// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
import "./Proxy.sol";
interface ERC165 {
    function supportsInterface(bytes4 id) external view returns (bool);
}
///@notice Proxy implementing EIP173 for ownership management
contract EIP173Proxy is Proxy {
    // ////////////////////////// EVENTS ///////////////////////////////////////////////////////////////////////
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    // /////////////////////// CONSTRUCTOR //////////////////////////////////////////////////////////////////////
    constructor(
        address implementationAddress,
        address ownerAddress,
        bytes memory data
    ) payable {
        _setImplementation(implementationAddress, data);
        _setOwner(ownerAddress);
    }
    // ///////////////////// EXTERNAL ///////////////////////////////////////////////////////////////////////////
    function owner() external view returns (address) {
        return _owner();
    }
    function supportsInterface(bytes4 id) external view returns (bool) {
        if (id == 0x01ffc9a7 || id == 0x7f5828d0) {
            return true;
        }
        if (id == 0xFFFFFFFF) {
            return false;
        }
        ERC165 implementation;
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            implementation := sload(0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc)
        }
        // Technically this is not standard compliant as ERC-165 require 30,000 gas which that call cannot ensure
        // because it is itself inside `supportsInterface` that might only get 30,000 gas.
        // In practise this is unlikely to be an issue.
        try implementation.supportsInterface(id) returns (bool support) {
            return support;
        } catch {
            return false;
        }
    }
    function transferOwnership(address newOwner) external onlyOwner {
        _setOwner(newOwner);
    }
    function upgradeTo(address newImplementation) external onlyOwner {
        _setImplementation(newImplementation, "");
    }
    function upgradeToAndCall(address newImplementation, bytes calldata data) external payable onlyOwner {
        _setImplementation(newImplementation, data);
    }
    // /////////////////////// MODIFIERS ////////////////////////////////////////////////////////////////////////
    modifier onlyOwner() {
        require(msg.sender == _owner(), "NOT_AUTHORIZED");
        _;
    }
    // ///////////////////////// INTERNAL //////////////////////////////////////////////////////////////////////
    function _owner() internal view returns (address adminAddress) {
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            adminAddress := sload(0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103)
        }
    }
    function _setOwner(address newOwner) internal {
        address previousOwner = _owner();
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            sstore(0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103, newOwner)
        }
        emit OwnershipTransferred(previousOwner, newOwner);
    }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
// EIP-1967
abstract contract Proxy {
    // /////////////////////// EVENTS ///////////////////////////////////////////////////////////////////////////
    event ProxyImplementationUpdated(address indexed previousImplementation, address indexed newImplementation);
    // ///////////////////// EXTERNAL ///////////////////////////////////////////////////////////////////////////
    receive() external payable virtual {
        revert("ETHER_REJECTED"); // explicit reject by default
    }
    fallback() external payable {
        _fallback();
    }
    // ///////////////////////// INTERNAL //////////////////////////////////////////////////////////////////////
    function _fallback() internal {
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            let implementationAddress := sload(0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc)
            calldatacopy(0x0, 0x0, calldatasize())
            let success := delegatecall(gas(), implementationAddress, 0x0, calldatasize(), 0, 0)
            let retSz := returndatasize()
            returndatacopy(0, 0, retSz)
            switch success
                case 0 {
                    revert(0, retSz)
                }
                default {
                    return(0, retSz)
                }
        }
    }
    function _setImplementation(address newImplementation, bytes memory data) internal {
        address previousImplementation;
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            previousImplementation := sload(0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc)
        }
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            sstore(0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc, newImplementation)
        }
        emit ProxyImplementationUpdated(previousImplementation, newImplementation);
        if (data.length > 0) {
            (bool success, ) = newImplementation.delegatecall(data);
            if (!success) {
                assembly {
                    // This assembly ensure the revert contains the exact string data
                    let returnDataSize := returndatasize()
                    returndatacopy(0, 0, returnDataSize)
                    revert(0, returnDataSize)
                }
            }
        }
    }
}

pragma solidity ^0.6.0;
import "../Initializable.sol";
/*
 * @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 ContextUpgradeSafe is Initializable {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    function __Context_init() internal initializer {
        __Context_init_unchained();
    }
    function __Context_init_unchained() internal initializer {
    }
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }
    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
    uint256[50] private __gap;
}
pragma solidity >=0.4.24 <0.7.0;
/**
 * @title Initializable
 *
 * @dev Helper contract to support initializer functions. To use it, replace
 * the constructor with a function that has the `initializer` modifier.
 * WARNING: Unlike constructors, initializer functions must be manually
 * invoked. This applies both to deploying an Initializable contract, as well
 * as extending an Initializable contract via inheritance.
 * WARNING: When used with inheritance, manual care must be taken to not invoke
 * a parent initializer twice, or ensure that all initializers are idempotent,
 * because this is not dealt with automatically as with constructors.
 */
contract Initializable {
  /**
   * @dev Indicates that the contract has been initialized.
   */
  bool private initialized;
  /**
   * @dev Indicates that the contract is in the process of being initialized.
   */
  bool private initializing;
  /**
   * @dev Modifier to use in the initializer function of a contract.
   */
  modifier initializer() {
    require(initializing || isConstructor() || !initialized, "Contract instance has already been initialized");
    bool isTopLevelCall = !initializing;
    if (isTopLevelCall) {
      initializing = true;
      initialized = true;
    }
    _;
    if (isTopLevelCall) {
      initializing = false;
    }
  }
  /// @dev Returns true if and only if the function is running in the constructor
  function isConstructor() private view returns (bool) {
    // extcodesize checks the size of the code stored in an address, and
    // address returns the current address. Since the code is still not
    // deployed when running a constructor, any checks on its code size will
    // yield zero, making it an effective way to detect if a contract is
    // under construction or not.
    address self = address(this);
    uint256 cs;
    assembly { cs := extcodesize(self) }
    return cs == 0;
  }
  // Reserved storage space to allow for layout changes in the future.
  uint256[50] private ______gap;
}
pragma solidity ^0.6.0;
import "../utils/EnumerableSet.sol";
import "../utils/Address.sol";
import "../GSN/Context.sol";
import "../Initializable.sol";
/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, _msgSender()));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 */
abstract contract AccessControlUpgradeSafe is Initializable, ContextUpgradeSafe {
    function __AccessControl_init() internal initializer {
        __Context_init_unchained();
        __AccessControl_init_unchained();
    }
    function __AccessControl_init_unchained() internal initializer {
    }
    using EnumerableSet for EnumerableSet.AddressSet;
    using Address for address;
    struct RoleData {
        EnumerableSet.AddressSet members;
        bytes32 adminRole;
    }
    mapping (bytes32 => RoleData) private _roles;
    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view returns (bool) {
        return _roles[role].members.contains(account);
    }
    /**
     * @dev Returns the number of accounts that have `role`. Can be used
     * together with {getRoleMember} to enumerate all bearers of a role.
     */
    function getRoleMemberCount(bytes32 role) public view returns (uint256) {
        return _roles[role].members.length();
    }
    /**
     * @dev Returns one of the accounts that have `role`. `index` must be a
     * value between 0 and {getRoleMemberCount}, non-inclusive.
     *
     * Role bearers are not sorted in any particular way, and their ordering may
     * change at any point.
     *
     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
     * you perform all queries on the same block. See the following
     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
     * for more information.
     */
    function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
        return _roles[role].members.at(index);
    }
    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view returns (bytes32) {
        return _roles[role].adminRole;
    }
    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");
        _grantRole(role, account);
    }
    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");
        _revokeRole(role, account);
    }
    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");
        _revokeRole(role, account);
    }
    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }
    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        _roles[role].adminRole = adminRole;
    }
    function _grantRole(bytes32 role, address account) private {
        if (_roles[role].members.add(account)) {
            emit RoleGranted(role, account, _msgSender());
        }
    }
    function _revokeRole(bytes32 role, address account) private {
        if (_roles[role].members.remove(account)) {
            emit RoleRevoked(role, account, _msgSender());
        }
    }
    uint256[49] private __gap;
}
pragma solidity ^0.6.0;
/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }
    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }
    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;
        return c;
    }
    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }
    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }
    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // 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.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}
pragma solidity ^0.6.0;
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);
    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);
    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);
    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);
    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);
    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);
    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
pragma solidity ^0.6.2;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }
    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}
pragma solidity ^0.6.0;
import "../math/SafeMath.sol";
/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}
 * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never
 * directly accessed.
 */
library Counters {
    using SafeMath for uint256;
    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }
    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }
    function increment(Counter storage counter) internal {
        // The {SafeMath} overflow check can be skipped here, see the comment at the top
        counter._value += 1;
    }
    function decrement(Counter storage counter) internal {
        counter._value = counter._value.sub(1);
    }
}
pragma solidity ^0.6.0;
/**
 * @dev Library for managing an enumerable variant of Solidity's
 * https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
 * type.
 *
 * Maps have the following properties:
 *
 * - Entries are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Entries are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableMap for EnumerableMap.UintToAddressMap;
 *
 *     // Declare a set state variable
 *     EnumerableMap.UintToAddressMap private myMap;
 * }
 * ```
 *
 * As of v3.0.0, only maps of type `uint256 -> address` (`UintToAddressMap`) are
 * supported.
 */
library EnumerableMap {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Map type with
    // bytes32 keys and values.
    // The Map implementation uses private functions, and user-facing
    // implementations (such as Uint256ToAddressMap) are just wrappers around
    // the underlying Map.
    // This means that we can only create new EnumerableMaps for types that fit
    // in bytes32.
    struct MapEntry {
        bytes32 _key;
        bytes32 _value;
    }
    struct Map {
        // Storage of map keys and values
        MapEntry[] _entries;
        // Position of the entry defined by a key in the `entries` array, plus 1
        // because index 0 means a key is not in the map.
        mapping (bytes32 => uint256) _indexes;
    }
    /**
     * @dev Adds a key-value pair to a map, or updates the value for an existing
     * key. O(1).
     *
     * Returns true if the key was added to the map, that is if it was not
     * already present.
     */
    function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {
        // We read and store the key's index to prevent multiple reads from the same storage slot
        uint256 keyIndex = map._indexes[key];
        if (keyIndex == 0) { // Equivalent to !contains(map, key)
            map._entries.push(MapEntry({ _key: key, _value: value }));
            // The entry is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            map._indexes[key] = map._entries.length;
            return true;
        } else {
            map._entries[keyIndex - 1]._value = value;
            return false;
        }
    }
    /**
     * @dev Removes a key-value pair from a map. O(1).
     *
     * Returns true if the key was removed from the map, that is if it was present.
     */
    function _remove(Map storage map, bytes32 key) private returns (bool) {
        // We read and store the key's index to prevent multiple reads from the same storage slot
        uint256 keyIndex = map._indexes[key];
        if (keyIndex != 0) { // Equivalent to contains(map, key)
            // To delete a key-value pair from the _entries array in O(1), we swap the entry to delete with the last one
            // in the array, and then remove the last entry (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.
            uint256 toDeleteIndex = keyIndex - 1;
            uint256 lastIndex = map._entries.length - 1;
            // When the entry to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
            MapEntry storage lastEntry = map._entries[lastIndex];
            // Move the last entry to the index where the entry to delete is
            map._entries[toDeleteIndex] = lastEntry;
            // Update the index for the moved entry
            map._indexes[lastEntry._key] = toDeleteIndex + 1; // All indexes are 1-based
            // Delete the slot where the moved entry was stored
            map._entries.pop();
            // Delete the index for the deleted slot
            delete map._indexes[key];
            return true;
        } else {
            return false;
        }
    }
    /**
     * @dev Returns true if the key is in the map. O(1).
     */
    function _contains(Map storage map, bytes32 key) private view returns (bool) {
        return map._indexes[key] != 0;
    }
    /**
     * @dev Returns the number of key-value pairs in the map. O(1).
     */
    function _length(Map storage map) private view returns (uint256) {
        return map._entries.length;
    }
   /**
    * @dev Returns the key-value pair stored at position `index` in the map. O(1).
    *
    * Note that there are no guarantees on the ordering of entries inside the
    * array, and it may change when more entries are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {
        require(map._entries.length > index, "EnumerableMap: index out of bounds");
        MapEntry storage entry = map._entries[index];
        return (entry._key, entry._value);
    }
    /**
     * @dev Returns the value associated with `key`.  O(1).
     *
     * Requirements:
     *
     * - `key` must be in the map.
     */
    function _get(Map storage map, bytes32 key) private view returns (bytes32) {
        return _get(map, key, "EnumerableMap: nonexistent key");
    }
    /**
     * @dev Same as {_get}, with a custom error message when `key` is not in the map.
     */
    function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {
        uint256 keyIndex = map._indexes[key];
        require(keyIndex != 0, errorMessage); // Equivalent to contains(map, key)
        return map._entries[keyIndex - 1]._value; // All indexes are 1-based
    }
    // UintToAddressMap
    struct UintToAddressMap {
        Map _inner;
    }
    /**
     * @dev Adds a key-value pair to a map, or updates the value for an existing
     * key. O(1).
     *
     * Returns true if the key was added to the map, that is if it was not
     * already present.
     */
    function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {
        return _set(map._inner, bytes32(key), bytes32(uint256(value)));
    }
    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the key was removed from the map, that is if it was present.
     */
    function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
        return _remove(map._inner, bytes32(key));
    }
    /**
     * @dev Returns true if the key is in the map. O(1).
     */
    function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
        return _contains(map._inner, bytes32(key));
    }
    /**
     * @dev Returns the number of elements in the map. O(1).
     */
    function length(UintToAddressMap storage map) internal view returns (uint256) {
        return _length(map._inner);
    }
   /**
    * @dev Returns the element stored at position `index` in the set. O(1).
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
        (bytes32 key, bytes32 value) = _at(map._inner, index);
        return (uint256(key), address(uint256(value)));
    }
    /**
     * @dev Returns the value associated with `key`.  O(1).
     *
     * Requirements:
     *
     * - `key` must be in the map.
     */
    function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
        return address(uint256(_get(map._inner, bytes32(key))));
    }
    /**
     * @dev Same as {get}, with a custom error message when `key` is not in the map.
     */
    function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {
        return address(uint256(_get(map._inner, bytes32(key), errorMessage)));
    }
}
pragma solidity ^0.6.0;
/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.0.0, only sets of type `address` (`AddressSet`) and `uint256`
 * (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.
    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }
    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }
    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];
        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.
            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;
            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
            bytes32 lastvalue = set._values[lastIndex];
            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based
            // Delete the slot where the moved value was stored
            set._values.pop();
            // Delete the index for the deleted slot
            delete set._indexes[value];
            return true;
        } else {
            return false;
        }
    }
    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }
    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }
   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }
    // AddressSet
    struct AddressSet {
        Set _inner;
    }
    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(value)));
    }
    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(value)));
    }
    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(value)));
    }
    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }
   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint256(_at(set._inner, index)));
    }
    // UintSet
    struct UintSet {
        Set _inner;
    }
    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }
    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }
    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }
    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }
   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}
pragma solidity ^0.6.0;
import "../GSN/Context.sol";
import "../Initializable.sol";
/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
contract PausableUpgradeSafe is Initializable, ContextUpgradeSafe {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);
    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);
    bool private _paused;
    /**
     * @dev Initializes the contract in unpaused state.
     */
    function __Pausable_init() internal initializer {
        __Context_init_unchained();
        __Pausable_init_unchained();
    }
    function __Pausable_init_unchained() internal initializer {
        _paused = false;
    }
    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view returns (bool) {
        return _paused;
    }
    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }
    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }
    /**
     * @dev Triggers stopped state.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }
    /**
     * @dev Returns to normal state.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
    uint256[49] private __gap;
}
pragma solidity ^0.6.0;
import "../Initializable.sol";
/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
contract ReentrancyGuardUpgradeSafe is Initializable {
    bool private _notEntered;
    function __ReentrancyGuard_init() internal initializer {
        __ReentrancyGuard_init_unchained();
    }
    function __ReentrancyGuard_init_unchained() internal initializer {
        // Storing an initial non-zero value makes deployment a bit more
        // expensive, but in exchange the refund on every call to nonReentrant
        // will be lower in amount. Since refunds are capped to a percetange of
        // the total transaction's gas, it is best to keep them low in cases
        // like this one, to increase the likelihood of the full refund coming
        // into effect.
        _notEntered = true;
    }
    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_notEntered, "ReentrancyGuard: reentrant call");
        // Any calls to nonReentrant after this point will fail
        _notEntered = false;
        _;
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _notEntered = true;
    }
    uint256[49] private __gap;
}
pragma solidity ^0.6.0;
/**
 * @dev String operations.
 */
library Strings {
    /**
     * @dev Converts a `uint256` to its ASCII `string` representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        uint256 index = digits - 1;
        temp = value;
        while (temp != 0) {
            buffer[index--] = byte(uint8(48 + temp % 10));
            temp /= 10;
        }
        return string(buffer);
    }
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2 <0.8.0;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.
        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }
    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }
    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}
// SPDX-License-Identifier: MIT
// solhint-disable
/*
  Vendored from @openzeppelin/[email protected]
  Alterations:
   * Make supportsInterface virtual so it can be overriden by inheriting contracts
*/
pragma solidity ^0.6.0;
import "../interfaces/openzeppelin/IERC165.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/Initializable.sol";
/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts may inherit from this and call {_registerInterface} to declare
 * their support of an interface.
 */
contract ERC165UpgradeSafe is Initializable, IERC165 {
  /*
   * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
   */
  bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
  /**
   * @dev Mapping of interface ids to whether or not it's supported.
   */
  mapping(bytes4 => bool) private _supportedInterfaces;
  function __ERC165_init() internal initializer {
    __ERC165_init_unchained();
  }
  function __ERC165_init_unchained() internal initializer {
    // Derived contracts need only register support for their own interfaces,
    // we register support for ERC165 itself here
    _registerInterface(_INTERFACE_ID_ERC165);
  }
  /**
   * @dev See {IERC165-supportsInterface}.
   *
   * Time complexity O(1), guaranteed to always use less than 30 000 gas.
   */
  function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
    return _supportedInterfaces[interfaceId];
  }
  /**
   * @dev Registers the contract as an implementer of the interface defined by
   * `interfaceId`. Support of the actual ERC165 interface is automatic and
   * registering its interface id is not required.
   *
   * See {IERC165-supportsInterface}.
   *
   * Requirements:
   *
   * - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
   */
  function _registerInterface(bytes4 interfaceId) internal virtual {
    require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
    _supportedInterfaces[interfaceId] = true;
  }
  uint256[49] private __gap;
}
// SPDX-License-Identifier: MIT
// solhint-disable
/*
  Vendored from @openzeppelin/[email protected]
  Alterations:
   * Use vendored ERC165 with virtual supportsInterface
*/
pragma solidity ^0.6.0;
import "@openzeppelin/contracts-ethereum-package/contracts/GSN/Context.sol";
import "../interfaces/openzeppelin/IERC721.sol";
import "../interfaces/openzeppelin/IERC721Metadata.sol";
import "../interfaces/openzeppelin/IERC721Enumerable.sol";
import "../interfaces/openzeppelin/IERC721Receiver.sol";
import "./ERC165.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/Address.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/EnumerableSet.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/EnumerableMap.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/Strings.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/Initializable.sol";
/**
 * @title ERC721 Non-Fungible Token Standard basic implementation
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721UpgradeSafe is
  Initializable,
  ContextUpgradeSafe,
  ERC165UpgradeSafe,
  IERC721,
  IERC721Metadata,
  IERC721Enumerable
{
  using SafeMath for uint256;
  using Address for address;
  using EnumerableSet for EnumerableSet.UintSet;
  using EnumerableMap for EnumerableMap.UintToAddressMap;
  using Strings for uint256;
  // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
  // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
  bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;
  // Mapping from holder address to their (enumerable) set of owned tokens
  mapping(address => EnumerableSet.UintSet) private _holderTokens;
  // Enumerable mapping from token ids to their owners
  EnumerableMap.UintToAddressMap private _tokenOwners;
  // Mapping from token ID to approved address
  mapping(uint256 => address) private _tokenApprovals;
  // Mapping from owner to operator approvals
  mapping(address => mapping(address => bool)) private _operatorApprovals;
  // Token name
  string private _name;
  // Token symbol
  string private _symbol;
  // Optional mapping for token URIs
  mapping(uint256 => string) private _tokenURIs;
  // Base URI
  string private _baseURI;
  /*
   *     bytes4(keccak256('balanceOf(address)')) == 0x70a08231
   *     bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e
   *     bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
   *     bytes4(keccak256('getApproved(uint256)')) == 0x081812fc
   *     bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465
   *     bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5
   *     bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
   *     bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e
   *     bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
   *
   *     => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
   *        0xa22cb465 ^ 0xe985e9c ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
   */
  bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;
  /*
   *     bytes4(keccak256('name()')) == 0x06fdde03
   *     bytes4(keccak256('symbol()')) == 0x95d89b41
   *     bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd
   *
   *     => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f
   */
  bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
  /*
   *     bytes4(keccak256('totalSupply()')) == 0x18160ddd
   *     bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59
   *     bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7
   *
   *     => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63
   */
  bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
  function __ERC721_init(string memory name, string memory symbol) internal initializer {
    __Context_init_unchained();
    __ERC165_init_unchained();
    __ERC721_init_unchained(name, symbol);
  }
  function __ERC721_init_unchained(string memory name, string memory symbol) internal initializer {
    _name = name;
    _symbol = symbol;
    // register the supported interfaces to conform to ERC721 via ERC165
    _registerInterface(_INTERFACE_ID_ERC721);
    _registerInterface(_INTERFACE_ID_ERC721_METADATA);
    _registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
  }
  /**
   * @dev Gets the balance of the specified address.
   * @param owner address to query the balance of
   * @return uint256 representing the amount owned by the passed address
   */
  function balanceOf(address owner) public view override returns (uint256) {
    require(owner != address(0), "ERC721: balance query for the zero address");
    return _holderTokens[owner].length();
  }
  /**
   * @dev Gets the owner of the specified token ID.
   * @param tokenId uint256 ID of the token to query the owner of
   * @return address currently marked as the owner of the given token ID
   */
  function ownerOf(uint256 tokenId) public view override returns (address) {
    return _tokenOwners.get(tokenId, "ERC721: owner query for nonexistent token");
  }
  /**
   * @dev Gets the token name.
   * @return string representing the token name
   */
  function name() public view override returns (string memory) {
    return _name;
  }
  /**
   * @dev Gets the token symbol.
   * @return string representing the token symbol
   */
  function symbol() public view override returns (string memory) {
    return _symbol;
  }
  /**
   * @dev Returns the URI for a given token ID. May return an empty string.
   *
   * If a base URI is set (via {_setBaseURI}), it is added as a prefix to the
   * token's own URI (via {_setTokenURI}).
   *
   * If there is a base URI but no token URI, the token's ID will be used as
   * its URI when appending it to the base URI. This pattern for autogenerated
   * token URIs can lead to large gas savings.
   *
   * .Examples
   * |===
   * |`_setBaseURI()` |`_setTokenURI()` |`tokenURI()`
   * | ""
   * | ""
   * | ""
   * | ""
   * | "token.uri/123"
   * | "token.uri/123"
   * | "token.uri/"
   * | "123"
   * | "token.uri/123"
   * | "token.uri/"
   * | ""
   * | "token.uri/<tokenId>"
   * |===
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function tokenURI(uint256 tokenId) public view override returns (string memory) {
    require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
    string memory _tokenURI = _tokenURIs[tokenId];
    // If there is no base URI, return the token URI.
    if (bytes(_baseURI).length == 0) {
      return _tokenURI;
    }
    // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
    if (bytes(_tokenURI).length > 0) {
      return string(abi.encodePacked(_baseURI, _tokenURI));
    }
    // If there is a baseURI but no tokenURI, concatenate the tokenID to the baseURI.
    return string(abi.encodePacked(_baseURI, tokenId.toString()));
  }
  /**
   * @dev Returns the base URI set via {_setBaseURI}. This will be
   * automatically added as a prefix in {tokenURI} to each token's URI, or
   * to the token ID if no specific URI is set for that token ID.
   */
  function baseURI() public view returns (string memory) {
    return _baseURI;
  }
  /**
   * @dev Gets the token ID at a given index of the tokens list of the requested owner.
   * @param owner address owning the tokens list to be accessed
   * @param index uint256 representing the index to be accessed of the requested tokens list
   * @return uint256 token ID at the given index of the tokens list owned by the requested address
   */
  function tokenOfOwnerByIndex(
    address owner,
    uint256 index
  ) public view override returns (uint256) {
    return _holderTokens[owner].at(index);
  }
  /**
   * @dev Gets the total amount of tokens stored by the contract.
   * @return uint256 representing the total amount of tokens
   */
  function totalSupply() public view override returns (uint256) {
    // _tokenOwners are indexed by tokenIds, so .length() returns the number of tokenIds
    return _tokenOwners.length();
  }
  /**
   * @dev Gets the token ID at a given index of all the tokens in this contract
   * Reverts if the index is greater or equal to the total number of tokens.
   * @param index uint256 representing the index to be accessed of the tokens list
   * @return uint256 token ID at the given index of the tokens list
   */
  function tokenByIndex(uint256 index) public view override returns (uint256) {
    (uint256 tokenId, ) = _tokenOwners.at(index);
    return tokenId;
  }
  /**
   * @dev Approves another address to transfer the given token ID
   * The zero address indicates there is no approved address.
   * There can only be one approved address per token at a given time.
   * Can only be called by the token owner or an approved operator.
   * @param to address to be approved for the given token ID
   * @param tokenId uint256 ID of the token to be approved
   */
  function approve(address to, uint256 tokenId) public virtual override {
    address owner = ownerOf(tokenId);
    require(to != owner, "ERC721: approval to current owner");
    require(
      _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
      "ERC721: approve caller is not owner nor approved for all"
    );
    _approve(to, tokenId);
  }
  /**
   * @dev Gets the approved address for a token ID, or zero if no address set
   * Reverts if the token ID does not exist.
   * @param tokenId uint256 ID of the token to query the approval of
   * @return address currently approved for the given token ID
   */
  function getApproved(uint256 tokenId) public view override returns (address) {
    require(_exists(tokenId), "ERC721: approved query for nonexistent token");
    return _tokenApprovals[tokenId];
  }
  /**
   * @dev Sets or unsets the approval of a given operator
   * An operator is allowed to transfer all tokens of the sender on their behalf.
   * @param operator operator address to set the approval
   * @param approved representing the status of the approval to be set
   */
  function setApprovalForAll(address operator, bool approved) public virtual override {
    require(operator != _msgSender(), "ERC721: approve to caller");
    _operatorApprovals[_msgSender()][operator] = approved;
    emit ApprovalForAll(_msgSender(), operator, approved);
  }
  /**
   * @dev Tells whether an operator is approved by a given owner.
   * @param owner owner address which you want to query the approval of
   * @param operator operator address which you want to query the approval of
   * @return bool whether the given operator is approved by the given owner
   */
  function isApprovedForAll(address owner, address operator) public view override returns (bool) {
    return _operatorApprovals[owner][operator];
  }
  /**
   * @dev Transfers the ownership of a given token ID to another address.
   * Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
   * Requires the msg.sender to be the owner, approved, or operator.
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
   */
  function transferFrom(address from, address to, uint256 tokenId) public virtual override {
    //solhint-disable-next-line max-line-length
    require(
      _isApprovedOrOwner(_msgSender(), tokenId),
      "ERC721: transfer caller is not owner nor approved"
    );
    _transfer(from, to, tokenId);
  }
  /**
   * @dev Safely transfers the ownership of a given token ID to another address
   * If the target address is a contract, it must implement {IERC721Receiver-onERC721Received},
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   * Requires the msg.sender to be the owner, approved, or operator
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
   */
  function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
    safeTransferFrom(from, to, tokenId, "");
  }
  /**
   * @dev Safely transfers the ownership of a given token ID to another address
   * If the target address is a contract, it must implement {IERC721Receiver-onERC721Received},
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   * Requires the _msgSender() to be the owner, approved, or operator
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
   * @param _data bytes data to send along with a safe transfer check
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) public virtual override {
    require(
      _isApprovedOrOwner(_msgSender(), tokenId),
      "ERC721: transfer caller is not owner nor approved"
    );
    _safeTransfer(from, to, tokenId, _data);
  }
  /**
   * @dev Safely transfers the ownership of a given token ID to another address
   * If the target address is a contract, it must implement `onERC721Received`,
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   * Requires the msg.sender to be the owner, approved, or operator
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
   * @param _data bytes data to send along with a safe transfer check
   */
  function _safeTransfer(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) internal virtual {
    _transfer(from, to, tokenId);
    require(
      _checkOnERC721Received(from, to, tokenId, _data),
      "ERC721: transfer to non ERC721Receiver implementer"
    );
  }
  /**
   * @dev Returns whether the specified token exists.
   * @param tokenId uint256 ID of the token to query the existence of
   * @return bool whether the token exists
   */
  function _exists(uint256 tokenId) internal view returns (bool) {
    return _tokenOwners.contains(tokenId);
  }
  /**
   * @dev Returns whether the given spender can transfer a given token ID.
   * @param spender address of the spender to query
   * @param tokenId uint256 ID of the token to be transferred
   * @return bool whether the msg.sender is approved for the given token ID,
   * is an operator of the owner, or is the owner of the token
   */
  function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool) {
    require(_exists(tokenId), "ERC721: operator query for nonexistent token");
    address owner = ownerOf(tokenId);
    return (spender == owner ||
      getApproved(tokenId) == spender ||
      isApprovedForAll(owner, spender));
  }
  /**
   * @dev Internal function to safely mint a new token.
   * Reverts if the given token ID already exists.
   * If the target address is a contract, it must implement `onERC721Received`,
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   * @param to The address that will own the minted token
   * @param tokenId uint256 ID of the token to be minted
   */
  function _safeMint(address to, uint256 tokenId) internal virtual {
    _safeMint(to, tokenId, "");
  }
  /**
   * @dev Internal function to safely mint a new token.
   * Reverts if the given token ID already exists.
   * If the target address is a contract, it must implement `onERC721Received`,
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   * @param to The address that will own the minted token
   * @param tokenId uint256 ID of the token to be minted
   * @param _data bytes data to send along with a safe transfer check
   */
  function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
    _mint(to, tokenId);
    require(
      _checkOnERC721Received(address(0), to, tokenId, _data),
      "ERC721: transfer to non ERC721Receiver implementer"
    );
  }
  /**
   * @dev Internal function to mint a new token.
   * Reverts if the given token ID already exists.
   * @param to The address that will own the minted token
   * @param tokenId uint256 ID of the token to be minted
   */
  function _mint(address to, uint256 tokenId) internal virtual {
    require(to != address(0), "ERC721: mint to the zero address");
    require(!_exists(tokenId), "ERC721: token already minted");
    _beforeTokenTransfer(address(0), to, tokenId);
    _holderTokens[to].add(tokenId);
    _tokenOwners.set(tokenId, to);
    emit Transfer(address(0), to, tokenId);
  }
  /**
   * @dev Internal function to burn a specific token.
   * Reverts if the token does not exist.
   * @param tokenId uint256 ID of the token being burned
   */
  function _burn(uint256 tokenId) internal virtual {
    address owner = ownerOf(tokenId);
    _beforeTokenTransfer(owner, address(0), tokenId);
    // Clear approvals
    _approve(address(0), tokenId);
    // Clear metadata (if any)
    if (bytes(_tokenURIs[tokenId]).length != 0) {
      delete _tokenURIs[tokenId];
    }
    _holderTokens[owner].remove(tokenId);
    _tokenOwners.remove(tokenId);
    emit Transfer(owner, address(0), tokenId);
  }
  /**
   * @dev Internal function to transfer ownership of a given token ID to another address.
   * As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
   */
  function _transfer(address from, address to, uint256 tokenId) internal virtual {
    require(ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
    require(to != address(0), "ERC721: transfer to the zero address");
    _beforeTokenTransfer(from, to, tokenId);
    // Clear approvals from the previous owner
    _approve(address(0), tokenId);
    _holderTokens[from].remove(tokenId);
    _holderTokens[to].add(tokenId);
    _tokenOwners.set(tokenId, to);
    emit Transfer(from, to, tokenId);
  }
  /**
   * @dev Internal function to set the token URI for a given token.
   *
   * Reverts if the token ID does not exist.
   *
   * TIP: If all token IDs share a prefix (for example, if your URIs look like
   * `https://api.myproject.com/token/<id>`), use {_setBaseURI} to store
   * it and save gas.
   */
  function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
    require(_exists(tokenId), "ERC721Metadata: URI set of nonexistent token");
    _tokenURIs[tokenId] = _tokenURI;
  }
  /**
   * @dev Internal function to set the base URI for all token IDs. It is
   * automatically added as a prefix to the value returned in {tokenURI},
   * or to the token ID if {tokenURI} is empty.
   */
  function _setBaseURI(string memory baseURI_) internal virtual {
    _baseURI = baseURI_;
  }
  /**
   * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
   * The call is not executed if the target address is not a contract.
   *
   * @param from address representing the previous owner of the given token ID
   * @param to target address that will receive the tokens
   * @param tokenId uint256 ID of the token to be transferred
   * @param _data bytes optional data to send along with the call
   * @return bool whether the call correctly returned the expected magic value
   */
  function _checkOnERC721Received(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) private returns (bool) {
    if (!to.isContract()) {
      return true;
    }
    // solhint-disable-next-line avoid-low-level-calls
    (bool success, bytes memory returndata) = to.call(
      abi.encodeWithSelector(
        IERC721Receiver(to).onERC721Received.selector,
        _msgSender(),
        from,
        tokenId,
        _data
      )
    );
    if (!success) {
      if (returndata.length > 0) {
        // solhint-disable-next-line no-inline-assembly
        assembly {
          let returndata_size := mload(returndata)
          revert(add(32, returndata), returndata_size)
        }
      } else {
        revert("ERC721: transfer to non ERC721Receiver implementer");
      }
    } else {
      bytes4 retval = abi.decode(returndata, (bytes4));
      return (retval == _ERC721_RECEIVED);
    }
  }
  function _approve(address to, uint256 tokenId) private {
    _tokenApprovals[tokenId] = to;
    emit Approval(ownerOf(tokenId), to, tokenId);
  }
  /**
   * @dev Hook that is called before any token transfer. This includes minting
   * and burning.
   *
   * Calling conditions:
   *
   * - when `from` and `to` are both non-zero, ``from``'s `tokenId` will be
   * transferred to `to`.
   * - when `from` is zero, `tokenId` will be minted for `to`.
   * - when `to` is zero, ``from``'s `tokenId` will be burned.
   * - `from` and `to` are never both zero.
   *
   * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
   */
  function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual {}
  uint256[41] private __gap;
}
// SPDX-License-Identifier: MIT
// solhint-disable
/*
  Vendored from @openzeppelin/[email protected]
  Alterations:
   * Use vendored ERC721, which inherits from vendored ERC165 with virtual supportsInterface
*/
pragma solidity ^0.6.0;
import "./ERC721.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/Pausable.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/Initializable.sol";
/**
 * @dev ERC721 token with pausable token transfers, minting and burning.
 *
 * Useful for scenarios such as preventing trades until the end of an evaluation
 * period, or having an emergency switch for freezing all token transfers in the
 * event of a large bug.
 */
abstract contract ERC721PausableUpgradeSafe is
  Initializable,
  ERC721UpgradeSafe,
  PausableUpgradeSafe
{
  function __ERC721Pausable_init() internal initializer {
    __Context_init_unchained();
    __ERC165_init_unchained();
    __Pausable_init_unchained();
    __ERC721Pausable_init_unchained();
  }
  function __ERC721Pausable_init_unchained() internal initializer {}
  /**
   * @dev See {ERC721-_beforeTokenTransfer}.
   *
   * Requirements:
   *
   * - the contract must not be paused.
   */
  function _beforeTokenTransfer(
    address from,
    address to,
    uint256 tokenId
  ) internal virtual override {
    super._beforeTokenTransfer(from, to, tokenId);
    require(!paused(), "ERC721Pausable: token transfer while paused");
  }
  uint256[50] private __gap;
}
// SPDX-License-Identifier: MIT
// solhint-disable
/*
  This is copied from OZ preset: https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/blob/release-v3.0.0/contracts/presets/ERC721PresetMinterPauserAutoId.sol
  Alterations:
   * Make the counter public, so that we can use it in our custom mint function
   * Removed ERC721Burnable parent contract, but added our own custom burn function.
   * Removed original "mint" function, because we have a custom one.
   * Removed default initialization functions, because they set msg.sender as the owner, which
     we do not want, because we use a deployer account, which is separate from the protocol owner.
*/
pragma solidity 0.6.12;
import "@openzeppelin/contracts-ethereum-package/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/GSN/Context.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/Counters.sol";
import "./ERC721Pausable.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/Initializable.sol";
/**
 * @dev {ERC721} token, including:
 *
 *  - ability for holders to burn (destroy) their tokens
 *  - a minter role that allows for token minting (creation)
 *  - a pauser role that allows to stop all token transfers
 *  - token ID and URI autogeneration
 *
 * This contract uses {AccessControl} to lock permissioned functions using the
 * different roles - head to its documentation for details.
 *
 * The account that deploys the contract will be granted the minter and pauser
 * roles, as well as the default admin role, which will let it grant both minter
 * and pauser roles to aother accounts
 */
contract ERC721PresetMinterPauserAutoIdUpgradeSafe is
  Initializable,
  ContextUpgradeSafe,
  AccessControlUpgradeSafe,
  ERC721PausableUpgradeSafe
{
  using Counters for Counters.Counter;
  bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
  bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
  Counters.Counter public _tokenIdTracker;
  /**
   * @dev Pauses all token transfers.
   *
   * See {ERC721Pausable} and {Pausable-_pause}.
   *
   * Requirements:
   *
   * - the caller must have the `PAUSER_ROLE`.
   */
  function pause() public {
    require(
      hasRole(PAUSER_ROLE, _msgSender()),
      "ERC721PresetMinterPauserAutoId: must have pauser role to pause"
    );
    _pause();
  }
  /**
   * @dev Unpauses all token transfers.
   *
   * See {ERC721Pausable} and {Pausable-_unpause}.
   *
   * Requirements:
   *
   * - the caller must have the `PAUSER_ROLE`.
   */
  function unpause() public {
    require(
      hasRole(PAUSER_ROLE, _msgSender()),
      "ERC721PresetMinterPauserAutoId: must have pauser role to unpause"
    );
    _unpause();
  }
  function _beforeTokenTransfer(
    address from,
    address to,
    uint256 tokenId
  ) internal virtual override(ERC721PausableUpgradeSafe) {
    super._beforeTokenTransfer(from, to, tokenId);
  }
  uint256[49] private __gap;
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import {ITranchedPool} from "./ITranchedPool.sol";
interface IBackerRewards {
  struct BackerRewardsTokenInfo {
    uint256 rewardsClaimed; // gfi claimed
    uint256 accRewardsPerPrincipalDollarAtMint; // Pool's accRewardsPerPrincipalDollar at PoolToken mint()
  }
  struct BackerRewardsInfo {
    uint256 accRewardsPerPrincipalDollar; // accumulator gfi per interest dollar
  }
  /// @notice Staking rewards parameters relevant to a TranchedPool
  struct StakingRewardsPoolInfo {
    // @notice the value `StakingRewards.accumulatedRewardsPerToken()` at the last checkpoint
    uint256 accumulatedRewardsPerTokenAtLastCheckpoint;
    // @notice last time the rewards info was updated
    //
    // we need this in order to know how much to pro rate rewards after the term is over.
    uint256 lastUpdateTime;
    // @notice staking rewards parameters for each slice of the tranched pool
    StakingRewardsSliceInfo[] slicesInfo;
  }
  /// @notice Staking rewards paramters relevant to a TranchedPool slice
  struct StakingRewardsSliceInfo {
    // @notice fidu share price when the slice is first drawn down
    //
    // we need to save this to calculate what an equivalent position in
    // the senior pool would be at the time the slice is downdown
    uint256 fiduSharePriceAtDrawdown;
    // @notice the amount of principal deployed at the last checkpoint
    //
    // we use this to calculate the amount of principal that should
    // acctually accrue rewards during between the last checkpoint and
    // and subsequent updates
    uint256 principalDeployedAtLastCheckpoint;
    // @notice the value of StakingRewards.accumulatedRewardsPerToken() at time of drawdown
    //
    // we need to keep track of this to use this as a base value to accumulate rewards
    // for tokens. If the token has never claimed staking rewards, we use this value
    // and the current staking rewards accumulator
    uint256 accumulatedRewardsPerTokenAtDrawdown;
    // @notice amount of rewards per token accumulated over the lifetime of the slice that a backer
    //          can claim
    uint256 accumulatedRewardsPerTokenAtLastCheckpoint;
    // @notice the amount of rewards per token accumulated over the lifetime of the slice
    //
    // this value is "unrealized" because backers will be unable to claim against this value.
    // we keep this value so that we can always accumulate rewards for the amount of capital
    // deployed at any point in time, but not allow backers to withdraw them until a payment
    // is made. For example: we want to accumulate rewards when a backer does a drawdown. but
    // a backer shouldn't be allowed to claim rewards until a payment is made.
    //
    // this value is scaled depending on the current proportion of capital currently deployed
    // in the slice. For example, if the staking rewards contract accrued 10 rewards per token
    // between the current checkpoint and a new update, and only 20% of the capital was deployed
    // during that period, we would accumulate 2 (10 * 20%) rewards.
    uint256 unrealizedAccumulatedRewardsPerTokenAtLastCheckpoint;
  }
  /// @notice Staking rewards parameters relevant to a PoolToken
  struct StakingRewardsTokenInfo {
    // @notice the amount of rewards accumulated the last time a token's rewards were withdrawn
    uint256 accumulatedRewardsPerTokenAtLastWithdraw;
  }
  /// @notice total amount of GFI rewards available, times 1e18
  function totalRewards() external view returns (uint256);
  /// @notice interest $ eligible for gfi rewards, times 1e18
  function maxInterestDollarsEligible() external view returns (uint256);
  /// @notice counter of total interest repayments, times 1e6
  function totalInterestReceived() external view returns (uint256);
  /// @notice totalRewards/totalGFISupply * 100, times 1e18
  function totalRewardPercentOfTotalGFI() external view returns (uint256);
  /// @notice Get backer rewards metadata for a pool token
  function getTokenInfo(uint256 poolTokenId) external view returns (BackerRewardsTokenInfo memory);
  /// @notice Get backer staking rewards metadata for a pool token
  function getStakingRewardsTokenInfo(
    uint256 poolTokenId
  ) external view returns (StakingRewardsTokenInfo memory);
  /// @notice Get backer staking rewards for a pool
  function getBackerStakingRewardsPoolInfo(
    ITranchedPool pool
  ) external view returns (StakingRewardsPoolInfo memory);
  /// @notice Calculates the accRewardsPerPrincipalDollar for a given pool,
  ///   when a interest payment is received by the protocol
  /// @param _interestPaymentAmount Atomic usdc amount of the interest payment
  function allocateRewards(uint256 _interestPaymentAmount) external;
  /// @notice callback for TranchedPools when they drawdown
  /// @param sliceIndex index of the tranched pool slice
  /// @dev initializes rewards info for the calling TranchedPool if it's the first
  ///  drawdown for the given slice
  function onTranchedPoolDrawdown(uint256 sliceIndex) external;
  /// @notice When a pool token is minted for multiple drawdowns,
  ///   set accRewardsPerPrincipalDollarAtMint to the current accRewardsPerPrincipalDollar price
  /// @param poolAddress Address of the pool associated with the pool token
  /// @param tokenId Pool token id
  function setPoolTokenAccRewardsPerPrincipalDollarAtMint(
    address poolAddress,
    uint256 tokenId
  ) external;
  /// @notice PoolToken request to withdraw all allocated rewards
  /// @param tokenId Pool token id
  /// @return amount of rewards withdrawn
  function withdraw(uint256 tokenId) external returns (uint256);
  /**
   * @notice Set BackerRewards and BackerStakingRewards metadata for tokens created by a pool token split.
   * @param originalBackerRewardsTokenInfo backer rewards info for the pool token that was split
   * @param originalStakingRewardsTokenInfo backer staking rewards info for the pool token that was split
   * @param newTokenId id of one of the tokens in the split
   * @param newRewardsClaimed rewardsClaimed value for the new token.
   */
  function setBackerAndStakingRewardsTokenInfoOnSplit(
    BackerRewardsTokenInfo memory originalBackerRewardsTokenInfo,
    StakingRewardsTokenInfo memory originalStakingRewardsTokenInfo,
    uint256 newTokenId,
    uint256 newRewardsClaimed
  ) external;
  /**
   * @notice Calculate the gross available gfi rewards for a PoolToken
   * @param tokenId Pool token id
   * @return The amount of GFI claimable
   */
  function poolTokenClaimableRewards(uint256 tokenId) external view returns (uint256);
  /// @notice Clear all BackerRewards and StakingRewards associated data for `tokenId`
  function clearTokenInfo(uint256 tokenId) external;
}
// SPDX-License-Identifier: MIT
// Taken from https://github.com/compound-finance/compound-protocol/blob/master/contracts/CTokenInterfaces.sol
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import "./IERC20withDec.sol";
interface ICUSDCContract is IERC20withDec {
  /*** User Interface ***/
  function mint(uint256 mintAmount) external returns (uint256);
  function redeem(uint256 redeemTokens) external returns (uint256);
  function redeemUnderlying(uint256 redeemAmount) external returns (uint256);
  function borrow(uint256 borrowAmount) external returns (uint256);
  function repayBorrow(uint256 repayAmount) external returns (uint256);
  function repayBorrowBehalf(address borrower, uint256 repayAmount) external returns (uint256);
  function liquidateBorrow(
    address borrower,
    uint256 repayAmount,
    address cTokenCollateral
  ) external returns (uint256);
  function getAccountSnapshot(
    address account
  ) external view returns (uint256, uint256, uint256, uint256);
  function balanceOfUnderlying(address owner) external returns (uint256);
  function exchangeRateCurrent() external returns (uint256);
  /*** Admin Functions ***/
  function _addReserves(uint256 addAmount) external returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
interface ICreditLine {
  function borrower() external view returns (address);
  function limit() external view returns (uint256);
  function maxLimit() external view returns (uint256);
  function interestApr() external view returns (uint256);
  function paymentPeriodInDays() external view returns (uint256);
  function principalGracePeriodInDays() external view returns (uint256);
  function termInDays() external view returns (uint256);
  function lateFeeApr() external view returns (uint256);
  function isLate() external view returns (bool);
  function withinPrincipalGracePeriod() external view returns (bool);
  // Accounting variables
  function balance() external view returns (uint256);
  function interestOwed() external view returns (uint256);
  function principalOwed() external view returns (uint256);
  function termEndTime() external view returns (uint256);
  function nextDueTime() external view returns (uint256);
  function interestAccruedAsOf() external view returns (uint256);
  function lastFullPaymentTime() external view returns (uint256);
}
// SPDX-License-Identifier: MIT
// Taken from https://github.com/compound-finance/compound-protocol/blob/master/contracts/CTokenInterfaces.sol
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
interface ICurveLP {
  function coins(uint256) external view returns (address);
  function token() external view returns (address);
  function calc_token_amount(uint256[2] calldata amounts) external view returns (uint256);
  function lp_price() external view returns (uint256);
  function add_liquidity(
    uint256[2] calldata amounts,
    uint256 min_mint_amount,
    bool use_eth,
    address receiver
  ) external returns (uint256);
  function remove_liquidity(
    uint256 _amount,
    uint256[2] calldata min_amounts
  ) external returns (uint256);
  function remove_liquidity_one_coin(
    uint256 token_amount,
    uint256 i,
    uint256 min_amount
  ) external returns (uint256);
  function get_dy(uint256 i, uint256 j, uint256 dx) external view returns (uint256);
  function exchange(uint256 i, uint256 j, uint256 dx, uint256 min_dy) external returns (uint256);
  function balances(uint256 arg0) external view returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import {IERC20} from "@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol";
/*
Only addition is the `decimals` function, which we need, and which both our Fidu and USDC use, along with most ERC20's.
*/
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20withDec is IERC20 {
  /**
   * @dev Returns the number of decimals used for the token
   */
  function decimals() external view returns (uint8);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
interface IERC2981 {
  /// @notice Called with the sale price to determine how much royalty
  //          is owed and to whom.
  /// @param _tokenId - the NFT asset queried for royalty information
  /// @param _salePrice - the sale price of the NFT asset specified by _tokenId
  /// @return receiver - address of who should be sent the royalty payment
  /// @return royaltyAmount - the royalty payment amount for _salePrice
  function royaltyInfo(
    uint256 _tokenId,
    uint256 _salePrice
  ) external view returns (address receiver, uint256 royaltyAmount);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import "./IERC20withDec.sol";
interface IFidu is IERC20withDec {
  function mintTo(address to, uint256 amount) external;
  function burnFrom(address to, uint256 amount) external;
  function renounceRole(bytes32 role, address account) external;
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
abstract contract IGo {
  uint256 public constant ID_TYPE_0 = 0;
  uint256 public constant ID_TYPE_1 = 1;
  uint256 public constant ID_TYPE_2 = 2;
  uint256 public constant ID_TYPE_3 = 3;
  uint256 public constant ID_TYPE_4 = 4;
  uint256 public constant ID_TYPE_5 = 5;
  uint256 public constant ID_TYPE_6 = 6;
  uint256 public constant ID_TYPE_7 = 7;
  uint256 public constant ID_TYPE_8 = 8;
  uint256 public constant ID_TYPE_9 = 9;
  uint256 public constant ID_TYPE_10 = 10;
  /// @notice Returns the address of the UniqueIdentity contract.
  function uniqueIdentity() external virtual returns (address);
  function go(address account) public view virtual returns (bool);
  function goOnlyIdTypes(
    address account,
    uint256[] calldata onlyIdTypes
  ) public view virtual returns (bool);
  /**
   * @notice Returns whether the provided account is go-listed for use of the SeniorPool on the Goldfinch protocol.
   * @param account The account whose go status to obtain
   * @return true if `account` is go listed
   */
  function goSeniorPool(address account) public view virtual returns (bool);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
interface IGoldfinchConfig {
  function getNumber(uint256 index) external returns (uint256);
  function getAddress(uint256 index) external returns (address);
  function setAddress(uint256 index, address newAddress) external returns (address);
  function setNumber(uint256 index, uint256 newNumber) external returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
interface IGoldfinchFactory {
  function createCreditLine() external returns (address);
  function createBorrower(address owner) external returns (address);
  function createPool(
    address _borrower,
    uint256 _juniorFeePercent,
    uint256 _limit,
    uint256 _interestApr,
    uint256 _paymentPeriodInDays,
    uint256 _termInDays,
    uint256 _lateFeeApr,
    uint256[] calldata _allowedUIDTypes
  ) external returns (address);
  function createMigratedPool(
    address _borrower,
    uint256 _juniorFeePercent,
    uint256 _limit,
    uint256 _interestApr,
    uint256 _paymentPeriodInDays,
    uint256 _termInDays,
    uint256 _lateFeeApr,
    uint256[] calldata _allowedUIDTypes
  ) external returns (address);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import "./openzeppelin/IERC721.sol";
interface IPoolTokens is IERC721 {
  struct TokenInfo {
    address pool;
    uint256 tranche;
    uint256 principalAmount;
    uint256 principalRedeemed;
    uint256 interestRedeemed;
  }
  struct MintParams {
    uint256 principalAmount;
    uint256 tranche;
  }
  struct PoolInfo {
    uint256 totalMinted;
    uint256 totalPrincipalRedeemed;
    bool created;
  }
  /**
   * @notice Called by pool to create a debt position in a particular tranche and amount
   * @param params Struct containing the tranche and the amount
   * @param to The address that should own the position
   * @return tokenId The token ID (auto-incrementing integer across all pools)
   */
  function mint(MintParams calldata params, address to) external returns (uint256);
  /**
   * @notice Redeem principal and interest on a pool token. Called by valid pools as part of their redemption
   *  flow
   * @param tokenId pool token id
   * @param principalRedeemed principal to redeem. This cannot exceed the token's principal amount, and
   *  the redemption cannot cause the pool's total principal redeemed to exceed the pool's total minted
   *  principal
   * @param interestRedeemed interest to redeem.
   */
  function redeem(uint256 tokenId, uint256 principalRedeemed, uint256 interestRedeemed) external;
  /**
   * @notice Withdraw a pool token's principal up to the token's principalAmount. Called by valid pools
   *  as part of their withdraw flow before the pool is locked (i.e. before the principal is committed)
   * @param tokenId pool token id
   * @param principalAmount principal to withdraw
   */
  function withdrawPrincipal(uint256 tokenId, uint256 principalAmount) external;
  /**
   * @notice Burns a specific ERC721 token and removes deletes the token metadata for PoolTokens, BackerReards,
   *  and BackerStakingRewards
   * @param tokenId uint256 id of the ERC721 token to be burned.
   */
  function burn(uint256 tokenId) external;
  /**
   * @notice Called by the GoldfinchFactory to register the pool as a valid pool. Only valid pools can mint/redeem
   * tokens
   * @param newPool The address of the newly created pool
   */
  function onPoolCreated(address newPool) external;
  function getTokenInfo(uint256 tokenId) external view returns (TokenInfo memory);
  function getPoolInfo(address pool) external view returns (PoolInfo memory);
  /// @notice Query if `pool` is a valid pool. A pool is valid if it was created by the Goldfinch Factory
  function validPool(address pool) external view returns (bool);
  function isApprovedOrOwner(address spender, uint256 tokenId) external view returns (bool);
  /**
   * @notice Splits a pool token into two smaller positions. The original token is burned and all
   * its associated data is deleted.
   * @param tokenId id of the token to split.
   * @param newPrincipal1 principal amount for the first token in the split. The principal amount for the
   *  second token in the split is implicitly the original token's principal amount less newPrincipal1
   * @return tokenId1 id of the first token in the split
   * @return tokenId2 id of the second token in the split
   */
  function splitToken(
    uint256 tokenId,
    uint256 newPrincipal1
  ) external returns (uint256 tokenId1, uint256 tokenId2);
  /**
   * @notice Mint event emitted for a new TranchedPool deposit or when an existing pool token is
   *  split
   * @param owner address to which the token was minted
   * @param pool tranched pool that the deposit was in
   * @param tokenId ERC721 tokenId
   * @param amount the deposit amount
   * @param tranche id of the tranche of the deposit
   */
  event TokenMinted(
    address indexed owner,
    address indexed pool,
    uint256 indexed tokenId,
    uint256 amount,
    uint256 tranche
  );
  /**
   * @notice Redeem event emitted when interest and/or principal is redeemed in the token's pool
   * @param owner owner of the pool token
   * @param pool tranched pool that the token belongs to
   * @param principalRedeemed amount of principal redeemed from the pool
   * @param interestRedeemed amount of interest redeemed from the pool
   * @param tranche id of the tranche the token belongs to
   */
  event TokenRedeemed(
    address indexed owner,
    address indexed pool,
    uint256 indexed tokenId,
    uint256 principalRedeemed,
    uint256 interestRedeemed,
    uint256 tranche
  );
  /**
   * @notice Burn event emitted when the token owner/operator manually burns the token or burns
   *  it implicitly by splitting it
   * @param owner owner of the pool token
   * @param pool tranched pool that the token belongs to
   */
  event TokenBurned(address indexed owner, address indexed pool, uint256 indexed tokenId);
  /**
   * @notice Split event emitted when the token owner/operator splits the token
   * @param pool tranched pool to which the orginal and split tokens belong
   * @param tokenId id of the original token that was split
   * @param newTokenId1 id of the first split token
   * @param newPrincipal1 principalAmount of the first split token
   * @param newTokenId2 id of the second split token
   * @param newPrincipal2 principalAmount of the second split token
   */
  event TokenSplit(
    address indexed owner,
    address indexed pool,
    uint256 indexed tokenId,
    uint256 newTokenId1,
    uint256 newPrincipal1,
    uint256 newTokenId2,
    uint256 newPrincipal2
  );
  /**
   * @notice Principal Withdrawn event emitted when a token's principal is withdrawn from the pool
   *  BEFORE the pool's drawdown period
   * @param pool tranched pool of the token
   * @param principalWithdrawn amount of principal withdrawn from the pool
   */
  event TokenPrincipalWithdrawn(
    address indexed owner,
    address indexed pool,
    uint256 indexed tokenId,
    uint256 principalWithdrawn,
    uint256 tranche
  );
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import {ITranchedPool} from "./ITranchedPool.sol";
import {ISeniorPoolEpochWithdrawals} from "./ISeniorPoolEpochWithdrawals.sol";
abstract contract ISeniorPool is ISeniorPoolEpochWithdrawals {
  uint256 public sharePrice;
  uint256 public totalLoansOutstanding;
  uint256 public totalWritedowns;
  function deposit(uint256 amount) external virtual returns (uint256 depositShares);
  function depositWithPermit(
    uint256 amount,
    uint256 deadline,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external virtual returns (uint256 depositShares);
  /**
   * @notice Withdraw `usdcAmount` of USDC, bypassing the epoch withdrawal system. Callable
   * by Zapper only.
   */
  function withdraw(uint256 usdcAmount) external virtual returns (uint256 amount);
  /**
   * @notice Withdraw `fiduAmount` of FIDU converted to USDC at the current share price,
   * bypassing the epoch withdrawal system. Callable by Zapper only
   */
  function withdrawInFidu(uint256 fiduAmount) external virtual returns (uint256 amount);
  function invest(ITranchedPool pool) external virtual returns (uint256);
  function estimateInvestment(ITranchedPool pool) external view virtual returns (uint256);
  function redeem(uint256 tokenId) external virtual;
  function writedown(uint256 tokenId) external virtual;
  function calculateWritedown(
    uint256 tokenId
  ) external view virtual returns (uint256 writedownAmount);
  function sharesOutstanding() external view virtual returns (uint256);
  function assets() external view virtual returns (uint256);
  function getNumShares(uint256 amount) public view virtual returns (uint256);
  event DepositMade(address indexed capitalProvider, uint256 amount, uint256 shares);
  event WithdrawalMade(address indexed capitalProvider, uint256 userAmount, uint256 reserveAmount);
  event InterestCollected(address indexed payer, uint256 amount);
  event PrincipalCollected(address indexed payer, uint256 amount);
  event ReserveFundsCollected(address indexed user, uint256 amount);
  event ReserveSharesCollected(address indexed user, address indexed reserve, uint256 amount);
  event PrincipalWrittenDown(address indexed tranchedPool, int256 amount);
  event InvestmentMadeInSenior(address indexed tranchedPool, uint256 amount);
  event InvestmentMadeInJunior(address indexed tranchedPool, uint256 amount);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
interface ISeniorPoolEpochWithdrawals {
  /**
   * @notice A withdrawal epoch
   * @param endsAt timestamp the epoch ends
   * @param fiduRequested amount of fidu requested in the epoch, including fidu
   *                      carried over from previous epochs
   * @param fiduLiquidated Amount of fidu that was liquidated at the end of this epoch
   * @param usdcAllocated Amount of usdc that was allocated to liquidate fidu.
   *                      Does not consider withdrawal fees.
   */
  struct Epoch {
    uint256 endsAt;
    uint256 fiduRequested;
    uint256 fiduLiquidated;
    uint256 usdcAllocated;
  }
  /**
   * @notice A user's request for withdrawal
   * @param epochCursor id of next epoch the user can liquidate their request
   * @param fiduRequested amount of fidu left to liquidate since last checkpoint
   * @param usdcWithdrawable amount of usdc available for a user to withdraw
   */
  struct WithdrawalRequest {
    uint256 epochCursor;
    uint256 usdcWithdrawable;
    uint256 fiduRequested;
  }
  /**
   * @notice Returns the amount of unallocated usdc in the senior pool, taking into account
   *         usdc that _will_ be allocated to withdrawals when a checkpoint happens
   */
  function usdcAvailable() external view returns (uint256);
  /// @notice Current duration of withdrawal epochs, in seconds
  function epochDuration() external view returns (uint256);
  /// @notice Update epoch duration
  function setEpochDuration(uint256 newEpochDuration) external;
  /// @notice The current withdrawal epoch
  function currentEpoch() external view returns (Epoch memory);
  /// @notice Get request by tokenId. A request is considered active if epochCursor > 0.
  function withdrawalRequest(uint256 tokenId) external view returns (WithdrawalRequest memory);
  /**
   * @notice Submit a request to withdraw `fiduAmount` of FIDU. Request is rejected
   * if caller already owns a request token. A non-transferrable request token is
   * minted to the caller
   * @return tokenId token minted to caller
   */
  function requestWithdrawal(uint256 fiduAmount) external returns (uint256 tokenId);
  /**
   * @notice Add `fiduAmount` FIDU to a withdrawal request for `tokenId`. Caller
   * must own tokenId
   */
  function addToWithdrawalRequest(uint256 fiduAmount, uint256 tokenId) external;
  /**
   * @notice Cancel request for tokenId. The fiduRequested (minus a fee) is returned
   * to the caller. Caller must own tokenId.
   * @return fiduReceived the fidu amount returned to the caller
   */
  function cancelWithdrawalRequest(uint256 tokenId) external returns (uint256 fiduReceived);
  /**
   * @notice Transfer the usdcWithdrawable of request for tokenId to the caller.
   * Caller must own tokenId
   */
  function claimWithdrawalRequest(uint256 tokenId) external returns (uint256 usdcReceived);
  /// @notice Emitted when the epoch duration is changed
  event EpochDurationChanged(uint256 newDuration);
  /// @notice Emitted when a new withdraw request has been created
  event WithdrawalRequested(
    uint256 indexed epochId,
    uint256 indexed tokenId,
    address indexed operator,
    uint256 fiduRequested
  );
  /// @notice Emitted when a user adds to their existing withdraw request
  /// @param epochId epoch that the withdraw was added to
  /// @param tokenId id of token that represents the position being added to
  /// @param operator address that added to the request
  /// @param fiduRequested amount of additional fidu added to request
  event WithdrawalAddedTo(
    uint256 indexed epochId,
    uint256 indexed tokenId,
    address indexed operator,
    uint256 fiduRequested
  );
  /// @notice Emitted when a withdraw request has been canceled
  event WithdrawalCanceled(
    uint256 indexed epochId,
    uint256 indexed tokenId,
    address indexed operator,
    uint256 fiduCanceled,
    uint256 reserveFidu
  );
  /// @notice Emitted when an epoch has been checkpointed
  /// @param epochId id of epoch that ended
  /// @param endTime timestamp the epoch ended
  /// @param fiduRequested amount of FIDU oustanding when the epoch ended
  /// @param usdcAllocated amount of USDC allocated to liquidate FIDU
  /// @param fiduLiquidated amount of FIDU liquidated using `usdcAllocated`
  event EpochEnded(
    uint256 indexed epochId,
    uint256 endTime,
    uint256 fiduRequested,
    uint256 usdcAllocated,
    uint256 fiduLiquidated
  );
  /// @notice Emitted when an epoch could not be finalized and is extended instead
  /// @param epochId id of epoch that was extended
  /// @param newEndTime new epoch end time
  /// @param oldEndTime previous epoch end time
  event EpochExtended(uint256 indexed epochId, uint256 newEndTime, uint256 oldEndTime);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import "./ISeniorPool.sol";
import "./ITranchedPool.sol";
abstract contract ISeniorPoolStrategy {
  function getLeverageRatio(ITranchedPool pool) public view virtual returns (uint256);
  /**
   * @notice Determines how much money to invest in the senior tranche based on what is committed to the junior
   * tranche, what is committed to the senior tranche, and a leverage ratio to the junior tranche. Because
   * it takes into account what is already committed to the senior tranche, the value returned by this
   * function can be used "idempotently" to achieve the investment target amount without exceeding that target.
   * @param seniorPool The senior pool to invest from
   * @param pool The tranched pool to invest into (as the senior)
   * @return amount of money to invest into the tranched pool's senior tranche, from the senior pool
   */
  function invest(
    ISeniorPool seniorPool,
    ITranchedPool pool
  ) public view virtual returns (uint256 amount);
  /**
   * @notice A companion of `invest()`: determines how much would be returned by `invest()`, as the
   * value to invest into the senior tranche, if the junior tranche were locked and the senior tranche
   * were not locked.
   * @param seniorPool The senior pool to invest from
   * @param pool The tranched pool to invest into (as the senior)
   * @return The amount of money to invest into the tranched pool's senior tranche, from the senior pool
   */
  function estimateInvestment(
    ISeniorPool seniorPool,
    ITranchedPool pool
  ) public view virtual returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import {IERC721} from "./openzeppelin/IERC721.sol";
import {IERC721Metadata} from "./openzeppelin/IERC721Metadata.sol";
import {IERC721Enumerable} from "./openzeppelin/IERC721Enumerable.sol";
interface IStakingRewards is IERC721, IERC721Metadata, IERC721Enumerable {
  /// @notice Get the staking rewards position
  /// @param tokenId id of the position token
  /// @return position the position
  function getPosition(uint256 tokenId) external view returns (StakedPosition memory position);
  /// @notice Unstake an amount of `stakingToken()` (FIDU, FiduUSDCCurveLP, etc) associated with
  ///   a given position and transfer to msg.sender. Any remaining staked amount will continue to
  ///   accrue rewards.
  /// @dev This function checkpoints rewards
  /// @param tokenId A staking position token ID
  /// @param amount Amount of `stakingToken()` to be unstaked from the position
  function unstake(uint256 tokenId, uint256 amount) external;
  /// @notice Add `amount` to an existing FIDU position (`tokenId`)
  /// @param tokenId A staking position token ID
  /// @param amount Amount of `stakingToken()` to be added to tokenId's position
  function addToStake(uint256 tokenId, uint256 amount) external;
  /// @notice Returns the staked balance of a given position token.
  /// @dev The value returned is the bare amount, not the effective amount. The bare amount represents
  ///   the number of tokens the user has staked for a given position. The effective amount is the bare
  ///   amount multiplied by the token's underlying asset type multiplier. This multiplier is a crypto-
  ///   economic parameter determined by governance.
  /// @param tokenId A staking position token ID
  /// @return Amount of staked tokens denominated in `stakingToken().decimals()`
  function stakedBalanceOf(uint256 tokenId) external view returns (uint256);
  /// @notice Deposit to FIDU and USDC into the Curve LP, and stake your Curve LP tokens in the same transaction.
  /// @param fiduAmount The amount of FIDU to deposit
  /// @param usdcAmount The amount of USDC to deposit
  function depositToCurveAndStakeFrom(
    address nftRecipient,
    uint256 fiduAmount,
    uint256 usdcAmount
  ) external;
  /// @notice "Kick" a user's reward multiplier. If they are past their lock-up period, their reward
  ///   multiplier will be reset to 1x.
  /// @dev This will also checkpoint their rewards up to the current time.
  function kick(uint256 tokenId) external;
  /// @notice Accumulated rewards per token at the last checkpoint
  function accumulatedRewardsPerToken() external view returns (uint256);
  /// @notice The block timestamp when rewards were last checkpointed
  function lastUpdateTime() external view returns (uint256);
  /// @notice Claim rewards for a given staked position
  /// @param tokenId A staking position token ID
  /// @return amount of rewards claimed
  function getReward(uint256 tokenId) external returns (uint256);
  /* ========== EVENTS ========== */
  event RewardAdded(uint256 reward);
  event Staked(
    address indexed user,
    uint256 indexed tokenId,
    uint256 amount,
    StakedPositionType positionType,
    uint256 baseTokenExchangeRate
  );
  event DepositedAndStaked(
    address indexed user,
    uint256 depositedAmount,
    uint256 indexed tokenId,
    uint256 amount
  );
  event DepositedToCurve(
    address indexed user,
    uint256 fiduAmount,
    uint256 usdcAmount,
    uint256 tokensReceived
  );
  event DepositedToCurveAndStaked(
    address indexed user,
    uint256 fiduAmount,
    uint256 usdcAmount,
    uint256 indexed tokenId,
    uint256 amount
  );
  event AddToStake(
    address indexed user,
    uint256 indexed tokenId,
    uint256 amount,
    StakedPositionType positionType
  );
  event Unstaked(
    address indexed user,
    uint256 indexed tokenId,
    uint256 amount,
    StakedPositionType positionType
  );
  event UnstakedMultiple(address indexed user, uint256[] tokenIds, uint256[] amounts);
  event RewardPaid(address indexed user, uint256 indexed tokenId, uint256 reward);
  event RewardsParametersUpdated(
    address indexed who,
    uint256 targetCapacity,
    uint256 minRate,
    uint256 maxRate,
    uint256 minRateAtPercent,
    uint256 maxRateAtPercent
  );
  event EffectiveMultiplierUpdated(
    address indexed who,
    StakedPositionType positionType,
    uint256 multiplier
  );
}
/// @notice Indicates which ERC20 is staked
enum StakedPositionType {
  Fidu,
  CurveLP
}
struct Rewards {
  uint256 totalUnvested;
  uint256 totalVested;
  // @dev DEPRECATED (definition kept for storage slot)
  //   For legacy vesting positions, this was used in the case of slashing.
  //   For non-vesting positions, this is unused.
  uint256 totalPreviouslyVested;
  uint256 totalClaimed;
  uint256 startTime;
  // @dev DEPRECATED (definition kept for storage slot)
  //   For legacy vesting positions, this is the endTime of the vesting.
  //   For non-vesting positions, this is 0.
  uint256 endTime;
}
struct StakedPosition {
  // @notice Staked amount denominated in `stakingToken().decimals()`
  uint256 amount;
  // @notice Struct describing rewards owed with vesting
  Rewards rewards;
  // @notice Multiplier applied to staked amount when locking up position
  uint256 leverageMultiplier;
  // @notice Time in seconds after which position can be unstaked
  uint256 lockedUntil;
  // @notice Type of the staked position
  StakedPositionType positionType;
  // @notice Multiplier applied to staked amount to denominate in `baseStakingToken().decimals()`
  // @dev This field should not be used directly; it may be 0 for staked positions created prior to GIP-1.
  //  If you need this field, use `safeEffectiveMultiplier()`, which correctly handles old staked positions.
  uint256 unsafeEffectiveMultiplier;
  // @notice Exchange rate applied to staked amount to denominate in `baseStakingToken().decimals()`
  // @dev This field should not be used directly; it may be 0 for staked positions created prior to GIP-1.
  //  If you need this field, use `safeBaseTokenExchangeRate()`, which correctly handles old staked positions.
  uint256 unsafeBaseTokenExchangeRate;
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import {IV2CreditLine} from "./IV2CreditLine.sol";
abstract contract ITranchedPool {
  IV2CreditLine public creditLine;
  uint256 public createdAt;
  enum Tranches {
    Reserved,
    Senior,
    Junior
  }
  struct TrancheInfo {
    uint256 id;
    uint256 principalDeposited;
    uint256 principalSharePrice;
    uint256 interestSharePrice;
    uint256 lockedUntil;
  }
  struct PoolSlice {
    TrancheInfo seniorTranche;
    TrancheInfo juniorTranche;
    uint256 totalInterestAccrued;
    uint256 principalDeployed;
  }
  function initialize(
    address _config,
    address _borrower,
    uint256 _juniorFeePercent,
    uint256 _limit,
    uint256 _interestApr,
    uint256 _paymentPeriodInDays,
    uint256 _termInDays,
    uint256 _lateFeeApr,
    uint256 _principalGracePeriodInDays,
    uint256 _fundableAt,
    uint256[] calldata _allowedUIDTypes
  ) public virtual;
  function getAllowedUIDTypes() external view virtual returns (uint256[] memory);
  function getTranche(uint256 tranche) external view virtual returns (TrancheInfo memory);
  function pay(uint256 amount) external virtual;
  function poolSlices(uint256 index) external view virtual returns (PoolSlice memory);
  function lockJuniorCapital() external virtual;
  function lockPool() external virtual;
  function initializeNextSlice(uint256 _fundableAt) external virtual;
  function totalJuniorDeposits() external view virtual returns (uint256);
  function drawdown(uint256 amount) external virtual;
  function setFundableAt(uint256 timestamp) external virtual;
  function deposit(uint256 tranche, uint256 amount) external virtual returns (uint256 tokenId);
  function assess() external virtual;
  function depositWithPermit(
    uint256 tranche,
    uint256 amount,
    uint256 deadline,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external virtual returns (uint256 tokenId);
  function availableToWithdraw(
    uint256 tokenId
  ) external view virtual returns (uint256 interestRedeemable, uint256 principalRedeemable);
  function withdraw(
    uint256 tokenId,
    uint256 amount
  ) external virtual returns (uint256 interestWithdrawn, uint256 principalWithdrawn);
  function withdrawMax(
    uint256 tokenId
  ) external virtual returns (uint256 interestWithdrawn, uint256 principalWithdrawn);
  function withdrawMultiple(
    uint256[] calldata tokenIds,
    uint256[] calldata amounts
  ) external virtual;
  function numSlices() external view virtual returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;
import {ICreditLine} from "./ICreditLine.sol";
abstract contract IV2CreditLine is ICreditLine {
  function principal() external view virtual returns (uint256);
  function totalInterestAccrued() external view virtual returns (uint256);
  function termStartTime() external view virtual returns (uint256);
  function setLimit(uint256 newAmount) external virtual;
  function setMaxLimit(uint256 newAmount) external virtual;
  function setBalance(uint256 newBalance) external virtual;
  function setPrincipal(uint256 _principal) external virtual;
  function setTotalInterestAccrued(uint256 _interestAccrued) external virtual;
  function drawdown(uint256 amount) external virtual;
  function assess() external virtual returns (uint256, uint256, uint256);
  function initialize(
    address _config,
    address owner,
    address _borrower,
    uint256 _limit,
    uint256 _interestApr,
    uint256 _paymentPeriodInDays,
    uint256 _termInDays,
    uint256 _lateFeeApr,
    uint256 _principalGracePeriodInDays
  ) public virtual;
  function setTermEndTime(uint256 newTermEndTime) external virtual;
  function setNextDueTime(uint256 newNextDueTime) external virtual;
  function setInterestOwed(uint256 newInterestOwed) external virtual;
  function setPrincipalOwed(uint256 newPrincipalOwed) external virtual;
  function setInterestAccruedAsOf(uint256 newInterestAccruedAsOf) external virtual;
  function setWritedownAmount(uint256 newWritedownAmount) external virtual;
  function setLastFullPaymentTime(uint256 newLastFullPaymentTime) external virtual;
  function setLateFeeApr(uint256 newLateFeeApr) external virtual;
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {IERC721Enumerable} from "./openzeppelin/IERC721Enumerable.sol";
interface IWithdrawalRequestToken is IERC721Enumerable {
  /// @notice Mint a withdrawal request token to `receiver`
  /// @dev succeeds if and only if called by senior pool
  function mint(address receiver) external returns (uint256 tokenId);
  /// @notice Burn token `tokenId`
  /// @dev suceeds if and only if called by senior pool
  function burn(uint256 tokenId) external;
}
pragma solidity >=0.6.0;
// This file copied from OZ, but with the version pragma updated to use >=.
/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
  /**
   * @dev Returns true if this contract implements the interface defined by
   * `interfaceId`. See the corresponding
   * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
   * to learn more about how these ids are created.
   *
   * This function call must use less than 30 000 gas.
   */
  function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
pragma solidity >=0.6.2;
// This file copied from OZ, but with the version pragma updated to use >= & reference other >= pragma interfaces.
// NOTE: Modified to reference our updated pragma version of IERC165
import "./IERC165.sol";
/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
  event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
  event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
  event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
  /**
   * @dev Returns the number of NFTs in ``owner``'s account.
   */
  function balanceOf(address owner) external view returns (uint256 balance);
  /**
   * @dev Returns the owner of the NFT specified by `tokenId`.
   */
  function ownerOf(uint256 tokenId) external view returns (address owner);
  /**
   * @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
   * another (`to`).
   *
   *
   *
   * Requirements:
   * - `from`, `to` cannot be zero.
   * - `tokenId` must be owned by `from`.
   * - If the caller is not `from`, it must be have been allowed to move this
   * NFT by either {approve} or {setApprovalForAll}.
   */
  function safeTransferFrom(address from, address to, uint256 tokenId) external;
  /**
   * @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
   * another (`to`).
   *
   * Requirements:
   * - If the caller is not `from`, it must be approved to move this NFT by
   * either {approve} or {setApprovalForAll}.
   */
  function transferFrom(address from, address to, uint256 tokenId) external;
  function approve(address to, uint256 tokenId) external;
  function getApproved(uint256 tokenId) external view returns (address operator);
  function setApprovalForAll(address operator, bool _approved) external;
  function isApprovedForAll(address owner, address operator) external view returns (bool);
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes calldata data
  ) external;
}
pragma solidity >=0.6.2;
// This file copied from OZ, but with the version pragma updated to use >=.
import "./IERC721.sol";
/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
  function totalSupply() external view returns (uint256);
  function tokenOfOwnerByIndex(
    address owner,
    uint256 index
  ) external view returns (uint256 tokenId);
  function tokenByIndex(uint256 index) external view returns (uint256);
}
pragma solidity >=0.6.2;
// This file copied from OZ, but with the version pragma updated to use >=.
import "./IERC721.sol";
/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
  function name() external view returns (string memory);
  function symbol() external view returns (string memory);
  function tokenURI(uint256 tokenId) external view returns (string memory);
}
pragma solidity >=0.6.12;
// This file copied from OZ, but with the version pragma updated to use >= & reference other >= pragma interfaces.
/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
  /**
   * @notice Handle the receipt of an NFT
   * @dev The ERC721 smart contract calls this function on the recipient
   * after a {IERC721-safeTransferFrom}. This function MUST return the function selector,
   * otherwise the caller will revert the transaction. The selector to be
   * returned can be obtained as `this.onERC721Received.selector`. This
   * function MAY throw to revert and reject the transfer.
   * Note: the ERC721 contract address is always the message sender.
   * @param operator The address which called `safeTransferFrom` function
   * @param from The address which previously owned the token
   * @param tokenId The NFT identifier which is being transferred
   * @param data Additional data with no specified format
   * @return bytes4 `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
   */
  function onERC721Received(
    address operator,
    address from,
    uint256 tokenId,
    bytes calldata data
  ) external returns (bytes4);
}
pragma solidity >=0.6.12;
// NOTE: this file exists only to remove the extremely long error messages in safe math.
import {SafeMath as OzSafeMath} from "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
/**
 * @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);
    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 OzSafeMath.sub(a, b, "");
  }
  /**
   * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
   * overflow (when the result is negative).
   *
   * Counterpart to Solidity's `-` operator.
   *
   * Requirements:
   * - Subtraction cannot overflow.
   */
  function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    return OzSafeMath.sub(a, b, errorMessage);
  }
  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);
    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 OzSafeMath.div(a, b, "");
  }
  /**
   * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
   * division by zero. The result is rounded towards zero.
   *
   * Counterpart to Solidity's `/` operator. Note: this function uses a
   * `revert` opcode (which leaves remaining gas untouched) while Solidity
   * uses an invalid opcode to revert (consuming all remaining gas).
   *
   * Requirements:
   * - The divisor cannot be zero.
   */
  function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    return OzSafeMath.div(a, b, errorMessage);
  }
  /**
   * @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 OzSafeMath.mod(a, b, "");
  }
  function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    return OzSafeMath.mod(a, b, errorMessage);
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {AccessControlUpgradeSafe} from "@openzeppelin/contracts-ethereum-package/contracts/access/AccessControl.sol";
import {ReentrancyGuardUpgradeSafe} from "@openzeppelin/contracts-ethereum-package/contracts/utils/ReentrancyGuard.sol";
import {Initializable} from "@openzeppelin/contracts-ethereum-package/contracts/Initializable.sol";
import {SafeMath} from "../../library/SafeMath.sol";
import {PauserPausable} from "./PauserPausable.sol";
/**
 * @title BaseUpgradeablePausable contract
 * @notice This is our Base contract that most other contracts inherit from. It includes many standard
 *  useful abilities like upgradeability, pausability, access control, and re-entrancy guards.
 * @author Goldfinch
 */
contract BaseUpgradeablePausable is
  Initializable,
  AccessControlUpgradeSafe,
  PauserPausable,
  ReentrancyGuardUpgradeSafe
{
  bytes32 public constant OWNER_ROLE = keccak256("OWNER_ROLE");
  using SafeMath for uint256;
  // Pre-reserving a few slots in the base contract in case we need to add things in the future.
  // This does not actually take up gas cost or storage cost, but it does reserve the storage slots.
  // See OpenZeppelin's use of this pattern here:
  // https://github.com/OpenZeppelin/openzeppelin-contracts-ethereum-package/blob/master/contracts/GSN/Context.sol#L37
  uint256[50] private __gap1;
  uint256[50] private __gap2;
  uint256[50] private __gap3;
  uint256[50] private __gap4;
  // solhint-disable-next-line func-name-mixedcase
  function __BaseUpgradeablePausable__init(address owner) public initializer {
    require(owner != address(0), "Owner cannot be the zero address");
    __AccessControl_init_unchained();
    __Pausable_init_unchained();
    __ReentrancyGuard_init_unchained();
    _setupRole(OWNER_ROLE, owner);
    _setupRole(PAUSER_ROLE, owner);
    _setRoleAdmin(PAUSER_ROLE, OWNER_ROLE);
    _setRoleAdmin(OWNER_ROLE, OWNER_ROLE);
  }
  function isAdmin() public view returns (bool) {
    return hasRole(OWNER_ROLE, _msgSender());
  }
  modifier onlyAdmin() {
    require(isAdmin(), "Must have admin role to perform this action");
    _;
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {ImplementationRepository} from "./proxy/ImplementationRepository.sol";
import {ConfigOptions} from "./ConfigOptions.sol";
import {GoldfinchConfig} from "./GoldfinchConfig.sol";
import {IFidu} from "../../interfaces/IFidu.sol";
import {IWithdrawalRequestToken} from "../../interfaces/IWithdrawalRequestToken.sol";
import {ISeniorPool} from "../../interfaces/ISeniorPool.sol";
import {ISeniorPoolStrategy} from "../../interfaces/ISeniorPoolStrategy.sol";
import {IERC20withDec} from "../../interfaces/IERC20withDec.sol";
import {ICUSDCContract} from "../../interfaces/ICUSDCContract.sol";
import {IPoolTokens} from "../../interfaces/IPoolTokens.sol";
import {IBackerRewards} from "../../interfaces/IBackerRewards.sol";
import {IGoldfinchFactory} from "../../interfaces/IGoldfinchFactory.sol";
import {IGo} from "../../interfaces/IGo.sol";
import {IStakingRewards} from "../../interfaces/IStakingRewards.sol";
import {ICurveLP} from "../../interfaces/ICurveLP.sol";
/**
 * @title ConfigHelper
 * @notice A convenience library for getting easy access to other contracts and constants within the
 *  protocol, through the use of the GoldfinchConfig contract
 * @author Goldfinch
 */
library ConfigHelper {
  function getSeniorPool(GoldfinchConfig config) internal view returns (ISeniorPool) {
    return ISeniorPool(seniorPoolAddress(config));
  }
  function getSeniorPoolStrategy(
    GoldfinchConfig config
  ) internal view returns (ISeniorPoolStrategy) {
    return ISeniorPoolStrategy(seniorPoolStrategyAddress(config));
  }
  function getUSDC(GoldfinchConfig config) internal view returns (IERC20withDec) {
    return IERC20withDec(usdcAddress(config));
  }
  function getFidu(GoldfinchConfig config) internal view returns (IFidu) {
    return IFidu(fiduAddress(config));
  }
  function getFiduUSDCCurveLP(GoldfinchConfig config) internal view returns (ICurveLP) {
    return ICurveLP(fiduUSDCCurveLPAddress(config));
  }
  function getCUSDCContract(GoldfinchConfig config) internal view returns (ICUSDCContract) {
    return ICUSDCContract(cusdcContractAddress(config));
  }
  function getPoolTokens(GoldfinchConfig config) internal view returns (IPoolTokens) {
    return IPoolTokens(poolTokensAddress(config));
  }
  function getBackerRewards(GoldfinchConfig config) internal view returns (IBackerRewards) {
    return IBackerRewards(backerRewardsAddress(config));
  }
  function getGoldfinchFactory(GoldfinchConfig config) internal view returns (IGoldfinchFactory) {
    return IGoldfinchFactory(goldfinchFactoryAddress(config));
  }
  function getGFI(GoldfinchConfig config) internal view returns (IERC20withDec) {
    return IERC20withDec(gfiAddress(config));
  }
  function getGo(GoldfinchConfig config) internal view returns (IGo) {
    return IGo(goAddress(config));
  }
  function getStakingRewards(GoldfinchConfig config) internal view returns (IStakingRewards) {
    return IStakingRewards(stakingRewardsAddress(config));
  }
  function getTranchedPoolImplementationRepository(
    GoldfinchConfig config
  ) internal view returns (ImplementationRepository) {
    return
      ImplementationRepository(
        config.getAddress(uint256(ConfigOptions.Addresses.TranchedPoolImplementationRepository))
      );
  }
  function getWithdrawalRequestToken(
    GoldfinchConfig config
  ) internal view returns (IWithdrawalRequestToken) {
    return
      IWithdrawalRequestToken(
        config.getAddress(uint256(ConfigOptions.Addresses.WithdrawalRequestToken))
      );
  }
  function oneInchAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.OneInch));
  }
  function creditLineImplementationAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.CreditLineImplementation));
  }
  /// @dev deprecated because we no longer use GSN
  function trustedForwarderAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.TrustedForwarder));
  }
  function configAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.GoldfinchConfig));
  }
  function poolTokensAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.PoolTokens));
  }
  function backerRewardsAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.BackerRewards));
  }
  function seniorPoolAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.SeniorPool));
  }
  function seniorPoolStrategyAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.SeniorPoolStrategy));
  }
  function goldfinchFactoryAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.GoldfinchFactory));
  }
  function gfiAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.GFI));
  }
  function fiduAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.Fidu));
  }
  function fiduUSDCCurveLPAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.FiduUSDCCurveLP));
  }
  function cusdcContractAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.CUSDCContract));
  }
  function usdcAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.USDC));
  }
  function tranchedPoolAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.TranchedPoolImplementation));
  }
  function reserveAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.TreasuryReserve));
  }
  function protocolAdminAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.ProtocolAdmin));
  }
  function borrowerImplementationAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.BorrowerImplementation));
  }
  function goAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.Go));
  }
  function stakingRewardsAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.StakingRewards));
  }
  function getReserveDenominator(GoldfinchConfig config) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.ReserveDenominator));
  }
  function getWithdrawFeeDenominator(GoldfinchConfig config) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.WithdrawFeeDenominator));
  }
  function getLatenessGracePeriodInDays(GoldfinchConfig config) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.LatenessGracePeriodInDays));
  }
  function getLatenessMaxDays(GoldfinchConfig config) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.LatenessMaxDays));
  }
  function getDrawdownPeriodInSeconds(GoldfinchConfig config) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.DrawdownPeriodInSeconds));
  }
  function getTransferRestrictionPeriodInDays(
    GoldfinchConfig config
  ) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.TransferRestrictionPeriodInDays));
  }
  function getLeverageRatio(GoldfinchConfig config) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.LeverageRatio));
  }
  function getSeniorPoolWithdrawalCancelationFeeInBps(
    GoldfinchConfig config
  ) internal view returns (uint256) {
    return config.getNumber(uint256(ConfigOptions.Numbers.SeniorPoolWithdrawalCancelationFeeInBps));
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
/**
 * @title ConfigOptions
 * @notice A central place for enumerating the configurable options of our GoldfinchConfig contract
 * @author Goldfinch
 */
library ConfigOptions {
  // NEVER EVER CHANGE THE ORDER OF THESE!
  // You can rename or append. But NEVER change the order.
  enum Numbers {
    TransactionLimit,
    /// @dev: TotalFundsLimit used to represent a total cap on senior pool deposits
    /// but is now deprecated
    TotalFundsLimit,
    MaxUnderwriterLimit,
    ReserveDenominator,
    WithdrawFeeDenominator,
    LatenessGracePeriodInDays,
    LatenessMaxDays,
    DrawdownPeriodInSeconds,
    TransferRestrictionPeriodInDays,
    LeverageRatio,
    /// A number in the range [0, 10000] representing basis points of FIDU taken as a fee
    /// when a withdrawal request is canceled.
    SeniorPoolWithdrawalCancelationFeeInBps
  }
  /// @dev TrustedForwarder is deprecated because we no longer use GSN. CreditDesk
  ///   and Pool are deprecated because they are no longer used in the protocol.
  enum Addresses {
    Pool, // deprecated
    CreditLineImplementation,
    GoldfinchFactory,
    CreditDesk, // deprecated
    Fidu,
    USDC,
    TreasuryReserve,
    ProtocolAdmin,
    OneInch,
    TrustedForwarder, // deprecated
    CUSDCContract,
    GoldfinchConfig,
    PoolTokens,
    TranchedPoolImplementation, // deprecated
    SeniorPool,
    SeniorPoolStrategy,
    MigratedTranchedPoolImplementation,
    BorrowerImplementation,
    GFI,
    Go,
    BackerRewards,
    StakingRewards,
    FiduUSDCCurveLP,
    TranchedPoolImplementationRepository,
    WithdrawalRequestToken
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {SafeMath} from "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
/// @notice Library to house logic around the ERC2981 royalty standard. Contracts
///   using this library should define a ConfigurableRoyaltyStandard.RoyaltyParams
///   state var and public functions that proxy to the logic here. Contracts should
///   take care to ensure that a public `setRoyaltyParams` method is only callable
///   by an admin.
library ConfigurableRoyaltyStandard {
  using SafeMath for uint256;
  /// @dev bytes4(keccak256("royaltyInfo(uint256,uint256)")) == 0x2a55205a
  bytes4 internal constant _INTERFACE_ID_ERC2981 = 0x2a55205a;
  uint256 internal constant _PERCENTAGE_DECIMALS = 1e18;
  struct RoyaltyParams {
    // The address that should receive royalties
    address receiver;
    // The percent of `salePrice` that should be taken for royalties.
    // Represented with `_PERCENTAGE_DECIMALS` where `_PERCENTAGE_DECIMALS` is 100%.
    uint256 royaltyPercent;
  }
  event RoyaltyParamsSet(address indexed sender, address newReceiver, uint256 newRoyaltyPercent);
  /// @notice Called with the sale price to determine how much royalty
  //    is owed and to whom.
  /// @param _tokenId The NFT asset queried for royalty information
  /// @param _salePrice The sale price of the NFT asset specified by _tokenId
  /// @return receiver Address that should receive royalties
  /// @return royaltyAmount The royalty payment amount for _salePrice
  function royaltyInfo(
    RoyaltyParams storage params,
    // solhint-disable-next-line no-unused-vars
    uint256 _tokenId,
    uint256 _salePrice
  ) internal view returns (address, uint256) {
    uint256 royaltyAmount = _salePrice.mul(params.royaltyPercent).div(_PERCENTAGE_DECIMALS);
    return (params.receiver, royaltyAmount);
  }
  /// @notice Set royalty params used in `royaltyInfo`. The calling contract should limit
  ///   public use of this function to owner or using some other access control scheme.
  /// @param newReceiver The new address which should receive royalties. See `receiver`.
  /// @param newRoyaltyPercent The new percent of `salePrice` that should be taken for royalties.
  ///   See `royaltyPercent`.
  /// @dev The receiver cannot be the null address
  function setRoyaltyParams(
    RoyaltyParams storage params,
    address newReceiver,
    uint256 newRoyaltyPercent
  ) internal {
    require(newReceiver != address(0), "Null receiver");
    params.receiver = newReceiver;
    params.royaltyPercent = newRoyaltyPercent;
    emit RoyaltyParamsSet(msg.sender, newReceiver, newRoyaltyPercent);
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {BaseUpgradeablePausable} from "./BaseUpgradeablePausable.sol";
import {IGoldfinchConfig} from "../../interfaces/IGoldfinchConfig.sol";
import {ConfigOptions} from "./ConfigOptions.sol";
/**
 * @title GoldfinchConfig
 * @notice This contract stores mappings of useful "protocol config state", giving a central place
 *  for all other contracts to access it. For example, the TransactionLimit, or the PoolAddress. These config vars
 *  are enumerated in the `ConfigOptions` library, and can only be changed by admins of the protocol.
 *  Note: While this inherits from BaseUpgradeablePausable, it is not deployed as an upgradeable contract (this
 *    is mostly to save gas costs of having each call go through a proxy)
 * @author Goldfinch
 */
contract GoldfinchConfig is BaseUpgradeablePausable {
  bytes32 public constant GO_LISTER_ROLE = keccak256("GO_LISTER_ROLE");
  mapping(uint256 => address) public addresses;
  mapping(uint256 => uint256) public numbers;
  mapping(address => bool) public goList;
  event AddressUpdated(address owner, uint256 index, address oldValue, address newValue);
  event NumberUpdated(address owner, uint256 index, uint256 oldValue, uint256 newValue);
  event GoListed(address indexed member);
  event NoListed(address indexed member);
  bool public valuesInitialized;
  function initialize(address owner) public initializer {
    require(owner != address(0), "Owner address cannot be empty");
    __BaseUpgradeablePausable__init(owner);
    _setupRole(GO_LISTER_ROLE, owner);
    _setRoleAdmin(GO_LISTER_ROLE, OWNER_ROLE);
  }
  function setAddress(uint256 addressIndex, address newAddress) public onlyAdmin {
    require(addresses[addressIndex] == address(0), "Address has already been initialized");
    emit AddressUpdated(msg.sender, addressIndex, addresses[addressIndex], newAddress);
    addresses[addressIndex] = newAddress;
  }
  function setNumber(uint256 index, uint256 newNumber) public onlyAdmin {
    emit NumberUpdated(msg.sender, index, numbers[index], newNumber);
    numbers[index] = newNumber;
  }
  function setTreasuryReserve(address newTreasuryReserve) public onlyAdmin {
    uint256 key = uint256(ConfigOptions.Addresses.TreasuryReserve);
    emit AddressUpdated(msg.sender, key, addresses[key], newTreasuryReserve);
    addresses[key] = newTreasuryReserve;
  }
  function setSeniorPoolStrategy(address newStrategy) public onlyAdmin {
    uint256 key = uint256(ConfigOptions.Addresses.SeniorPoolStrategy);
    emit AddressUpdated(msg.sender, key, addresses[key], newStrategy);
    addresses[key] = newStrategy;
  }
  function setCreditLineImplementation(address newAddress) public onlyAdmin {
    uint256 key = uint256(ConfigOptions.Addresses.CreditLineImplementation);
    emit AddressUpdated(msg.sender, key, addresses[key], newAddress);
    addresses[key] = newAddress;
  }
  function setTranchedPoolImplementation(address newAddress) public onlyAdmin {
    uint256 key = uint256(ConfigOptions.Addresses.TranchedPoolImplementation);
    emit AddressUpdated(msg.sender, key, addresses[key], newAddress);
    addresses[key] = newAddress;
  }
  function setBorrowerImplementation(address newAddress) public onlyAdmin {
    uint256 key = uint256(ConfigOptions.Addresses.BorrowerImplementation);
    emit AddressUpdated(msg.sender, key, addresses[key], newAddress);
    addresses[key] = newAddress;
  }
  function setGoldfinchConfig(address newAddress) public onlyAdmin {
    uint256 key = uint256(ConfigOptions.Addresses.GoldfinchConfig);
    emit AddressUpdated(msg.sender, key, addresses[key], newAddress);
    addresses[key] = newAddress;
  }
  function initializeFromOtherConfig(
    address _initialConfig,
    uint256 numbersLength,
    uint256 addressesLength
  ) public onlyAdmin {
    require(!valuesInitialized, "Already initialized values");
    IGoldfinchConfig initialConfig = IGoldfinchConfig(_initialConfig);
    for (uint256 i = 0; i < numbersLength; i++) {
      setNumber(i, initialConfig.getNumber(i));
    }
    for (uint256 i = 0; i < addressesLength; i++) {
      if (getAddress(i) == address(0)) {
        setAddress(i, initialConfig.getAddress(i));
      }
    }
    valuesInitialized = true;
  }
  /**
   * @dev Adds a user to go-list
   * @param _member address to add to go-list
   */
  function addToGoList(address _member) public onlyGoListerRole {
    goList[_member] = true;
    emit GoListed(_member);
  }
  /**
   * @dev removes a user from go-list
   * @param _member address to remove from go-list
   */
  function removeFromGoList(address _member) public onlyGoListerRole {
    goList[_member] = false;
    emit NoListed(_member);
  }
  /**
   * @dev adds many users to go-list at once
   * @param _members addresses to ad to go-list
   */
  function bulkAddToGoList(address[] calldata _members) external onlyGoListerRole {
    for (uint256 i = 0; i < _members.length; i++) {
      addToGoList(_members[i]);
    }
  }
  /**
   * @dev removes many users from go-list at once
   * @param _members addresses to remove from go-list
   */
  function bulkRemoveFromGoList(address[] calldata _members) external onlyGoListerRole {
    for (uint256 i = 0; i < _members.length; i++) {
      removeFromGoList(_members[i]);
    }
  }
  /*
    Using custom getters in case we want to change underlying implementation later,
    or add checks or validations later on.
  */
  function getAddress(uint256 index) public view returns (address) {
    return addresses[index];
  }
  function getNumber(uint256 index) public view returns (uint256) {
    return numbers[index];
  }
  modifier onlyGoListerRole() {
    require(
      hasRole(GO_LISTER_ROLE, _msgSender()),
      "Must have go-lister role to perform this action"
    );
    _;
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
import "@openzeppelin/contracts-ethereum-package/contracts/access/AccessControl.sol";
/// @notice Base contract that provides an OWNER_ROLE and convenience function/modifier for
///   checking sender against this role. Inherting contracts must set up this role using
///   `_setupRole` and `_setRoleAdmin`.
contract HasAdmin is AccessControlUpgradeSafe {
  /// @notice ID for OWNER_ROLE
  bytes32 public constant OWNER_ROLE = keccak256("OWNER_ROLE");
  /// @notice Determine whether msg.sender has OWNER_ROLE
  /// @return isAdmin True when msg.sender has OWNER_ROLE
  function isAdmin() public view returns (bool) {
    return hasRole(OWNER_ROLE, msg.sender);
  }
  modifier onlyAdmin() {
    /// @dev AD: Must have admin role to perform this action
    require(isAdmin(), "AD");
    _;
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import "@openzeppelin/contracts-ethereum-package/contracts/utils/Pausable.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/access/AccessControl.sol";
/**
 * @title PauserPausable
 * @notice Inheriting from OpenZeppelin's Pausable contract, this does small
 *  augmentations to make it work with a PAUSER_ROLE, leveraging the AccessControl contract.
 *  It is meant to be inherited.
 * @author Goldfinch
 */
contract PauserPausable is AccessControlUpgradeSafe, PausableUpgradeSafe {
  bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
  // solhint-disable-next-line func-name-mixedcase
  function __PauserPausable__init() public initializer {
    __Pausable_init_unchained();
  }
  /**
   * @dev Pauses all functions guarded by Pause
   *
   * See {Pausable-_pause}.
   *
   * Requirements:
   *
   * - the caller must have the PAUSER_ROLE.
   */
  function pause() public onlyPauserRole {
    _pause();
  }
  /**
   * @dev Unpauses the contract
   *
   * See {Pausable-_unpause}.
   *
   * Requirements:
   *
   * - the caller must have the Pauser role
   */
  function unpause() public onlyPauserRole {
    _unpause();
  }
  modifier onlyPauserRole() {
    /// @dev NA: not authorized
    require(hasRole(PAUSER_ROLE, _msgSender()), "NA");
    _;
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {ERC721PresetMinterPauserAutoIdUpgradeSafe} from "../../external/ERC721PresetMinterPauserAutoId.sol";
import {ERC165UpgradeSafe} from "../../external/ERC721PresetMinterPauserAutoId.sol";
import {IERC165} from "../../external/ERC721PresetMinterPauserAutoId.sol";
import {GoldfinchConfig} from "./GoldfinchConfig.sol";
import {ConfigHelper} from "./ConfigHelper.sol";
import {HasAdmin} from "./HasAdmin.sol";
import {ConfigurableRoyaltyStandard} from "./ConfigurableRoyaltyStandard.sol";
import {IERC2981} from "../../interfaces/IERC2981.sol";
import {ITranchedPool} from "../../interfaces/ITranchedPool.sol";
import {IPoolTokens} from "../../interfaces/IPoolTokens.sol";
import {IBackerRewards} from "../../interfaces/IBackerRewards.sol";
/**
 * @title PoolTokens
 * @notice PoolTokens is an ERC721 compliant contract, which can represent
 *  junior tranche or senior tranche shares of any of the borrower pools.
 * @author Goldfinch
 */
contract PoolTokens is IPoolTokens, ERC721PresetMinterPauserAutoIdUpgradeSafe, HasAdmin, IERC2981 {
  bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;
  bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
  bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
  bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
  GoldfinchConfig public config;
  using ConfigHelper for GoldfinchConfig;
  // tokenId => tokenInfo
  mapping(uint256 => TokenInfo) public tokens;
  // poolAddress => poolInfo
  mapping(address => PoolInfo) public pools;
  ConfigurableRoyaltyStandard.RoyaltyParams public royaltyParams;
  using ConfigurableRoyaltyStandard for ConfigurableRoyaltyStandard.RoyaltyParams;
  /*
    We are using our own initializer function so that OZ doesn't automatically
    set owner as msg.sender. Also, it lets us set our config contract
  */
  // solhint-disable-next-line func-name-mixedcase
  function __initialize__(address owner, GoldfinchConfig _config) external initializer {
    require(
      owner != address(0) && address(_config) != address(0),
      "Owner and config addresses cannot be empty"
    );
    __Context_init_unchained();
    __AccessControl_init_unchained();
    __ERC165_init_unchained();
    // This is setting name and symbol of the NFT's
    __ERC721_init_unchained("Goldfinch V2 Pool Tokens", "GFI-V2-PT");
    __Pausable_init_unchained();
    __ERC721Pausable_init_unchained();
    config = _config;
    _setupRole(PAUSER_ROLE, owner);
    _setupRole(OWNER_ROLE, owner);
    _setRoleAdmin(PAUSER_ROLE, OWNER_ROLE);
    _setRoleAdmin(OWNER_ROLE, OWNER_ROLE);
  }
  /// @inheritdoc IPoolTokens
  function mint(
    MintParams calldata params,
    address to
  ) external virtual override onlyPool whenNotPaused returns (uint256 tokenId) {
    address poolAddress = _msgSender();
    PoolInfo storage pool = pools[poolAddress];
    pool.totalMinted = pool.totalMinted.add(params.principalAmount);
    tokenId = _createToken({
      principalAmount: params.principalAmount,
      tranche: params.tranche,
      principalRedeemed: 0,
      interestRedeemed: 0,
      poolAddress: poolAddress,
      mintTo: to
    });
    config.getBackerRewards().setPoolTokenAccRewardsPerPrincipalDollarAtMint(_msgSender(), tokenId);
  }
  /// @inheritdoc IPoolTokens
  function redeem(
    uint256 tokenId,
    uint256 principalRedeemed,
    uint256 interestRedeemed
  ) external virtual override onlyPool whenNotPaused {
    TokenInfo storage token = tokens[tokenId];
    address poolAddr = token.pool;
    require(token.pool != address(0), "Invalid tokenId");
    require(_msgSender() == poolAddr, "Only the token's pool can redeem");
    PoolInfo storage pool = pools[poolAddr];
    pool.totalPrincipalRedeemed = pool.totalPrincipalRedeemed.add(principalRedeemed);
    require(pool.totalPrincipalRedeemed <= pool.totalMinted, "Cannot redeem more than we minted");
    token.principalRedeemed = token.principalRedeemed.add(principalRedeemed);
    require(
      token.principalRedeemed <= token.principalAmount,
      "Cannot redeem more than principal-deposited amount for token"
    );
    token.interestRedeemed = token.interestRedeemed.add(interestRedeemed);
    emit TokenRedeemed(
      ownerOf(tokenId),
      poolAddr,
      tokenId,
      principalRedeemed,
      interestRedeemed,
      token.tranche
    );
  }
  /** @notice reduce a given pool token's principalAmount and principalRedeemed by a specified amount
   *  @dev uses safemath to prevent underflow
   *  @dev this function is only intended for use as part of the v2.6.0 upgrade
   *    to rectify a bug that allowed users to create a PoolToken that had a
   *    larger amount of principal than they actually made available to the
   *    borrower.  This bug is fixed in v2.6.0 but still requires past pool tokens
   *    to have their principal redeemed and deposited to be rectified.
   *  @param tokenId id of token to decrease
   *  @param amount amount to decrease by
   */
  function reducePrincipalAmount(uint256 tokenId, uint256 amount) external onlyAdmin {
    TokenInfo storage tokenInfo = tokens[tokenId];
    tokenInfo.principalAmount = tokenInfo.principalAmount.sub(amount);
    tokenInfo.principalRedeemed = tokenInfo.principalRedeemed.sub(amount);
  }
  /// @inheritdoc IPoolTokens
  function withdrawPrincipal(
    uint256 tokenId,
    uint256 principalAmount
  ) external virtual override onlyPool whenNotPaused {
    TokenInfo storage token = tokens[tokenId];
    address poolAddr = token.pool;
    require(_msgSender() == poolAddr, "Invalid sender");
    require(token.principalRedeemed == 0, "Token redeemed");
    require(token.principalAmount >= principalAmount, "Insufficient principal");
    PoolInfo storage pool = pools[poolAddr];
    pool.totalMinted = pool.totalMinted.sub(principalAmount);
    require(pool.totalPrincipalRedeemed <= pool.totalMinted, "Cannot withdraw more than redeemed");
    token.principalAmount = token.principalAmount.sub(principalAmount);
    emit TokenPrincipalWithdrawn(
      ownerOf(tokenId),
      poolAddr,
      tokenId,
      principalAmount,
      token.tranche
    );
  }
  /// @inheritdoc IPoolTokens
  function burn(uint256 tokenId) external virtual override whenNotPaused {
    TokenInfo memory token = _getTokenInfo(tokenId);
    bool canBurn = _isApprovedOrOwner(_msgSender(), tokenId);
    bool fromTokenPool = _validPool(_msgSender()) && token.pool == _msgSender();
    address owner = ownerOf(tokenId);
    require(canBurn || fromTokenPool, "ERC721Burnable: caller cannot burn this token");
    require(
      token.principalRedeemed == token.principalAmount,
      "Can only burn fully redeemed tokens"
    );
    // If we let you burn with claimable backer rewards then it would blackhole your rewards,
    // so you must claim all rewards before burning
    require(config.getBackerRewards().poolTokenClaimableRewards(tokenId) == 0, "rewards>0");
    _destroyAndBurn(owner, address(token.pool), tokenId);
  }
  function getTokenInfo(uint256 tokenId) external view virtual override returns (TokenInfo memory) {
    return _getTokenInfo(tokenId);
  }
  function getPoolInfo(address pool) external view override returns (PoolInfo memory) {
    return pools[pool];
  }
  /// @inheritdoc IPoolTokens
  function onPoolCreated(address newPool) external override onlyGoldfinchFactory {
    pools[newPool].created = true;
  }
  /**
   * @notice Returns a boolean representing whether the spender is the owner or the approved spender of the token
   * @param spender The address to check
   * @param tokenId The token id to check for
   * @return True if approved to redeem/transfer/burn the token, false if not
   */
  function isApprovedOrOwner(
    address spender,
    uint256 tokenId
  ) external view override returns (bool) {
    return _isApprovedOrOwner(spender, tokenId);
  }
  /**
   * @inheritdoc IPoolTokens
   * @dev NA: Not Authorized
   * @dev IA: Invalid Amount - newPrincipal1 not in range (0, principalAmount)
   */
  function splitToken(
    uint256 tokenId,
    uint256 newPrincipal1
  ) external override returns (uint256 tokenId1, uint256 tokenId2) {
    require(_isApprovedOrOwner(msg.sender, tokenId), "NA");
    TokenInfo memory tokenInfo = _getTokenInfo(tokenId);
    require(0 < newPrincipal1 && newPrincipal1 < tokenInfo.principalAmount, "IA");
    IBackerRewards.BackerRewardsTokenInfo memory backerRewardsTokenInfo = config
      .getBackerRewards()
      .getTokenInfo(tokenId);
    IBackerRewards.StakingRewardsTokenInfo memory backerStakingRewardsTokenInfo = config
      .getBackerRewards()
      .getStakingRewardsTokenInfo(tokenId);
    // Burn the original token before calling out to other contracts to prevent possible reentrancy attacks.
    // A reentrancy guard on this function alone is insufficient because someone may be able to reenter the
    // protocol through a different contract that reads pool token metadata. Following checks-effects-interactions
    // here leads to a clunky implementation (fn's with many params) but guarding against potential reentrancy
    // is more important.
    address tokenOwner = ownerOf(tokenId);
    _destroyAndBurn(tokenOwner, address(tokenInfo.pool), tokenId);
    (tokenId1, tokenId2) = _createSplitTokens(tokenInfo, tokenOwner, newPrincipal1);
    _setBackerRewardsForSplitTokens(
      tokenInfo,
      backerRewardsTokenInfo,
      backerStakingRewardsTokenInfo,
      tokenId1,
      tokenId2,
      newPrincipal1
    );
    emit TokenSplit({
      owner: tokenOwner,
      pool: tokenInfo.pool,
      tokenId: tokenId,
      newTokenId1: tokenId1,
      newPrincipal1: newPrincipal1,
      newTokenId2: tokenId2,
      newPrincipal2: tokenInfo.principalAmount.sub(newPrincipal1)
    });
  }
  /// @notice Initialize the backer rewards metadata for split tokens
  function _setBackerRewardsForSplitTokens(
    TokenInfo memory tokenInfo,
    IBackerRewards.BackerRewardsTokenInfo memory backerRewardsTokenInfo,
    IBackerRewards.StakingRewardsTokenInfo memory stakingRewardsTokenInfo,
    uint256 newTokenId1,
    uint256 newTokenId2,
    uint256 newPrincipal1
  ) internal {
    uint256 rewardsClaimed1 = backerRewardsTokenInfo.rewardsClaimed.mul(newPrincipal1).div(
      tokenInfo.principalAmount
    );
    config.getBackerRewards().setBackerAndStakingRewardsTokenInfoOnSplit({
      originalBackerRewardsTokenInfo: backerRewardsTokenInfo,
      originalStakingRewardsTokenInfo: stakingRewardsTokenInfo,
      newTokenId: newTokenId1,
      newRewardsClaimed: rewardsClaimed1
    });
    config.getBackerRewards().setBackerAndStakingRewardsTokenInfoOnSplit({
      originalBackerRewardsTokenInfo: backerRewardsTokenInfo,
      originalStakingRewardsTokenInfo: stakingRewardsTokenInfo,
      newTokenId: newTokenId2,
      newRewardsClaimed: backerRewardsTokenInfo.rewardsClaimed.sub(rewardsClaimed1)
    });
  }
  /// @notice Split tokenId into two new tokens. Assumes that newPrincipal1 is valid for the token's principalAmount
  function _createSplitTokens(
    TokenInfo memory tokenInfo,
    address tokenOwner,
    uint256 newPrincipal1
  ) internal returns (uint256 newTokenId1, uint256 newTokenId2) {
    // All new vals are proportional to the new token's principal
    uint256 principalRedeemed1 = tokenInfo.principalRedeemed.mul(newPrincipal1).div(
      tokenInfo.principalAmount
    );
    uint256 interestRedeemed1 = tokenInfo.interestRedeemed.mul(newPrincipal1).div(
      tokenInfo.principalAmount
    );
    newTokenId1 = _createToken(
      newPrincipal1,
      tokenInfo.tranche,
      principalRedeemed1,
      interestRedeemed1,
      tokenInfo.pool,
      tokenOwner
    );
    newTokenId2 = _createToken(
      tokenInfo.principalAmount.sub(newPrincipal1),
      tokenInfo.tranche,
      tokenInfo.principalRedeemed.sub(principalRedeemed1),
      tokenInfo.interestRedeemed.sub(interestRedeemed1),
      tokenInfo.pool,
      tokenOwner
    );
  }
  /// @inheritdoc IPoolTokens
  function validPool(address sender) public view virtual override returns (bool) {
    return _validPool(sender);
  }
  /**
   * @notice Mint the token and save its metadata to storage
   * @param principalAmount token principal
   * @param tranche tranche of the pool to which the token belongs
   * @param principalRedeemed amount of principal already redeemed for the token. This is
   *  0 for tokens created from a deposit, and could be non-zero for tokens created from a split
   * @param interestRedeemed amount of interest already redeemed for the token. This is
   *  0 for tokens created from a deposit, and could be non-zero for tokens created from a split
   * @param poolAddress pool to which the token belongs
   * @param mintTo the token owner
   * @return tokenId id of the created token
   */
  function _createToken(
    uint256 principalAmount,
    uint256 tranche,
    uint256 principalRedeemed,
    uint256 interestRedeemed,
    address poolAddress,
    address mintTo
  ) internal returns (uint256 tokenId) {
    _tokenIdTracker.increment();
    tokenId = _tokenIdTracker.current();
    tokens[tokenId] = TokenInfo({
      pool: poolAddress,
      tranche: tranche,
      principalAmount: principalAmount,
      principalRedeemed: principalRedeemed,
      interestRedeemed: interestRedeemed
    });
    _mint(mintTo, tokenId);
    emit TokenMinted({
      owner: mintTo,
      pool: poolAddress,
      tokenId: tokenId,
      amount: principalAmount,
      tranche: tranche
    });
  }
  function _destroyAndBurn(address owner, address pool, uint256 tokenId) internal {
    delete tokens[tokenId];
    _burn(tokenId);
    config.getBackerRewards().clearTokenInfo(tokenId);
    emit TokenBurned(owner, pool, tokenId);
  }
  function _validPool(address poolAddress) internal view virtual returns (bool) {
    return pools[poolAddress].created;
  }
  function _getTokenInfo(uint256 tokenId) internal view returns (TokenInfo memory) {
    return tokens[tokenId];
  }
  /// @notice Called with the sale price to determine how much royalty
  //    is owed and to whom.
  /// @param _tokenId The NFT asset queried for royalty information
  /// @param _salePrice The sale price of the NFT asset specified by _tokenId
  /// @return receiver Address that should receive royalties
  /// @return royaltyAmount The royalty payment amount for _salePrice
  function royaltyInfo(
    uint256 _tokenId,
    uint256 _salePrice
  ) external view override returns (address, uint256) {
    return royaltyParams.royaltyInfo(_tokenId, _salePrice);
  }
  /// @notice Set royalty params used in `royaltyInfo`. This function is only callable by
  ///   an address with `OWNER_ROLE`.
  /// @param newReceiver The new address which should receive royalties. See `receiver`.
  /// @param newRoyaltyPercent The new percent of `salePrice` that should be taken for royalties.
  ///   See `royaltyPercent`.
  function setRoyaltyParams(address newReceiver, uint256 newRoyaltyPercent) external onlyAdmin {
    royaltyParams.setRoyaltyParams(newReceiver, newRoyaltyPercent);
  }
  function setBaseURI(string calldata baseURI_) external onlyAdmin {
    _setBaseURI(baseURI_);
  }
  function supportsInterface(
    bytes4 id
  ) public view override(ERC165UpgradeSafe, IERC165) returns (bool) {
    return (id == _INTERFACE_ID_ERC721 ||
      id == _INTERFACE_ID_ERC721_METADATA ||
      id == _INTERFACE_ID_ERC721_ENUMERABLE ||
      id == _INTERFACE_ID_ERC165 ||
      id == ConfigurableRoyaltyStandard._INTERFACE_ID_ERC2981);
  }
  modifier onlyGoldfinchFactory() {
    require(_msgSender() == config.goldfinchFactoryAddress(), "Only Goldfinch factory is allowed");
    _;
  }
  modifier onlyPool() {
    require(_validPool(_msgSender()), "Invalid pool!");
    _;
  }
}
// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {BaseUpgradeablePausable} from "../BaseUpgradeablePausable.sol";
import {Address} from "@openzeppelin/contracts/utils/Address.sol";
/// @title User Controlled Upgrades (UCU) Proxy Repository
/// A repository maintaing a collection of "lineages" of implementation contracts
///
/// Lineages are a sequence of implementations each lineage can be thought of as
/// a "major" revision of implementations. Implementations between lineages are
/// considered incompatible.
contract ImplementationRepository is BaseUpgradeablePausable {
  address internal constant INVALID_IMPL = address(0);
  uint256 internal constant INVALID_LINEAGE_ID = 0;
  /// @notice returns data that will be delegatedCalled when the given implementation
  ///           is upgraded to
  mapping(address => bytes) public upgradeDataFor;
  /// @dev mapping from one implementation to the succeeding implementation
  mapping(address => address) internal _nextImplementationOf;
  /// @notice Returns the id of the lineage a given implementation belongs to
  mapping(address => uint256) public lineageIdOf;
  /// @dev internal because we expose this through the `currentImplementation(uint256)` api
  mapping(uint256 => address) internal _currentOfLineage;
  /// @notice Returns the id of the most recently created lineage
  uint256 public currentLineageId;
  // //////// External ////////////////////////////////////////////////////////////
  /// @notice initialize the repository's state
  /// @dev reverts if `_owner` is the null address
  /// @dev reverts if `implementation` is not a contract
  /// @param _owner owner of the repository
  /// @param implementation initial implementation in the repository
  function initialize(address _owner, address implementation) external initializer {
    __BaseUpgradeablePausable__init(_owner);
    _createLineage(implementation);
    require(currentLineageId != INVALID_LINEAGE_ID);
  }
  /// @notice set data that will be delegate called when a proxy upgrades to the given `implementation`
  /// @dev reverts when caller is not an admin
  /// @dev reverts when the contract is paused
  /// @dev reverts if the given implementation isn't registered
  function setUpgradeDataFor(
    address implementation,
    bytes calldata data
  ) external onlyAdmin whenNotPaused {
    _setUpgradeDataFor(implementation, data);
  }
  /// @notice Create a new lineage of implementations.
  ///
  /// This creates a new "root" of a new lineage
  /// @dev reverts if `implementation` is not a contract
  /// @param implementation implementation that will be the first implementation in the lineage
  /// @return newly created lineage's id
  function createLineage(
    address implementation
  ) external onlyAdmin whenNotPaused returns (uint256) {
    return _createLineage(implementation);
  }
  /// @notice add a new implementation and set it as the current implementation
  /// @dev reverts if the sender is not an owner
  /// @dev reverts if the contract is paused
  /// @dev reverts if `implementation` is not a contract
  /// @param implementation implementation to append
  function append(address implementation) external onlyAdmin whenNotPaused {
    _append(implementation, currentLineageId);
  }
  /// @notice Append an implementation to a specified lineage
  /// @dev reverts if the contract is paused
  /// @dev reverts if the sender is not an owner
  /// @dev reverts if `implementation` is not a contract
  /// @param implementation implementation to append
  /// @param lineageId id of lineage to append to
  function append(address implementation, uint256 lineageId) external onlyAdmin whenNotPaused {
    _append(implementation, lineageId);
  }
  /// @notice Remove an implementation from the chain and "stitch" together its neighbors
  /// @dev If you have a chain of `A -> B -> C` and I call `remove(B, C)` it will result in `A -> C`
  /// @dev reverts if `previos` is not the ancestor of `toRemove`
  /// @dev we need to provide the previous implementation here to be able to successfully "stitch"
  ///       the chain back together. Because this is an admin action, we can source what the previous
  ///       version is from events.
  /// @param toRemove Implementation to remove
  /// @param previous Implementation that currently has `toRemove` as its successor
  function remove(address toRemove, address previous) external onlyAdmin whenNotPaused {
    _remove(toRemove, previous);
  }
  // //////// External view ////////////////////////////////////////////////////////////
  /// @notice Returns `true` if an implementation has a next implementation set
  /// @param implementation implementation to check
  /// @return The implementation following the given implementation
  function hasNext(address implementation) external view returns (bool) {
    return _nextImplementationOf[implementation] != INVALID_IMPL;
  }
  /// @notice Returns `true` if an implementation has already been added
  /// @param implementation Implementation to check existence of
  /// @return `true` if the implementation has already been added
  function has(address implementation) external view returns (bool) {
    return _has(implementation);
  }
  /// @notice Get the next implementation for a given implementation or
  ///           `address(0)` if it doesn't exist
  /// @dev reverts when contract is paused
  /// @param implementation implementation to get the upgraded implementation for
  /// @return Next Implementation
  function nextImplementationOf(
    address implementation
  ) external view whenNotPaused returns (address) {
    return _nextImplementationOf[implementation];
  }
  /// @notice Returns `true` if a given lineageId exists
  function lineageExists(uint256 lineageId) external view returns (bool) {
    return _lineageExists(lineageId);
  }
  /// @notice Return the current implementation of a lineage with the given `lineageId`
  function currentImplementation(uint256 lineageId) external view whenNotPaused returns (address) {
    return _currentImplementation(lineageId);
  }
  /// @notice return current implementaton of the current lineage
  function currentImplementation() external view whenNotPaused returns (address) {
    return _currentImplementation(currentLineageId);
  }
  // //////// Internal ////////////////////////////////////////////////////////////
  function _setUpgradeDataFor(address implementation, bytes memory data) internal {
    require(_has(implementation), "unknown impl");
    upgradeDataFor[implementation] = data;
    emit UpgradeDataSet(implementation, data);
  }
  function _createLineage(address implementation) internal virtual returns (uint256) {
    require(Address.isContract(implementation), "not a contract");
    // NOTE: impractical to overflow
    currentLineageId += 1;
    _currentOfLineage[currentLineageId] = implementation;
    lineageIdOf[implementation] = currentLineageId;
    emit Added(currentLineageId, implementation, address(0));
    return currentLineageId;
  }
  function _currentImplementation(uint256 lineageId) internal view returns (address) {
    return _currentOfLineage[lineageId];
  }
  /// @notice Returns `true` if an implementation has already been added
  /// @param implementation implementation to check for
  /// @return `true` if the implementation has already been added
  function _has(address implementation) internal view virtual returns (bool) {
    return lineageIdOf[implementation] != INVALID_LINEAGE_ID;
  }
  /// @notice Set an implementation to the current implementation
  /// @param implementation implementation to set as current implementation
  /// @param lineageId id of lineage to append to
  function _append(address implementation, uint256 lineageId) internal virtual {
    require(Address.isContract(implementation), "not a contract");
    require(!_has(implementation), "exists");
    require(_lineageExists(lineageId), "invalid lineageId");
    require(_currentOfLineage[lineageId] != INVALID_IMPL, "empty lineage");
    address oldImplementation = _currentOfLineage[lineageId];
    _currentOfLineage[lineageId] = implementation;
    lineageIdOf[implementation] = lineageId;
    _nextImplementationOf[oldImplementation] = implementation;
    emit Added(lineageId, implementation, oldImplementation);
  }
  function _remove(address toRemove, address previous) internal virtual {
    require(toRemove != INVALID_IMPL && previous != INVALID_IMPL, "ZERO");
    require(_nextImplementationOf[previous] == toRemove, "Not prev");
    uint256 lineageId = lineageIdOf[toRemove];
    // need to reset the head pointer to the previous version if we remove the head
    if (toRemove == _currentOfLineage[lineageId]) {
      _currentOfLineage[lineageId] = previous;
    }
    _setUpgradeDataFor(toRemove, ""); // reset upgrade data
    _nextImplementationOf[previous] = _nextImplementationOf[toRemove];
    _nextImplementationOf[toRemove] = INVALID_IMPL;
    lineageIdOf[toRemove] = INVALID_LINEAGE_ID;
    emit Removed(lineageId, toRemove);
  }
  function _lineageExists(uint256 lineageId) internal view returns (bool) {
    return lineageId != INVALID_LINEAGE_ID && lineageId <= currentLineageId;
  }
  // //////// Events //////////////////////////////////////////////////////////////
  event Added(
    uint256 indexed lineageId,
    address indexed newImplementation,
    address indexed oldImplementation
  );
  event Removed(uint256 indexed lineageId, address indexed implementation);
  event UpgradeDataSet(address indexed implementation, bytes data);
}