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

pragma solidity ^0.5.0;

/*
 * @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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view 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 ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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 ^0.5.0;

/**
 * @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.
     *
     * _Available since v2.4.0._
     */
    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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

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

pragma solidity ^0.5.0;




/**
 * @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 {ERC20Mintable}.
 *
 * 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;

    mapping (address => uint256) private _balances;

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

    uint256 private _totalSupply;

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

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view 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 returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

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

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public 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 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 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 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 {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _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 {
        require(account != address(0), "ERC20: mint to the zero address");

        _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 {
        require(account != address(0), "ERC20: burn from the zero address");

        _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 {
        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 Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

// File: contracts/lib/CompoundOracleInterface.sol

pragma solidity ^0.5.0;
// AT MAINNET ADDRESS: 0x02557a5E05DeFeFFD4cAe6D83eA3d173B272c904

contract CompoundOracleInterface {
    // returns asset:eth -- to get USDC:eth, have to do 10**24/result,


    constructor() public {
    }

    /**
  * @notice retrieves price of an asset
  * @dev function to get price for an asset
  * @param asset Asset for which to get the price
  * @return uint mantissa of asset price (scaled by 1e18) or zero if unset or contract paused
  */
    function getPrice(address asset) public view returns (uint);
    function getUnderlyingPrice(ERC20 cToken) public view returns (uint);
    // function getPrice(address asset) public view returns (uint) {
    //     return 527557000000000;
    // }

}

// File: contracts/lib/UniswapExchangeInterface.sol

pragma solidity 0.5.10;


// Solidity Interface
contract UniswapExchangeInterface {
    // Address of ERC20 token sold on this exchange
    function tokenAddress() external view returns (address token);
    // Address of Uniswap Factory
    function factoryAddress() external view returns (address factory);
    // Provide Liquidity
    function addLiquidity(uint256 min_liquidity, uint256 max_tokens, uint256 deadline) external payable returns (uint256);
    function removeLiquidity(uint256 amount, uint256 min_eth, uint256 min_tokens, uint256 deadline) external returns (uint256, uint256);
    // Get Prices
    function getEthToTokenInputPrice(uint256 eth_sold) external view returns (uint256 tokens_bought);
    function getEthToTokenOutputPrice(uint256 tokens_bought) external view returns (uint256 eth_sold);
    function getTokenToEthInputPrice(uint256 tokens_sold) external view returns (uint256 eth_bought);
    function getTokenToEthOutputPrice(uint256 eth_bought) external view returns (uint256 tokens_sold);
    // Trade ETH to ERC20
    function ethToTokenSwapInput(uint256 min_tokens, uint256 deadline) external payable returns (uint256  tokens_bought);
    function ethToTokenTransferInput(uint256 min_tokens, uint256 deadline, address recipient) external payable returns (uint256  tokens_bought);
    function ethToTokenSwapOutput(uint256 tokens_bought, uint256 deadline) external payable returns (uint256  eth_sold);
    function ethToTokenTransferOutput(uint256 tokens_bought, uint256 deadline, address recipient) external payable returns (uint256  eth_sold);
    // Trade ERC20 to ETH
    function tokenToEthSwapInput(uint256 tokens_sold, uint256 min_eth, uint256 deadline) external returns (uint256  eth_bought);
    function tokenToEthTransferInput(uint256 tokens_sold, uint256 min_eth, uint256 deadline, address recipient) external returns (uint256  eth_bought);
    function tokenToEthSwapOutput(uint256 eth_bought, uint256 max_tokens, uint256 deadline) external returns (uint256  tokens_sold);
    function tokenToEthTransferOutput(uint256 eth_bought, uint256 max_tokens, uint256 deadline, address recipient) external returns (uint256  tokens_sold);
    // Trade ERC20 to ERC20
    function tokenToTokenSwapInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address token_addr) external returns (uint256  tokens_bought);
    function tokenToTokenTransferInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address recipient, address token_addr) external returns (uint256  tokens_bought);
    function tokenToTokenSwapOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address token_addr) external returns (uint256  tokens_sold);
    function tokenToTokenTransferOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address recipient, address token_addr) external returns (uint256  tokens_sold);
    // Trade ERC20 to Custom Pool
    function tokenToExchangeSwapInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address exchange_addr) external returns (uint256  tokens_bought);
    function tokenToExchangeTransferInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address recipient, address exchange_addr) external returns (uint256  tokens_bought);
    function tokenToExchangeSwapOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address exchange_addr) external returns (uint256  tokens_sold);
    function tokenToExchangeTransferOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address recipient, address exchange_addr) external returns (uint256  tokens_sold);
    // ERC20 comaptibility for liquidity tokens
    bytes32 public name;
    bytes32 public symbol;
    uint256 public decimals;
    function transfer(address _to, uint256 _value) external returns (bool);
    function transferFrom(address _from, address _to, uint256 value) external returns (bool);
    function approve(address _spender, uint256 _value) external returns (bool);
    function allowance(address _owner, address _spender) external view returns (uint256);
    function balanceOf(address _owner) external view returns (uint256);
    function totalSupply() external view returns (uint256);
    // Never use
    function setup(address token_addr) external;
}

// File: contracts/lib/UniswapFactoryInterface.sol

pragma solidity 0.5.10;


// Solidity Interface
contract UniswapFactoryInterface {
    // Public Variables
    address public exchangeTemplate;
    uint256 public tokenCount;
    // // Create Exchange
    function createExchange(address token) external returns (address exchange);
    // Get Exchange and Token Info
    function getExchange(address token) external view returns (address exchange);
    function getToken(address exchange) external view returns (address token);
    function getTokenWithId(uint256 tokenId) external view returns (address token);
    // Never use
    function initializeFactory(address template) external;
    // function createExchange(address token) external returns (address exchange) {
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
    // // Get Exchange and Token Info
    // function getExchange(address token) external view returns (address exchange){
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
    // function getToken(address exchange) external view returns (address token) {
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
    // function getTokenWithId(uint256 tokenId) external view returns (address token) {
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
}

// File: contracts/OptionsUtils.sol

pragma solidity 0.5.10;





contract OptionsUtils {
    // defauls are for mainnet
    UniswapFactoryInterface public UNISWAP_FACTORY;

    CompoundOracleInterface public COMPOUND_ORACLE;

    constructor(address _uniswapFactory, address _compoundOracle) public {
        UNISWAP_FACTORY = UniswapFactoryInterface(_uniswapFactory);
        COMPOUND_ORACLE = CompoundOracleInterface(_compoundOracle);
    }

    // TODO: for now gets Uniswap, later update to get other exchanges
    function getExchange(address _token)
        public
        view
        returns (UniswapExchangeInterface)
    {
        if (address(UNISWAP_FACTORY.getExchange(_token)) == address(0)) {
            revert("No payout exchange");
        }

        UniswapExchangeInterface exchange = UniswapExchangeInterface(
            UNISWAP_FACTORY.getExchange(_token)
        );

        return exchange;
    }

    function isETH(IERC20 _ierc20) public pure returns (bool) {
        return _ierc20 == IERC20(0);
    }
}

// File: contracts/OptionsExchange.sol

pragma solidity 0.5.10;






contract OptionsExchange {
    uint256 constant LARGE_BLOCK_SIZE = 1651753129000;
    uint256 constant LARGE_APPROVAL_NUMBER = 10**30;

    UniswapFactoryInterface public UNISWAP_FACTORY;

    constructor(address _uniswapFactory) public {
        UNISWAP_FACTORY = UniswapFactoryInterface(_uniswapFactory);
    }

    /*** Events ***/
    event SellOTokens(
        address seller,
        address payable receiver,
        address oTokenAddress,
        address payoutTokenAddress,
        uint256 oTokensToSell,
        uint256 payoutTokensReceived
    );
    event BuyOTokens(
        address buyer,
        address payable receiver,
        address oTokenAddress,
        address paymentTokenAddress,
        uint256 oTokensToBuy,
        uint256 premiumPaid
    );

    /**
    * @notice This function sells oTokens on Uniswap and sends back payoutTokens to the receiver
    * @param receiver The address to send the payout tokens back to
    * @param oTokenAddress The address of the oToken to sell
    * @param payoutTokenAddress The address of the token to receive the premiums in
    * @param oTokensToSell The number of oTokens to sell
    */
    function sellOTokens(
        address payable receiver,
        address oTokenAddress,
        address payoutTokenAddress,
        uint256 oTokensToSell
    ) public {
        // @note: first need to bootstrap the uniswap exchange to get the address.
        IERC20 oToken = IERC20(oTokenAddress);
        IERC20 payoutToken = IERC20(payoutTokenAddress);
        oToken.transferFrom(msg.sender, address(this), oTokensToSell);
        uint256 payoutTokensReceived = uniswapSellOToken(
            oToken,
            payoutToken,
            oTokensToSell,
            receiver
        );

        emit SellOTokens(
            msg.sender,
            receiver,
            oTokenAddress,
            payoutTokenAddress,
            oTokensToSell,
            payoutTokensReceived
        );
    }

    /**
    * @notice This function buys oTokens on Uniswap and using paymentTokens from the receiver
    * @param receiver The address to send the oTokens back to
    * @param oTokenAddress The address of the oToken to buy
    * @param paymentTokenAddress The address of the token to pay the premiums in
    * @param oTokensToBuy The number of oTokens to buy
    */
    function buyOTokens(
        address payable receiver,
        address oTokenAddress,
        address paymentTokenAddress,
        uint256 oTokensToBuy
    ) public payable {
        IERC20 oToken = IERC20(oTokenAddress);
        IERC20 paymentToken = IERC20(paymentTokenAddress);
        uniswapBuyOToken(paymentToken, oToken, oTokensToBuy, receiver);
    }

    /**
    * @notice This function calculates the amount of premiums that the seller
    * will receive if they sold oTokens on Uniswap
    * @param oTokenAddress The address of the oToken to sell
    * @param payoutTokenAddress The address of the token to receive the premiums in
    * @param oTokensToSell The number of oTokens to sell
    */
    function premiumReceived(
        address oTokenAddress,
        address payoutTokenAddress,
        uint256 oTokensToSell
    ) public view returns (uint256) {
        // get the amount of ETH that will be paid out if oTokensToSell is sold.
        UniswapExchangeInterface oTokenExchange = getExchange(oTokenAddress);
        uint256 ethReceived = oTokenExchange.getTokenToEthInputPrice(
            oTokensToSell
        );

        if (!isETH(IERC20(payoutTokenAddress))) {
            // get the amount of payout tokens that will be received if the ethRecieved is sold.
            UniswapExchangeInterface payoutExchange = getExchange(
                payoutTokenAddress
            );
            return payoutExchange.getEthToTokenInputPrice(ethReceived);
        }
        return ethReceived;

    }

    /**
    * @notice This function calculates the premiums to be paid if a buyer wants to
    * buy oTokens on Uniswap
    * @param oTokenAddress The address of the oToken to buy
    * @param paymentTokenAddress The address of the token to pay the premiums in
    * @param oTokensToBuy The number of oTokens to buy
    */
    function premiumToPay(
        address oTokenAddress,
        address paymentTokenAddress,
        uint256 oTokensToBuy
    ) public view returns (uint256) {
        // get the amount of ETH that needs to be paid for oTokensToBuy.
        UniswapExchangeInterface oTokenExchange = getExchange(oTokenAddress);
        uint256 ethToPay = oTokenExchange.getEthToTokenOutputPrice(
            oTokensToBuy
        );

        if (!isETH(IERC20(paymentTokenAddress))) {
            // get the amount of paymentTokens that needs to be paid to get the desired ethToPay.
            UniswapExchangeInterface paymentTokenExchange = getExchange(
                paymentTokenAddress
            );
            return paymentTokenExchange.getTokenToEthOutputPrice(ethToPay);
        }

        return ethToPay;
    }

    function uniswapSellOToken(
        IERC20 oToken,
        IERC20 payoutToken,
        uint256 _amt,
        address payable _transferTo
    ) internal returns (uint256) {
        require(!isETH(oToken), "Can only sell oTokens");
        UniswapExchangeInterface exchange = getExchange(address(oToken));

        if (isETH(payoutToken)) {
            //Token to ETH
            oToken.approve(address(exchange), _amt);
            return
                exchange.tokenToEthTransferInput(
                    _amt,
                    1,
                    LARGE_BLOCK_SIZE,
                    _transferTo
                );
        } else {
            //Token to Token
            oToken.approve(address(exchange), _amt);
            return
                exchange.tokenToTokenTransferInput(
                    _amt,
                    1,
                    1,
                    LARGE_BLOCK_SIZE,
                    _transferTo,
                    address(payoutToken)
                );
        }
    }

    function uniswapBuyOToken(
        IERC20 paymentToken,
        IERC20 oToken,
        uint256 _amt,
        address payable _transferTo
    ) public returns (uint256) {
        require(!isETH(oToken), "Can only buy oTokens");

        if (!isETH(paymentToken)) {
            UniswapExchangeInterface exchange = getExchange(
                address(paymentToken)
            );

            uint256 paymentTokensToTransfer = premiumToPay(
                address(oToken),
                address(paymentToken),
                _amt
            );
            paymentToken.transferFrom(
                msg.sender,
                address(this),
                paymentTokensToTransfer
            );

            // Token to Token
            paymentToken.approve(address(exchange), LARGE_APPROVAL_NUMBER);

            emit BuyOTokens(
                msg.sender,
                _transferTo,
                address(oToken),
                address(paymentToken),
                _amt,
                paymentTokensToTransfer
            );

            return
                exchange.tokenToTokenTransferInput(
                    paymentTokensToTransfer,
                    1,
                    1,
                    LARGE_BLOCK_SIZE,
                    _transferTo,
                    address(oToken)
                );
        } else {
            // ETH to Token
            UniswapExchangeInterface exchange = UniswapExchangeInterface(
                UNISWAP_FACTORY.getExchange(address(oToken))
            );

            uint256 ethToTransfer = exchange.getEthToTokenOutputPrice(_amt);

            emit BuyOTokens(
                msg.sender,
                _transferTo,
                address(oToken),
                address(paymentToken),
                _amt,
                ethToTransfer
            );

            return
                exchange.ethToTokenTransferOutput.value(ethToTransfer)(
                    _amt,
                    LARGE_BLOCK_SIZE,
                    _transferTo
                );
        }
    }

    function getExchange(address _token)
        internal
        view
        returns (UniswapExchangeInterface)
    {
        UniswapExchangeInterface exchange = UniswapExchangeInterface(
            UNISWAP_FACTORY.getExchange(_token)
        );

        if (address(exchange) == address(0)) {
            revert("No payout exchange");
        }

        return exchange;
    }

    function isETH(IERC20 _ierc20) internal pure returns (bool) {
        return _ierc20 == IERC20(0);
    }

    function() external payable {
        // to get ether from uniswap exchanges
    }

}

// File: @openzeppelin/contracts/token/ERC20/ERC20Detailed.sol

pragma solidity ^0.5.0;


/**
 * @dev Optional functions from the ERC20 standard.
 */
contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @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.
     *
     * 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;
    }
}

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

pragma solidity ^0.5.0;

/**
 * @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.
 *
 * 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 {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @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(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _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 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 onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/OptionsContract.sol

pragma solidity 0.5.10;











/**
 * @title Opyn's Options Contract
 * @author Opyn
 */
contract OptionsContract is Ownable, ERC20 {
    using SafeMath for uint256;

    /* represents floting point numbers, where number = value * 10 ** exponent
    i.e 0.1 = 10 * 10 ** -3 */
    struct Number {
        uint256 value;
        int32 exponent;
    }

    // Keeps track of the weighted collateral and weighted debt for each vault.
    struct Vault {
        uint256 collateral;
        uint256 oTokensIssued;
        uint256 underlying;
        bool owned;
    }

    OptionsExchange public optionsExchange;

    mapping(address => Vault) internal vaults;

    address payable[] internal vaultOwners;

    // 10 is 0.01 i.e. 1% incentive.
    Number public liquidationIncentive = Number(10, -3);

    // 100 is egs. 0.1 i.e. 10%.
    Number public transactionFee = Number(0, -3);

    /* 500 is 0.5. Max amount that a Vault can be liquidated by i.e.
    max collateral that can be taken in one function call */
    Number public liquidationFactor = Number(500, -3);

    /* 16 means 1.6. The minimum ratio of a Vault's collateral to insurance promised.
    The ratio is calculated as below:
    vault.collateral / (Vault.oTokensIssued * strikePrice) */
    Number public minCollateralizationRatio = Number(16, -1);

    // The amount of insurance promised per oToken
    Number public strikePrice;

    // The amount of underlying that 1 oToken protects.
    Number public oTokenExchangeRate;

    /* UNIX time.
    Exercise period starts at `(expiry - windowSize)` and ends at `expiry` */
    uint256 internal windowSize;

    /* The total fees accumulated in the contract any time liquidate or exercise is called */
    uint256 internal totalFee;

    // The time of expiry of the options contract
    uint256 public expiry;

    // The precision of the collateral
    int32 public collateralExp = -18;

    // The precision of the underlying
    int32 public underlyingExp = -18;

    // The collateral asset
    IERC20 public collateral;

    // The asset being protected by the insurance
    IERC20 public underlying;

    // The asset in which insurance is denominated in.
    IERC20 public strike;

    // The Oracle used for the contract
    CompoundOracleInterface public COMPOUND_ORACLE;

    // The name of  the contract
    string public name;

    // The symbol of  the contract
    string public symbol;

    // The number of decimals of the contract
    uint8 public decimals;

    /**
    * @param _collateral The collateral asset
    * @param _collExp The precision of the collateral (-18 if ETH)
    * @param _underlying The asset that is being protected
    * @param _underlyingExp The precision of the underlying asset
    * @param _oTokenExchangeExp The precision of the `amount of underlying` that 1 oToken protects
    * @param _strikePrice The amount of strike asset that will be paid out per oToken
    * @param _strikeExp The precision of the strike price.
    * @param _strike The asset in which the insurance is calculated
    * @param _expiry The time at which the insurance expires
    * @param _optionsExchange The contract which interfaces with the exchange + oracle
    * @param _oracleAddress The address of the oracle
    * @param _windowSize UNIX time. Exercise window is from `expiry - _windowSize` to `expiry`.
    */
    constructor(
        IERC20 _collateral,
        int32 _collExp,
        IERC20 _underlying,
        int32 _underlyingExp,
        int32 _oTokenExchangeExp,
        uint256 _strikePrice,
        int32 _strikeExp,
        IERC20 _strike,
        uint256 _expiry,
        OptionsExchange _optionsExchange,
        address _oracleAddress,
        uint256 _windowSize
    ) public {
        require(block.timestamp < _expiry, "Can't deploy an expired contract");
        require(
            _windowSize <= _expiry,
            "Exercise window can't be longer than the contract's lifespan"
        );
        require(
            isWithinExponentRange(_collExp),
            "collateral exponent not within expected range"
        );
        require(
            isWithinExponentRange(_underlyingExp),
            "underlying exponent not within expected range"
        );
        require(
            isWithinExponentRange(_strikeExp),
            "strike price exponent not within expected range"
        );
        require(
            isWithinExponentRange(_oTokenExchangeExp),
            "oToken exchange rate exponent not within expected range"
        );

        collateral = _collateral;
        collateralExp = _collExp;

        underlying = _underlying;
        underlyingExp = _underlyingExp;
        oTokenExchangeRate = Number(1, _oTokenExchangeExp);

        strikePrice = Number(_strikePrice, _strikeExp);
        strike = _strike;

        expiry = _expiry;
        COMPOUND_ORACLE = CompoundOracleInterface(_oracleAddress);
        optionsExchange = _optionsExchange;
        windowSize = _windowSize;
    }

    /*** Events ***/
    event VaultOpened(address payable vaultOwner);
    event ETHCollateralAdded(
        address payable vaultOwner,
        uint256 amount,
        address payer
    );
    event ERC20CollateralAdded(
        address payable vaultOwner,
        uint256 amount,
        address payer
    );
    event IssuedOTokens(
        address issuedTo,
        uint256 oTokensIssued,
        address payable vaultOwner
    );
    event Liquidate(
        uint256 amtCollateralToPay,
        address payable vaultOwner,
        address payable liquidator
    );
    event Exercise(
        uint256 amtUnderlyingToPay,
        uint256 amtCollateralToPay,
        address payable exerciser,
        address payable vaultExercisedFrom
    );
    event RedeemVaultBalance(
        uint256 amtCollateralRedeemed,
        uint256 amtUnderlyingRedeemed,
        address payable vaultOwner
    );
    event BurnOTokens(address payable vaultOwner, uint256 oTokensBurned);
    event RemoveCollateral(uint256 amtRemoved, address payable vaultOwner);
    event UpdateParameters(
        uint256 liquidationIncentive,
        uint256 liquidationFactor,
        uint256 transactionFee,
        uint256 minCollateralizationRatio,
        address owner
    );
    event TransferFee(address payable to, uint256 fees);
    event RemoveUnderlying(
        uint256 amountUnderlying,
        address payable vaultOwner
    );

    /**
     * @dev Throws if called Options contract is expired.
     */
    modifier notExpired() {
        require(!hasExpired(), "Options contract expired");
        _;
    }

    /**
     * @notice This function gets the array of vaultOwners
     */
    function getVaultOwners() public view returns (address payable[] memory) {
        address payable[] memory owners;
        uint256 index = 0;
        for (uint256 i = 0; i < vaultOwners.length; i++) {
            if (hasVault(vaultOwners[i])) {
                owners[index] = vaultOwners[i];
                index++;
            }
        }

        return owners;
    }

    /**
     * @notice Can only be called by owner. Used to update the fees, minminCollateralizationRatio, etc
     * @param _liquidationIncentive The incentive paid to liquidator. 10 is 0.01 i.e. 1% incentive.
     * @param _liquidationFactor Max amount that a Vault can be liquidated by. 500 is 0.5.
     * @param _transactionFee The fees paid to our protocol every time a execution happens. 100 is egs. 0.1 i.e. 10%.
     * @param _minCollateralizationRatio The minimum ratio of a Vault's collateral to insurance promised. 16 means 1.6.
     */
    function updateParameters(
        uint256 _liquidationIncentive,
        uint256 _liquidationFactor,
        uint256 _transactionFee,
        uint256 _minCollateralizationRatio
    ) public onlyOwner {
        require(
            _liquidationIncentive <= 200,
            "Can't have >20% liquidation incentive"
        );
        require(
            _liquidationFactor <= 1000,
            "Can't liquidate more than 100% of the vault"
        );
        require(_transactionFee <= 100, "Can't have transaction fee > 10%");
        require(
            _minCollateralizationRatio >= 10,
            "Can't have minCollateralizationRatio < 1"
        );

        liquidationIncentive.value = _liquidationIncentive;
        liquidationFactor.value = _liquidationFactor;
        transactionFee.value = _transactionFee;
        minCollateralizationRatio.value = _minCollateralizationRatio;

        emit UpdateParameters(
            _liquidationIncentive,
            _liquidationFactor,
            _transactionFee,
            _minCollateralizationRatio,
            owner()
        );
    }

    /**
     * @notice Can only be called by owner. Used to set the name, symbol and decimals of the contract
     * @param _name The name of the contract
     * @param _symbol The symbol of the contract
     */
    function setDetails(string memory _name, string memory _symbol)
        public
        onlyOwner
    {
        name = _name;
        symbol = _symbol;
        decimals = uint8(-1 * oTokenExchangeRate.exponent);
        require(
            decimals >= 0,
            "1 oToken cannot protect less than the smallest unit of the asset"
        );
    }

    /**
     * @notice Can only be called by owner. Used to take out the protocol fees from the contract.
     * @param _address The address to send the fee to.
     */
    function transferFee(address payable _address) public onlyOwner {
        uint256 fees = totalFee;
        totalFee = 0;
        transferCollateral(_address, fees);

        emit TransferFee(_address, fees);
    }

    /**
     * @notice Checks if a `owner` has already created a Vault
     * @param owner The address of the supposed owner
     * @return true or false
     */
    function hasVault(address payable owner) public view returns (bool) {
        return vaults[owner].owned;
    }

    /**
     * @notice Creates a new empty Vault and sets the owner of the vault to be the msg.sender.
     */
    function openVault() public notExpired returns (bool) {
        require(!hasVault(msg.sender), "Vault already created");

        vaults[msg.sender] = Vault(0, 0, 0, true);
        vaultOwners.push(msg.sender);

        emit VaultOpened(msg.sender);
        return true;
    }

    /**
     * @notice If the collateral type is ETH, anyone can call this function any time before
     * expiry to increase the amount of collateral in a Vault. Will fail if ETH is not the
     * collateral asset.
     * Remember that adding ETH collateral even if no oTokens have been created can put the owner at a
     * risk of losing the collateral if an exercise event happens.
     * Ensure that you issue and immediately sell oTokens to allow the owner to earn premiums.
     * (Either call the createAndSell function in the oToken contract or batch the
     * addERC20Collateral, issueOTokens and sell transactions and ensure they happen atomically to protect
     * the end user).
     * @param vaultOwner the index of the Vault to which collateral will be added.
     */
    function addETHCollateral(address payable vaultOwner)
        public
        payable
        notExpired
        returns (uint256)
    {
        require(isETH(collateral), "ETH is not the specified collateral type");
        require(hasVault(vaultOwner), "Vault does not exist");

        emit ETHCollateralAdded(vaultOwner, msg.value, msg.sender);
        return _addCollateral(vaultOwner, msg.value);
    }

    /**
     * @notice If the collateral type is any ERC20, anyone can call this function any time before
     * expiry to increase the amount of collateral in a Vault. Can only transfer in the collateral asset.
     * Will fail if ETH is the collateral asset.
     * The user has to allow the contract to handle their ERC20 tokens on his behalf before these
     * functions are called.
     * Remember that adding ERC20 collateral even if no oTokens have been created can put the owner at a
     * risk of losing the collateral. Ensure that you issue and immediately sell the oTokens!
     * (Either call the createAndSell function in the oToken contract or batch the
     * addERC20Collateral, issueOTokens and sell transactions and ensure they happen atomically to protect
     * the end user).
     * @param vaultOwner the index of the Vault to which collateral will be added.
     * @param amt the amount of collateral to be transferred in.
     */
    function addERC20Collateral(address payable vaultOwner, uint256 amt)
        public
        notExpired
        returns (uint256)
    {
        require(
            collateral.transferFrom(msg.sender, address(this), amt),
            "Could not transfer in collateral tokens"
        );
        require(hasVault(vaultOwner), "Vault does not exist");

        emit ERC20CollateralAdded(vaultOwner, amt, msg.sender);
        return _addCollateral(vaultOwner, amt);
    }

    /**
     * @notice Returns the amount of underlying to be transferred during an exercise call
     */
    function underlyingRequiredToExercise(uint256 oTokensToExercise)
        public
        view
        returns (uint256)
    {
        uint64 underlyingPerOTokenExp = uint64(
            oTokenExchangeRate.exponent - underlyingExp
        );
        return oTokensToExercise.mul(10**underlyingPerOTokenExp);
    }

    /**
     * @notice Returns true if exercise can be called
     */
    function isExerciseWindow() public view returns (bool) {
        return ((block.timestamp >= expiry.sub(windowSize)) &&
            (block.timestamp < expiry));
    }

    /**
     * @notice Returns true if the oToken contract has expired
     */
    function hasExpired() public view returns (bool) {
        return (block.timestamp >= expiry);
    }

    /**
     * @notice Called by anyone holding the oTokens and underlying during the
     * exercise window i.e. from `expiry - windowSize` time to `expiry` time. The caller
     * transfers in their oTokens and corresponding amount of underlying and gets
     * `strikePrice * oTokens` amount of collateral out. The collateral paid out is taken from
     * the each vault owner starting with the first and iterating until the oTokens to exercise
     * are found.
     * NOTE: This uses a for loop and hence could run out of gas if the array passed in is too big!
     * @param oTokensToExercise the number of oTokens being exercised.
     * @param vaultsToExerciseFrom the array of vaults to exercise from.
     */
    function exercise(
        uint256 oTokensToExercise,
        address payable[] memory vaultsToExerciseFrom
    ) public payable {
        for (uint256 i = 0; i < vaultsToExerciseFrom.length; i++) {
            address payable vaultOwner = vaultsToExerciseFrom[i];
            require(
                hasVault(vaultOwner),
                "Cannot exercise from a vault that doesn't exist"
            );
            Vault storage vault = vaults[vaultOwner];
            if (oTokensToExercise == 0) {
                return;
            } else if (vault.oTokensIssued >= oTokensToExercise) {
                _exercise(oTokensToExercise, vaultOwner);
                return;
            } else {
                oTokensToExercise = oTokensToExercise.sub(vault.oTokensIssued);
                _exercise(vault.oTokensIssued, vaultOwner);
            }
        }
        require(
            oTokensToExercise == 0,
            "Specified vaults have insufficient collateral"
        );
    }

    /**
     * @notice This function allows the vault owner to remove their share of underlying after an exercise
     */
    function removeUnderlying() public {
        require(hasVault(msg.sender), "Vault does not exist");
        Vault storage vault = vaults[msg.sender];

        require(vault.underlying > 0, "No underlying balance");

        uint256 underlyingToTransfer = vault.underlying;
        vault.underlying = 0;

        transferUnderlying(msg.sender, underlyingToTransfer);
        emit RemoveUnderlying(underlyingToTransfer, msg.sender);

    }

    /**
     * @notice This function is called to issue the option tokens. Remember that issuing oTokens even if they
     * haven't been sold can put the owner at a risk of not making premiums on the oTokens. Ensure that you
     * issue and immidiately sell the oTokens! (Either call the createAndSell function in the oToken contract
     * of batch the issueOTokens transaction with a sell transaction and ensure it happens atomically).
     * @dev The owner of a Vault should only be able to have a max of
     * repo.collateral * collateralToStrike / (minminCollateralizationRatio * strikePrice) tokens issued.
     * @param oTokensToIssue The number of o tokens to issue
     * @param receiver The address to send the oTokens to
     */
    function issueOTokens(uint256 oTokensToIssue, address receiver)
        public
        notExpired
    {
        //check that we're properly collateralized to mint this number, then call _mint(address account, uint256 amount)
        require(hasVault(msg.sender), "Vault does not exist");

        Vault storage vault = vaults[msg.sender];

        // checks that the vault is sufficiently collateralized
        uint256 newOTokensBalance = vault.oTokensIssued.add(oTokensToIssue);
        require(isSafe(vault.collateral, newOTokensBalance), "unsafe to mint");

        // issue the oTokens
        vault.oTokensIssued = newOTokensBalance;
        _mint(receiver, oTokensToIssue);

        emit IssuedOTokens(receiver, oTokensToIssue, msg.sender);
        return;
    }

    /**
     * @notice Returns the vault for a given address
     * @param vaultOwner the owner of the Vault to return
     */
    function getVault(address payable vaultOwner)
        public
        view
        returns (uint256, uint256, uint256, bool)
    {
        Vault storage vault = vaults[vaultOwner];
        return (
            vault.collateral,
            vault.oTokensIssued,
            vault.underlying,
            vault.owned
        );
    }

    /**
     * @notice Returns true if the given ERC20 is ETH.
     * @param _ierc20 the ERC20 asset.
     */
    function isETH(IERC20 _ierc20) public pure returns (bool) {
        return _ierc20 == IERC20(0);
    }

    /**
     * @notice allows the owner to burn their oTokens to increase the collateralization ratio of
     * their vault.
     * @param amtToBurn number of oTokens to burn
     * @dev only want to call this function before expiry. After expiry, no benefit to calling it.
     */
    function burnOTokens(uint256 amtToBurn) public notExpired {
        require(hasVault(msg.sender), "Vault does not exist");

        Vault storage vault = vaults[msg.sender];

        vault.oTokensIssued = vault.oTokensIssued.sub(amtToBurn);
        _burn(msg.sender, amtToBurn);

        emit BurnOTokens(msg.sender, amtToBurn);
    }

    /**
     * @notice allows the owner to remove excess collateral from the vault before expiry. Removing collateral lowers
     * the collateralization ratio of the vault.
     * @param amtToRemove Amount of collateral to remove in 10^-18.
     */
    function removeCollateral(uint256 amtToRemove) public notExpired {
        require(amtToRemove > 0, "Cannot remove 0 collateral");
        require(hasVault(msg.sender), "Vault does not exist");

        Vault storage vault = vaults[msg.sender];
        require(
            amtToRemove <= getCollateral(msg.sender),
            "Can't remove more collateral than owned"
        );

        // check that vault will remain safe after removing collateral
        uint256 newCollateralBalance = vault.collateral.sub(amtToRemove);

        require(
            isSafe(newCollateralBalance, vault.oTokensIssued),
            "Vault is unsafe"
        );

        // remove the collateral
        vault.collateral = newCollateralBalance;
        transferCollateral(msg.sender, amtToRemove);

        emit RemoveCollateral(amtToRemove, msg.sender);
    }

    /**
     * @notice after expiry, each vault holder can get back their proportional share of collateral
     * from vaults that they own.
     * @dev The owner gets all of their collateral back if no exercise event took their collateral.
     */
    function redeemVaultBalance() public {
        require(hasExpired(), "Can't collect collateral until expiry");
        require(hasVault(msg.sender), "Vault does not exist");

        // pay out owner their share
        Vault storage vault = vaults[msg.sender];

        // To deal with lower precision
        uint256 collateralToTransfer = vault.collateral;
        uint256 underlyingToTransfer = vault.underlying;

        vault.collateral = 0;
        vault.oTokensIssued = 0;
        vault.underlying = 0;

        transferCollateral(msg.sender, collateralToTransfer);
        transferUnderlying(msg.sender, underlyingToTransfer);

        emit RedeemVaultBalance(
            collateralToTransfer,
            underlyingToTransfer,
            msg.sender
        );
    }

    /**
     * This function returns the maximum amount of collateral liquidatable if the given vault is unsafe
     * @param vaultOwner The index of the vault to be liquidated
     */
    function maxOTokensLiquidatable(address payable vaultOwner)
        public
        view
        returns (uint256)
    {
        if (isUnsafe(vaultOwner)) {
            Vault storage vault = vaults[vaultOwner];
            uint256 maxCollateralLiquidatable = vault
                .collateral
                .mul(liquidationFactor.value)
                .div(10**uint256(-liquidationFactor.exponent));

            uint256 one = 10**uint256(-liquidationIncentive.exponent);
            Number memory liqIncentive = Number(
                liquidationIncentive.value.add(one),
                liquidationIncentive.exponent
            );
            return calculateOTokens(maxCollateralLiquidatable, liqIncentive);
        } else {
            return 0;
        }
    }

    /**
     * @notice This function can be called by anyone who notices a vault is undercollateralized.
     * The caller gets a reward for reducing the amount of oTokens in circulation.
     * @dev Liquidator comes with _oTokens. They get _oTokens * strikePrice * (incentive + fee)
     * amount of collateral out. They can liquidate a max of liquidationFactor * vault.collateral out
     * in one function call i.e. partial liquidations.
     * @param vaultOwner The index of the vault to be liquidated
     * @param oTokensToLiquidate The number of oTokens being taken out of circulation
     */
    function liquidate(address payable vaultOwner, uint256 oTokensToLiquidate)
        public
        notExpired
    {
        require(hasVault(vaultOwner), "Vault does not exist");

        Vault storage vault = vaults[vaultOwner];

        // cannot liquidate a safe vault.
        require(isUnsafe(vaultOwner), "Vault is safe");

        // Owner can't liquidate themselves
        require(msg.sender != vaultOwner, "Owner can't liquidate themselves");

        uint256 amtCollateral = calculateCollateralToPay(
            oTokensToLiquidate,
            Number(1, 0)
        );
        uint256 amtIncentive = calculateCollateralToPay(
            oTokensToLiquidate,
            liquidationIncentive
        );
        uint256 amtCollateralToPay = amtCollateral.add(amtIncentive);

        // calculate the maximum amount of collateral that can be liquidated
        uint256 maxCollateralLiquidatable = vault.collateral.mul(
            liquidationFactor.value
        );

        if (liquidationFactor.exponent > 0) {
            maxCollateralLiquidatable = maxCollateralLiquidatable.mul(
                10**uint256(liquidationFactor.exponent)
            );
        } else {
            maxCollateralLiquidatable = maxCollateralLiquidatable.div(
                10**uint256(-1 * liquidationFactor.exponent)
            );
        }

        require(
            amtCollateralToPay <= maxCollateralLiquidatable,
            "Can only liquidate liquidation factor at any given time"
        );

        // deduct the collateral and oTokensIssued
        vault.collateral = vault.collateral.sub(amtCollateralToPay);
        vault.oTokensIssued = vault.oTokensIssued.sub(oTokensToLiquidate);

        // transfer the collateral and burn the _oTokens
        _burn(msg.sender, oTokensToLiquidate);
        transferCollateral(msg.sender, amtCollateralToPay);

        emit Liquidate(amtCollateralToPay, vaultOwner, msg.sender);
    }

    /**
     * @notice checks if a vault is unsafe. If so, it can be liquidated
     * @param vaultOwner The number of the vault to check
     * @return true or false
     */
    function isUnsafe(address payable vaultOwner) public view returns (bool) {
        bool stillUnsafe = !isSafe(
            getCollateral(vaultOwner),
            getOTokensIssued(vaultOwner)
        );
        return stillUnsafe;
    }

    /**
     * @notice This function returns if an -30 <= exponent <= 30
     */
    function isWithinExponentRange(int32 val) internal pure returns (bool) {
        return ((val <= 30) && (val >= -30));
    }

    /**
     * @notice This function calculates and returns the amount of collateral in the vault
    */
    function getCollateral(address payable vaultOwner)
        internal
        view
        returns (uint256)
    {
        Vault storage vault = vaults[vaultOwner];
        return vault.collateral;
    }

    /**
     * @notice This function calculates and returns the amount of puts issued by the Vault
    */
    function getOTokensIssued(address payable vaultOwner)
        internal
        view
        returns (uint256)
    {
        Vault storage vault = vaults[vaultOwner];
        return vault.oTokensIssued;
    }

    /**
     * @notice Called by anyone holding the oTokens and underlying during the
     * exercise window i.e. from `expiry - windowSize` time to `expiry` time. The caller
     * transfers in their oTokens and corresponding amount of underlying and gets
     * `strikePrice * oTokens` amount of collateral out. The collateral paid out is taken from
     * the specified vault holder. At the end of the expiry window, the vault holder can redeem their balance
     * of collateral. The vault owner can withdraw their underlying at any time.
     * The user has to allow the contract to handle their oTokens and underlying on his behalf before these functions are called.
     * @param oTokensToExercise the number of oTokens being exercised.
     * @param vaultToExerciseFrom the address of the vaultOwner to take collateral from.
     * @dev oTokenExchangeRate is the number of underlying tokens that 1 oToken protects.
     */
    function _exercise(
        uint256 oTokensToExercise,
        address payable vaultToExerciseFrom
    ) internal {
        // 1. before exercise window: revert
        require(
            isExerciseWindow(),
            "Can't exercise outside of the exercise window"
        );

        require(hasVault(vaultToExerciseFrom), "Vault does not exist");

        Vault storage vault = vaults[vaultToExerciseFrom];
        require(oTokensToExercise > 0, "Can't exercise 0 oTokens");
        // Check correct amount of oTokens passed in)
        require(
            oTokensToExercise <= vault.oTokensIssued,
            "Can't exercise more oTokens than the owner has"
        );
        // Ensure person calling has enough oTokens
        require(
            balanceOf(msg.sender) >= oTokensToExercise,
            "Not enough oTokens"
        );

        // 1. Check sufficient underlying
        // 1.1 update underlying balances
        uint256 amtUnderlyingToPay = underlyingRequiredToExercise(
            oTokensToExercise
        );
        vault.underlying = vault.underlying.add(amtUnderlyingToPay);

        // 2. Calculate Collateral to pay
        // 2.1 Payout enough collateral to get (strikePrice * oTokens) amount of collateral
        uint256 amtCollateralToPay = calculateCollateralToPay(
            oTokensToExercise,
            Number(1, 0)
        );

        // 2.2 Take a small fee on every exercise
        uint256 amtFee = calculateCollateralToPay(
            oTokensToExercise,
            transactionFee
        );
        totalFee = totalFee.add(amtFee);

        uint256 totalCollateralToPay = amtCollateralToPay.add(amtFee);
        require(
            totalCollateralToPay <= vault.collateral,
            "Vault underwater, can't exercise"
        );

        // 3. Update collateral + oToken balances
        vault.collateral = vault.collateral.sub(totalCollateralToPay);
        vault.oTokensIssued = vault.oTokensIssued.sub(oTokensToExercise);

        // 4. Transfer in underlying, burn oTokens + pay out collateral
        // 4.1 Transfer in underlying
        if (isETH(underlying)) {
            require(msg.value == amtUnderlyingToPay, "Incorrect msg.value");
        } else {
            require(
                underlying.transferFrom(
                    msg.sender,
                    address(this),
                    amtUnderlyingToPay
                ),
                "Could not transfer in tokens"
            );
        }
        // 4.2 burn oTokens
        _burn(msg.sender, oTokensToExercise);

        // 4.3 Pay out collateral
        transferCollateral(msg.sender, amtCollateralToPay);

        emit Exercise(
            amtUnderlyingToPay,
            amtCollateralToPay,
            msg.sender,
            vaultToExerciseFrom
        );

    }

    /**
     * @notice adds `_amt` collateral to `vaultOwner` and returns the new balance of the vault
     * @param vaultOwner the index of the vault
     * @param amt the amount of collateral to add
     */
    function _addCollateral(address payable vaultOwner, uint256 amt)
        internal
        notExpired
        returns (uint256)
    {
        Vault storage vault = vaults[vaultOwner];
        vault.collateral = vault.collateral.add(amt);

        return vault.collateral;
    }

    /**
     * @notice checks if a hypothetical vault is safe with the given collateralAmt and oTokensIssued
     * @param collateralAmt The amount of collateral the hypothetical vault has
     * @param oTokensIssued The amount of oTokens generated by the hypothetical vault
     * @return true or false
     */
    function isSafe(uint256 collateralAmt, uint256 oTokensIssued)
        internal
        view
        returns (bool)
    {
        // get price from Oracle
        uint256 collateralToEthPrice = getPrice(address(collateral));
        uint256 strikeToEthPrice = getPrice(address(strike));

        // check `oTokensIssued * minCollateralizationRatio * strikePrice <= collAmt * collateralToStrikePrice`
        uint256 leftSideVal = oTokensIssued
            .mul(minCollateralizationRatio.value)
            .mul(strikePrice.value);
        int32 leftSideExp = minCollateralizationRatio.exponent +
            strikePrice.exponent;

        uint256 rightSideVal = (collateralAmt.mul(collateralToEthPrice)).div(
            strikeToEthPrice
        );
        int32 rightSideExp = collateralExp;

        uint256 exp = 0;
        bool stillSafe = false;

        if (rightSideExp < leftSideExp) {
            exp = uint256(leftSideExp - rightSideExp);
            stillSafe = leftSideVal.mul(10**exp) <= rightSideVal;
        } else {
            exp = uint256(rightSideExp - leftSideExp);
            stillSafe = leftSideVal <= rightSideVal.mul(10**exp);
        }

        return stillSafe;
    }

    /**
     * This function returns the maximum amount of oTokens that can safely be issued against the specified amount of collateral.
     * @param collateralAmt The amount of collateral against which oTokens will be issued.
     */
    function maxOTokensIssuable(uint256 collateralAmt)
        public
        view
        returns (uint256)
    {
        return calculateOTokens(collateralAmt, minCollateralizationRatio);

    }

    /**
     * @notice This function is used to calculate the amount of tokens that can be issued.
     * @dev The amount of oTokens is determined by:
     * oTokensIssued  <= collateralAmt * collateralToStrikePrice / (proportion * strikePrice)
     * @param collateralAmt The amount of collateral
     * @param proportion The proportion of the collateral to pay out. If 100% of collateral
     * should be paid out, pass in Number(1, 0). The proportion might be less than 100% if
     * you are calculating fees.
     */
    function calculateOTokens(uint256 collateralAmt, Number memory proportion)
        internal
        view
        returns (uint256)
    {
        uint256 collateralToEthPrice = getPrice(address(collateral));
        uint256 strikeToEthPrice = getPrice(address(strike));

        // oTokensIssued  <= collAmt * collateralToStrikePrice / (proportion * strikePrice)
        uint256 denomVal = proportion.value.mul(strikePrice.value);
        int32 denomExp = proportion.exponent + strikePrice.exponent;

        uint256 numeratorVal = (collateralAmt.mul(collateralToEthPrice)).div(
            strikeToEthPrice
        );
        int32 numeratorExp = collateralExp;

        uint256 exp = 0;
        uint256 numOptions = 0;

        if (numeratorExp < denomExp) {
            exp = uint256(denomExp - numeratorExp);
            numOptions = numeratorVal.div(denomVal.mul(10**exp));
        } else {
            exp = uint256(numeratorExp - denomExp);
            numOptions = numeratorVal.mul(10**exp).div(denomVal);
        }

        return numOptions;
    }

    /**
     * @notice This function calculates the amount of collateral to be paid out.
     * @dev The amount of collateral to paid out is determined by:
     * (proportion * strikePrice * strikeToCollateralPrice * oTokens) amount of collateral.
     * @param _oTokens The number of oTokens.
     * @param proportion The proportion of the collateral to pay out. If 100% of collateral
     * should be paid out, pass in Number(1, 0). The proportion might be less than 100% if
     * you are calculating fees.
     */
    function calculateCollateralToPay(
        uint256 _oTokens,
        Number memory proportion
    ) internal view returns (uint256) {
        // Get price from oracle
        uint256 collateralToEthPrice = getPrice(address(collateral));
        uint256 strikeToEthPrice = getPrice(address(strike));

        // calculate how much should be paid out
        uint256 amtCollateralToPayInEthNum = _oTokens
            .mul(strikePrice.value)
            .mul(proportion.value)
            .mul(strikeToEthPrice);
        int32 amtCollateralToPayExp = strikePrice.exponent +
            proportion.exponent -
            collateralExp;
        uint256 amtCollateralToPay = 0;
        if (amtCollateralToPayExp > 0) {
            uint32 exp = uint32(amtCollateralToPayExp);
            amtCollateralToPay = amtCollateralToPayInEthNum.mul(10**exp).div(
                collateralToEthPrice
            );
        } else {
            uint32 exp = uint32(-1 * amtCollateralToPayExp);
            amtCollateralToPay = (amtCollateralToPayInEthNum.div(10**exp)).div(
                collateralToEthPrice
            );
        }

        return amtCollateralToPay;

    }

    /**
     * @notice This function transfers `amt` collateral to `_addr`
     * @param _addr The address to send the collateral to
     * @param _amt The amount of the collateral to pay out.
     */
    function transferCollateral(address payable _addr, uint256 _amt) internal {
        if (isETH(collateral)) {
            _addr.transfer(_amt);
        } else {
            collateral.transfer(_addr, _amt);
        }
    }

    /**
     * @notice This function transfers `amt` underlying to `_addr`
     * @param _addr The address to send the underlying to
     * @param _amt The amount of the underlying to pay out.
     */
    function transferUnderlying(address payable _addr, uint256 _amt) internal {
        if (isETH(underlying)) {
            _addr.transfer(_amt);
        } else {
            underlying.transfer(_addr, _amt);
        }
    }

    /**
     * @notice This function gets the price ETH (wei) to asset price.
     * @param asset The address of the asset to get the price of
     */
    function getPrice(address asset) internal view returns (uint256) {
        if (address(collateral) == address(strike)) {
            return 1;
        } else if (asset == address(0)) {
            return (10**18);
        } else {
            return COMPOUND_ORACLE.getPrice(asset);
        }
    }
}

// File: contracts/oToken.sol

pragma solidity 0.5.10;


/**
 * @title Opyn's Options Contract
 * @author Opyn
 */

contract oToken is OptionsContract {
    /**
    * @param _collateral The collateral asset
    * @param _collExp The precision of the collateral (-18 if ETH)
    * @param _underlying The asset that is being protected
    * @param _underlyingExp The precision of the underlying asset
    * @param _oTokenExchangeExp The precision of the `amount of underlying` that 1 oToken protects
    * @param _strikePrice The amount of strike asset that will be paid out
    * @param _strikeExp The precision of the strike asset (-18 if ETH)
    * @param _strike The asset in which the insurance is calculated
    * @param _expiry The time at which the insurance expires
    * @param _optionsExchange The contract which interfaces with the exchange + oracle
    * @param _oracleAddress The address of the oracle
    * @param _windowSize UNIX time. Exercise window is from `expiry - _windowSize` to `expiry`.
    */
    constructor(
        IERC20 _collateral,
        int32 _collExp,
        IERC20 _underlying,
        int32 _underlyingExp,
        int32 _oTokenExchangeExp,
        uint256 _strikePrice,
        int32 _strikeExp,
        IERC20 _strike,
        uint256 _expiry,
        OptionsExchange _optionsExchange,
        address _oracleAddress,
        uint256 _windowSize
    )
        public
        OptionsContract(
            _collateral,
            _collExp,
            _underlying,
            _underlyingExp,
            _oTokenExchangeExp,
            _strikePrice,
            _strikeExp,
            _strike,
            _expiry,
            _optionsExchange,
            _oracleAddress,
            _windowSize
        )
    {}

    /**
     * @notice opens a Vault, adds ETH collateral, and mints new oTokens in one step
     * Remember that creating oTokens can put the owner at a risk of losing the collateral
     * if an exercise event happens.
     * The sell function provides the owner a chance to earn premiums.
     * Ensure that you create and immediately sell oTokens atmoically.
     * @param amtToCreate number of oTokens to create
     * @param receiver address to send the Options to
     */
    function createETHCollateralOption(uint256 amtToCreate, address receiver)
        external
        payable
    {
        openVault();
        addETHCollateralOption(amtToCreate, receiver);
    }

    /**
     * @notice adds ETH collateral, and mints new oTokens in one step to an existing Vault
     * Remember that creating oTokens can put the owner at a risk of losing the collateral
     * if an exercise event happens.
     * The sell function provides the owner a chance to earn premiums.
     * Ensure that you create and immediately sell oTokens atmoically.
     * @param amtToCreate number of oTokens to create
     * @param receiver address to send the Options to
     */
    function addETHCollateralOption(uint256 amtToCreate, address receiver)
        public
        payable
    {
        addETHCollateral(msg.sender);
        issueOTokens(amtToCreate, receiver);
    }

    /**
     * @notice opens a Vault, adds ETH collateral, mints new oTokens and sell in one step
     * @param amtToCreate number of oTokens to create
     * @param receiver address to receive the premiums
     */
    function createAndSellETHCollateralOption(
        uint256 amtToCreate,
        address payable receiver
    ) external payable {
        openVault();
        addETHCollateralOption(amtToCreate, address(this));
        this.approve(address(optionsExchange), amtToCreate);
        optionsExchange.sellOTokens(
            receiver,
            address(this),
            address(0),
            amtToCreate
        );
    }

    /**
     * @notice adds ETH collateral to an existing Vault, and mints new oTokens and sells the oTokens in one step
     * @param amtToCreate number of oTokens to create
     * @param receiver address to send the Options to
     */
    function addAndSellETHCollateralOption(
        uint256 amtToCreate,
        address payable receiver
    ) public payable {
        addETHCollateral(msg.sender);
        issueOTokens(amtToCreate, address(this));
        this.approve(address(optionsExchange), amtToCreate);
        optionsExchange.sellOTokens(
            receiver,
            address(this),
            address(0),
            amtToCreate
        );
    }

    /**
     * @notice opens a Vault, adds ERC20 collateral, and mints new oTokens in one step
     * Remember that creating oTokens can put the owner at a risk of losing the collateral
     * if an exercise event happens.
     * The sell function provides the owner a chance to earn premiums.
     * Ensure that you create and immediately sell oTokens atmoically.
     * @param amtToCreate number of oTokens to create
     * @param amtCollateral amount of collateral added
     * @param receiver address to send the Options to
     */
    function createERC20CollateralOption(
        uint256 amtToCreate,
        uint256 amtCollateral,
        address receiver
    ) external {
        openVault();
        addERC20CollateralOption(amtToCreate, amtCollateral, receiver);
    }

    /**
     * @notice adds ERC20 collateral, and mints new oTokens in one step
     * Remember that creating oTokens can put the owner at a risk of losing the collateral
     * if an exercise event happens.
     * The sell function provides the owner a chance to earn premiums.
     * Ensure that you create and immediately sell oTokens atmoically.
     * @param amtToCreate number of oTokens to create
     * @param amtCollateral amount of collateral added
     * @param receiver address to send the Options to
     */
    function addERC20CollateralOption(
        uint256 amtToCreate,
        uint256 amtCollateral,
        address receiver
    ) public {
        addERC20Collateral(msg.sender, amtCollateral);
        issueOTokens(amtToCreate, receiver);
    }

    /**
     * @notice opens a Vault, adds ERC20 collateral, mints new oTokens and sells the oTokens in one step
     * @param amtToCreate number of oTokens to create
     * @param amtCollateral amount of collateral added
     * @param receiver address to send the Options to
     */
    function createAndSellERC20CollateralOption(
        uint256 amtToCreate,
        uint256 amtCollateral,
        address payable receiver
    ) external {
        openVault();
        addERC20CollateralOption(amtToCreate, amtCollateral, address(this));
        this.approve(address(optionsExchange), amtToCreate);
        optionsExchange.sellOTokens(
            receiver,
            address(this),
            address(0),
            amtToCreate
        );
    }

    /**
     * @notice adds ERC20 collateral, mints new oTokens and sells the oTokens in one step
     * @param amtToCreate number of oTokens to create
     * @param amtCollateral amount of collateral added
     * @param receiver address to send the Options to
     */
    function addAndSellERC20CollateralOption(
        uint256 amtToCreate,
        uint256 amtCollateral,
        address payable receiver
    ) public {
        addERC20Collateral(msg.sender, amtCollateral);
        issueOTokens(amtToCreate, address(this));
        this.approve(address(optionsExchange), amtToCreate);
        optionsExchange.sellOTokens(
            receiver,
            address(this),
            address(0),
            amtToCreate
        );
    }
}

pragma solidity ^0.4.24;

// File: zos-lib/contracts/upgradeability/Proxy.sol

/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  function () payable external {
    _fallback();
  }

  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal view returns (address);

  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize)

      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas, implementation, 0, calldatasize, 0, 0)

      // Copy the returned data.
      returndatacopy(0, 0, returndatasize)

      switch result
      // delegatecall returns 0 on error.
      case 0 { revert(0, returndatasize) }
      default { return(0, returndatasize) }
    }
  }

  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal {
  }

  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}

// File: openzeppelin-solidity/contracts/AddressUtils.sol

/**
 * Utility library of inline functions on addresses
 */
library AddressUtils {

  /**
   * Returns whether the target address is a contract
   * @dev This function will return false if invoked during the constructor of a contract,
   * as the code is not actually created until after the constructor finishes.
   * @param addr address to check
   * @return whether the target address is a contract
   */
  function isContract(address addr) internal view returns (bool) {
    uint256 size;
    // XXX Currently there is no better way to check if there is a contract in an address
    // than to check the size of the code at that address.
    // See https://ethereum.stackexchange.com/a/14016/36603
    // for more details about how this works.
    // TODO Check this again before the Serenity release, because all addresses will be
    // contracts then.
    // solium-disable-next-line security/no-inline-assembly
    assembly { size := extcodesize(addr) }
    return size > 0;
  }

}

// File: zos-lib/contracts/upgradeability/UpgradeabilityProxy.sol

/**
 * @title UpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract UpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address implementation);

  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "org.zeppelinos.proxy.implementation", and is
   * validated in the constructor.
   */
  bytes32 private constant IMPLEMENTATION_SLOT = 0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3;

  /**
   * @dev Contract constructor.
   * @param _implementation Address of the initial implementation.
   */
  constructor(address _implementation) public {
    assert(IMPLEMENTATION_SLOT == keccak256("org.zeppelinos.proxy.implementation"));

    _setImplementation(_implementation);
  }

  /**
   * @dev Returns the current implementation.
   * @return Address of the current implementation
   */
  function _implementation() internal view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      impl := sload(slot)
    }
  }

  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }

  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) private {
    require(AddressUtils.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");

    bytes32 slot = IMPLEMENTATION_SLOT;

    assembly {
      sstore(slot, newImplementation)
    }
  }
}

// File: zos-lib/contracts/upgradeability/AdminUpgradeabilityProxy.sol

/**
 * @title AdminUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks.
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
  /**
   * @dev Emitted when the administration has been transferred.
   * @param previousAdmin Address of the previous admin.
   * @param newAdmin Address of the new admin.
   */
  event AdminChanged(address previousAdmin, address newAdmin);

  /**
   * @dev Storage slot with the admin of the contract.
   * This is the keccak-256 hash of "org.zeppelinos.proxy.admin", and is
   * validated in the constructor.
   */
  bytes32 private constant ADMIN_SLOT = 0x10d6a54a4754c8869d6886b5f5d7fbfa5b4522237ea5c60d11bc4e7a1ff9390b;

  /**
   * @dev Modifier to check whether the `msg.sender` is the admin.
   * If it is, it will run the function. Otherwise, it will delegate the call
   * to the implementation.
   */
  modifier ifAdmin() {
    if (msg.sender == _admin()) {
      _;
    } else {
      _fallback();
    }
  }

  /**
   * Contract constructor.
   * It sets the `msg.sender` as the proxy administrator.
   * @param _implementation address of the initial implementation.
   */
  constructor(address _implementation) UpgradeabilityProxy(_implementation) public {
    assert(ADMIN_SLOT == keccak256("org.zeppelinos.proxy.admin"));

    _setAdmin(msg.sender);
  }

  /**
   * @return The address of the proxy admin.
   */
  function admin() external view ifAdmin returns (address) {
    return _admin();
  }

  /**
   * @return The address of the implementation.
   */
  function implementation() external view ifAdmin returns (address) {
    return _implementation();
  }

  /**
   * @dev Changes the admin of the proxy.
   * Only the current admin can call this function.
   * @param newAdmin Address to transfer proxy administration to.
   */
  function changeAdmin(address newAdmin) external ifAdmin {
    require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
    emit AdminChanged(_admin(), newAdmin);
    _setAdmin(newAdmin);
  }

  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }

  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be
   * called, as described in
   * https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes data) payable external ifAdmin {
    _upgradeTo(newImplementation);
    require(address(this).call.value(msg.value)(data));
  }

  /**
   * @return The admin slot.
   */
  function _admin() internal view returns (address adm) {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      adm := sload(slot)
    }
  }

  /**
   * @dev Sets the address of the proxy admin.
   * @param newAdmin Address of the new proxy admin.
   */
  function _setAdmin(address newAdmin) internal {
    bytes32 slot = ADMIN_SLOT;

    assembly {
      sstore(slot, newAdmin)
    }
  }

  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal {
    require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
    super._willFallback();
  }
}

// File: contracts/FiatTokenProxy.sol

/**
* Copyright CENTRE SECZ 2018
*
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is furnished to 
* do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all 
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

pragma solidity ^0.4.24;


/**
 * @title FiatTokenProxy
 * @dev This contract proxies FiatToken calls and enables FiatToken upgrades
*/ 
contract FiatTokenProxy is AdminUpgradeabilityProxy {
    constructor(address _implementation) public AdminUpgradeabilityProxy(_implementation) {
    }
}

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

pragma solidity ^0.5.0;

/*
 * @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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view 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 ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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 ^0.5.0;

/**
 * @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.
     *
     * _Available since v2.4.0._
     */
    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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

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

pragma solidity ^0.5.0;




/**
 * @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 {ERC20Mintable}.
 *
 * 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;

    mapping (address => uint256) private _balances;

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

    uint256 private _totalSupply;

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

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view 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 returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

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

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public 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 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 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 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 {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _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 {
        require(account != address(0), "ERC20: mint to the zero address");

        _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 {
        require(account != address(0), "ERC20: burn from the zero address");

        _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 {
        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 Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

// File: contracts/lib/CompoundOracleInterface.sol

pragma solidity ^0.5.0;
// AT MAINNET ADDRESS: 0x02557a5E05DeFeFFD4cAe6D83eA3d173B272c904

contract CompoundOracleInterface {
    // returns asset:eth -- to get USDC:eth, have to do 10**24/result,


    constructor() public {
    }

    /**
  * @notice retrieves price of an asset
  * @dev function to get price for an asset
  * @param asset Asset for which to get the price
  * @return uint mantissa of asset price (scaled by 1e18) or zero if unset or contract paused
  */
    function getPrice(address asset) public view returns (uint);
    function getUnderlyingPrice(ERC20 cToken) public view returns (uint);
    // function getPrice(address asset) public view returns (uint) {
    //     return 527557000000000;
    // }

}

// File: contracts/lib/UniswapExchangeInterface.sol

pragma solidity 0.5.10;


// Solidity Interface
contract UniswapExchangeInterface {
    // Address of ERC20 token sold on this exchange
    function tokenAddress() external view returns (address token);
    // Address of Uniswap Factory
    function factoryAddress() external view returns (address factory);
    // Provide Liquidity
    function addLiquidity(uint256 min_liquidity, uint256 max_tokens, uint256 deadline) external payable returns (uint256);
    function removeLiquidity(uint256 amount, uint256 min_eth, uint256 min_tokens, uint256 deadline) external returns (uint256, uint256);
    // Get Prices
    function getEthToTokenInputPrice(uint256 eth_sold) external view returns (uint256 tokens_bought);
    function getEthToTokenOutputPrice(uint256 tokens_bought) external view returns (uint256 eth_sold);
    function getTokenToEthInputPrice(uint256 tokens_sold) external view returns (uint256 eth_bought);
    function getTokenToEthOutputPrice(uint256 eth_bought) external view returns (uint256 tokens_sold);
    // Trade ETH to ERC20
    function ethToTokenSwapInput(uint256 min_tokens, uint256 deadline) external payable returns (uint256  tokens_bought);
    function ethToTokenTransferInput(uint256 min_tokens, uint256 deadline, address recipient) external payable returns (uint256  tokens_bought);
    function ethToTokenSwapOutput(uint256 tokens_bought, uint256 deadline) external payable returns (uint256  eth_sold);
    function ethToTokenTransferOutput(uint256 tokens_bought, uint256 deadline, address recipient) external payable returns (uint256  eth_sold);
    // Trade ERC20 to ETH
    function tokenToEthSwapInput(uint256 tokens_sold, uint256 min_eth, uint256 deadline) external returns (uint256  eth_bought);
    function tokenToEthTransferInput(uint256 tokens_sold, uint256 min_eth, uint256 deadline, address recipient) external returns (uint256  eth_bought);
    function tokenToEthSwapOutput(uint256 eth_bought, uint256 max_tokens, uint256 deadline) external returns (uint256  tokens_sold);
    function tokenToEthTransferOutput(uint256 eth_bought, uint256 max_tokens, uint256 deadline, address recipient) external returns (uint256  tokens_sold);
    // Trade ERC20 to ERC20
    function tokenToTokenSwapInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address token_addr) external returns (uint256  tokens_bought);
    function tokenToTokenTransferInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address recipient, address token_addr) external returns (uint256  tokens_bought);
    function tokenToTokenSwapOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address token_addr) external returns (uint256  tokens_sold);
    function tokenToTokenTransferOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address recipient, address token_addr) external returns (uint256  tokens_sold);
    // Trade ERC20 to Custom Pool
    function tokenToExchangeSwapInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address exchange_addr) external returns (uint256  tokens_bought);
    function tokenToExchangeTransferInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address recipient, address exchange_addr) external returns (uint256  tokens_bought);
    function tokenToExchangeSwapOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address exchange_addr) external returns (uint256  tokens_sold);
    function tokenToExchangeTransferOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address recipient, address exchange_addr) external returns (uint256  tokens_sold);
    // ERC20 comaptibility for liquidity tokens
    bytes32 public name;
    bytes32 public symbol;
    uint256 public decimals;
    function transfer(address _to, uint256 _value) external returns (bool);
    function transferFrom(address _from, address _to, uint256 value) external returns (bool);
    function approve(address _spender, uint256 _value) external returns (bool);
    function allowance(address _owner, address _spender) external view returns (uint256);
    function balanceOf(address _owner) external view returns (uint256);
    function totalSupply() external view returns (uint256);
    // Never use
    function setup(address token_addr) external;
}

// File: contracts/lib/UniswapFactoryInterface.sol

pragma solidity 0.5.10;


// Solidity Interface
contract UniswapFactoryInterface {
    // Public Variables
    address public exchangeTemplate;
    uint256 public tokenCount;
    // // Create Exchange
    function createExchange(address token) external returns (address exchange);
    // Get Exchange and Token Info
    function getExchange(address token) external view returns (address exchange);
    function getToken(address exchange) external view returns (address token);
    function getTokenWithId(uint256 tokenId) external view returns (address token);
    // Never use
    function initializeFactory(address template) external;
    // function createExchange(address token) external returns (address exchange) {
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
    // // Get Exchange and Token Info
    // function getExchange(address token) external view returns (address exchange){
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
    // function getToken(address exchange) external view returns (address token) {
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
    // function getTokenWithId(uint256 tokenId) external view returns (address token) {
    //     return 0x06D014475F84Bb45b9cdeD1Cf3A1b8FE3FbAf128;
    // }
}

// File: contracts/OptionsUtils.sol

pragma solidity 0.5.10;





contract OptionsUtils {
    // defauls are for mainnet
    UniswapFactoryInterface public UNISWAP_FACTORY;

    CompoundOracleInterface public COMPOUND_ORACLE;

    constructor(address _uniswapFactory, address _compoundOracle) public {
        UNISWAP_FACTORY = UniswapFactoryInterface(_uniswapFactory);
        COMPOUND_ORACLE = CompoundOracleInterface(_compoundOracle);
    }

    // TODO: for now gets Uniswap, later update to get other exchanges
    function getExchange(address _token)
        public
        view
        returns (UniswapExchangeInterface)
    {
        if (address(UNISWAP_FACTORY.getExchange(_token)) == address(0)) {
            revert("No payout exchange");
        }

        UniswapExchangeInterface exchange = UniswapExchangeInterface(
            UNISWAP_FACTORY.getExchange(_token)
        );

        return exchange;
    }

    function isETH(IERC20 _ierc20) public pure returns (bool) {
        return _ierc20 == IERC20(0);
    }
}

// File: contracts/OptionsExchange.sol

pragma solidity 0.5.10;






contract OptionsExchange {
    uint256 constant LARGE_BLOCK_SIZE = 1651753129000;
    uint256 constant LARGE_APPROVAL_NUMBER = 10**30;

    UniswapFactoryInterface public UNISWAP_FACTORY;

    constructor(address _uniswapFactory) public {
        UNISWAP_FACTORY = UniswapFactoryInterface(_uniswapFactory);
    }

    /*** Events ***/
    event SellOTokens(
        address seller,
        address payable receiver,
        address oTokenAddress,
        address payoutTokenAddress,
        uint256 oTokensToSell,
        uint256 payoutTokensReceived
    );
    event BuyOTokens(
        address buyer,
        address payable receiver,
        address oTokenAddress,
        address paymentTokenAddress,
        uint256 oTokensToBuy,
        uint256 premiumPaid
    );

    /**
    * @notice This function sells oTokens on Uniswap and sends back payoutTokens to the receiver
    * @param receiver The address to send the payout tokens back to
    * @param oTokenAddress The address of the oToken to sell
    * @param payoutTokenAddress The address of the token to receive the premiums in
    * @param oTokensToSell The number of oTokens to sell
    */
    function sellOTokens(
        address payable receiver,
        address oTokenAddress,
        address payoutTokenAddress,
        uint256 oTokensToSell
    ) public {
        // @note: first need to bootstrap the uniswap exchange to get the address.
        IERC20 oToken = IERC20(oTokenAddress);
        IERC20 payoutToken = IERC20(payoutTokenAddress);
        oToken.transferFrom(msg.sender, address(this), oTokensToSell);
        uint256 payoutTokensReceived = uniswapSellOToken(
            oToken,
            payoutToken,
            oTokensToSell,
            receiver
        );

        emit SellOTokens(
            msg.sender,
            receiver,
            oTokenAddress,
            payoutTokenAddress,
            oTokensToSell,
            payoutTokensReceived
        );
    }

    /**
    * @notice This function buys oTokens on Uniswap and using paymentTokens from the receiver
    * @param receiver The address to send the oTokens back to
    * @param oTokenAddress The address of the oToken to buy
    * @param paymentTokenAddress The address of the token to pay the premiums in
    * @param oTokensToBuy The number of oTokens to buy
    */
    function buyOTokens(
        address payable receiver,
        address oTokenAddress,
        address paymentTokenAddress,
        uint256 oTokensToBuy
    ) public payable {
        IERC20 oToken = IERC20(oTokenAddress);
        IERC20 paymentToken = IERC20(paymentTokenAddress);
        uniswapBuyOToken(paymentToken, oToken, oTokensToBuy, receiver);
    }

    /**
    * @notice This function calculates the amount of premiums that the seller
    * will receive if they sold oTokens on Uniswap
    * @param oTokenAddress The address of the oToken to sell
    * @param payoutTokenAddress The address of the token to receive the premiums in
    * @param oTokensToSell The number of oTokens to sell
    */
    function premiumReceived(
        address oTokenAddress,
        address payoutTokenAddress,
        uint256 oTokensToSell
    ) public view returns (uint256) {
        // get the amount of ETH that will be paid out if oTokensToSell is sold.
        UniswapExchangeInterface oTokenExchange = getExchange(oTokenAddress);
        uint256 ethReceived = oTokenExchange.getTokenToEthInputPrice(
            oTokensToSell
        );

        if (!isETH(IERC20(payoutTokenAddress))) {
            // get the amount of payout tokens that will be received if the ethRecieved is sold.
            UniswapExchangeInterface payoutExchange = getExchange(
                payoutTokenAddress
            );
            return payoutExchange.getEthToTokenInputPrice(ethReceived);
        }
        return ethReceived;

    }

    /**
    * @notice This function calculates the premiums to be paid if a buyer wants to
    * buy oTokens on Uniswap
    * @param oTokenAddress The address of the oToken to buy
    * @param paymentTokenAddress The address of the token to pay the premiums in
    * @param oTokensToBuy The number of oTokens to buy
    */
    function premiumToPay(
        address oTokenAddress,
        address paymentTokenAddress,
        uint256 oTokensToBuy
    ) public view returns (uint256) {
        // get the amount of ETH that needs to be paid for oTokensToBuy.
        UniswapExchangeInterface oTokenExchange = getExchange(oTokenAddress);
        uint256 ethToPay = oTokenExchange.getEthToTokenOutputPrice(
            oTokensToBuy
        );

        if (!isETH(IERC20(paymentTokenAddress))) {
            // get the amount of paymentTokens that needs to be paid to get the desired ethToPay.
            UniswapExchangeInterface paymentTokenExchange = getExchange(
                paymentTokenAddress
            );
            return paymentTokenExchange.getTokenToEthOutputPrice(ethToPay);
        }

        return ethToPay;
    }

    function uniswapSellOToken(
        IERC20 oToken,
        IERC20 payoutToken,
        uint256 _amt,
        address payable _transferTo
    ) internal returns (uint256) {
        require(!isETH(oToken), "Can only sell oTokens");
        UniswapExchangeInterface exchange = getExchange(address(oToken));

        if (isETH(payoutToken)) {
            //Token to ETH
            oToken.approve(address(exchange), _amt);
            return
                exchange.tokenToEthTransferInput(
                    _amt,
                    1,
                    LARGE_BLOCK_SIZE,
                    _transferTo
                );
        } else {
            //Token to Token
            oToken.approve(address(exchange), _amt);
            return
                exchange.tokenToTokenTransferInput(
                    _amt,
                    1,
                    1,
                    LARGE_BLOCK_SIZE,
                    _transferTo,
                    address(payoutToken)
                );
        }
    }

    function uniswapBuyOToken(
        IERC20 paymentToken,
        IERC20 oToken,
        uint256 _amt,
        address payable _transferTo
    ) public returns (uint256) {
        require(!isETH(oToken), "Can only buy oTokens");

        if (!isETH(paymentToken)) {
            UniswapExchangeInterface exchange = getExchange(
                address(paymentToken)
            );

            uint256 paymentTokensToTransfer = premiumToPay(
                address(oToken),
                address(paymentToken),
                _amt
            );
            paymentToken.transferFrom(
                msg.sender,
                address(this),
                paymentTokensToTransfer
            );

            // Token to Token
            paymentToken.approve(address(exchange), LARGE_APPROVAL_NUMBER);

            emit BuyOTokens(
                msg.sender,
                _transferTo,
                address(oToken),
                address(paymentToken),
                _amt,
                paymentTokensToTransfer
            );

            return
                exchange.tokenToTokenTransferInput(
                    paymentTokensToTransfer,
                    1,
                    1,
                    LARGE_BLOCK_SIZE,
                    _transferTo,
                    address(oToken)
                );
        } else {
            // ETH to Token
            UniswapExchangeInterface exchange = UniswapExchangeInterface(
                UNISWAP_FACTORY.getExchange(address(oToken))
            );

            uint256 ethToTransfer = exchange.getEthToTokenOutputPrice(_amt);

            emit BuyOTokens(
                msg.sender,
                _transferTo,
                address(oToken),
                address(paymentToken),
                _amt,
                ethToTransfer
            );

            return
                exchange.ethToTokenTransferOutput.value(ethToTransfer)(
                    _amt,
                    LARGE_BLOCK_SIZE,
                    _transferTo
                );
        }
    }

    function getExchange(address _token)
        internal
        view
        returns (UniswapExchangeInterface)
    {
        UniswapExchangeInterface exchange = UniswapExchangeInterface(
            UNISWAP_FACTORY.getExchange(_token)
        );

        if (address(exchange) == address(0)) {
            revert("No payout exchange");
        }

        return exchange;
    }

    function isETH(IERC20 _ierc20) internal pure returns (bool) {
        return _ierc20 == IERC20(0);
    }

    function() external payable {
        // to get ether from uniswap exchanges
    }

}

# @title Uniswap Exchange Interface V1
# @notice Source code found at https://github.com/uniswap
# @notice Use at your own risk

contract Factory():
    def getExchange(token_addr: address) -> address: constant

contract Exchange():
    def getEthToTokenOutputPrice(tokens_bought: uint256) -> uint256(wei): constant
    def ethToTokenTransferInput(min_tokens: uint256, deadline: timestamp, recipient: address) -> uint256: modifying
    def ethToTokenTransferOutput(tokens_bought: uint256, deadline: timestamp, recipient: address) -> uint256(wei): modifying

TokenPurchase: event({buyer: indexed(address), eth_sold: indexed(uint256(wei)), tokens_bought: indexed(uint256)})
EthPurchase: event({buyer: indexed(address), tokens_sold: indexed(uint256), eth_bought: indexed(uint256(wei))})
AddLiquidity: event({provider: indexed(address), eth_amount: indexed(uint256(wei)), token_amount: indexed(uint256)})
RemoveLiquidity: event({provider: indexed(address), eth_amount: indexed(uint256(wei)), token_amount: indexed(uint256)})
Transfer: event({_from: indexed(address), _to: indexed(address), _value: uint256})
Approval: event({_owner: indexed(address), _spender: indexed(address), _value: uint256})

name: public(bytes32)                             # Uniswap V1
symbol: public(bytes32)                           # UNI-V1
decimals: public(uint256)                         # 18
totalSupply: public(uint256)                      # total number of UNI in existence
balances: uint256[address]                        # UNI balance of an address
allowances: (uint256[address])[address]           # UNI allowance of one address on another
token: address(ERC20)                             # address of the ERC20 token traded on this contract
factory: Factory                                  # interface for the factory that created this contract

# @dev This function acts as a contract constructor which is not currently supported in contracts deployed
#      using create_with_code_of(). It is called once by the factory during contract creation.
@public
def setup(token_addr: address):
    assert (self.factory == ZERO_ADDRESS and self.token == ZERO_ADDRESS) and token_addr != ZERO_ADDRESS
    self.factory = msg.sender
    self.token = token_addr
    self.name = 0x556e697377617020563100000000000000000000000000000000000000000000
    self.symbol = 0x554e492d56310000000000000000000000000000000000000000000000000000
    self.decimals = 18

# @notice Deposit ETH and Tokens (self.token) at current ratio to mint UNI tokens.
# @dev min_liquidity does nothing when total UNI supply is 0.
# @param min_liquidity Minimum number of UNI sender will mint if total UNI supply is greater than 0.
# @param max_tokens Maximum number of tokens deposited. Deposits max amount if total UNI supply is 0.
# @param deadline Time after which this transaction can no longer be executed.
# @return The amount of UNI minted.
@public
@payable
def addLiquidity(min_liquidity: uint256, max_tokens: uint256, deadline: timestamp) -> uint256:
    assert deadline > block.timestamp and (max_tokens > 0 and msg.value > 0)
    total_liquidity: uint256 = self.totalSupply
    if total_liquidity > 0:
        assert min_liquidity > 0
        eth_reserve: uint256(wei) = self.balance - msg.value
        token_reserve: uint256 = self.token.balanceOf(self)
        token_amount: uint256 = msg.value * token_reserve / eth_reserve + 1
        liquidity_minted: uint256 = msg.value * total_liquidity / eth_reserve
        assert max_tokens >= token_amount and liquidity_minted >= min_liquidity
        self.balances[msg.sender] += liquidity_minted
        self.totalSupply = total_liquidity + liquidity_minted
        assert self.token.transferFrom(msg.sender, self, token_amount)
        log.AddLiquidity(msg.sender, msg.value, token_amount)
        log.Transfer(ZERO_ADDRESS, msg.sender, liquidity_minted)
        return liquidity_minted
    else:
        assert (self.factory != ZERO_ADDRESS and self.token != ZERO_ADDRESS) and msg.value >= 1000000000
        assert self.factory.getExchange(self.token) == self
        token_amount: uint256 = max_tokens
        initial_liquidity: uint256 = as_unitless_number(self.balance)
        self.totalSupply = initial_liquidity
        self.balances[msg.sender] = initial_liquidity
        assert self.token.transferFrom(msg.sender, self, token_amount)
        log.AddLiquidity(msg.sender, msg.value, token_amount)
        log.Transfer(ZERO_ADDRESS, msg.sender, initial_liquidity)
        return initial_liquidity

# @dev Burn UNI tokens to withdraw ETH and Tokens at current ratio.
# @param amount Amount of UNI burned.
# @param min_eth Minimum ETH withdrawn.
# @param min_tokens Minimum Tokens withdrawn.
# @param deadline Time after which this transaction can no longer be executed.
# @return The amount of ETH and Tokens withdrawn.
@public
def removeLiquidity(amount: uint256, min_eth: uint256(wei), min_tokens: uint256, deadline: timestamp) -> (uint256(wei), uint256):
    assert (amount > 0 and deadline > block.timestamp) and (min_eth > 0 and min_tokens > 0)
    total_liquidity: uint256 = self.totalSupply
    assert total_liquidity > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_amount: uint256(wei) = amount * self.balance / total_liquidity
    token_amount: uint256 = amount * token_reserve / total_liquidity
    assert eth_amount >= min_eth and token_amount >= min_tokens
    self.balances[msg.sender] -= amount
    self.totalSupply = total_liquidity - amount
    send(msg.sender, eth_amount)
    assert self.token.transfer(msg.sender, token_amount)
    log.RemoveLiquidity(msg.sender, eth_amount, token_amount)
    log.Transfer(msg.sender, ZERO_ADDRESS, amount)
    return eth_amount, token_amount

# @dev Pricing function for converting between ETH and Tokens.
# @param input_amount Amount of ETH or Tokens being sold.
# @param input_reserve Amount of ETH or Tokens (input type) in exchange reserves.
# @param output_reserve Amount of ETH or Tokens (output type) in exchange reserves.
# @return Amount of ETH or Tokens bought.
@private
@constant
def getInputPrice(input_amount: uint256, input_reserve: uint256, output_reserve: uint256) -> uint256:
    assert input_reserve > 0 and output_reserve > 0
    input_amount_with_fee: uint256 = input_amount * 997
    numerator: uint256 = input_amount_with_fee * output_reserve
    denominator: uint256 = (input_reserve * 1000) + input_amount_with_fee
    return numerator / denominator

# @dev Pricing function for converting between ETH and Tokens.
# @param output_amount Amount of ETH or Tokens being bought.
# @param input_reserve Amount of ETH or Tokens (input type) in exchange reserves.
# @param output_reserve Amount of ETH or Tokens (output type) in exchange reserves.
# @return Amount of ETH or Tokens sold.
@private
@constant
def getOutputPrice(output_amount: uint256, input_reserve: uint256, output_reserve: uint256) -> uint256:
    assert input_reserve > 0 and output_reserve > 0
    numerator: uint256 = input_reserve * output_amount * 1000
    denominator: uint256 = (output_reserve - output_amount) * 997
    return numerator / denominator + 1

@private
def ethToTokenInput(eth_sold: uint256(wei), min_tokens: uint256, deadline: timestamp, buyer: address, recipient: address) -> uint256:
    assert deadline >= block.timestamp and (eth_sold > 0 and min_tokens > 0)
    token_reserve: uint256 = self.token.balanceOf(self)
    tokens_bought: uint256 = self.getInputPrice(as_unitless_number(eth_sold), as_unitless_number(self.balance - eth_sold), token_reserve)
    assert tokens_bought >= min_tokens
    assert self.token.transfer(recipient, tokens_bought)
    log.TokenPurchase(buyer, eth_sold, tokens_bought)
    return tokens_bought

# @notice Convert ETH to Tokens.
# @dev User specifies exact input (msg.value).
# @dev User cannot specify minimum output or deadline.
@public
@payable
def __default__():
    self.ethToTokenInput(msg.value, 1, block.timestamp, msg.sender, msg.sender)

# @notice Convert ETH to Tokens.
# @dev User specifies exact input (msg.value) and minimum output.
# @param min_tokens Minimum Tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of Tokens bought.
@public
@payable
def ethToTokenSwapInput(min_tokens: uint256, deadline: timestamp) -> uint256:
    return self.ethToTokenInput(msg.value, min_tokens, deadline, msg.sender, msg.sender)

# @notice Convert ETH to Tokens and transfers Tokens to recipient.
# @dev User specifies exact input (msg.value) and minimum output
# @param min_tokens Minimum Tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output Tokens.
# @return Amount of Tokens bought.
@public
@payable
def ethToTokenTransferInput(min_tokens: uint256, deadline: timestamp, recipient: address) -> uint256:
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.ethToTokenInput(msg.value, min_tokens, deadline, msg.sender, recipient)

@private
def ethToTokenOutput(tokens_bought: uint256, max_eth: uint256(wei), deadline: timestamp, buyer: address, recipient: address) -> uint256(wei):
    assert deadline >= block.timestamp and (tokens_bought > 0 and max_eth > 0)
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_sold: uint256 = self.getOutputPrice(tokens_bought, as_unitless_number(self.balance - max_eth), token_reserve)
    # Throws if eth_sold > max_eth
    eth_refund: uint256(wei) = max_eth - as_wei_value(eth_sold, 'wei')
    if eth_refund > 0:
        send(buyer, eth_refund)
    assert self.token.transfer(recipient, tokens_bought)
    log.TokenPurchase(buyer, as_wei_value(eth_sold, 'wei'), tokens_bought)
    return as_wei_value(eth_sold, 'wei')

# @notice Convert ETH to Tokens.
# @dev User specifies maximum input (msg.value) and exact output.
# @param tokens_bought Amount of tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of ETH sold.
@public
@payable
def ethToTokenSwapOutput(tokens_bought: uint256, deadline: timestamp) -> uint256(wei):
    return self.ethToTokenOutput(tokens_bought, msg.value, deadline, msg.sender, msg.sender)

# @notice Convert ETH to Tokens and transfers Tokens to recipient.
# @dev User specifies maximum input (msg.value) and exact output.
# @param tokens_bought Amount of tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output Tokens.
# @return Amount of ETH sold.
@public
@payable
def ethToTokenTransferOutput(tokens_bought: uint256, deadline: timestamp, recipient: address) -> uint256(wei):
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.ethToTokenOutput(tokens_bought, msg.value, deadline, msg.sender, recipient)

@private
def tokenToEthInput(tokens_sold: uint256, min_eth: uint256(wei), deadline: timestamp, buyer: address, recipient: address) -> uint256(wei):
    assert deadline >= block.timestamp and (tokens_sold > 0 and min_eth > 0)
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_bought: uint256 = self.getInputPrice(tokens_sold, token_reserve, as_unitless_number(self.balance))
    wei_bought: uint256(wei) = as_wei_value(eth_bought, 'wei')
    assert wei_bought >= min_eth
    send(recipient, wei_bought)
    assert self.token.transferFrom(buyer, self, tokens_sold)
    log.EthPurchase(buyer, tokens_sold, wei_bought)
    return wei_bought


# @notice Convert Tokens to ETH.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_eth Minimum ETH purchased.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of ETH bought.
@public
def tokenToEthSwapInput(tokens_sold: uint256, min_eth: uint256(wei), deadline: timestamp) -> uint256(wei):
    return self.tokenToEthInput(tokens_sold, min_eth, deadline, msg.sender, msg.sender)

# @notice Convert Tokens to ETH and transfers ETH to recipient.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_eth Minimum ETH purchased.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @return Amount of ETH bought.
@public
def tokenToEthTransferInput(tokens_sold: uint256, min_eth: uint256(wei), deadline: timestamp, recipient: address) -> uint256(wei):
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.tokenToEthInput(tokens_sold, min_eth, deadline, msg.sender, recipient)

@private
def tokenToEthOutput(eth_bought: uint256(wei), max_tokens: uint256, deadline: timestamp, buyer: address, recipient: address) -> uint256:
    assert deadline >= block.timestamp and eth_bought > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    tokens_sold: uint256 = self.getOutputPrice(as_unitless_number(eth_bought), token_reserve, as_unitless_number(self.balance))
    # tokens sold is always > 0
    assert max_tokens >= tokens_sold
    send(recipient, eth_bought)
    assert self.token.transferFrom(buyer, self, tokens_sold)
    log.EthPurchase(buyer, tokens_sold, eth_bought)
    return tokens_sold

# @notice Convert Tokens to ETH.
# @dev User specifies maximum input and exact output.
# @param eth_bought Amount of ETH purchased.
# @param max_tokens Maximum Tokens sold.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of Tokens sold.
@public
def tokenToEthSwapOutput(eth_bought: uint256(wei), max_tokens: uint256, deadline: timestamp) -> uint256:
    return self.tokenToEthOutput(eth_bought, max_tokens, deadline, msg.sender, msg.sender)

# @notice Convert Tokens to ETH and transfers ETH to recipient.
# @dev User specifies maximum input and exact output.
# @param eth_bought Amount of ETH purchased.
# @param max_tokens Maximum Tokens sold.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @return Amount of Tokens sold.
@public
def tokenToEthTransferOutput(eth_bought: uint256(wei), max_tokens: uint256, deadline: timestamp, recipient: address) -> uint256:
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.tokenToEthOutput(eth_bought, max_tokens, deadline, msg.sender, recipient)

@private
def tokenToTokenInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, buyer: address, recipient: address, exchange_addr: address) -> uint256:
    assert (deadline >= block.timestamp and tokens_sold > 0) and (min_tokens_bought > 0 and min_eth_bought > 0)
    assert exchange_addr != self and exchange_addr != ZERO_ADDRESS
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_bought: uint256 = self.getInputPrice(tokens_sold, token_reserve, as_unitless_number(self.balance))
    wei_bought: uint256(wei) = as_wei_value(eth_bought, 'wei')
    assert wei_bought >= min_eth_bought
    assert self.token.transferFrom(buyer, self, tokens_sold)
    tokens_bought: uint256 = Exchange(exchange_addr).ethToTokenTransferInput(min_tokens_bought, deadline, recipient, value=wei_bought)
    log.EthPurchase(buyer, tokens_sold, wei_bought)
    return tokens_bought

# @notice Convert Tokens (self.token) to Tokens (token_addr).
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (token_addr) bought.
@public
def tokenToTokenSwapInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (token_addr) and transfers
#         Tokens (token_addr) to recipient.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (token_addr) bought.
@public
def tokenToTokenTransferInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, recipient: address, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, recipient, exchange_addr)

@private
def tokenToTokenOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, buyer: address, recipient: address, exchange_addr: address) -> uint256:
    assert deadline >= block.timestamp and (tokens_bought > 0 and max_eth_sold > 0)
    assert exchange_addr != self and exchange_addr != ZERO_ADDRESS
    eth_bought: uint256(wei) = Exchange(exchange_addr).getEthToTokenOutputPrice(tokens_bought)
    token_reserve: uint256 = self.token.balanceOf(self)
    tokens_sold: uint256 = self.getOutputPrice(as_unitless_number(eth_bought), token_reserve, as_unitless_number(self.balance))
    # tokens sold is always > 0
    assert max_tokens_sold >= tokens_sold and max_eth_sold >= eth_bought
    assert self.token.transferFrom(buyer, self, tokens_sold)
    eth_sold: uint256(wei) = Exchange(exchange_addr).ethToTokenTransferOutput(tokens_bought, deadline, recipient, value=eth_bought)
    log.EthPurchase(buyer, tokens_sold, eth_bought)
    return tokens_sold

# @notice Convert Tokens (self.token) to Tokens (token_addr).
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToTokenSwapOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (token_addr) and transfers
#         Tokens (token_addr) to recipient.
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToTokenTransferOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, recipient: address, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, recipient, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token).
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param exchange_addr The address of the exchange for the token being purchased.
# @return Amount of Tokens (exchange_addr.token) bought.
@public
def tokenToExchangeSwapInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, exchange_addr: address) -> uint256:
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token) and transfers
#         Tokens (exchange_addr.token) to recipient.
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param exchange_addr The address of the exchange for the token being purchased.
# @return Amount of Tokens (exchange_addr.token) bought.
@public
def tokenToExchangeTransferInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, recipient: address, exchange_addr: address) -> uint256:
    assert recipient != self
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, recipient, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token).
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param exchange_addr The address of the exchange for the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToExchangeSwapOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, exchange_addr: address) -> uint256:
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token) and transfers
#         Tokens (exchange_addr.token) to recipient.
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToExchangeTransferOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, recipient: address, exchange_addr: address) -> uint256:
    assert recipient != self
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, recipient, exchange_addr)

# @notice Public price function for ETH to Token trades with an exact input.
# @param eth_sold Amount of ETH sold.
# @return Amount of Tokens that can be bought with input ETH.
@public
@constant
def getEthToTokenInputPrice(eth_sold: uint256(wei)) -> uint256:
    assert eth_sold > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    return self.getInputPrice(as_unitless_number(eth_sold), as_unitless_number(self.balance), token_reserve)

# @notice Public price function for ETH to Token trades with an exact output.
# @param tokens_bought Amount of Tokens bought.
# @return Amount of ETH needed to buy output Tokens.
@public
@constant
def getEthToTokenOutputPrice(tokens_bought: uint256) -> uint256(wei):
    assert tokens_bought > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_sold: uint256 = self.getOutputPrice(tokens_bought, as_unitless_number(self.balance), token_reserve)
    return as_wei_value(eth_sold, 'wei')

# @notice Public price function for Token to ETH trades with an exact input.
# @param tokens_sold Amount of Tokens sold.
# @return Amount of ETH that can be bought with input Tokens.
@public
@constant
def getTokenToEthInputPrice(tokens_sold: uint256) -> uint256(wei):
    assert tokens_sold > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_bought: uint256 = self.getInputPrice(tokens_sold, token_reserve, as_unitless_number(self.balance))
    return as_wei_value(eth_bought, 'wei')

# @notice Public price function for Token to ETH trades with an exact output.
# @param eth_bought Amount of output ETH.
# @return Amount of Tokens needed to buy output ETH.
@public
@constant
def getTokenToEthOutputPrice(eth_bought: uint256(wei)) -> uint256:
    assert eth_bought > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    return self.getOutputPrice(as_unitless_number(eth_bought), token_reserve, as_unitless_number(self.balance))

# @return Address of Token that is sold on this exchange.
@public
@constant
def tokenAddress() -> address:
    return self.token

# @return Address of factory that created this exchange.
@public
@constant
def factoryAddress() -> address(Factory):
    return self.factory

# ERC20 compatibility for exchange liquidity modified from
# https://github.com/ethereum/vyper/blob/master/examples/tokens/ERC20.vy
@public
@constant
def balanceOf(_owner : address) -> uint256:
    return self.balances[_owner]

@public
def transfer(_to : address, _value : uint256) -> bool:
    self.balances[msg.sender] -= _value
    self.balances[_to] += _value
    log.Transfer(msg.sender, _to, _value)
    return True

@public
def transferFrom(_from : address, _to : address, _value : uint256) -> bool:
    self.balances[_from] -= _value
    self.balances[_to] += _value
    self.allowances[_from][msg.sender] -= _value
    log.Transfer(_from, _to, _value)
    return True

@public
def approve(_spender : address, _value : uint256) -> bool:
    self.allowances[msg.sender][_spender] = _value
    log.Approval(msg.sender, _spender, _value)
    return True

@public
@constant
def allowance(_owner : address, _spender : address) -> uint256:
    return self.allowances[_owner][_spender]

pragma solidity ^0.4.24;

// File: contracts/Ownable.sol

/**
* Copyright CENTRE SECZ 2018
*
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is furnished to 
* do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all 
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

pragma solidity ^0.4.24;

/**
 * @title Ownable
 * @dev The Ownable contract from https://github.com/zeppelinos/labs/blob/master/upgradeability_ownership/contracts/ownership/Ownable.sol 
 * branch: master commit: 3887ab77b8adafba4a26ace002f3a684c1a3388b modified to:
 * 1) Add emit prefix to OwnershipTransferred event (7/13/18)
 * 2) Replace constructor with constructor syntax (7/13/18)
 * 3) consolidate OwnableStorage into this contract
 */
contract Ownable {

  // Owner of the contract
  address private _owner;

  /**
  * @dev Event to show ownership has been transferred
  * @param previousOwner representing the address of the previous owner
  * @param newOwner representing the address of the new owner
  */
  event OwnershipTransferred(address previousOwner, address newOwner);

  /**
  * @dev The constructor sets the original owner of the contract to the sender account.
  */
  constructor() public {
    setOwner(msg.sender);
  }

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

  /**
   * @dev Sets a new owner address
   */
  function setOwner(address newOwner) internal {
    _owner = newOwner;
  }

  /**
  * @dev Throws if called by any account other than the owner.
  */
  modifier onlyOwner() {
    require(msg.sender == owner());
    _;
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    emit OwnershipTransferred(owner(), newOwner);
    setOwner(newOwner);
  }
}

// File: contracts/Blacklistable.sol

/**
* Copyright CENTRE SECZ 2018
*
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is furnished to 
* do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all 
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

pragma solidity ^0.4.24;


/**
 * @title Blacklistable Token
 * @dev Allows accounts to be blacklisted by a "blacklister" role
*/
contract Blacklistable is Ownable {

    address public blacklister;
    mapping(address => bool) internal blacklisted;

    event Blacklisted(address indexed _account);
    event UnBlacklisted(address indexed _account);
    event BlacklisterChanged(address indexed newBlacklister);

    /**
     * @dev Throws if called by any account other than the blacklister
    */
    modifier onlyBlacklister() {
        require(msg.sender == blacklister);
        _;
    }

    /**
     * @dev Throws if argument account is blacklisted
     * @param _account The address to check
    */
    modifier notBlacklisted(address _account) {
        require(blacklisted[_account] == false);
        _;
    }

    /**
     * @dev Checks if account is blacklisted
     * @param _account The address to check    
    */
    function isBlacklisted(address _account) public view returns (bool) {
        return blacklisted[_account];
    }

    /**
     * @dev Adds account to blacklist
     * @param _account The address to blacklist
    */
    function blacklist(address _account) public onlyBlacklister {
        blacklisted[_account] = true;
        emit Blacklisted(_account);
    }

    /**
     * @dev Removes account from blacklist
     * @param _account The address to remove from the blacklist
    */
    function unBlacklist(address _account) public onlyBlacklister {
        blacklisted[_account] = false;
        emit UnBlacklisted(_account);
    }

    function updateBlacklister(address _newBlacklister) public onlyOwner {
        require(_newBlacklister != address(0));
        blacklister = _newBlacklister;
        emit BlacklisterChanged(blacklister);
    }
}

// File: contracts/Pausable.sol

/**
* Copyright CENTRE SECZ 2018
*
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is furnished to 
* do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all 
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

pragma solidity ^0.4.24;


/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 * Based on openzeppelin tag v1.10.0 commit: feb665136c0dae9912e08397c1a21c4af3651ef3
 * Modifications:
 * 1) Added pauser role, switched pause/unpause to be onlyPauser (6/14/2018)
 * 2) Removed whenNotPause/whenPaused from pause/unpause (6/14/2018)
 * 3) Removed whenPaused (6/14/2018)
 * 4) Switches ownable library to use zeppelinos (7/12/18)
 * 5) Remove constructor (7/13/18)
 */
contract Pausable is Ownable {
  event Pause();
  event Unpause();
  event PauserChanged(address indexed newAddress);


  address public pauser;
  bool public paused = false;

  /**
   * @dev Modifier to make a function callable only when the contract is not paused.
   */
  modifier whenNotPaused() {
    require(!paused);
    _;
  }

  /**
   * @dev throws if called by any account other than the pauser
   */
  modifier onlyPauser() {
    require(msg.sender == pauser);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() onlyPauser public {
    paused = true;
    emit Pause();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() onlyPauser public {
    paused = false;
    emit Unpause();
  }

  /**
   * @dev update the pauser role
   */
  function updatePauser(address _newPauser) onlyOwner public {
    require(_newPauser != address(0));
    pauser = _newPauser;
    emit PauserChanged(pauser);
  }

}

// File: openzeppelin-solidity/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
    // Gas optimization: this is cheaper than asserting '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;
    }

    c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    // uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return a / b;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Basic.sol

/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * See https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender)
    public view returns (uint256);

  function transferFrom(address from, address to, uint256 value)
    public returns (bool);

  function approve(address spender, uint256 value) public returns (bool);
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

// File: contracts/FiatTokenV1.sol

/**
* Copyright CENTRE SECZ 2018
*
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is furnished to 
* do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all 
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

pragma solidity ^0.4.24;






/**
 * @title FiatToken
 * @dev ERC20 Token backed by fiat reserves
 */
contract FiatTokenV1 is Ownable, ERC20, Pausable, Blacklistable {
    using SafeMath for uint256;

    string public name;
    string public symbol;
    uint8 public decimals;
    string public currency;
    address public masterMinter;
    bool internal initialized;

    mapping(address => uint256) internal balances;
    mapping(address => mapping(address => uint256)) internal allowed;
    uint256 internal totalSupply_ = 0;
    mapping(address => bool) internal minters;
    mapping(address => uint256) internal minterAllowed;

    event Mint(address indexed minter, address indexed to, uint256 amount);
    event Burn(address indexed burner, uint256 amount);
    event MinterConfigured(address indexed minter, uint256 minterAllowedAmount);
    event MinterRemoved(address indexed oldMinter);
    event MasterMinterChanged(address indexed newMasterMinter);

    function initialize(
        string _name,
        string _symbol,
        string _currency,
        uint8 _decimals,
        address _masterMinter,
        address _pauser,
        address _blacklister,
        address _owner
    ) public {
        require(!initialized);
        require(_masterMinter != address(0));
        require(_pauser != address(0));
        require(_blacklister != address(0));
        require(_owner != address(0));

        name = _name;
        symbol = _symbol;
        currency = _currency;
        decimals = _decimals;
        masterMinter = _masterMinter;
        pauser = _pauser;
        blacklister = _blacklister;
        setOwner(_owner);
        initialized = true;
    }

    /**
     * @dev Throws if called by any account other than a minter
    */
    modifier onlyMinters() {
        require(minters[msg.sender] == true);
        _;
    }

    /**
     * @dev Function to mint tokens
     * @param _to The address that will receive the minted tokens.
     * @param _amount The amount of tokens to mint. Must be less than or equal to the minterAllowance of the caller.
     * @return A boolean that indicates if the operation was successful.
    */
    function mint(address _to, uint256 _amount) whenNotPaused onlyMinters notBlacklisted(msg.sender) notBlacklisted(_to) public returns (bool) {
        require(_to != address(0));
        require(_amount > 0);

        uint256 mintingAllowedAmount = minterAllowed[msg.sender];
        require(_amount <= mintingAllowedAmount);

        totalSupply_ = totalSupply_.add(_amount);
        balances[_to] = balances[_to].add(_amount);
        minterAllowed[msg.sender] = mintingAllowedAmount.sub(_amount);
        emit Mint(msg.sender, _to, _amount);
        emit Transfer(0x0, _to, _amount);
        return true;
    }

    /**
     * @dev Throws if called by any account other than the masterMinter
    */
    modifier onlyMasterMinter() {
        require(msg.sender == masterMinter);
        _;
    }

    /**
     * @dev Get minter allowance for an account
     * @param minter The address of the minter
    */
    function minterAllowance(address minter) public view returns (uint256) {
        return minterAllowed[minter];
    }

    /**
     * @dev Checks if account is a minter
     * @param account The address to check    
    */
    function isMinter(address account) public view returns (bool) {
        return minters[account];
    }

    /**
     * @dev Get allowed amount for an account
     * @param owner address The account owner
     * @param spender address The account spender
    */
    function allowance(address owner, address spender) public view returns (uint256) {
        return allowed[owner][spender];
    }

    /**
     * @dev Get totalSupply of token
    */
    function totalSupply() public view returns (uint256) {
        return totalSupply_;
    }

    /**
     * @dev Get token balance of an account
     * @param account address The account
    */
    function balanceOf(address account) public view returns (uint256) {
        return balances[account];
    }

    /**
     * @dev Adds blacklisted check to approve
     * @return True if the operation was successful.
    */
    function approve(address _spender, uint256 _value) whenNotPaused notBlacklisted(msg.sender) notBlacklisted(_spender) public returns (bool) {
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * @param _from address The address which you want to send tokens from
     * @param _to address The address which you want to transfer to
     * @param _value uint256 the amount of tokens to be transferred
     * @return bool success
    */
    function transferFrom(address _from, address _to, uint256 _value) whenNotPaused notBlacklisted(_to) notBlacklisted(msg.sender) notBlacklisted(_from) public returns (bool) {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    /**
     * @dev transfer token for a specified address
     * @param _to The address to transfer to.
     * @param _value The amount to be transferred.
     * @return bool success
    */
    function transfer(address _to, uint256 _value) whenNotPaused notBlacklisted(msg.sender) notBlacklisted(_to) public returns (bool) {
        require(_to != address(0));
        require(_value <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * @dev Function to add/update a new minter
     * @param minter The address of the minter
     * @param minterAllowedAmount The minting amount allowed for the minter
     * @return True if the operation was successful.
    */
    function configureMinter(address minter, uint256 minterAllowedAmount) whenNotPaused onlyMasterMinter public returns (bool) {
        minters[minter] = true;
        minterAllowed[minter] = minterAllowedAmount;
        emit MinterConfigured(minter, minterAllowedAmount);
        return true;
    }

    /**
     * @dev Function to remove a minter
     * @param minter The address of the minter to remove
     * @return True if the operation was successful.
    */
    function removeMinter(address minter) onlyMasterMinter public returns (bool) {
        minters[minter] = false;
        minterAllowed[minter] = 0;
        emit MinterRemoved(minter);
        return true;
    }

    /**
     * @dev allows a minter to burn some of its own tokens
     * Validates that caller is a minter and that sender is not blacklisted
     * amount is less than or equal to the minter's account balance
     * @param _amount uint256 the amount of tokens to be burned
    */
    function burn(uint256 _amount) whenNotPaused onlyMinters notBlacklisted(msg.sender) public {
        uint256 balance = balances[msg.sender];
        require(_amount > 0);
        require(balance >= _amount);

        totalSupply_ = totalSupply_.sub(_amount);
        balances[msg.sender] = balance.sub(_amount);
        emit Burn(msg.sender, _amount);
        emit Transfer(msg.sender, address(0), _amount);
    }

    function updateMasterMinter(address _newMasterMinter) onlyOwner public {
        require(_newMasterMinter != address(0));
        masterMinter = _newMasterMinter;
        emit MasterMinterChanged(masterMinter);
    }
}

contract Exchange():
    def setup(token_addr: address): modifying

NewExchange: event({token: indexed(address), exchange: indexed(address)})

exchangeTemplate: public(address)
tokenCount: public(uint256)
token_to_exchange: address[address]
exchange_to_token: address[address]
id_to_token: address[uint256]

@public
def initializeFactory(template: address):
    assert self.exchangeTemplate == ZERO_ADDRESS
    assert template != ZERO_ADDRESS
    self.exchangeTemplate = template

@public
def createExchange(token: address) -> address:
    assert token != ZERO_ADDRESS
    assert self.exchangeTemplate != ZERO_ADDRESS
    assert self.token_to_exchange[token] == ZERO_ADDRESS
    exchange: address = create_with_code_of(self.exchangeTemplate)
    Exchange(exchange).setup(token)
    self.token_to_exchange[token] = exchange
    self.exchange_to_token[exchange] = token
    token_id: uint256 = self.tokenCount + 1
    self.tokenCount = token_id
    self.id_to_token[token_id] = token
    log.NewExchange(token, exchange)
    return exchange

@public
@constant
def getExchange(token: address) -> address:
    return self.token_to_exchange[token]

@public
@constant
def getToken(exchange: address) -> address:
    return self.exchange_to_token[exchange]

@public
@constant
def getTokenWithId(token_id: uint256) -> address:
    return self.id_to_token[token_id]

# @title Uniswap Exchange Interface V1
# @notice Source code found at https://github.com/uniswap
# @notice Use at your own risk

contract Factory():
    def getExchange(token_addr: address) -> address: constant

contract Exchange():
    def getEthToTokenOutputPrice(tokens_bought: uint256) -> uint256(wei): constant
    def ethToTokenTransferInput(min_tokens: uint256, deadline: timestamp, recipient: address) -> uint256: modifying
    def ethToTokenTransferOutput(tokens_bought: uint256, deadline: timestamp, recipient: address) -> uint256(wei): modifying

TokenPurchase: event({buyer: indexed(address), eth_sold: indexed(uint256(wei)), tokens_bought: indexed(uint256)})
EthPurchase: event({buyer: indexed(address), tokens_sold: indexed(uint256), eth_bought: indexed(uint256(wei))})
AddLiquidity: event({provider: indexed(address), eth_amount: indexed(uint256(wei)), token_amount: indexed(uint256)})
RemoveLiquidity: event({provider: indexed(address), eth_amount: indexed(uint256(wei)), token_amount: indexed(uint256)})
Transfer: event({_from: indexed(address), _to: indexed(address), _value: uint256})
Approval: event({_owner: indexed(address), _spender: indexed(address), _value: uint256})

name: public(bytes32)                             # Uniswap V1
symbol: public(bytes32)                           # UNI-V1
decimals: public(uint256)                         # 18
totalSupply: public(uint256)                      # total number of UNI in existence
balances: uint256[address]                        # UNI balance of an address
allowances: (uint256[address])[address]           # UNI allowance of one address on another
token: address(ERC20)                             # address of the ERC20 token traded on this contract
factory: Factory                                  # interface for the factory that created this contract

# @dev This function acts as a contract constructor which is not currently supported in contracts deployed
#      using create_with_code_of(). It is called once by the factory during contract creation.
@public
def setup(token_addr: address):
    assert (self.factory == ZERO_ADDRESS and self.token == ZERO_ADDRESS) and token_addr != ZERO_ADDRESS
    self.factory = msg.sender
    self.token = token_addr
    self.name = 0x556e697377617020563100000000000000000000000000000000000000000000
    self.symbol = 0x554e492d56310000000000000000000000000000000000000000000000000000
    self.decimals = 18

# @notice Deposit ETH and Tokens (self.token) at current ratio to mint UNI tokens.
# @dev min_liquidity does nothing when total UNI supply is 0.
# @param min_liquidity Minimum number of UNI sender will mint if total UNI supply is greater than 0.
# @param max_tokens Maximum number of tokens deposited. Deposits max amount if total UNI supply is 0.
# @param deadline Time after which this transaction can no longer be executed.
# @return The amount of UNI minted.
@public
@payable
def addLiquidity(min_liquidity: uint256, max_tokens: uint256, deadline: timestamp) -> uint256:
    assert deadline > block.timestamp and (max_tokens > 0 and msg.value > 0)
    total_liquidity: uint256 = self.totalSupply
    if total_liquidity > 0:
        assert min_liquidity > 0
        eth_reserve: uint256(wei) = self.balance - msg.value
        token_reserve: uint256 = self.token.balanceOf(self)
        token_amount: uint256 = msg.value * token_reserve / eth_reserve + 1
        liquidity_minted: uint256 = msg.value * total_liquidity / eth_reserve
        assert max_tokens >= token_amount and liquidity_minted >= min_liquidity
        self.balances[msg.sender] += liquidity_minted
        self.totalSupply = total_liquidity + liquidity_minted
        assert self.token.transferFrom(msg.sender, self, token_amount)
        log.AddLiquidity(msg.sender, msg.value, token_amount)
        log.Transfer(ZERO_ADDRESS, msg.sender, liquidity_minted)
        return liquidity_minted
    else:
        assert (self.factory != ZERO_ADDRESS and self.token != ZERO_ADDRESS) and msg.value >= 1000000000
        assert self.factory.getExchange(self.token) == self
        token_amount: uint256 = max_tokens
        initial_liquidity: uint256 = as_unitless_number(self.balance)
        self.totalSupply = initial_liquidity
        self.balances[msg.sender] = initial_liquidity
        assert self.token.transferFrom(msg.sender, self, token_amount)
        log.AddLiquidity(msg.sender, msg.value, token_amount)
        log.Transfer(ZERO_ADDRESS, msg.sender, initial_liquidity)
        return initial_liquidity

# @dev Burn UNI tokens to withdraw ETH and Tokens at current ratio.
# @param amount Amount of UNI burned.
# @param min_eth Minimum ETH withdrawn.
# @param min_tokens Minimum Tokens withdrawn.
# @param deadline Time after which this transaction can no longer be executed.
# @return The amount of ETH and Tokens withdrawn.
@public
def removeLiquidity(amount: uint256, min_eth: uint256(wei), min_tokens: uint256, deadline: timestamp) -> (uint256(wei), uint256):
    assert (amount > 0 and deadline > block.timestamp) and (min_eth > 0 and min_tokens > 0)
    total_liquidity: uint256 = self.totalSupply
    assert total_liquidity > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_amount: uint256(wei) = amount * self.balance / total_liquidity
    token_amount: uint256 = amount * token_reserve / total_liquidity
    assert eth_amount >= min_eth and token_amount >= min_tokens
    self.balances[msg.sender] -= amount
    self.totalSupply = total_liquidity - amount
    send(msg.sender, eth_amount)
    assert self.token.transfer(msg.sender, token_amount)
    log.RemoveLiquidity(msg.sender, eth_amount, token_amount)
    log.Transfer(msg.sender, ZERO_ADDRESS, amount)
    return eth_amount, token_amount

# @dev Pricing function for converting between ETH and Tokens.
# @param input_amount Amount of ETH or Tokens being sold.
# @param input_reserve Amount of ETH or Tokens (input type) in exchange reserves.
# @param output_reserve Amount of ETH or Tokens (output type) in exchange reserves.
# @return Amount of ETH or Tokens bought.
@private
@constant
def getInputPrice(input_amount: uint256, input_reserve: uint256, output_reserve: uint256) -> uint256:
    assert input_reserve > 0 and output_reserve > 0
    input_amount_with_fee: uint256 = input_amount * 997
    numerator: uint256 = input_amount_with_fee * output_reserve
    denominator: uint256 = (input_reserve * 1000) + input_amount_with_fee
    return numerator / denominator

# @dev Pricing function for converting between ETH and Tokens.
# @param output_amount Amount of ETH or Tokens being bought.
# @param input_reserve Amount of ETH or Tokens (input type) in exchange reserves.
# @param output_reserve Amount of ETH or Tokens (output type) in exchange reserves.
# @return Amount of ETH or Tokens sold.
@private
@constant
def getOutputPrice(output_amount: uint256, input_reserve: uint256, output_reserve: uint256) -> uint256:
    assert input_reserve > 0 and output_reserve > 0
    numerator: uint256 = input_reserve * output_amount * 1000
    denominator: uint256 = (output_reserve - output_amount) * 997
    return numerator / denominator + 1

@private
def ethToTokenInput(eth_sold: uint256(wei), min_tokens: uint256, deadline: timestamp, buyer: address, recipient: address) -> uint256:
    assert deadline >= block.timestamp and (eth_sold > 0 and min_tokens > 0)
    token_reserve: uint256 = self.token.balanceOf(self)
    tokens_bought: uint256 = self.getInputPrice(as_unitless_number(eth_sold), as_unitless_number(self.balance - eth_sold), token_reserve)
    assert tokens_bought >= min_tokens
    assert self.token.transfer(recipient, tokens_bought)
    log.TokenPurchase(buyer, eth_sold, tokens_bought)
    return tokens_bought

# @notice Convert ETH to Tokens.
# @dev User specifies exact input (msg.value).
# @dev User cannot specify minimum output or deadline.
@public
@payable
def __default__():
    self.ethToTokenInput(msg.value, 1, block.timestamp, msg.sender, msg.sender)

# @notice Convert ETH to Tokens.
# @dev User specifies exact input (msg.value) and minimum output.
# @param min_tokens Minimum Tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of Tokens bought.
@public
@payable
def ethToTokenSwapInput(min_tokens: uint256, deadline: timestamp) -> uint256:
    return self.ethToTokenInput(msg.value, min_tokens, deadline, msg.sender, msg.sender)

# @notice Convert ETH to Tokens and transfers Tokens to recipient.
# @dev User specifies exact input (msg.value) and minimum output
# @param min_tokens Minimum Tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output Tokens.
# @return Amount of Tokens bought.
@public
@payable
def ethToTokenTransferInput(min_tokens: uint256, deadline: timestamp, recipient: address) -> uint256:
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.ethToTokenInput(msg.value, min_tokens, deadline, msg.sender, recipient)

@private
def ethToTokenOutput(tokens_bought: uint256, max_eth: uint256(wei), deadline: timestamp, buyer: address, recipient: address) -> uint256(wei):
    assert deadline >= block.timestamp and (tokens_bought > 0 and max_eth > 0)
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_sold: uint256 = self.getOutputPrice(tokens_bought, as_unitless_number(self.balance - max_eth), token_reserve)
    # Throws if eth_sold > max_eth
    eth_refund: uint256(wei) = max_eth - as_wei_value(eth_sold, 'wei')
    if eth_refund > 0:
        send(buyer, eth_refund)
    assert self.token.transfer(recipient, tokens_bought)
    log.TokenPurchase(buyer, as_wei_value(eth_sold, 'wei'), tokens_bought)
    return as_wei_value(eth_sold, 'wei')

# @notice Convert ETH to Tokens.
# @dev User specifies maximum input (msg.value) and exact output.
# @param tokens_bought Amount of tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of ETH sold.
@public
@payable
def ethToTokenSwapOutput(tokens_bought: uint256, deadline: timestamp) -> uint256(wei):
    return self.ethToTokenOutput(tokens_bought, msg.value, deadline, msg.sender, msg.sender)

# @notice Convert ETH to Tokens and transfers Tokens to recipient.
# @dev User specifies maximum input (msg.value) and exact output.
# @param tokens_bought Amount of tokens bought.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output Tokens.
# @return Amount of ETH sold.
@public
@payable
def ethToTokenTransferOutput(tokens_bought: uint256, deadline: timestamp, recipient: address) -> uint256(wei):
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.ethToTokenOutput(tokens_bought, msg.value, deadline, msg.sender, recipient)

@private
def tokenToEthInput(tokens_sold: uint256, min_eth: uint256(wei), deadline: timestamp, buyer: address, recipient: address) -> uint256(wei):
    assert deadline >= block.timestamp and (tokens_sold > 0 and min_eth > 0)
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_bought: uint256 = self.getInputPrice(tokens_sold, token_reserve, as_unitless_number(self.balance))
    wei_bought: uint256(wei) = as_wei_value(eth_bought, 'wei')
    assert wei_bought >= min_eth
    send(recipient, wei_bought)
    assert self.token.transferFrom(buyer, self, tokens_sold)
    log.EthPurchase(buyer, tokens_sold, wei_bought)
    return wei_bought


# @notice Convert Tokens to ETH.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_eth Minimum ETH purchased.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of ETH bought.
@public
def tokenToEthSwapInput(tokens_sold: uint256, min_eth: uint256(wei), deadline: timestamp) -> uint256(wei):
    return self.tokenToEthInput(tokens_sold, min_eth, deadline, msg.sender, msg.sender)

# @notice Convert Tokens to ETH and transfers ETH to recipient.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_eth Minimum ETH purchased.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @return Amount of ETH bought.
@public
def tokenToEthTransferInput(tokens_sold: uint256, min_eth: uint256(wei), deadline: timestamp, recipient: address) -> uint256(wei):
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.tokenToEthInput(tokens_sold, min_eth, deadline, msg.sender, recipient)

@private
def tokenToEthOutput(eth_bought: uint256(wei), max_tokens: uint256, deadline: timestamp, buyer: address, recipient: address) -> uint256:
    assert deadline >= block.timestamp and eth_bought > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    tokens_sold: uint256 = self.getOutputPrice(as_unitless_number(eth_bought), token_reserve, as_unitless_number(self.balance))
    # tokens sold is always > 0
    assert max_tokens >= tokens_sold
    send(recipient, eth_bought)
    assert self.token.transferFrom(buyer, self, tokens_sold)
    log.EthPurchase(buyer, tokens_sold, eth_bought)
    return tokens_sold

# @notice Convert Tokens to ETH.
# @dev User specifies maximum input and exact output.
# @param eth_bought Amount of ETH purchased.
# @param max_tokens Maximum Tokens sold.
# @param deadline Time after which this transaction can no longer be executed.
# @return Amount of Tokens sold.
@public
def tokenToEthSwapOutput(eth_bought: uint256(wei), max_tokens: uint256, deadline: timestamp) -> uint256:
    return self.tokenToEthOutput(eth_bought, max_tokens, deadline, msg.sender, msg.sender)

# @notice Convert Tokens to ETH and transfers ETH to recipient.
# @dev User specifies maximum input and exact output.
# @param eth_bought Amount of ETH purchased.
# @param max_tokens Maximum Tokens sold.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @return Amount of Tokens sold.
@public
def tokenToEthTransferOutput(eth_bought: uint256(wei), max_tokens: uint256, deadline: timestamp, recipient: address) -> uint256:
    assert recipient != self and recipient != ZERO_ADDRESS
    return self.tokenToEthOutput(eth_bought, max_tokens, deadline, msg.sender, recipient)

@private
def tokenToTokenInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, buyer: address, recipient: address, exchange_addr: address) -> uint256:
    assert (deadline >= block.timestamp and tokens_sold > 0) and (min_tokens_bought > 0 and min_eth_bought > 0)
    assert exchange_addr != self and exchange_addr != ZERO_ADDRESS
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_bought: uint256 = self.getInputPrice(tokens_sold, token_reserve, as_unitless_number(self.balance))
    wei_bought: uint256(wei) = as_wei_value(eth_bought, 'wei')
    assert wei_bought >= min_eth_bought
    assert self.token.transferFrom(buyer, self, tokens_sold)
    tokens_bought: uint256 = Exchange(exchange_addr).ethToTokenTransferInput(min_tokens_bought, deadline, recipient, value=wei_bought)
    log.EthPurchase(buyer, tokens_sold, wei_bought)
    return tokens_bought

# @notice Convert Tokens (self.token) to Tokens (token_addr).
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (token_addr) bought.
@public
def tokenToTokenSwapInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (token_addr) and transfers
#         Tokens (token_addr) to recipient.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (token_addr) bought.
@public
def tokenToTokenTransferInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, recipient: address, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, recipient, exchange_addr)

@private
def tokenToTokenOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, buyer: address, recipient: address, exchange_addr: address) -> uint256:
    assert deadline >= block.timestamp and (tokens_bought > 0 and max_eth_sold > 0)
    assert exchange_addr != self and exchange_addr != ZERO_ADDRESS
    eth_bought: uint256(wei) = Exchange(exchange_addr).getEthToTokenOutputPrice(tokens_bought)
    token_reserve: uint256 = self.token.balanceOf(self)
    tokens_sold: uint256 = self.getOutputPrice(as_unitless_number(eth_bought), token_reserve, as_unitless_number(self.balance))
    # tokens sold is always > 0
    assert max_tokens_sold >= tokens_sold and max_eth_sold >= eth_bought
    assert self.token.transferFrom(buyer, self, tokens_sold)
    eth_sold: uint256(wei) = Exchange(exchange_addr).ethToTokenTransferOutput(tokens_bought, deadline, recipient, value=eth_bought)
    log.EthPurchase(buyer, tokens_sold, eth_bought)
    return tokens_sold

# @notice Convert Tokens (self.token) to Tokens (token_addr).
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToTokenSwapOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (token_addr) and transfers
#         Tokens (token_addr) to recipient.
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToTokenTransferOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, recipient: address, token_addr: address) -> uint256:
    exchange_addr: address = self.factory.getExchange(token_addr)
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, recipient, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token).
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param exchange_addr The address of the exchange for the token being purchased.
# @return Amount of Tokens (exchange_addr.token) bought.
@public
def tokenToExchangeSwapInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, exchange_addr: address) -> uint256:
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token) and transfers
#         Tokens (exchange_addr.token) to recipient.
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies exact input and minimum output.
# @param tokens_sold Amount of Tokens sold.
# @param min_tokens_bought Minimum Tokens (token_addr) purchased.
# @param min_eth_bought Minimum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param exchange_addr The address of the exchange for the token being purchased.
# @return Amount of Tokens (exchange_addr.token) bought.
@public
def tokenToExchangeTransferInput(tokens_sold: uint256, min_tokens_bought: uint256, min_eth_bought: uint256(wei), deadline: timestamp, recipient: address, exchange_addr: address) -> uint256:
    assert recipient != self
    return self.tokenToTokenInput(tokens_sold, min_tokens_bought, min_eth_bought, deadline, msg.sender, recipient, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token).
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param exchange_addr The address of the exchange for the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToExchangeSwapOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, exchange_addr: address) -> uint256:
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, msg.sender, exchange_addr)

# @notice Convert Tokens (self.token) to Tokens (exchange_addr.token) and transfers
#         Tokens (exchange_addr.token) to recipient.
# @dev Allows trades through contracts that were not deployed from the same factory.
# @dev User specifies maximum input and exact output.
# @param tokens_bought Amount of Tokens (token_addr) bought.
# @param max_tokens_sold Maximum Tokens (self.token) sold.
# @param max_eth_sold Maximum ETH purchased as intermediary.
# @param deadline Time after which this transaction can no longer be executed.
# @param recipient The address that receives output ETH.
# @param token_addr The address of the token being purchased.
# @return Amount of Tokens (self.token) sold.
@public
def tokenToExchangeTransferOutput(tokens_bought: uint256, max_tokens_sold: uint256, max_eth_sold: uint256(wei), deadline: timestamp, recipient: address, exchange_addr: address) -> uint256:
    assert recipient != self
    return self.tokenToTokenOutput(tokens_bought, max_tokens_sold, max_eth_sold, deadline, msg.sender, recipient, exchange_addr)

# @notice Public price function for ETH to Token trades with an exact input.
# @param eth_sold Amount of ETH sold.
# @return Amount of Tokens that can be bought with input ETH.
@public
@constant
def getEthToTokenInputPrice(eth_sold: uint256(wei)) -> uint256:
    assert eth_sold > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    return self.getInputPrice(as_unitless_number(eth_sold), as_unitless_number(self.balance), token_reserve)

# @notice Public price function for ETH to Token trades with an exact output.
# @param tokens_bought Amount of Tokens bought.
# @return Amount of ETH needed to buy output Tokens.
@public
@constant
def getEthToTokenOutputPrice(tokens_bought: uint256) -> uint256(wei):
    assert tokens_bought > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_sold: uint256 = self.getOutputPrice(tokens_bought, as_unitless_number(self.balance), token_reserve)
    return as_wei_value(eth_sold, 'wei')

# @notice Public price function for Token to ETH trades with an exact input.
# @param tokens_sold Amount of Tokens sold.
# @return Amount of ETH that can be bought with input Tokens.
@public
@constant
def getTokenToEthInputPrice(tokens_sold: uint256) -> uint256(wei):
    assert tokens_sold > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    eth_bought: uint256 = self.getInputPrice(tokens_sold, token_reserve, as_unitless_number(self.balance))
    return as_wei_value(eth_bought, 'wei')

# @notice Public price function for Token to ETH trades with an exact output.
# @param eth_bought Amount of output ETH.
# @return Amount of Tokens needed to buy output ETH.
@public
@constant
def getTokenToEthOutputPrice(eth_bought: uint256(wei)) -> uint256:
    assert eth_bought > 0
    token_reserve: uint256 = self.token.balanceOf(self)
    return self.getOutputPrice(as_unitless_number(eth_bought), token_reserve, as_unitless_number(self.balance))

# @return Address of Token that is sold on this exchange.
@public
@constant
def tokenAddress() -> address:
    return self.token

# @return Address of factory that created this exchange.
@public
@constant
def factoryAddress() -> address(Factory):
    return self.factory

# ERC20 compatibility for exchange liquidity modified from
# https://github.com/ethereum/vyper/blob/master/examples/tokens/ERC20.vy
@public
@constant
def balanceOf(_owner : address) -> uint256:
    return self.balances[_owner]

@public
def transfer(_to : address, _value : uint256) -> bool:
    self.balances[msg.sender] -= _value
    self.balances[_to] += _value
    log.Transfer(msg.sender, _to, _value)
    return True

@public
def transferFrom(_from : address, _to : address, _value : uint256) -> bool:
    self.balances[_from] -= _value
    self.balances[_to] += _value
    self.allowances[_from][msg.sender] -= _value
    log.Transfer(_from, _to, _value)
    return True

@public
def approve(_spender : address, _value : uint256) -> bool:
    self.allowances[msg.sender][_spender] = _value
    log.Approval(msg.sender, _spender, _value)
    return True

@public
@constant
def allowance(_owner : address, _spender : address) -> uint256:
    return self.allowances[_owner][_spender]