
    * opcode (which leaves remaining gas untouched) while Solidity uses an
    * invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function mod(uint32 a, uint32 b) internal pure returns (uint32) {
    require(b != 0, "SafeMath: modulo by zero");
    return a % b;
  }
}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * This library is a version of Open Zeppelin's SafeMath, modified to support
 * unsigned 64 bit integers.
 */
library SafeMath64 {
  /**
    * @dev Returns the addition of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `+` operator.
    *
    * Requirements:
    * - Addition cannot overflow.
    */
  function add(uint64 a, uint64 b) internal pure returns (uint64) {
    uint64 c = a + b;
    require(c >= a, "SafeMath: addition overflow");

    return c;
  }

  /**
    * @dev Returns the subtraction of two unsigned integers, reverting on
    * overflow (when the result is negative).
    *
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
    * - Subtraction cannot overflow.
    */
  function sub(uint64 a, uint64 b) internal pure returns (uint64) {
    require(b <= a, "SafeMath: subtraction overflow");
    uint64 c = a - b;

    return c;
  }

  /**
    * @dev Returns the multiplication of two unsigned integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
    * - Multiplication cannot overflow.
    */
  function mul(uint64 a, uint64 b) internal pure returns (uint64) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint64 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");

    return c;
  }

  /**
    * @dev Returns the integer division of two unsigned integers. Reverts on
    * division by zero. The result is rounded towards zero.
    *
    * Counterpart to Solidity's `/` operator. Note: this function uses a
    * `revert` opcode (which leaves remaining gas untouched) while Solidity
    * uses an invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function div(uint64 a, uint64 b) internal pure returns (uint64) {
    // Solidity only automatically asserts when dividing by 0
    require(b > 0, "SafeMath: division by zero");
    uint64 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
    * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
    * Reverts when dividing by zero.
    *
    * Counterpart to Solidity's `%` operator. This function uses a `revert`
    * opcode (which leaves remaining gas untouched) while Solidity uses an
    * invalid opcode to revert (consuming all remaining gas).
    *
    * Requirements:
    * - The divisor cannot be zero.
    */
  function mod(uint64 a, uint64 b) internal pure returns (uint64) {
    require(b != 0, "SafeMath: modulo by zero");
    return a % b;
  }
}

interface AggregatorInterface {
  function latestAnswer() external view returns (int256);
  function latestTimestamp() external view returns (uint256);
  function latestRound() external view returns (uint256);
  function getAnswer(uint256 roundId) external view returns (int256);
  function getTimestamp(uint256 roundId) external view returns (uint256);

  event AnswerUpdated(int256 indexed current, uint256 indexed roundId, uint256 updatedAt);
  event NewRound(uint256 indexed roundId, address indexed startedBy, uint256 startedAt);
}

interface AggregatorV3Interface {

  function decimals() external view returns (uint8);
  function description() external view returns (string memory);
  function version() external view returns (uint256);

  // getRoundData and latestRoundData should both raise "No data present"
  // if they do not have data to report, instead of returning unset values
  // which could be misinterpreted as actual reported values.
  function getRoundData(uint80 _roundId)
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );
  function latestRoundData()
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );

}

interface AggregatorV2V3Interface is AggregatorInterface, AggregatorV3Interface
{
}

interface AggregatorValidatorInterface {
  function validate(
    uint256 previousRoundId,
    int256 previousAnswer,
    uint256 currentRoundId,
    int256 currentAnswer
  ) external returns (bool);
}

interface LinkTokenInterface {
  function allowance(address owner, address spender) external view returns (uint256 remaining);
  function approve(address spender, uint256 value) external returns (bool success);
  function balanceOf(address owner) external view returns (uint256 balance);
  function decimals() external view returns (uint8 decimalPlaces);
  function decreaseApproval(address spender, uint256 addedValue) external returns (bool success);
  function increaseApproval(address spender, uint256 subtractedValue) external;
  function name() external view returns (string memory tokenName);
  function symbol() external view returns (string memory tokenSymbol);
  function totalSupply() external view returns (uint256 totalTokensIssued);
  function transfer(address to, uint256 value) external returns (bool success);
  function transferAndCall(address to, uint256 value, bytes calldata data) external returns (bool success);
  function transferFrom(address from, address to, uint256 value) external returns (bool success);
}

/**
 * @title The Prepaid Aggregator contract
 * @notice Handles aggregating data pushed in from off-chain, and unlocks
 * payment for oracles as they report. Oracles' submissions are gathered in
 * rounds, with each round aggregating the submissions for each oracle into a
 * single answer. The latest aggregated answer is exposed as well as historical
 * answers and their updated at timestamp.
 */
contract FluxAggregator is AggregatorV2V3Interface, Owned {
  using SafeMath for uint256;
  using SafeMath128 for uint128;
  using SafeMath64 for uint64;
  using SafeMath32 for uint32;

  struct Round {
    int256 answer;
    uint64 startedAt;
    uint64 updatedAt;
    uint32 answeredInRound;
  }

  struct RoundDetails {
    int256[] submissions;
    uint32 maxSubmissions;
    uint32 minSubmissions;
    uint32 timeout;
    uint128 paymentAmount;
  }

  struct OracleStatus {
    uint128 withdrawable;
    uint32 startingRound;
    uint32 endingRound;
    uint32 lastReportedRound;
    uint32 lastStartedRound;
    int256 latestSubmission;
    uint16 index;
    address admin;
    address pendingAdmin;
  }

  struct Requester {
    bool authorized;
    uint32 delay;
    uint32 lastStartedRound;
  }

  struct Funds {
    uint128 available;
    uint128 allocated;
  }

  LinkTokenInterface public linkToken;
  AggregatorValidatorInterface public validator;

  // Round related params
  uint128 public paymentAmount;
  uint32 public maxSubmissionCount;
  uint32 public minSubmissionCount;
  uint32 public restartDelay;
  uint32 public timeout;
  uint8 public override decimals;
  string public override description;

  int256 immutable public minSubmissionValue;
  int256 immutable public maxSubmissionValue;

  uint256 constant public override version = 3;

  /**
   * @notice To ensure owner isn't withdrawing required funds as oracles are
   * submitting updates, we enforce that the contract maintains a minimum
   * reserve of RESERVE_ROUNDS * oracleCount() LINK earmarked for payment to
   * oracles. (Of course, this doesn't prevent the contract from running out of
   * funds without the owner's intervention.)
   */
  uint256 constant private RESERVE_ROUNDS = 2;
  uint256 constant private MAX_ORACLE_COUNT = 77;
  uint32 constant private ROUND_MAX = 2**32-1;
  uint256 private constant VALIDATOR_GAS_LIMIT = 100000;
  // An error specific to the Aggregator V3 Interface, to prevent possible
  // confusion around accidentally reading unset values as reported values.
  string constant private V3_NO_DATA_ERROR = "No data present";

  uint32 private reportingRoundId;
  uint32 internal latestRoundId;
  mapping(address => OracleStatus) private oracles;
  mapping(uint32 => Round) internal rounds;
  mapping(uint32 => RoundDetails) internal details;
  mapping(address => Requester) internal requesters;
  address[] private oracleAddresses;
  Funds private recordedFunds;

  event AvailableFundsUpdated(
    uint256 indexed amount
  );
  event RoundDetailsUpdated(
    uint128 indexed paymentAmount,
    uint32 indexed minSubmissionCount,
    uint32 indexed maxSubmissionCount,
    uint32 restartDelay,
    uint32 timeout // measured in seconds
  );
  event OraclePermissionsUpdated(
    address indexed oracle,
    bool indexed whitelisted
  );
  event OracleAdminUpdated(
    address indexed oracle,
    address indexed newAdmin
  );
  event OracleAdminUpdateRequested(
    address indexed oracle,
    address admin,
    address newAdmin
  );
  event SubmissionReceived(
    int256 indexed submission,
    uint32 indexed round,
    address indexed oracle
  );
  event RequesterPermissionsSet(
    address indexed requester,
    bool authorized,
    uint32 delay
  );
  event ValidatorUpdated(
    address indexed previous,
    address indexed current
  );

  /**
   * @notice set up the aggregator with initial configuration
   * @param _link The address of the LINK token
   * @param _paymentAmount The amount paid of LINK paid to each oracle per submission, in wei (units of 10⁻¹⁸ LINK)
   * @param _timeout is the number of seconds after the previous round that are
   * allowed to lapse before allowing an oracle to skip an unfinished round
   * @param _validator is an optional contract address for validating
   * external validation of answers
   * @param _minSubmissionValue is an immutable check for a lower bound of what
   * submission values are accepted from an oracle
   * @param _maxSubmissionValue is an immutable check for an upper bound of what
   * submission values are accepted from an oracle
   * @param _decimals represents the number of decimals to offset the answer by
   * @param _description a short description of what is being reported
   */
  constructor(
    address _link,
    uint128 _paymentAmount,
    uint32 _timeout,
    address _validator,
    int256 _minSubmissionValue,
    int256 _maxSubmissionValue,
    uint8 _decimals,
    string memory _description
  ) public {
    linkToken = LinkTokenInterface(_link);
    updateFutureRounds(_paymentAmount, 0, 0, 0, _timeout);
    setValidator(_validator);
    minSubmissionValue = _minSubmissionValue;
    maxSubmissionValue = _maxSubmissionValue;
    decimals = _decimals;
    description = _description;
    rounds[0].updatedAt = uint64(block.timestamp.sub(uint256(_timeout)));
  }

  /**
   * @notice called by oracles when they have witnessed a need to update
   * @param _roundId is the ID of the round this submission pertains to
   * @param _submission is the updated data that the oracle is submitting
   */
  function submit(uint256 _roundId, int256 _submission)
    external
  {
    bytes memory error = validateOracleRound(msg.sender, uint32(_roundId));
    require(_submission >= minSubmissionValue, "value below minSubmissionValue");
    require(_submission <= maxSubmissionValue, "value above maxSubmissionValue");
    require(error.length == 0, string(error));

    oracleInitializeNewRound(uint32(_roundId));
    recordSubmission(_submission, uint32(_roundId));
    (bool updated, int256 newAnswer) = updateRoundAnswer(uint32(_roundId));
    payOracle(uint32(_roundId));
    deleteRoundDetails(uint32(_roundId));
    if (updated) {
      validateAnswer(uint32(_roundId), newAnswer);
    }
  }

  /**
   * @notice called by the owner to remove and add new oracles as well as
   * update the round related parameters that pertain to total oracle count
   * @param _removed is the list of addresses for the new Oracles being removed
   * @param _added is the list of addresses for the new Oracles being added
   * @param _addedAdmins is the admin addresses for the new respective _added
   * list. Only this address is allowed to access the respective oracle's funds
   * @param _minSubmissions is the new minimum submission count for each round
   * @param _maxSubmissions is the new maximum submission count for each round
   * @param _restartDelay is the number of rounds an Oracle has to wait before
   * they can initiate a round
   */
  function changeOracles(
    address[] calldata _removed,
    address[] calldata _added,
    address[] calldata _addedAdmins,
    uint32 _minSubmissions,
    uint32 _maxSubmissions,
    uint32 _restartDelay
  )
    external
    onlyOwner()
  {
    for (uint256 i = 0; i < _removed.length; i++) {
      removeOracle(_removed[i]);
    }

    require(_added.length == _addedAdmins.length, "need same oracle and admin count");
    require(uint256(oracleCount()).add(_added.length) <= MAX_ORACLE_COUNT, "max oracles allowed");

    for (uint256 i = 0; i < _added.length; i++) {
      addOracle(_added[i], _addedAdmins[i]);
    }

    updateFutureRounds(paymentAmount, _minSubmissions, _maxSubmissions, _restartDelay, timeout);
  }

  /**
   * @notice update the round and payment related parameters for subsequent
   * rounds
   * @param _paymentAmount is the payment amount for subsequent rounds
   * @param _minSubmissions is the new minimum submission count for each round
   * @param _maxSubmissions is the new maximum submission count for each round
   * @param _restartDelay is the number of rounds an Oracle has to wait before
   * they can initiate a round
   */
  function updateFutureRounds(
    uint128 _paymentAmount,
    uint32 _minSubmissions,
    uint32 _maxSubmissions,
    uint32 _restartDelay,
    uint32 _timeout
  )
    public
    onlyOwner()
  {
    uint32 oracleNum = oracleCount(); // Save on storage reads
    require(_maxSubmissions >= _minSubmissions, "max must equal/exceed min");
    require(oracleNum >= _maxSubmissions, "max cannot exceed total");
    require(oracleNum == 0 || oracleNum > _restartDelay, "delay cannot exceed total");
    require(recordedFunds.available >= requiredReserve(_paymentAmount), "insufficient funds for payment");
    if (oracleCount() > 0) {
      require(_minSubmissions > 0, "min must be greater than 0");
    }

    paymentAmount = _paymentAmount;
    minSubmissionCount = _minSubmissions;
    maxSubmissionCount = _maxSubmissions;
    restartDelay = _restartDelay;
    timeout = _timeout;

    emit RoundDetailsUpdated(
      paymentAmount,
      _minSubmissions,
      _maxSubmissions,
      _restartDelay,
      _timeout
    );
  }

  /**
   * @notice the amount of payment yet to be withdrawn by oracles
   */
  function allocatedFunds()
    external
    view
    returns (uint128)
  {
    return recordedFunds.allocated;
  }

  /**
   * @notice the amount of future funding available to oracles
   */
  function availableFunds()
    external
    view
    returns (uint128)
  {
    return recordedFunds.available;
  }

  /**
   * @notice recalculate the amount of LINK available for payouts
   */
  function updateAvailableFunds()
    public
  {
    Funds memory funds = recordedFunds;

    uint256 nowAvailable = linkToken.balanceOf(address(this)).sub(funds.allocated);

    if (funds.available != nowAvailable) {
      recordedFunds.available = uint128(nowAvailable);
      emit AvailableFundsUpdated(nowAvailable);
    }
  }

  /**
   * @notice returns the number of oracles
   */
  function oracleCount() public view returns (uint8) {
    return uint8(oracleAddresses.length);
  }

  /**
   * @notice returns an array of addresses containing the oracles on contract
   */
  function getOracles() external view returns (address[] memory) {
    return oracleAddresses;
  }

  /**
   * @notice get the most recently reported answer
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestAnswer()
    public
    view
    virtual
    override
    returns (int256)
  {
    return rounds[latestRoundId].answer;
  }

  /**
   * @notice get the most recent updated at timestamp
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestTimestamp()
    public
    view
    virtual
    override
    returns (uint256)
  {
    return rounds[latestRoundId].updatedAt;
  }

  /**
   * @notice get the ID of the last updated round
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestRound()
    public
    view
    virtual
    override
    returns (uint256)
  {
    return latestRoundId;
  }

  /**
   * @notice get past rounds answers
   * @param _roundId the round number to retrieve the answer for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getAnswer(uint256 _roundId)
    public
    view
    virtual
    override
    returns (int256)
  {
    if (validRoundId(_roundId)) {
      return rounds[uint32(_roundId)].answer;
    }
    return 0;
  }

  /**
   * @notice get timestamp when an answer was last updated
   * @param _roundId the round number to retrieve the updated timestamp for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getTimestamp(uint256 _roundId)
    public
    view
    virtual
    override
    returns (uint256)
  {
    if (validRoundId(_roundId)) {
      return rounds[uint32(_roundId)].updatedAt;
    }
    return 0;
  }

  /**
   * @notice get data about a round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * @param _roundId the round ID to retrieve the round data for
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started. This is 0
   * if the round hasn't been started yet.
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed. answeredInRound may be smaller than roundId when the round
   * timed out. answeredInRound is equal to roundId when the round didn't time out
   * and was completed regularly.
   * @dev Note that for in-progress rounds (i.e. rounds that haven't yet received
   * maxSubmissions) answer and updatedAt may change between queries.
   */
  function getRoundData(uint80 _roundId)
    public
    view
    virtual
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    Round memory r = rounds[uint32(_roundId)];

    require(r.answeredInRound > 0 && validRoundId(_roundId), V3_NO_DATA_ERROR);

    return (
      _roundId,
      r.answer,
      r.startedAt,
      r.updatedAt,
      r.answeredInRound
    );
  }

  /**
   * @notice get data about the latest round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values. Consumers are encouraged to
   * use this more fully featured method over the "legacy" latestRound/
   * latestAnswer/latestTimestamp functions. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started. This is 0
   * if the round hasn't been started yet.
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed. answeredInRound may be smaller than roundId when the round
   * timed out. answeredInRound is equal to roundId when the round didn't time
   * out and was completed regularly.
   * @dev Note that for in-progress rounds (i.e. rounds that haven't yet
   * received maxSubmissions) answer and updatedAt may change between queries.
   */
   function latestRoundData()
    public
    view
    virtual
    override
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return getRoundData(latestRoundId);
  }


  /**
   * @notice query the available amount of LINK for an oracle to withdraw
   */
  function withdrawablePayment(address _oracle)
    external
    view
    returns (uint256)
  {
    return oracles[_oracle].withdrawable;
  }

  /**
   * @notice transfers the oracle's LINK to another address. Can only be called
   * by the oracle's admin.
   * @param _oracle is the oracle whose LINK is transferred
   * @param _recipient is the address to send the LINK to
   * @param _amount is the amount of LINK to send
   */
  function withdrawPayment(address _oracle, address _recipient, uint256 _amount)
    external
  {
    require(oracles[_oracle].admin == msg.sender, "only callable by admin");

    // Safe to downcast _amount because the total amount of LINK is less than 2^128.
    uint128 amount = uint128(_amount);
    uint128 available = oracles[_oracle].withdrawable;
    require(available >= amount, "insufficient withdrawable funds");

    oracles[_oracle].withdrawable = available.sub(amount);
    recordedFunds.allocated = recordedFunds.allocated.sub(amount);

    assert(linkToken.transfer(_recipient, uint256(amount)));
  }

  /**
   * @notice transfers the owner's LINK to another address
   * @param _recipient is the address to send the LINK to
   * @param _amount is the amount of LINK to send
   */
  function withdrawFunds(address _recipient, uint256 _amount)
    external
    onlyOwner()
  {
    uint256 available = uint256(recordedFunds.available);
    require(available.sub(requiredReserve(paymentAmount)) >= _amount, "insufficient reserve funds");
    require(linkToken.transfer(_recipient, _amount), "token transfer failed");
    updateAvailableFunds();
  }

  /**
   * @notice get the admin address of an oracle
   * @param _oracle is the address of the oracle whose admin is being queried
   */
  function getAdmin(address _oracle)
    external
    view
    returns (address)
  {
    return oracles[_oracle].admin;
  }

  /**
   * @notice transfer the admin address for an oracle
   * @param _oracle is the address of the oracle whose admin is being transferred
   * @param _newAdmin is the new admin address
   */
  function transferAdmin(address _oracle, address _newAdmin)
    external
  {
    require(oracles[_oracle].admin == msg.sender, "only callable by admin");
    oracles[_oracle].pendingAdmin = _newAdmin;

    emit OracleAdminUpdateRequested(_oracle, msg.sender, _newAdmin);
  }

  /**
   * @notice accept the admin address transfer for an oracle
   * @param _oracle is the address of the oracle whose admin is being transferred
   */
  function acceptAdmin(address _oracle)
    external
  {
    require(oracles[_oracle].pendingAdmin == msg.sender, "only callable by pending admin");
    oracles[_oracle].pendingAdmin = address(0);
    oracles[_oracle].admin = msg.sender;

    emit OracleAdminUpdated(_oracle, msg.sender);
  }

  /**
   * @notice allows non-oracles to request a new round
   */
  function requestNewRound()
    external
    returns (uint80)
  {
    require(requesters[msg.sender].authorized, "not authorized requester");

    uint32 current = reportingRoundId;
    require(rounds[current].updatedAt > 0 || timedOut(current), "prev round must be supersedable");

    uint32 newRoundId = current.add(1);
    requesterInitializeNewRound(newRoundId);
    return newRoundId;
  }

  /**
   * @notice allows the owner to specify new non-oracles to start new rounds
   * @param _requester is the address to set permissions for
   * @param _authorized is a boolean specifying whether they can start new rounds or not
   * @param _delay is the number of rounds the requester must wait before starting another round
   */
  function setRequesterPermissions(address _requester, bool _authorized, uint32 _delay)
    external
    onlyOwner()
  {
    if (requesters[_requester].authorized == _authorized) return;

    if (_authorized) {
      requesters[_requester].authorized = _authorized;
      requesters[_requester].delay = _delay;
    } else {
      delete requesters[_requester];
    }

    emit RequesterPermissionsSet(_requester, _authorized, _delay);
  }

  /**
   * @notice called through LINK's transferAndCall to update available funds
   * in the same transaction as the funds were transferred to the aggregator
   * @param _data is mostly ignored. It is checked for length, to be sure
   * nothing strange is passed in.
   */
  function onTokenTransfer(address, uint256, bytes calldata _data)
    external
  {
    require(_data.length == 0, "transfer doesn't accept calldata");
    updateAvailableFunds();
  }

  /**
   * @notice a method to provide all current info oracles need. Intended only
   * only to be callable by oracles. Not for use by contracts to read state.
   * @param _oracle the address to look up information for.
   */
  function oracleRoundState(address _oracle, uint32 _queriedRoundId)
    external
    view
    returns (
      bool _eligibleToSubmit,
      uint32 _roundId,
      int256 _latestSubmission,
      uint64 _startedAt,
      uint64 _timeout,
      uint128 _availableFunds,
      uint8 _oracleCount,
      uint128 _paymentAmount
    )
  {
    require(msg.sender == tx.origin, "off-chain reading only");

    if (_queriedRoundId > 0) {
      Round storage round = rounds[_queriedRoundId];
      RoundDetails storage details = details[_queriedRoundId];
      return (
        eligibleForSpecificRound(_oracle, _queriedRoundId),
        _queriedRoundId,
        oracles[_oracle].latestSubmission,
        round.startedAt,
        details.timeout,
        recordedFunds.available,
        oracleCount(),
        (round.startedAt > 0 ? details.paymentAmount : paymentAmount)
      );
    } else {
      return oracleRoundStateSuggestRound(_oracle);
    }
  }

  /**
   * @notice method to update the address which does external data validation.
   * @param _newValidator designates the address of the new validation contract.
   */
  function setValidator(address _newValidator)
    public
    onlyOwner()
  {
    address previous = address(validator);

    if (previous != _newValidator) {
      validator = AggregatorValidatorInterface(_newValidator);

      emit ValidatorUpdated(previous, _newValidator);
    }
  }


  /**
   * Private
   */

  function initializeNewRound(uint32 _roundId)
    private
  {
    updateTimedOutRoundInfo(_roundId.sub(1));

    reportingRoundId = _roundId;
    RoundDetails memory nextDetails = RoundDetails(
      new int256[](0),
      maxSubmissionCount,
      minSubmissionCount,
      timeout,
      paymentAmount
    );
    details[_roundId] = nextDetails;
    rounds[_roundId].startedAt = uint64(block.timestamp);

    emit NewRound(_roundId, msg.sender, rounds[_roundId].startedAt);
  }

  function oracleInitializeNewRound(uint32 _roundId)
    private
  {
    if (!newRound(_roundId)) return;
    uint256 lastStarted = oracles[msg.sender].lastStartedRound; // cache storage reads
    if (_roundId <= lastStarted + restartDelay && lastStarted != 0) return;

    initializeNewRound(_roundId);

    oracles[msg.sender].lastStartedRound = _roundId;
  }

  function requesterInitializeNewRound(uint32 _roundId)
    private
  {
    if (!newRound(_roundId)) return;
    uint256 lastStarted = requesters[msg.sender].lastStartedRound; // cache storage reads
    require(_roundId > lastStarted + requesters[msg.sender].delay || lastStarted == 0, "must delay requests");

    initializeNewRound(_roundId);

    requesters[msg.sender].lastStartedRound = _roundId;
  }

  function updateTimedOutRoundInfo(uint32 _roundId)
    private
  {
    if (!timedOut(_roundId)) return;

    uint32 prevId = _roundId.sub(1);
    rounds[_roundId].answer = rounds[prevId].answer;
    rounds[_roundId].answeredInRound = rounds[prevId].answeredInRound;
    rounds[_roundId].updatedAt = uint64(block.timestamp);

    delete details[_roundId];
  }

  function eligibleForSpecificRound(address _oracle, uint32 _queriedRoundId)
    private
    view
    returns (bool _eligible)
  {
    if (rounds[_queriedRoundId].startedAt > 0) {
      return acceptingSubmissions(_queriedRoundId) && validateOracleRound(_oracle, _queriedRoundId).length == 0;
    } else {
      return delayed(_oracle, _queriedRoundId) && validateOracleRound(_oracle, _queriedRoundId).length == 0;
    }
  }

  function oracleRoundStateSuggestRound(address _oracle)
    private
    view
    returns (
      bool _eligibleToSubmit,
      uint32 _roundId,
      int256 _latestSubmission,
      uint64 _startedAt,
      uint64 _timeout,
      uint128 _availableFunds,
      uint8 _oracleCount,
      uint128 _paymentAmount
    )
  {
    Round storage round = rounds[0];
    OracleStatus storage oracle = oracles[_oracle];

    bool shouldSupersede = oracle.lastReportedRound == reportingRoundId || !acceptingSubmissions(reportingRoundId);
    // Instead of nudging oracles to submit to the next round, the inclusion of
    // the shouldSupersede bool in the if condition pushes them towards
    // submitting in a currently open round.
    if (supersedable(reportingRoundId) && shouldSupersede) {
      _roundId = reportingRoundId.add(1);
      round = rounds[_roundId];

      _paymentAmount = paymentAmount;
      _eligibleToSubmit = delayed(_oracle, _roundId);
    } else {
      _roundId = reportingRoundId;
      round = rounds[_roundId];

      _paymentAmount = details[_roundId].paymentAmount;
      _eligibleToSubmit = acceptingSubmissions(_roundId);
    }

    if (validateOracleRound(_oracle, _roundId).length != 0) {
      _eligibleToSubmit = false;
    }

    return (
      _eligibleToSubmit,
      _roundId,
      oracle.latestSubmission,
      round.startedAt,
      details[_roundId].timeout,
      recordedFunds.available,
      oracleCount(),
      _paymentAmount
    );
  }

  function updateRoundAnswer(uint32 _roundId)
    internal
    returns (bool, int256)
  {
    if (details[_roundId].submissions.length < details[_roundId].minSubmissions) {
      return (false, 0);
    }

    int256 newAnswer = Median.calculateInplace(details[_roundId].submissions);
    rounds[_roundId].answer = newAnswer;
    rounds[_roundId].updatedAt = uint64(block.timestamp);
    rounds[_roundId].answeredInRound = _roundId;
    latestRoundId = _roundId;

    emit AnswerUpdated(newAnswer, _roundId, now);

    return (true, newAnswer);
  }

  function validateAnswer(
    uint32 _roundId,
    int256 _newAnswer
  )
    private
  {
    AggregatorValidatorInterface av = validator; // cache storage reads
    if (address(av) == address(0)) return;

    uint32 prevRound = _roundId.sub(1);
    uint32 prevAnswerRoundId = rounds[prevRound].answeredInRound;
    int256 prevRoundAnswer = rounds[prevRound].answer;
    // We do not want the validator to ever prevent reporting, so we limit its
    // gas usage and catch any errors that may arise.
    try av.validate{gas: VALIDATOR_GAS_LIMIT}(
      prevAnswerRoundId,
      prevRoundAnswer,
      _roundId,
      _newAnswer
    ) {} catch {}
  }

  function payOracle(uint32 _roundId)
    private
  {
    uint128 payment = details[_roundId].paymentAmount;
    Funds memory funds = recordedFunds;
    funds.available = funds.available.sub(payment);
    funds.allocated = funds.allocated.add(payment);
    recordedFunds = funds;
    oracles[msg.sender].withdrawable = oracles[msg.sender].withdrawable.add(payment);

    emit AvailableFundsUpdated(funds.available);
  }

  function recordSubmission(int256 _submission, uint32 _roundId)
    private
  {
    require(acceptingSubmissions(_roundId), "round not accepting submissions");

    details[_roundId].submissions.push(_submission);
    oracles[msg.sender].lastReportedRound = _roundId;
    oracles[msg.sender].latestSubmission = _submission;

    emit SubmissionReceived(_submission, _roundId, msg.sender);
  }

  function deleteRoundDetails(uint32 _roundId)
    private
  {
    if (details[_roundId].submissions.length < details[_roundId].maxSubmissions) return;

    delete details[_roundId];
  }

  function timedOut(uint32 _roundId)
    private
    view
    returns (bool)
  {
    uint64 startedAt = rounds[_roundId].startedAt;
    uint32 roundTimeout = details[_roundId].timeout;
    return startedAt > 0 && roundTimeout > 0 && startedAt.add(roundTimeout) < block.timestamp;
  }

  function getStartingRound(address _oracle)
    private
    view
    returns (uint32)
  {
    uint32 currentRound = reportingRoundId;
    if (currentRound != 0 && currentRound == oracles[_oracle].endingRound) {
      return currentRound;
    }
    return currentRound.add(1);
  }

  function previousAndCurrentUnanswered(uint32 _roundId, uint32 _rrId)
    private
    view
    returns (bool)
  {
    return _roundId.add(1) == _rrId && rounds[_rrId].updatedAt == 0;
  }

  function requiredReserve(uint256 payment)
    private
    view
    returns (uint256)
  {
    return payment.mul(oracleCount()).mul(RESERVE_ROUNDS);
  }

  function addOracle(
    address _oracle,
    address _admin
  )
    private
  {
    require(!oracleEnabled(_oracle), "oracle already enabled");

    require(_admin != address(0), "cannot set admin to 0");
    require(oracles[_oracle].admin == address(0) || oracles[_oracle].admin == _admin, "owner cannot overwrite admin");

    oracles[_oracle].startingRound = getStartingRound(_oracle);
    oracles[_oracle].endingRound = ROUND_MAX;
    oracles[_oracle].index = uint16(oracleAddresses.length);
    oracleAddresses.push(_oracle);
    oracles[_oracle].admin = _admin;

    emit OraclePermissionsUpdated(_oracle, true);
    emit OracleAdminUpdated(_oracle, _admin);
  }

  function removeOracle(
    address _oracle
  )
    private
  {
    require(oracleEnabled(_oracle), "oracle not enabled");

    oracles[_oracle].endingRound = reportingRoundId.add(1);
    address tail = oracleAddresses[uint256(oracleCount()).sub(1)];
    uint16 index = oracles[_oracle].index;
    oracles[tail].index = index;
    delete oracles[_oracle].index;
    oracleAddresses[index] = tail;
    oracleAddresses.pop();

    emit OraclePermissionsUpdated(_oracle, false);
  }

  function validateOracleRound(address _oracle, uint32 _roundId)
    private
    view
    returns (bytes memory)
  {
    // cache storage reads
    uint32 startingRound = oracles[_oracle].startingRound;
    uint32 rrId = reportingRoundId;

    if (startingRound == 0) return "not enabled oracle";
    if (startingRound > _roundId) return "not yet enabled oracle";
    if (oracles[_oracle].endingRound < _roundId) return "no longer allowed oracle";
    if (oracles[_oracle].lastReportedRound >= _roundId) return "cannot report on previous rounds";
    if (_roundId != rrId && _roundId != rrId.add(1) && !previousAndCurrentUnanswered(_roundId, rrId)) return "invalid round to report";
    if (_roundId != 1 && !supersedable(_roundId.sub(1))) return "previous round not supersedable";
  }

  function supersedable(uint32 _roundId)
    private
    view
    returns (bool)
  {
    return rounds[_roundId].updatedAt > 0 || timedOut(_roundId);
  }

  function oracleEnabled(address _oracle)
    private
    view
    returns (bool)
  {
    return oracles[_oracle].endingRound == ROUND_MAX;
  }

  function acceptingSubmissions(uint32 _roundId)
    private
    view
    returns (bool)
  {
    return details[_roundId].maxSubmissions != 0;
  }

  function delayed(address _oracle, uint32 _roundId)
    private
    view
    returns (bool)
  {
    uint256 lastStarted = oracles[_oracle].lastStartedRound;
    return _roundId > lastStarted + restartDelay || lastStarted == 0;
  }

  function newRound(uint32 _roundId)
    private
    view
    returns (bool)
  {
    return _roundId == reportingRoundId.add(1);
  }

  function validRoundId(uint256 _roundId)
    private
    view
    returns (bool)
  {
    return _roundId <= ROUND_MAX;
  }

}

interface AccessControllerInterface {
  function hasAccess(address user, bytes calldata data) external view returns (bool);
}

/**
 * @title SimpleWriteAccessController
 * @notice Gives access to accounts explicitly added to an access list by the
 * controller's owner.
 * @dev does not make any special permissions for externally, see
 * SimpleReadAccessController for that.
 */
contract SimpleWriteAccessController is AccessControllerInterface, Owned {

  bool public checkEnabled;
  mapping(address => bool) internal accessList;

  event AddedAccess(address user);
  event RemovedAccess(address user);
  event CheckAccessEnabled();
  event CheckAccessDisabled();

  constructor()
    public
  {
    checkEnabled = true;
  }

  /**
   * @notice Returns the access of an address
   * @param _user The address to query
   */
  function hasAccess(
    address _user,
    bytes memory
  )
    public
    view
    virtual
    override
    returns (bool)
  {
    return accessList[_user] || !checkEnabled;
  }

  /**
   * @notice Adds an address to the access list
   * @param _user The address to add
   */
  function addAccess(address _user)
    external
    onlyOwner()
  {
    if (!accessList[_user]) {
      accessList[_user] = true;

      emit AddedAccess(_user);
    }
  }

  /**
   * @notice Removes an address from the access list
   * @param _user The address to remove
   */
  function removeAccess(address _user)
    external
    onlyOwner()
  {
    if (accessList[_user]) {
      accessList[_user] = false;

      emit RemovedAccess(_user);
    }
  }

  /**
   * @notice makes the access check enforced
   */
  function enableAccessCheck()
    external
    onlyOwner()
  {
    if (!checkEnabled) {
      checkEnabled = true;

      emit CheckAccessEnabled();
    }
  }

  /**
   * @notice makes the access check unenforced
   */
  function disableAccessCheck()
    external
    onlyOwner()
  {
    if (checkEnabled) {
      checkEnabled = false;

      emit CheckAccessDisabled();
    }
  }

  /**
   * @dev reverts if the caller does not have access
   */
  modifier checkAccess() {
    require(hasAccess(msg.sender, msg.data), "No access");
    _;
  }
}

/**
 * @title SimpleReadAccessController
 * @notice Gives access to:
 * - any externally owned account (note that offchain actors can always read
 * any contract storage regardless of onchain access control measures, so this
 * does not weaken the access control while improving usability)
 * - accounts explicitly added to an access list
 * @dev SimpleReadAccessController is not suitable for access controlling writes
 * since it grants any externally owned account access! See
 * SimpleWriteAccessController for that.
 */
contract SimpleReadAccessController is SimpleWriteAccessController {

  /**
   * @notice Returns the access of an address
   * @param _user The address to query
   */
  function hasAccess(
    address _user,
    bytes memory _calldata
  )
    public
    view
    virtual
    override
    returns (bool)
  {
    return super.hasAccess(_user, _calldata) || _user == tx.origin;
  }

}

/**
 * @title AccessControlled FluxAggregator contract
 * @notice This contract requires addresses to be added to a controller
 * in order to read the answers stored in the FluxAggregator contract
 */
contract AccessControlledAggregator is FluxAggregator, SimpleReadAccessController {

  /**
   * @notice set up the aggregator with initial configuration
   * @param _link The address of the LINK token
   * @param _paymentAmount The amount paid of LINK paid to each oracle per submission, in wei (units of 10⁻¹⁸ LINK)
   * @param _timeout is the number of seconds after the previous round that are
   * allowed to lapse before allowing an oracle to skip an unfinished round
   * @param _validator is an optional contract address for validating
   * external validation of answers
   * @param _minSubmissionValue is an immutable check for a lower bound of what
   * submission values are accepted from an oracle
   * @param _maxSubmissionValue is an immutable check for an upper bound of what
   * submission values are accepted from an oracle
   * @param _decimals represents the number of decimals to offset the answer by
   * @param _description a short description of what is being reported
   */
  constructor(
    address _link,
    uint128 _paymentAmount,
    uint32 _timeout,
    address _validator,
    int256 _minSubmissionValue,
    int256 _maxSubmissionValue,
    uint8 _decimals,
    string memory _description
  ) public FluxAggregator(
    _link,
    _paymentAmount,
    _timeout,
    _validator,
    _minSubmissionValue,
    _maxSubmissionValue,
    _decimals,
    _description
  ){}

  /**
   * @notice get data about a round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values.
   * @param _roundId the round ID to retrieve the round data for
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started. This is 0
   * if the round hasn't been started yet.
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed. answeredInRound may be smaller than roundId when the round
   * timed out. answerInRound is equal to roundId when the round didn't time out
   * and was completed regularly.
   * @dev overridden funcion to add the checkAccess() modifier
   * @dev Note that for in-progress rounds (i.e. rounds that haven't yet
   * received maxSubmissions) answer and updatedAt may change between queries.
   */
  function getRoundData(uint80 _roundId)
    public
    view
    override
    checkAccess()
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return super.getRoundData(_roundId);
  }

  /**
   * @notice get data about the latest round. Consumers are encouraged to check
   * that they're receiving fresh data by inspecting the updatedAt and
   * answeredInRound return values. Consumers are encouraged to
   * use this more fully featured method over the "legacy" latestAnswer
   * functions. Consumers are encouraged to check that they're receiving fresh
   * data by inspecting the updatedAt and answeredInRound return values.
   * @return roundId is the round ID for which data was retrieved
   * @return answer is the answer for the given round
   * @return startedAt is the timestamp when the round was started. This is 0
   * if the round hasn't been started yet.
   * @return updatedAt is the timestamp when the round last was updated (i.e.
   * answer was last computed)
   * @return answeredInRound is the round ID of the round in which the answer
   * was computed. answeredInRound may be smaller than roundId when the round
   * timed out. answerInRound is equal to roundId when the round didn't time out
   * and was completed regularly.
   * @dev overridden funcion to add the checkAccess() modifier
   * @dev Note that for in-progress rounds (i.e. rounds that haven't yet
   * received maxSubmissions) answer and updatedAt may change between queries.
   */
  function latestRoundData()
    public
    view
    override
    checkAccess()
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    )
  {
    return super.latestRoundData();
  }

  /**
   * @notice get the most recently reported answer
   * @dev overridden funcion to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestAnswer()
    public
    view
    override
    checkAccess()
    returns (int256)
  {
    return super.latestAnswer();
  }

  /**
   * @notice get the most recently reported round ID
   * @dev overridden funcion to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestRound()
    public
    view
    override
    checkAccess()
    returns (uint256)
  {
    return super.latestRound();
  }

  /**
   * @notice get the most recent updated at timestamp
   * @dev overridden funcion to add the checkAccess() modifier
   *
   * @dev #[deprecated] Use latestRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended latestRoundData
   * instead which includes better verification information.
   */
  function latestTimestamp()
    public
    view
    override
    checkAccess()
    returns (uint256)
  {
    return super.latestTimestamp();
  }

  /**
   * @notice get past rounds answers
   * @dev overridden funcion to add the checkAccess() modifier
   * @param _roundId the round number to retrieve the answer for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getAnswer(uint256 _roundId)
    public
    view
    override
    checkAccess()
    returns (int256)
  {
    return super.getAnswer(_roundId);
  }

  /**
   * @notice get timestamp when an answer was last updated
   * @dev overridden funcion to add the checkAccess() modifier
   * @param _roundId the round number to retrieve the updated timestamp for
   *
   * @dev #[deprecated] Use getRoundData instead. This does not error if no
   * answer has been reached, it will simply return 0. Either wait to point to
   * an already answered Aggregator or use the recommended getRoundData
   * instead which includes better verification information.
   */
  function getTimestamp(uint256 _roundId)
    public
    view
    override
    checkAccess()
    returns (uint256)
  {
    return super.getTimestamp(_roundId);
  }

}

/**
 *Submitted for verification at Etherscan.io on 2020-08-03
*/

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.6.10;
pragma experimental ABIEncoderV2;








/**
 * @title The Open Oracle Data Base Contract
 * @author Compound Labs, Inc.
 */
contract OpenOracleData {
    /**
     * @notice The event emitted when a source writes to its storage
     */
    //event Write(address indexed source, <Key> indexed key, string kind, uint64 timestamp, <Value> value);

    /**
     * @notice Write a bunch of signed datum to the authenticated storage mapping
     * @param message The payload containing the timestamp, and (key, value) pairs
     * @param signature The cryptographic signature of the message payload, authorizing the source to write
     * @return The keys that were written
     */
    //function put(bytes calldata message, bytes calldata signature) external returns (<Key> memory);

    /**
     * @notice Read a single key with a pre-defined type signature from an authenticated source
     * @param source The verifiable author of the data
     * @param key The selector for the value to return
     * @return The claimed Unix timestamp for the data and the encoded value (defaults to (0, 0x))
     */
    //function get(address source, <Key> key) external view returns (uint, <Value>);

    /**
     * @notice Recovers the source address which signed a message
     * @dev Comparing to a claimed address would add nothing,
     *  as the caller could simply perform the recover and claim that address.
     * @param message The data that was presumably signed
     * @param signature The fingerprint of the data + private key
     * @return The source address which signed the message, presumably
     */
    function source(bytes memory message, bytes memory signature) public pure returns (address) {
        (bytes32 r, bytes32 s, uint8 v) = abi.decode(signature, (bytes32, bytes32, uint8));
        bytes32 hash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", keccak256(message)));
        return ecrecover(hash, v, r, s);
    }
}


/**
 * @title The Open Oracle Price Data Contract
 * @notice Values stored in this contract should represent a USD price with 6 decimals precision
 * @author Compound Labs, Inc.
 */
contract OpenOraclePriceData is OpenOracleData {
    ///@notice The event emitted when a source writes to its storage
    event Write(address indexed source, string key, uint64 timestamp, uint64 value);
    ///@notice The event emitted when the timestamp on a price is invalid and it is not written to storage
    event NotWritten(uint64 priorTimestamp, uint256 messageTimestamp, uint256 blockTimestamp);

    ///@notice The fundamental unit of storage for a reporter source
    struct Datum {
        uint64 timestamp;
        uint64 value;
    }

    /**
     * @dev The most recent authenticated data from all sources.
     *  This is private because dynamic mapping keys preclude auto-generated getters.
     */
    mapping(address => mapping(string => Datum)) private data;

    /**
     * @notice Write a bunch of signed datum to the authenticated storage mapping
     * @param message The payload containing the timestamp, and (key, value) pairs
     * @param signature The cryptographic signature of the message payload, authorizing the source to write
     * @return The keys that were written
     */
    function put(bytes calldata message, bytes calldata signature) external returns (string memory) {
        (address source, uint64 timestamp, string memory key, uint64 value) = decodeMessage(message, signature);
        return putInternal(source, timestamp, key, value);
    }

    function putInternal(address source, uint64 timestamp, string memory key, uint64 value) internal returns (string memory) {
        // Only update if newer than stored, according to source
        Datum storage prior = data[source][key];
        if (timestamp > prior.timestamp && timestamp < block.timestamp + 60 minutes && source != address(0)) {
            data[source][key] = Datum(timestamp, value);
            emit Write(source, key, timestamp, value);
        } else {
            emit NotWritten(prior.timestamp, timestamp, block.timestamp);
        }
        return key;
    }

    function decodeMessage(bytes calldata message, bytes calldata signature) internal pure returns (address, uint64, string memory, uint64) {
        // Recover the source address
        address source = source(message, signature);

        // Decode the message and check the kind
        (string memory kind, uint64 timestamp, string memory key, uint64 value) = abi.decode(message, (string, uint64, string, uint64));
        require(keccak256(abi.encodePacked(kind)) == keccak256(abi.encodePacked("prices")), "Kind of data must be 'prices'");
        return (source, timestamp, key, value);
    }

    /**
     * @notice Read a single key from an authenticated source
     * @param source The verifiable author of the data
     * @param key The selector for the value to return
     * @return The claimed Unix timestamp for the data and the price value (defaults to (0, 0))
     */
    function get(address source, string calldata key) external view returns (uint64, uint64) {
        Datum storage datum = data[source][key];
        return (datum.timestamp, datum.value);
    }

    /**
     * @notice Read only the value for a single key from an authenticated source
     * @param source The verifiable author of the data
     * @param key The selector for the value to return
     * @return The price value (defaults to 0)
     */
    function getPrice(address source, string calldata key) external view returns (uint64) {
        return data[source][key].value;
    }
}





interface CErc20 {
    function underlying() external view returns (address);
}

contract UniswapConfig {
    /// @dev Describe how to interpret the fixedPrice in the TokenConfig.
    enum PriceSource {
        FIXED_ETH, /// implies the fixedPrice is a constant multiple of the ETH price (which varies)
        FIXED_USD, /// implies the fixedPrice is a constant multiple of the USD price (which is 1)
        REPORTER   /// implies the price is set by the reporter
    }

    /// @dev Describe how the USD price should be determined for an asset.
    ///  There should be 1 TokenConfig object for each supported asset, passed in the constructor.
    struct TokenConfig {
        address cToken;
        address underlying;
        bytes32 symbolHash;
        uint256 baseUnit;
        PriceSource priceSource;
        uint256 fixedPrice;
        address uniswapMarket;
        bool isUniswapReversed;
    }

    /// @notice The max number of tokens this contract is hardcoded to support
    /// @dev Do not change this variable without updating all the fields throughout the contract.
    uint public constant maxTokens = 30;

    /// @notice The number of tokens this contract actually supports
    uint public immutable numTokens;

    address internal immutable cToken00;
    address internal immutable cToken01;
    address internal immutable cToken02;
    address internal immutable cToken03;
    address internal immutable cToken04;
    address internal immutable cToken05;
    address internal immutable cToken06;
    address internal immutable cToken07;
    address internal immutable cToken08;
    address internal immutable cToken09;
    address internal immutable cToken10;
    address internal immutable cToken11;
    address internal immutable cToken12;
    address internal immutable cToken13;
    address internal immutable cToken14;
    address internal immutable cToken15;
    address internal immutable cToken16;
    address internal immutable cToken17;
    address internal immutable cToken18;
    address internal immutable cToken19;
    address internal immutable cToken20;
    address internal immutable cToken21;
    address internal immutable cToken22;
    address internal immutable cToken23;
    address internal immutable cToken24;
    address internal immutable cToken25;
    address internal immutable cToken26;
    address internal immutable cToken27;
    address internal immutable cToken28;
    address internal immutable cToken29;

    address internal immutable underlying00;
    address internal immutable underlying01;
    address internal immutable underlying02;
    address internal immutable underlying03;
    address internal immutable underlying04;
    address internal immutable underlying05;
    address internal immutable underlying06;
    address internal immutable underlying07;
    address internal immutable underlying08;
    address internal immutable underlying09;
    address internal immutable underlying10;
    address internal immutable underlying11;
    address internal immutable underlying12;
    address internal immutable underlying13;
    address internal immutable underlying14;
    address internal immutable underlying15;
    address internal immutable underlying16;
    address internal immutable underlying17;
    address internal immutable underlying18;
    address internal immutable underlying19;
    address internal immutable underlying20;
    address internal immutable underlying21;
    address internal immutable underlying22;
    address internal immutable underlying23;
    address internal immutable underlying24;
    address internal immutable underlying25;
    address internal immutable underlying26;
    address internal immutable underlying27;
    address internal immutable underlying28;
    address internal immutable underlying29;

    bytes32 internal immutable symbolHash00;
    bytes32 internal immutable symbolHash01;
    bytes32 internal immutable symbolHash02;
    bytes32 internal immutable symbolHash03;
    bytes32 internal immutable symbolHash04;
    bytes32 internal immutable symbolHash05;
    bytes32 internal immutable symbolHash06;
    bytes32 internal immutable symbolHash07;
    bytes32 internal immutable symbolHash08;
    bytes32 internal immutable symbolHash09;
    bytes32 internal immutable symbolHash10;
    bytes32 internal immutable symbolHash11;
    bytes32 internal immutable symbolHash12;
    bytes32 internal immutable symbolHash13;
    bytes32 internal immutable symbolHash14;
    bytes32 internal immutable symbolHash15;
    bytes32 internal immutable symbolHash16;
    bytes32 internal immutable symbolHash17;
    bytes32 internal immutable symbolHash18;
    bytes32 internal immutable symbolHash19;
    bytes32 internal immutable symbolHash20;
    bytes32 internal immutable symbolHash21;
    bytes32 internal immutable symbolHash22;
    bytes32 internal immutable symbolHash23;
    bytes32 internal immutable symbolHash24;
    bytes32 internal immutable symbolHash25;
    bytes32 internal immutable symbolHash26;
    bytes32 internal immutable symbolHash27;
    bytes32 internal immutable symbolHash28;
    bytes32 internal immutable symbolHash29;

    uint256 internal immutable baseUnit00;
    uint256 internal immutable baseUnit01;
    uint256 internal immutable baseUnit02;
    uint256 internal immutable baseUnit03;
    uint256 internal immutable baseUnit04;
    uint256 internal immutable baseUnit05;
    uint256 internal immutable baseUnit06;
    uint256 internal immutable baseUnit07;
    uint256 internal immutable baseUnit08;
    uint256 internal immutable baseUnit09;
    uint256 internal immutable baseUnit10;
    uint256 internal immutable baseUnit11;
    uint256 internal immutable baseUnit12;
    uint256 internal immutable baseUnit13;
    uint256 internal immutable baseUnit14;
    uint256 internal immutable baseUnit15;
    uint256 internal immutable baseUnit16;
    uint256 internal immutable baseUnit17;
    uint256 internal immutable baseUnit18;
    uint256 internal immutable baseUnit19;
    uint256 internal immutable baseUnit20;
    uint256 internal immutable baseUnit21;
    uint256 internal immutable baseUnit22;
    uint256 internal immutable baseUnit23;
    uint256 internal immutable baseUnit24;
    uint256 internal immutable baseUnit25;
    uint256 internal immutable baseUnit26;
    uint256 internal immutable baseUnit27;
    uint256 internal immutable baseUnit28;
    uint256 internal immutable baseUnit29;

    PriceSource internal immutable priceSource00;
    PriceSource internal immutable priceSource01;
    PriceSource internal immutable priceSource02;
    PriceSource internal immutable priceSource03;
    PriceSource internal immutable priceSource04;
    PriceSource internal immutable priceSource05;
    PriceSource internal immutable priceSource06;
    PriceSource internal immutable priceSource07;
    PriceSource internal immutable priceSource08;
    PriceSource internal immutable priceSource09;
    PriceSource internal immutable priceSource10;
    PriceSource internal immutable priceSource11;
    PriceSource internal immutable priceSource12;
    PriceSource internal immutable priceSource13;
    PriceSource internal immutable priceSource14;
    PriceSource internal immutable priceSource15;
    PriceSource internal immutable priceSource16;
    PriceSource internal immutable priceSource17;
    PriceSource internal immutable priceSource18;
    PriceSource internal immutable priceSource19;
    PriceSource internal immutable priceSource20;
    PriceSource internal immutable priceSource21;
    PriceSource internal immutable priceSource22;
    PriceSource internal immutable priceSource23;
    PriceSource internal immutable priceSource24;
    PriceSource internal immutable priceSource25;
    PriceSource internal immutable priceSource26;
    PriceSource internal immutable priceSource27;
    PriceSource internal immutable priceSource28;
    PriceSource internal immutable priceSource29;

    uint256 internal immutable fixedPrice00;
    uint256 internal immutable fixedPrice01;
    uint256 internal immutable fixedPrice02;
    uint256 internal immutable fixedPrice03;
    uint256 internal immutable fixedPrice04;
    uint256 internal immutable fixedPrice05;
    uint256 internal immutable fixedPrice06;
    uint256 internal immutable fixedPrice07;
    uint256 internal immutable fixedPrice08;
    uint256 internal immutable fixedPrice09;
    uint256 internal immutable fixedPrice10;
    uint256 internal immutable fixedPrice11;
    uint256 internal immutable fixedPrice12;
    uint256 internal immutable fixedPrice13;
    uint256 internal immutable fixedPrice14;
    uint256 internal immutable fixedPrice15;
    uint256 internal immutable fixedPrice16;
    uint256 internal immutable fixedPrice17;
    uint256 internal immutable fixedPrice18;
    uint256 internal immutable fixedPrice19;
    uint256 internal immutable fixedPrice20;
    uint256 internal immutable fixedPrice21;
    uint256 internal immutable fixedPrice22;
    uint256 internal immutable fixedPrice23;
    uint256 internal immutable fixedPrice24;
    uint256 internal immutable fixedPrice25;
    uint256 internal immutable fixedPrice26;
    uint256 internal immutable fixedPrice27;
    uint256 internal immutable fixedPrice28;
    uint256 internal immutable fixedPrice29;

    address internal immutable uniswapMarket00;
    address internal immutable uniswapMarket01;
    address internal immutable uniswapMarket02;
    address internal immutable uniswapMarket03;
    address internal immutable uniswapMarket04;
    address internal immutable uniswapMarket05;
    address internal immutable uniswapMarket06;
    address internal immutable uniswapMarket07;
    address internal immutable uniswapMarket08;
    address internal immutable uniswapMarket09;
    address internal immutable uniswapMarket10;
    address internal immutable uniswapMarket11;
    address internal immutable uniswapMarket12;
    address internal immutable uniswapMarket13;
    address internal immutable uniswapMarket14;
    address internal immutable uniswapMarket15;
    address internal immutable uniswapMarket16;
    address internal immutable uniswapMarket17;
    address internal immutable uniswapMarket18;
    address internal immutable uniswapMarket19;
    address internal immutable uniswapMarket20;
    address internal immutable uniswapMarket21;
    address internal immutable uniswapMarket22;
    address internal immutable uniswapMarket23;
    address internal immutable uniswapMarket24;
    address internal immutable uniswapMarket25;
    address internal immutable uniswapMarket26;
    address internal immutable uniswapMarket27;
    address internal immutable uniswapMarket28;
    address internal immutable uniswapMarket29;

    bool internal immutable isUniswapReversed00;
    bool internal immutable isUniswapReversed01;
    bool internal immutable isUniswapReversed02;
    bool internal immutable isUniswapReversed03;
    bool internal immutable isUniswapReversed04;
    bool internal immutable isUniswapReversed05;
    bool internal immutable isUniswapReversed06;
    bool internal immutable isUniswapReversed07;
    bool internal immutable isUniswapReversed08;
    bool internal immutable isUniswapReversed09;
    bool internal immutable isUniswapReversed10;
    bool internal immutable isUniswapReversed11;
    bool internal immutable isUniswapReversed12;
    bool internal immutable isUniswapReversed13;
    bool internal immutable isUniswapReversed14;
    bool internal immutable isUniswapReversed15;
    bool internal immutable isUniswapReversed16;
    bool internal immutable isUniswapReversed17;
    bool internal immutable isUniswapReversed18;
    bool internal immutable isUniswapReversed19;
    bool internal immutable isUniswapReversed20;
    bool internal immutable isUniswapReversed21;
    bool internal immutable isUniswapReversed22;
    bool internal immutable isUniswapReversed23;
    bool internal immutable isUniswapReversed24;
    bool internal immutable isUniswapReversed25;
    bool internal immutable isUniswapReversed26;
    bool internal immutable isUniswapReversed27;
    bool internal immutable isUniswapReversed28;
    bool internal immutable isUniswapReversed29;

    /**
     * @notice Construct an immutable store of configs into the contract data
     * @param configs The configs for the supported assets
     */
    constructor(TokenConfig[] memory configs) public {
        require(configs.length <= maxTokens, "too many configs");
        numTokens = configs.length;

        cToken00 = get(configs, 0).cToken;
        cToken01 = get(configs, 1).cToken;
        cToken02 = get(configs, 2).cToken;
        cToken03 = get(configs, 3).cToken;
        cToken04 = get(configs, 4).cToken;
        cToken05 = get(configs, 5).cToken;
        cToken06 = get(configs, 6).cToken;
        cToken07 = get(configs, 7).cToken;
        cToken08 = get(configs, 8).cToken;
        cToken09 = get(configs, 9).cToken;
        cToken10 = get(configs, 10).cToken;
        cToken11 = get(configs, 11).cToken;
        cToken12 = get(configs, 12).cToken;
        cToken13 = get(configs, 13).cToken;
        cToken14 = get(configs, 14).cToken;
        cToken15 = get(configs, 15).cToken;
        cToken16 = get(configs, 16).cToken;
        cToken17 = get(configs, 17).cToken;
        cToken18 = get(configs, 18).cToken;
        cToken19 = get(configs, 19).cToken;
        cToken20 = get(configs, 20).cToken;
        cToken21 = get(configs, 21).cToken;
        cToken22 = get(configs, 22).cToken;
        cToken23 = get(configs, 23).cToken;
        cToken24 = get(configs, 24).cToken;
        cToken25 = get(configs, 25).cToken;
        cToken26 = get(configs, 26).cToken;
        cToken27 = get(configs, 27).cToken;
        cToken28 = get(configs, 28).cToken;
        cToken29 = get(configs, 29).cToken;

        underlying00 = get(configs, 0).underlying;
        underlying01 = get(configs, 1).underlying;
        underlying02 = get(configs, 2).underlying;
        underlying03 = get(configs, 3).underlying;
        underlying04 = get(configs, 4).underlying;
        underlying05 = get(configs, 5).underlying;
        underlying06 = get(configs, 6).underlying;
        underlying07 = get(configs, 7).underlying;
        underlying08 = get(configs, 8).underlying;
        underlying09 = get(configs, 9).underlying;
        underlying10 = get(configs, 10).underlying;
        underlying11 = get(configs, 11).underlying;
        underlying12 = get(configs, 12).underlying;
        underlying13 = get(configs, 13).underlying;
        underlying14 = get(configs, 14).underlying;
        underlying15 = get(configs, 15).underlying;
        underlying16 = get(configs, 16).underlying;
        underlying17 = get(configs, 17).underlying;
        underlying18 = get(configs, 18).underlying;
        underlying19 = get(configs, 19).underlying;
        underlying20 = get(configs, 20).underlying;
        underlying21 = get(configs, 21).underlying;
        underlying22 = get(configs, 22).underlying;
        underlying23 = get(configs, 23).underlying;
        underlying24 = get(configs, 24).underlying;
        underlying25 = get(configs, 25).underlying;
        underlying26 = get(configs, 26).underlying;
        underlying27 = get(configs, 27).underlying;
        underlying28 = get(configs, 28).underlying;
        underlying29 = get(configs, 29).underlying;

        symbolHash00 = get(configs, 0).symbolHash;
        symbolHash01 = get(configs, 1).symbolHash;
        symbolHash02 = get(configs, 2).symbolHash;
        symbolHash03 = get(configs, 3).symbolHash;
        symbolHash04 = get(configs, 4).symbolHash;
        symbolHash05 = get(configs, 5).symbolHash;
        symbolHash06 = get(configs, 6).symbolHash;
        symbolHash07 = get(configs, 7).symbolHash;
        symbolHash08 = get(configs, 8).symbolHash;
        symbolHash09 = get(configs, 9).symbolHash;
        symbolHash10 = get(configs, 10).symbolHash;
        symbolHash11 = get(configs, 11).symbolHash;
        symbolHash12 = get(configs, 12).symbolHash;
        symbolHash13 = get(configs, 13).symbolHash;
        symbolHash14 = get(configs, 14).symbolHash;
        symbolHash15 = get(configs, 15).symbolHash;
        symbolHash16 = get(configs, 16).symbolHash;
        symbolHash17 = get(configs, 17).symbolHash;
        symbolHash18 = get(configs, 18).symbolHash;
        symbolHash19 = get(configs, 19).symbolHash;
        symbolHash20 = get(configs, 20).symbolHash;
        symbolHash21 = get(configs, 21).symbolHash;
        symbolHash22 = get(configs, 22).symbolHash;
        symbolHash23 = get(configs, 23).symbolHash;
        symbolHash24 = get(configs, 24).symbolHash;
        symbolHash25 = get(configs, 25).symbolHash;
        symbolHash26 = get(configs, 26).symbolHash;
        symbolHash27 = get(configs, 27).symbolHash;
        symbolHash28 = get(configs, 28).symbolHash;
        symbolHash29 = get(configs, 29).symbolHash;

        baseUnit00 = get(configs, 0).baseUnit;
        baseUnit01 = get(configs, 1).baseUnit;
        baseUnit02 = get(configs, 2).baseUnit;
        baseUnit03 = get(configs, 3).baseUnit;
        baseUnit04 = get(configs, 4).baseUnit;
        baseUnit05 = get(configs, 5).baseUnit;
        baseUnit06 = get(configs, 6).baseUnit;
        baseUnit07 = get(configs, 7).baseUnit;
        baseUnit08 = get(configs, 8).baseUnit;
        baseUnit09 = get(configs, 9).baseUnit;
        baseUnit10 = get(configs, 10).baseUnit;
        baseUnit11 = get(configs, 11).baseUnit;
        baseUnit12 = get(configs, 12).baseUnit;
        baseUnit13 = get(configs, 13).baseUnit;
        baseUnit14 = get(configs, 14).baseUnit;
        baseUnit15 = get(configs, 15).baseUnit;
        baseUnit16 = get(configs, 16).baseUnit;
        baseUnit17 = get(configs, 17).baseUnit;
        baseUnit18 = get(configs, 18).baseUnit;
        baseUnit19 = get(configs, 19).baseUnit;
        baseUnit20 = get(configs, 20).baseUnit;
        baseUnit21 = get(configs, 21).baseUnit;
        baseUnit22 = get(configs, 22).baseUnit;
        baseUnit23 = get(configs, 23).baseUnit;
        baseUnit24 = get(configs, 24).baseUnit;
        baseUnit25 = get(configs, 25).baseUnit;
        baseUnit26 = get(configs, 26).baseUnit;
        baseUnit27 = get(configs, 27).baseUnit;
        baseUnit28 = get(configs, 28).baseUnit;
        baseUnit29 = get(configs, 29).baseUnit;

        priceSource00 = get(configs, 0).priceSource;
        priceSource01 = get(configs, 1).priceSource;
        priceSource02 = get(configs, 2).priceSource;
        priceSource03 = get(configs, 3).priceSource;
        priceSource04 = get(configs, 4).priceSource;
        priceSource05 = get(configs, 5).priceSource;
        priceSource06 = get(configs, 6).priceSource;
        priceSource07 = get(configs, 7).priceSource;
        priceSource08 = get(configs, 8).priceSource;
        priceSource09 = get(configs, 9).priceSource;
        priceSource10 = get(configs, 10).priceSource;
        priceSource11 = get(configs, 11).priceSource;
        priceSource12 = get(configs, 12).priceSource;
        priceSource13 = get(configs, 13).priceSource;
        priceSource14 = get(configs, 14).priceSource;
        priceSource15 = get(configs, 15).priceSource;
        priceSource16 = get(configs, 16).priceSource;
        priceSource17 = get(configs, 17).priceSource;
        priceSource18 = get(configs, 18).priceSource;
        priceSource19 = get(configs, 19).priceSource;
        priceSource20 = get(configs, 20).priceSource;
        priceSource21 = get(configs, 21).priceSource;
        priceSource22 = get(configs, 22).priceSource;
        priceSource23 = get(configs, 23).priceSource;
        priceSource24 = get(configs, 24).priceSource;
        priceSource25 = get(configs, 25).priceSource;
        priceSource26 = get(configs, 26).priceSource;
        priceSource27 = get(configs, 27).priceSource;
        priceSource28 = get(configs, 28).priceSource;
        priceSource29 = get(configs, 29).priceSource;

        fixedPrice00 = get(configs, 0).fixedPrice;
        fixedPrice01 = get(configs, 1).fixedPrice;
        fixedPrice02 = get(configs, 2).fixedPrice;
        fixedPrice03 = get(configs, 3).fixedPrice;
        fixedPrice04 = get(configs, 4).fixedPrice;
        fixedPrice05 = get(configs, 5).fixedPrice;
        fixedPrice06 = get(configs, 6).fixedPrice;
        fixedPrice07 = get(configs, 7).fixedPrice;
        fixedPrice08 = get(configs, 8).fixedPrice;
        fixedPrice09 = get(configs, 9).fixedPrice;
        fixedPrice10 = get(configs, 10).fixedPrice;
        fixedPrice11 = get(configs, 11).fixedPrice;
        fixedPrice12 = get(configs, 12).fixedPrice;
        fixedPrice13 = get(configs, 13).fixedPrice;
        fixedPrice14 = get(configs, 14).fixedPrice;
        fixedPrice15 = get(configs, 15).fixedPrice;
        fixedPrice16 = get(configs, 16).fixedPrice;
        fixedPrice17 = get(configs, 17).fixedPrice;
        fixedPrice18 = get(configs, 18).fixedPrice;
        fixedPrice19 = get(configs, 19).fixedPrice;
        fixedPrice20 = get(configs, 20).fixedPrice;
        fixedPrice21 = get(configs, 21).fixedPrice;
        fixedPrice22 = get(configs, 22).fixedPrice;
        fixedPrice23 = get(configs, 23).fixedPrice;
        fixedPrice24 = get(configs, 24).fixedPrice;
        fixedPrice25 = get(configs, 25).fixedPrice;
        fixedPrice26 = get(configs, 26).fixedPrice;
        fixedPrice27 = get(configs, 27).fixedPrice;
        fixedPrice28 = get(configs, 28).fixedPrice;
        fixedPrice29 = get(configs, 29).fixedPrice;

        uniswapMarket00 = get(configs, 0).uniswapMarket;
        uniswapMarket01 = get(configs, 1).uniswapMarket;
        uniswapMarket02 = get(configs, 2).uniswapMarket;
        uniswapMarket03 = get(configs, 3).uniswapMarket;
        uniswapMarket04 = get(configs, 4).uniswapMarket;
        uniswapMarket05 = get(configs, 5).uniswapMarket;
        uniswapMarket06 = get(configs, 6).uniswapMarket;
        uniswapMarket07 = get(configs, 7).uniswapMarket;
        uniswapMarket08 = get(configs, 8).uniswapMarket;
        uniswapMarket09 = get(configs, 9).uniswapMarket;
        uniswapMarket10 = get(configs, 10).uniswapMarket;
        uniswapMarket11 = get(configs, 11).uniswapMarket;
        uniswapMarket12 = get(configs, 12).uniswapMarket;
        uniswapMarket13 = get(configs, 13).uniswapMarket;
        uniswapMarket14 = get(configs, 14).uniswapMarket;
        uniswapMarket15 = get(configs, 15).uniswapMarket;
        uniswapMarket16 = get(configs, 16).uniswapMarket;
        uniswapMarket17 = get(configs, 17).uniswapMarket;
        uniswapMarket18 = get(configs, 18).uniswapMarket;
        uniswapMarket19 = get(configs, 19).uniswapMarket;
        uniswapMarket20 = get(configs, 20).uniswapMarket;
        uniswapMarket21 = get(configs, 21).uniswapMarket;
        uniswapMarket22 = get(configs, 22).uniswapMarket;
        uniswapMarket23 = get(configs, 23).uniswapMarket;
        uniswapMarket24 = get(configs, 24).uniswapMarket;
        uniswapMarket25 = get(configs, 25).uniswapMarket;
        uniswapMarket26 = get(configs, 26).uniswapMarket;
        uniswapMarket27 = get(configs, 27).uniswapMarket;
        uniswapMarket28 = get(configs, 28).uniswapMarket;
        uniswapMarket29 = get(configs, 29).uniswapMarket;

        isUniswapReversed00 = get(configs, 0).isUniswapReversed;
        isUniswapReversed01 = get(configs, 1).isUniswapReversed;
        isUniswapReversed02 = get(configs, 2).isUniswapReversed;
        isUniswapReversed03 = get(configs, 3).isUniswapReversed;
        isUniswapReversed04 = get(configs, 4).isUniswapReversed;
        isUniswapReversed05 = get(configs, 5).isUniswapReversed;
        isUniswapReversed06 = get(configs, 6).isUniswapReversed;
        isUniswapReversed07 = get(configs, 7).isUniswapReversed;
        isUniswapReversed08 = get(configs, 8).isUniswapReversed;
        isUniswapReversed09 = get(configs, 9).isUniswapReversed;
        isUniswapReversed10 = get(configs, 10).isUniswapReversed;
        isUniswapReversed11 = get(configs, 11).isUniswapReversed;
        isUniswapReversed12 = get(configs, 12).isUniswapReversed;
        isUniswapReversed13 = get(configs, 13).isUniswapReversed;
        isUniswapReversed14 = get(configs, 14).isUniswapReversed;
        isUniswapReversed15 = get(configs, 15).isUniswapReversed;
        isUniswapReversed16 = get(configs, 16).isUniswapReversed;
        isUniswapReversed17 = get(configs, 17).isUniswapReversed;
        isUniswapReversed18 = get(configs, 18).isUniswapReversed;
        isUniswapReversed19 = get(configs, 19).isUniswapReversed;
        isUniswapReversed20 = get(configs, 20).isUniswapReversed;
        isUniswapReversed21 = get(configs, 21).isUniswapReversed;
        isUniswapReversed22 = get(configs, 22).isUniswapReversed;
        isUniswapReversed23 = get(configs, 23).isUniswapReversed;
        isUniswapReversed24 = get(configs, 24).isUniswapReversed;
        isUniswapReversed25 = get(configs, 25).isUniswapReversed;
        isUniswapReversed26 = get(configs, 26).isUniswapReversed;
        isUniswapReversed27 = get(configs, 27).isUniswapReversed;
        isUniswapReversed28 = get(configs, 28).isUniswapReversed;
        isUniswapReversed29 = get(configs, 29).isUniswapReversed;
    }

    function get(TokenConfig[] memory configs, uint i) internal pure returns (TokenConfig memory) {
        if (i < configs.length)
            return configs[i];
        return TokenConfig({
            cToken: address(0),
            underlying: address(0),
            symbolHash: bytes32(0),
            baseUnit: uint256(0),
            priceSource: PriceSource(0),
            fixedPrice: uint256(0),
            uniswapMarket: address(0),
            isUniswapReversed: false
        });
    }

    function getCTokenIndex(address cToken) internal view returns (uint) {
        if (cToken == cToken00) return 0;
        if (cToken == cToken01) return 1;
        if (cToken == cToken02) return 2;
        if (cToken == cToken03) return 3;
        if (cToken == cToken04) return 4;
        if (cToken == cToken05) return 5;
        if (cToken == cToken06) return 6;
        if (cToken == cToken07) return 7;
        if (cToken == cToken08) return 8;
        if (cToken == cToken09) return 9;
        if (cToken == cToken10) return 10;
        if (cToken == cToken11) return 11;
        if (cToken == cToken12) return 12;
        if (cToken == cToken13) return 13;
        if (cToken == cToken14) return 14;
        if (cToken == cToken15) return 15;
        if (cToken == cToken16) return 16;
        if (cToken == cToken17) return 17;
        if (cToken == cToken18) return 18;
        if (cToken == cToken19) return 19;
        if (cToken == cToken20) return 20;
        if (cToken == cToken21) return 21;
        if (cToken == cToken22) return 22;
        if (cToken == cToken23) return 23;
        if (cToken == cToken24) return 24;
        if (cToken == cToken25) return 25;
        if (cToken == cToken26) return 26;
        if (cToken == cToken27) return 27;
        if (cToken == cToken28) return 28;
        if (cToken == cToken29) return 29;

        return uint(-1);
    }

    function getUnderlyingIndex(address underlying) internal view returns (uint) {
        if (underlying == underlying00) return 0;
        if (underlying == underlying01) return 1;
        if (underlying == underlying02) return 2;
        if (underlying == underlying03) return 3;
        if (underlying == underlying04) return 4;
        if (underlying == underlying05) return 5;
        if (underlying == underlying06) return 6;
        if (underlying == underlying07) return 7;
        if (underlying == underlying08) return 8;
        if (underlying == underlying09) return 9;
        if (underlying == underlying10) return 10;
        if (underlying == underlying11) return 11;
        if (underlying == underlying12) return 12;
        if (underlying == underlying13) return 13;
        if (underlying == underlying14) return 14;
        if (underlying == underlying15) return 15;
        if (underlying == underlying16) return 16;
        if (underlying == underlying17) return 17;
        if (underlying == underlying18) return 18;
        if (underlying == underlying19) return 19;
        if (underlying == underlying20) return 20;
        if (underlying == underlying21) return 21;
        if (underlying == underlying22) return 22;
        if (underlying == underlying23) return 23;
        if (underlying == underlying24) return 24;
        if (underlying == underlying25) return 25;
        if (underlying == underlying26) return 26;
        if (underlying == underlying27) return 27;
        if (underlying == underlying28) return 28;
        if (underlying == underlying29) return 29;

        return uint(-1);
    }

    function getSymbolHashIndex(bytes32 symbolHash) internal view returns (uint) {
        if (symbolHash == symbolHash00) return 0;
        if (symbolHash == symbolHash01) return 1;
        if (symbolHash == symbolHash02) return 2;
        if (symbolHash == symbolHash03) return 3;
        if (symbolHash == symbolHash04) return 4;
        if (symbolHash == symbolHash05) return 5;
        if (symbolHash == symbolHash06) return 6;
        if (symbolHash == symbolHash07) return 7;
        if (symbolHash == symbolHash08) return 8;
        if (symbolHash == symbolHash09) return 9;
        if (symbolHash == symbolHash10) return 10;
        if (symbolHash == symbolHash11) return 11;
        if (symbolHash == symbolHash12) return 12;
        if (symbolHash == symbolHash13) return 13;
        if (symbolHash == symbolHash14) return 14;
        if (symbolHash == symbolHash15) return 15;
        if (symbolHash == symbolHash16) return 16;
        if (symbolHash == symbolHash17) return 17;
        if (symbolHash == symbolHash18) return 18;
        if (symbolHash == symbolHash19) return 19;
        if (symbolHash == symbolHash20) return 20;
        if (symbolHash == symbolHash21) return 21;
        if (symbolHash == symbolHash22) return 22;
        if (symbolHash == symbolHash23) return 23;
        if (symbolHash == symbolHash24) return 24;
        if (symbolHash == symbolHash25) return 25;
        if (symbolHash == symbolHash26) return 26;
        if (symbolHash == symbolHash27) return 27;
        if (symbolHash == symbolHash28) return 28;
        if (symbolHash == symbolHash29) return 29;

        return uint(-1);
    }

    /**
     * @notice Get the i-th config, according to the order they were passed in originally
     * @param i The index of the config to get
     * @return The config object
     */
    function getTokenConfig(uint i) public view returns (TokenConfig memory) {
        require(i < numTokens, "token config not found");

        if (i == 0) return TokenConfig({cToken: cToken00, underlying: underlying00, symbolHash: symbolHash00, baseUnit: baseUnit00, priceSource: priceSource00, fixedPrice: fixedPrice00, uniswapMarket: uniswapMarket00, isUniswapReversed: isUniswapReversed00});
        if (i == 1) return TokenConfig({cToken: cToken01, underlying: underlying01, symbolHash: symbolHash01, baseUnit: baseUnit01, priceSource: priceSource01, fixedPrice: fixedPrice01, uniswapMarket: uniswapMarket01, isUniswapReversed: isUniswapReversed01});
        if (i == 2) return TokenConfig({cToken: cToken02, underlying: underlying02, symbolHash: symbolHash02, baseUnit: baseUnit02, priceSource: priceSource02, fixedPrice: fixedPrice02, uniswapMarket: uniswapMarket02, isUniswapReversed: isUniswapReversed02});
        if (i == 3) return TokenConfig({cToken: cToken03, underlying: underlying03, symbolHash: symbolHash03, baseUnit: baseUnit03, priceSource: priceSource03, fixedPrice: fixedPrice03, uniswapMarket: uniswapMarket03, isUniswapReversed: isUniswapReversed03});
        if (i == 4) return TokenConfig({cToken: cToken04, underlying: underlying04, symbolHash: symbolHash04, baseUnit: baseUnit04, priceSource: priceSource04, fixedPrice: fixedPrice04, uniswapMarket: uniswapMarket04, isUniswapReversed: isUniswapReversed04});
        if (i == 5) return TokenConfig({cToken: cToken05, underlying: underlying05, symbolHash: symbolHash05, baseUnit: baseUnit05, priceSource: priceSource05, fixedPrice: fixedPrice05, uniswapMarket: uniswapMarket05, isUniswapReversed: isUniswapReversed05});
        if (i == 6) return TokenConfig({cToken: cToken06, underlying: underlying06, symbolHash: symbolHash06, baseUnit: baseUnit06, priceSource: priceSource06, fixedPrice: fixedPrice06, uniswapMarket: uniswapMarket06, isUniswapReversed: isUniswapReversed06});
        if (i == 7) return TokenConfig({cToken: cToken07, underlying: underlying07, symbolHash: symbolHash07, baseUnit: baseUnit07, priceSource: priceSource07, fixedPrice: fixedPrice07, uniswapMarket: uniswapMarket07, isUniswapReversed: isUniswapReversed07});
        if (i == 8) return TokenConfig({cToken: cToken08, underlying: underlying08, symbolHash: symbolHash08, baseUnit: baseUnit08, priceSource: priceSource08, fixedPrice: fixedPrice08, uniswapMarket: uniswapMarket08, isUniswapReversed: isUniswapReversed08});
        if (i == 9) return TokenConfig({cToken: cToken09, underlying: underlying09, symbolHash: symbolHash09, baseUnit: baseUnit09, priceSource: priceSource09, fixedPrice: fixedPrice09, uniswapMarket: uniswapMarket09, isUniswapReversed: isUniswapReversed09});

        if (i == 10) return TokenConfig({cToken: cToken10, underlying: underlying10, symbolHash: symbolHash10, baseUnit: baseUnit10, priceSource: priceSource10, fixedPrice: fixedPrice10, uniswapMarket: uniswapMarket10, isUniswapReversed: isUniswapReversed10});
        if (i == 11) return TokenConfig({cToken: cToken11, underlying: underlying11, symbolHash: symbolHash11, baseUnit: baseUnit11, priceSource: priceSource11, fixedPrice: fixedPrice11, uniswapMarket: uniswapMarket11, isUniswapReversed: isUniswapReversed11});
        if (i == 12) return TokenConfig({cToken: cToken12, underlying: underlying12, symbolHash: symbolHash12, baseUnit: baseUnit12, priceSource: priceSource12, fixedPrice: fixedPrice12, uniswapMarket: uniswapMarket12, isUniswapReversed: isUniswapReversed12});
        if (i == 13) return TokenConfig({cToken: cToken13, underlying: underlying13, symbolHash: symbolHash13, baseUnit: baseUnit13, priceSource: priceSource13, fixedPrice: fixedPrice13, uniswapMarket: uniswapMarket13, isUniswapReversed: isUniswapReversed13});
        if (i == 14) return TokenConfig({cToken: cToken14, underlying: underlying14, symbolHash: symbolHash14, baseUnit: baseUnit14, priceSource: priceSource14, fixedPrice: fixedPrice14, uniswapMarket: uniswapMarket14, isUniswapReversed: isUniswapReversed14});
        if (i == 15) return TokenConfig({cToken: cToken15, underlying: underlying15, symbolHash: symbolHash15, baseUnit: baseUnit15, priceSource: priceSource15, fixedPrice: fixedPrice15, uniswapMarket: uniswapMarket15, isUniswapReversed: isUniswapReversed15});
        if (i == 16) return TokenConfig({cToken: cToken16, underlying: underlying16, symbolHash: symbolHash16, baseUnit: baseUnit16, priceSource: priceSource16, fixedPrice: fixedPrice16, uniswapMarket: uniswapMarket16, isUniswapReversed: isUniswapReversed16});
        if (i == 17) return TokenConfig({cToken: cToken17, underlying: underlying17, symbolHash: symbolHash17, baseUnit: baseUnit17, priceSource: priceSource17, fixedPrice: fixedPrice17, uniswapMarket: uniswapMarket17, isUniswapReversed: isUniswapReversed17});
        if (i == 18) return TokenConfig({cToken: cToken18, underlying: underlying18, symbolHash: symbolHash18, baseUnit: baseUnit18, priceSource: priceSource18, fixedPrice: fixedPrice18, uniswapMarket: uniswapMarket18, isUniswapReversed: isUniswapReversed18});
        if (i == 19) return TokenConfig({cToken: cToken19, underlying: underlying19, symbolHash: symbolHash19, baseUnit: baseUnit19, priceSource: priceSource19, fixedPrice: fixedPrice19, uniswapMarket: uniswapMarket19, isUniswapReversed: isUniswapReversed19});

        if (i == 20) return TokenConfig({cToken: cToken20, underlying: underlying20, symbolHash: symbolHash20, baseUnit: baseUnit20, priceSource: priceSource20, fixedPrice: fixedPrice20, uniswapMarket: uniswapMarket20, isUniswapReversed: isUniswapReversed20});
        if (i == 21) return TokenConfig({cToken: cToken21, underlying: underlying21, symbolHash: symbolHash21, baseUnit: baseUnit21, priceSource: priceSource21, fixedPrice: fixedPrice21, uniswapMarket: uniswapMarket21, isUniswapReversed: isUniswapReversed21});
        if (i == 22) return TokenConfig({cToken: cToken22, underlying: underlying22, symbolHash: symbolHash22, baseUnit: baseUnit22, priceSource: priceSource22, fixedPrice: fixedPrice22, uniswapMarket: uniswapMarket22, isUniswapReversed: isUniswapReversed22});
        if (i == 23) return TokenConfig({cToken: cToken23, underlying: underlying23, symbolHash: symbolHash23, baseUnit: baseUnit23, priceSource: priceSource23, fixedPrice: fixedPrice23, uniswapMarket: uniswapMarket23, isUniswapReversed: isUniswapReversed23});
        if (i == 24) return TokenConfig({cToken: cToken24, underlying: underlying24, symbolHash: symbolHash24, baseUnit: baseUnit24, priceSource: priceSource24, fixedPrice: fixedPrice24, uniswapMarket: uniswapMarket24, isUniswapReversed: isUniswapReversed24});
        if (i == 25) return TokenConfig({cToken: cToken25, underlying: underlying25, symbolHash: symbolHash25, baseUnit: baseUnit25, priceSource: priceSource25, fixedPrice: fixedPrice25, uniswapMarket: uniswapMarket25, isUniswapReversed: isUniswapReversed25});
        if (i == 26) return TokenConfig({cToken: cToken26, underlying: underlying26, symbolHash: symbolHash26, baseUnit: baseUnit26, priceSource: priceSource26, fixedPrice: fixedPrice26, uniswapMarket: uniswapMarket26, isUniswapReversed: isUniswapReversed26});
        if (i == 27) return TokenConfig({cToken: cToken27, underlying: underlying27, symbolHash: symbolHash27, baseUnit: baseUnit27, priceSource: priceSource27, fixedPrice: fixedPrice27, uniswapMarket: uniswapMarket27, isUniswapReversed: isUniswapReversed27});
        if (i == 28) return TokenConfig({cToken: cToken28, underlying: underlying28, symbolHash: symbolHash28, baseUnit: baseUnit28, priceSource: priceSource28, fixedPrice: fixedPrice28, uniswapMarket: uniswapMarket28, isUniswapReversed: isUniswapReversed28});
        if (i == 29) return TokenConfig({cToken: cToken29, underlying: underlying29, symbolHash: symbolHash29, baseUnit: baseUnit29, priceSource: priceSource29, fixedPrice: fixedPrice29, uniswapMarket: uniswapMarket29, isUniswapReversed: isUniswapReversed29});
    }

    /**
     * @notice Get the config for symbol
     * @param symbol The symbol of the config to get
     * @return The config object
     */
    function getTokenConfigBySymbol(string memory symbol) public view returns (TokenConfig memory) {
        return getTokenConfigBySymbolHash(keccak256(abi.encodePacked(symbol)));
    }

    /**
     * @notice Get the config for the symbolHash
     * @param symbolHash The keccack256 of the symbol of the config to get
     * @return The config object
     */
    function getTokenConfigBySymbolHash(bytes32 symbolHash) public view returns (TokenConfig memory) {
        uint index = getSymbolHashIndex(symbolHash);
        if (index != uint(-1)) {
            return getTokenConfig(index);
        }

        revert("token config not found");
    }

    /**
     * @notice Get the config for the cToken
     * @dev If a config for the cToken is not found, falls back to searching for the underlying.
     * @param cToken The address of the cToken of the config to get
     * @return The config object
     */
    function getTokenConfigByCToken(address cToken) public view returns (TokenConfig memory) {
        uint index = getCTokenIndex(cToken);
        if (index != uint(-1)) {
            return getTokenConfig(index);
        }

        return getTokenConfigByUnderlying(CErc20(cToken).underlying());
    }

    /**
     * @notice Get the config for an underlying asset
     * @param underlying The address of the underlying asset of the config to get
     * @return The config object
     */
    function getTokenConfigByUnderlying(address underlying) public view returns (TokenConfig memory) {
        uint index = getUnderlyingIndex(underlying);
        if (index != uint(-1)) {
            return getTokenConfig(index);
        }

        revert("token config not found");
    }
}




// Based on code from https://github.com/Uniswap/uniswap-v2-periphery

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
    // range: [0, 2**112 - 1]
    // resolution: 1 / 2**112
    struct uq112x112 {
        uint224 _x;
    }

    // returns a uq112x112 which represents the ratio of the numerator to the denominator
    // equivalent to encode(numerator).div(denominator)
    function fraction(uint112 numerator, uint112 denominator) internal pure returns (uq112x112 memory) {
        require(denominator > 0, "FixedPoint: DIV_BY_ZERO");
        return uq112x112((uint224(numerator) << 112) / denominator);
    }

    // decode a uq112x112 into a uint with 18 decimals of precision
    function decode112with18(uq112x112 memory self) internal pure returns (uint) {
        // we only have 256 - 224 = 32 bits to spare, so scaling up by ~60 bits is dangerous
        // instead, get close to:
        //  (x * 1e18) >> 112
        // without risk of overflowing, e.g.:
        //  (x) / 2 ** (112 - lg(1e18))
        return uint(self._x) / 5192296858534827;
    }
}

// library with helper methods for oracles that are concerned with computing average prices
library UniswapV2OracleLibrary {
    using FixedPoint for *;

    // helper function that returns the current block timestamp within the range of uint32, i.e. [0, 2**32 - 1]
    function currentBlockTimestamp() internal view returns (uint32) {
        return uint32(block.timestamp % 2 ** 32);
    }

    // produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
    function currentCumulativePrices(
        address pair
    ) internal view returns (uint price0Cumulative, uint price1Cumulative, uint32 blockTimestamp) {
        blockTimestamp = currentBlockTimestamp();
        price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();
        price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();

        // if time has elapsed since the last update on the pair, mock the accumulated price values
        (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast) = IUniswapV2Pair(pair).getReserves();
        if (blockTimestampLast != blockTimestamp) {
            // subtraction overflow is desired
            uint32 timeElapsed = blockTimestamp - blockTimestampLast;
            // addition overflow is desired
            // counterfactual
            price0Cumulative += uint(FixedPoint.fraction(reserve1, reserve0)._x) * timeElapsed;
            // counterfactual
            price1Cumulative += uint(FixedPoint.fraction(reserve0, reserve1)._x) * timeElapsed;
        }
    }
}

interface IUniswapV2Pair {
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
}


struct Observation {
    uint timestamp;
    uint acc;
}

contract UniswapAnchoredView is UniswapConfig {
    using FixedPoint for *;

    /// @notice The Open Oracle Price Data contract
    OpenOraclePriceData public immutable priceData;

    /// @notice The number of wei in 1 ETH
    uint public constant ethBaseUnit = 1e18;

    /// @notice A common scaling factor to maintain precision
    uint public constant expScale = 1e18;

    /// @notice The Open Oracle Reporter
    address public immutable reporter;

    /// @notice The highest ratio of the new price to the anchor price that will still trigger the price to be updated
    uint public immutable upperBoundAnchorRatio;

    /// @notice The lowest ratio of the new price to the anchor price that will still trigger the price to be updated
    uint public immutable lowerBoundAnchorRatio;

    /// @notice The minimum amount of time in seconds required for the old uniswap price accumulator to be replaced
    uint public immutable anchorPeriod;

    /// @notice Official prices by symbol hash
    mapping(bytes32 => uint) public prices;

    /// @notice Circuit breaker for using anchor price oracle directly, ignoring reporter
    bool public reporterInvalidated;

    /// @notice The old observation for each symbolHash
    mapping(bytes32 => Observation) public oldObservations;

    /// @notice The new observation for each symbolHash
    mapping(bytes32 => Observation) public newObservations;

    /// @notice The event emitted when new prices are posted but the stored price is not updated due to the anchor
    event PriceGuarded(string symbol, uint reporter, uint anchor);

    /// @notice The event emitted when the stored price is updated
    event PriceUpdated(string symbol, uint price);

    /// @notice The event emitted when anchor price is updated
    event AnchorPriceUpdated(string symbol, uint anchorPrice, uint oldTimestamp, uint newTimestamp);

    /// @notice The event emitted when the uniswap window changes
    event UniswapWindowUpdated(bytes32 indexed symbolHash, uint oldTimestamp, uint newTimestamp, uint oldPrice, uint newPrice);

    /// @notice The event emitted when reporter invalidates itself
    event ReporterInvalidated(address reporter);

    bytes32 constant ethHash = keccak256(abi.encodePacked("ETH"));
    bytes32 constant rotateHash = keccak256(abi.encodePacked("rotate"));

    /**
     * @notice Construct a uniswap anchored view for a set of token configurations
     * @dev Note that to avoid immature TWAPs, the system must run for at least a single anchorPeriod before using.
     * @param reporter_ The reporter whose prices are to be used
     * @param anchorToleranceMantissa_ The percentage tolerance that the reporter may deviate from the uniswap anchor
     * @param anchorPeriod_ The minimum amount of time required for the old uniswap price accumulator to be replaced
     * @param configs The static token configurations which define what prices are supported and how
     */
    constructor(OpenOraclePriceData priceData_,
                address reporter_,
                uint anchorToleranceMantissa_,
                uint anchorPeriod_,
                TokenConfig[] memory configs) UniswapConfig(configs) public {
        priceData = priceData_;
        reporter = reporter_;
        anchorPeriod = anchorPeriod_;

        // Allow the tolerance to be whatever the deployer chooses, but prevent under/overflow (and prices from being 0)
        upperBoundAnchorRatio = anchorToleranceMantissa_ > uint(-1) - 100e16 ? uint(-1) : 100e16 + anchorToleranceMantissa_;
        lowerBoundAnchorRatio = anchorToleranceMantissa_ < 100e16 ? 100e16 - anchorToleranceMantissa_ : 1;

        for (uint i = 0; i < configs.length; i++) {
            TokenConfig memory config = configs[i];
            require(config.baseUnit > 0, "baseUnit must be greater than zero");
            address uniswapMarket = config.uniswapMarket;
            if (config.priceSource == PriceSource.REPORTER) {
                require(uniswapMarket != address(0), "reported prices must have an anchor");
                bytes32 symbolHash = config.symbolHash;
                uint cumulativePrice = currentCumulativePrice(config);
                oldObservations[symbolHash].timestamp = block.timestamp;
                newObservations[symbolHash].timestamp = block.timestamp;
                oldObservations[symbolHash].acc = cumulativePrice;
                newObservations[symbolHash].acc = cumulativePrice;
                emit UniswapWindowUpdated(symbolHash, block.timestamp, block.timestamp, cumulativePrice, cumulativePrice);
            } else {
                require(uniswapMarket == address(0), "only reported prices utilize an anchor");
            }
        }
    }

    /**
     * @notice Get the official price for a symbol
     * @param symbol The symbol to fetch the price of
     * @return Price denominated in USD, with 6 decimals
     */
    function price(string memory symbol) external view returns (uint) {
        TokenConfig memory config = getTokenConfigBySymbol(symbol);
        return priceInternal(config);
    }

    function priceInternal(TokenConfig memory config) internal view returns (uint) {
        if (config.priceSource == PriceSource.REPORTER) return prices[config.symbolHash];
        if (config.priceSource == PriceSource.FIXED_USD) return config.fixedPrice;
        if (config.priceSource == PriceSource.FIXED_ETH) {
            uint usdPerEth = prices[ethHash];
            require(usdPerEth > 0, "ETH price not set, cannot convert to dollars");
            return mul(usdPerEth, config.fixedPrice) / ethBaseUnit;
        }
    }

    /**
     * @notice Get the underlying price of a cToken
     * @dev Implements the PriceOracle interface for Compound v2.
     * @param cToken The cToken address for price retrieval
     * @return Price denominated in USD, with 18 decimals, for the given cToken address
     */
    function getUnderlyingPrice(address cToken) external view returns (uint) {
        TokenConfig memory config = getTokenConfigByCToken(cToken);
         // Comptroller needs prices in the format: ${raw price} * 1e(36 - baseUnit)
         // Since the prices in this view have 6 decimals, we must scale them by 1e(36 - 6 - baseUnit)
        return mul(1e30, priceInternal(config)) / config.baseUnit;
    }

    /**
     * @notice Post open oracle reporter prices, and recalculate stored price by comparing to anchor
     * @dev We let anyone pay to post anything, but only prices from configured reporter will be stored in the view.
     * @param messages The messages to post to the oracle
     * @param signatures The signatures for the corresponding messages
     * @param symbols The symbols to compare to anchor for authoritative reading
     */
    function postPrices(bytes[] calldata messages, bytes[] calldata signatures, string[] calldata symbols) external {
        require(messages.length == signatures.length, "messages and signatures must be 1:1");

        // Save the prices
        for (uint i = 0; i < messages.length; i++) {
            priceData.put(messages[i], signatures[i]);
        }

        uint ethPrice = fetchEthPrice();

        // Try to update the view storage
        for (uint i = 0; i < symbols.length; i++) {
            postPriceInternal(symbols[i], ethPrice);
        }
    }

    function postPriceInternal(string memory symbol, uint ethPrice) internal {
        TokenConfig memory config = getTokenConfigBySymbol(symbol);
        require(config.priceSource == PriceSource.REPORTER, "only reporter prices get posted");

        bytes32 symbolHash = keccak256(abi.encodePacked(symbol));
        uint reporterPrice = priceData.getPrice(reporter, symbol);
        uint anchorPrice;
        if (symbolHash == ethHash) {
            anchorPrice = ethPrice;
        } else {
            anchorPrice = fetchAnchorPrice(symbol, config, ethPrice);
        }

        if (reporterInvalidated) {
            prices[symbolHash] = anchorPrice;
            emit PriceUpdated(symbol, anchorPrice);
        } else if (isWithinAnchor(reporterPrice, anchorPrice)) {
            prices[symbolHash] = reporterPrice;
            emit PriceUpdated(symbol, reporterPrice);
        } else {
            emit PriceGuarded(symbol, reporterPrice, anchorPrice);
        }
    }

    function isWithinAnchor(uint reporterPrice, uint anchorPrice) internal view returns (bool) {
        if (reporterPrice > 0) {
            uint anchorRatio = mul(anchorPrice, 100e16) / reporterPrice;
            return anchorRatio <= upperBoundAnchorRatio && anchorRatio >= lowerBoundAnchorRatio;
        }
        return false;
    }

    /**
     * @dev Fetches the current token/eth price accumulator from uniswap.
     */
    function currentCumulativePrice(TokenConfig memory config) internal view returns (uint) {
        (uint cumulativePrice0, uint cumulativePrice1,) = UniswapV2OracleLibrary.currentCumulativePrices(config.uniswapMarket);
        if (config.isUniswapReversed) {
            return cumulativePrice1;
        } else {
            return cumulativePrice0;
        }
    }

    /**
     * @dev Fetches the current eth/usd price from uniswap, with 6 decimals of precision.
     *  Conversion factor is 1e18 for eth/usdc market, since we decode uniswap price statically with 18 decimals.
     */
    function fetchEthPrice() internal returns (uint) {
        return fetchAnchorPrice("ETH", getTokenConfigBySymbolHash(ethHash), ethBaseUnit);
    }

    /**
     * @dev Fetches the current token/usd price from uniswap, with 6 decimals of precision.
     * @param conversionFactor 1e18 if seeking the ETH price, and a 6 decimal ETH-USDC price in the case of other assets
     */
    function fetchAnchorPrice(string memory symbol, TokenConfig memory config, uint conversionFactor) internal virtual returns (uint) {
        (uint nowCumulativePrice, uint oldCumulativePrice, uint oldTimestamp) = pokeWindowValues(config);

        // This should be impossible, but better safe than sorry
        require(block.timestamp > oldTimestamp, "now must come after before");
        uint timeElapsed = block.timestamp - oldTimestamp;

        // Calculate uniswap time-weighted average price
        // Underflow is a property of the accumulators: https://uniswap.org/audit.html#orgc9b3190
        FixedPoint.uq112x112 memory priceAverage = FixedPoint.uq112x112(uint224((nowCumulativePrice - oldCumulativePrice) / timeElapsed));
        uint rawUniswapPriceMantissa = priceAverage.decode112with18();
        uint unscaledPriceMantissa = mul(rawUniswapPriceMantissa, conversionFactor);
        uint anchorPrice;

        // Adjust rawUniswapPrice according to the units of the non-ETH asset
        // In the case of ETH, we would have to scale by 1e6 / USDC_UNITS, but since baseUnit2 is 1e6 (USDC), it cancels
        if (config.isUniswapReversed) {
            // unscaledPriceMantissa * ethBaseUnit / config.baseUnit / expScale, but we simplify bc ethBaseUnit == expScale
            anchorPrice = unscaledPriceMantissa / config.baseUnit;
        } else {
            anchorPrice = mul(unscaledPriceMantissa, config.baseUnit) / ethBaseUnit / expScale;
        }

        emit AnchorPriceUpdated(symbol, anchorPrice, oldTimestamp, block.timestamp);

        return anchorPrice;
    }

    /**
     * @dev Get time-weighted average prices for a token at the current timestamp.
     *  Update new and old observations of lagging window if period elapsed.
     */
    function pokeWindowValues(TokenConfig memory config) internal returns (uint, uint, uint) {
        bytes32 symbolHash = config.symbolHash;
        uint cumulativePrice = currentCumulativePrice(config);

        Observation memory newObservation = newObservations[symbolHash];

        // Update new and old observations if elapsed time is greater than or equal to anchor period
        uint timeElapsed = block.timestamp - newObservation.timestamp;
        if (timeElapsed >= anchorPeriod) {
            oldObservations[symbolHash].timestamp = newObservation.timestamp;
            oldObservations[symbolHash].acc = newObservation.acc;

            newObservations[symbolHash].timestamp = block.timestamp;
            newObservations[symbolHash].acc = cumulativePrice;
            emit UniswapWindowUpdated(config.symbolHash, newObservation.timestamp, block.timestamp, newObservation.acc, cumulativePrice);
        }
        return (cumulativePrice, oldObservations[symbolHash].acc, oldObservations[symbolHash].timestamp);
    }

    /**
     * @notice Invalidate the reporter, and fall back to using anchor directly in all cases
     * @dev Only the reporter may sign a message which allows it to invalidate itself.
     *  To be used in cases of emergency, if the reporter thinks their key may be compromised.
     * @param message The data that was presumably signed
     * @param signature The fingerprint of the data + private key
     */
    function invalidateReporter(bytes memory message, bytes memory signature) external {
        (string memory decodedMessage, ) = abi.decode(message, (string, address));
        require(keccak256(abi.encodePacked(decodedMessage)) == rotateHash, "invalid message must be 'rotate'");
        require(source(message, signature) == reporter, "invalidation message must come from the reporter");
        reporterInvalidated = true;
        emit ReporterInvalidated(reporter);
    }

    /**
     * @notice Recovers the source address which signed a message
     * @dev Comparing to a claimed address would add nothing,
     *  as the caller could simply perform the recover and claim that address.
     * @param message The data that was presumably signed
     * @param signature The fingerprint of the data + private key
     * @return The source address which signed the message, presumably
     */
    function source(bytes memory message, bytes memory signature) public pure returns (address) {
        (bytes32 r, bytes32 s, uint8 v) = abi.decode(signature, (bytes32, bytes32, uint8));
        bytes32 hash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", keccak256(message)));
        return ecrecover(hash, v, r, s);
    }

    /// @dev Overflow proof multiplication
    function mul(uint a, uint b) internal pure returns (uint) {
        if (a == 0) return 0;
        uint c = a * b;
        require(c / a == b, "multiplication overflow");
        return c;
    }
}

// File: contracts/interfaces/IUniswapV2Pair.sol

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

// File: contracts/interfaces/IUniswapV2ERC20.sol

pragma solidity >=0.5.0;

interface IUniswapV2ERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
}

// File: contracts/libraries/SafeMath.sol

pragma solidity =0.5.16;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

// File: contracts/UniswapV2ERC20.sol

pragma solidity =0.5.16;



contract UniswapV2ERC20 is IUniswapV2ERC20 {
    using SafeMath for uint;

    string public constant name = 'Uniswap V2';
    string public constant symbol = 'UNI-V2';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor() public {
        uint chainId;
        assembly {
            chainId := chainid
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        balanceOf[from] = balanceOf[from].sub(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}

// File: contracts/libraries/Math.sol

pragma solidity =0.5.16;

// a library for performing various math operations

library Math {
    function min(uint x, uint y) internal pure returns (uint z) {
        z = x < y ? x : y;
    }

    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}

// File: contracts/libraries/UQ112x112.sol

pragma solidity =0.5.16;

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))

// range: [0, 2**112 - 1]
// resolution: 1 / 2**112

library UQ112x112 {
    uint224 constant Q112 = 2**112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 y) internal pure returns (uint224 z) {
        z = uint224(y) * Q112; // never overflows
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
        z = x / uint224(y);
    }
}

// File: contracts/interfaces/IERC20.sol

pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

// File: contracts/interfaces/IUniswapV2Factory.sol

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

// File: contracts/interfaces/IUniswapV2Callee.sol

pragma solidity >=0.5.0;

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

// File: contracts/UniswapV2Pair.sol

pragma solidity =0.5.16;








contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
    using SafeMath  for uint;
    using UQ112x112 for uint224;

    uint public constant MINIMUM_LIQUIDITY = 10**3;
    bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));

    address public factory;
    address public token0;
    address public token1;

    uint112 private reserve0;           // uses single storage slot, accessible via getReserves
    uint112 private reserve1;           // uses single storage slot, accessible via getReserves
    uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves

    uint public price0CumulativeLast;
    uint public price1CumulativeLast;
    uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event

    uint private unlocked = 1;
    modifier lock() {
        require(unlocked == 1, 'UniswapV2: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
    }

    function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _blockTimestampLast = blockTimestampLast;
    }

    function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
    }

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    constructor() public {
        factory = msg.sender;
    }

    // called once by the factory at time of deployment
    function initialize(address _token0, address _token1) external {
        require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
        token0 = _token0;
        token1 = _token1;
    }

    // update reserves and, on the first call per block, price accumulators
    function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
        require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
        uint32 blockTimestamp = uint32(block.timestamp % 2**32);
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            // * never overflows, and + overflow is desired
            price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
            price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
        }
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
    function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        address feeTo = IUniswapV2Factory(factory).feeTo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast; // gas savings
        if (feeOn) {
            if (_kLast != 0) {
                uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                uint rootKLast = Math.sqrt(_kLast);
                if (rootK > rootKLast) {
                    uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                    uint denominator = rootK.mul(5).add(rootKLast);
                    uint liquidity = numerator / denominator;
                    if (liquidity > 0) _mint(feeTo, liquidity);
                }
            }
        } else if (_kLast != 0) {
            kLast = 0;
        }
    }

    // this low-level function should be called from a contract which performs important safety checks
    function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        uint balance0 = IERC20(token0).balanceOf(address(this));
        uint balance1 = IERC20(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
           _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
            liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        address _token0 = token0;                                // gas savings
        address _token1 = token1;                                // gas savings
        uint balance0 = IERC20(_token0).balanceOf(address(this));
        uint balance1 = IERC20(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
        require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');

        uint balance0;
        uint balance1;
        { // scope for _token{0,1}, avoids stack too deep errors
        address _token0 = token0;
        address _token1 = token1;
        require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
        if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
        if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
        if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));
        }
        uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
        uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
        { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
        uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
        uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
        require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
        }

        _update(balance0, balance1, _reserve0, _reserve1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    // force balances to match reserves
    function skim(address to) external lock {
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
    }

    // force reserves to match balances
    function sync() external lock {
        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
    }
}