// File: @openzeppelin/contracts-ethereum-package/contracts/GSN/Context.sol



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;
}

// File: @openzeppelin/contracts-ethereum-package/contracts/Initializable.sol



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;
}

// File: @openzeppelin/contracts-ethereum-package/contracts/access/AccessControl.sol



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;
}

// File: @openzeppelin/contracts-ethereum-package/contracts/introspection/IERC165.sol



pragma solidity ^0.6.0;

/**
 * @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);
}

// File: @openzeppelin/contracts-ethereum-package/contracts/math/Math.sol



pragma solidity ^0.6.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

// File: @openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol



pragma solidity ^0.6.0;

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

        return c;
    }

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

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

        return c;
    }

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

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

        return c;
    }

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

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

// File: @openzeppelin/contracts-ethereum-package/contracts/math/SignedSafeMath.sol



pragma solidity ^0.6.0;

/**
 * @title SignedSafeMath
 * @dev Signed math operations with safety checks that revert on error.
 */
library SignedSafeMath {
    int256 constant private _INT256_MIN = -2**255;

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

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

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

        return c;
    }

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

        int256 c = a / b;

        return c;
    }

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

        return c;
    }

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

        return c;
    }
}

// File: @openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol



pragma solidity ^0.6.0;

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

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

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

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

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

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

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

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

// File: @openzeppelin/contracts-ethereum-package/contracts/token/ERC721/IERC721.sol



pragma solidity ^0.6.2;

import "../../introspection/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;
}

// File: @openzeppelin/contracts-ethereum-package/contracts/utils/Address.sol



pragma solidity ^0.6.2;

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

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

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

// File: @openzeppelin/contracts-ethereum-package/contracts/utils/EnumerableSet.sol



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));
    }
}

// File: @openzeppelin/contracts-ethereum-package/contracts/utils/Pausable.sol



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;
}

// File: @openzeppelin/contracts-ethereum-package/contracts/utils/ReentrancyGuard.sol



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;
}

// File: @openzeppelin/contracts/drafts/IERC20Permit.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;

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

    /**
     * @dev Returns the domain separator used in the encoding of the signature for `permit`, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// File: contracts/external/FixedPoint.sol



// SPDX-License-Identifier: AGPL-3.0-only
// solhint-disable
// Imported from https://github.com/UMAprotocol/protocol/blob/4d1c8cc47a4df5e79f978cb05647a7432e111a3d/packages/core/contracts/common/implementation/FixedPoint.sol
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/SignedSafeMath.sol";

/**
 * @title Library for fixed point arithmetic on uints
 */
library FixedPoint {
  using SafeMath for uint256;
  using SignedSafeMath for int256;

  // Supports 18 decimals. E.g., 1e18 represents "1", 5e17 represents "0.5".
  // For unsigned values:
  //   This can represent a value up to (2^256 - 1)/10^18 = ~10^59. 10^59 will be stored internally as uint256 10^77.
  uint256 private constant FP_SCALING_FACTOR = 10**18;

  // --------------------------------------- UNSIGNED -----------------------------------------------------------------------------
  struct Unsigned {
    uint256 rawValue;
  }

  /**
   * @notice Constructs an `Unsigned` from an unscaled uint, e.g., `b=5` gets stored internally as `5**18`.
   * @param a uint to convert into a FixedPoint.
   * @return the converted FixedPoint.
   */
  function fromUnscaledUint(uint256 a) internal pure returns (Unsigned memory) {
    return Unsigned(a.mul(FP_SCALING_FACTOR));
  }

  /**
   * @notice Whether `a` is equal to `b`.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return True if equal, or False.
   */
  function isEqual(Unsigned memory a, uint256 b) internal pure returns (bool) {
    return a.rawValue == fromUnscaledUint(b).rawValue;
  }

  /**
   * @notice Whether `a` is equal to `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return True if equal, or False.
   */
  function isEqual(Unsigned memory a, Unsigned memory b) internal pure returns (bool) {
    return a.rawValue == b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return True if `a > b`, or False.
   */
  function isGreaterThan(Unsigned memory a, Unsigned memory b) internal pure returns (bool) {
    return a.rawValue > b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than `b`.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return True if `a > b`, or False.
   */
  function isGreaterThan(Unsigned memory a, uint256 b) internal pure returns (bool) {
    return a.rawValue > fromUnscaledUint(b).rawValue;
  }

  /**
   * @notice Whether `a` is greater than `b`.
   * @param a a uint256.
   * @param b a FixedPoint.
   * @return True if `a > b`, or False.
   */
  function isGreaterThan(uint256 a, Unsigned memory b) internal pure returns (bool) {
    return fromUnscaledUint(a).rawValue > b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than or equal to `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return True if `a >= b`, or False.
   */
  function isGreaterThanOrEqual(Unsigned memory a, Unsigned memory b) internal pure returns (bool) {
    return a.rawValue >= b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than or equal to `b`.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return True if `a >= b`, or False.
   */
  function isGreaterThanOrEqual(Unsigned memory a, uint256 b) internal pure returns (bool) {
    return a.rawValue >= fromUnscaledUint(b).rawValue;
  }

  /**
   * @notice Whether `a` is greater than or equal to `b`.
   * @param a a uint256.
   * @param b a FixedPoint.
   * @return True if `a >= b`, or False.
   */
  function isGreaterThanOrEqual(uint256 a, Unsigned memory b) internal pure returns (bool) {
    return fromUnscaledUint(a).rawValue >= b.rawValue;
  }

  /**
   * @notice Whether `a` is less than `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return True if `a < b`, or False.
   */
  function isLessThan(Unsigned memory a, Unsigned memory b) internal pure returns (bool) {
    return a.rawValue < b.rawValue;
  }

  /**
   * @notice Whether `a` is less than `b`.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return True if `a < b`, or False.
   */
  function isLessThan(Unsigned memory a, uint256 b) internal pure returns (bool) {
    return a.rawValue < fromUnscaledUint(b).rawValue;
  }

  /**
   * @notice Whether `a` is less than `b`.
   * @param a a uint256.
   * @param b a FixedPoint.
   * @return True if `a < b`, or False.
   */
  function isLessThan(uint256 a, Unsigned memory b) internal pure returns (bool) {
    return fromUnscaledUint(a).rawValue < b.rawValue;
  }

  /**
   * @notice Whether `a` is less than or equal to `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return True if `a <= b`, or False.
   */
  function isLessThanOrEqual(Unsigned memory a, Unsigned memory b) internal pure returns (bool) {
    return a.rawValue <= b.rawValue;
  }

  /**
   * @notice Whether `a` is less than or equal to `b`.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return True if `a <= b`, or False.
   */
  function isLessThanOrEqual(Unsigned memory a, uint256 b) internal pure returns (bool) {
    return a.rawValue <= fromUnscaledUint(b).rawValue;
  }

  /**
   * @notice Whether `a` is less than or equal to `b`.
   * @param a a uint256.
   * @param b a FixedPoint.
   * @return True if `a <= b`, or False.
   */
  function isLessThanOrEqual(uint256 a, Unsigned memory b) internal pure returns (bool) {
    return fromUnscaledUint(a).rawValue <= b.rawValue;
  }

  /**
   * @notice The minimum of `a` and `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the minimum of `a` and `b`.
   */
  function min(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    return a.rawValue < b.rawValue ? a : b;
  }

  /**
   * @notice The maximum of `a` and `b`.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the maximum of `a` and `b`.
   */
  function max(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    return a.rawValue > b.rawValue ? a : b;
  }

  /**
   * @notice Adds two `Unsigned`s, reverting on overflow.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the sum of `a` and `b`.
   */
  function add(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    return Unsigned(a.rawValue.add(b.rawValue));
  }

  /**
   * @notice Adds an `Unsigned` to an unscaled uint, reverting on overflow.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return the sum of `a` and `b`.
   */
  function add(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory) {
    return add(a, fromUnscaledUint(b));
  }

  /**
   * @notice Subtracts two `Unsigned`s, reverting on overflow.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the difference of `a` and `b`.
   */
  function sub(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    return Unsigned(a.rawValue.sub(b.rawValue));
  }

  /**
   * @notice Subtracts an unscaled uint256 from an `Unsigned`, reverting on overflow.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return the difference of `a` and `b`.
   */
  function sub(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory) {
    return sub(a, fromUnscaledUint(b));
  }

  /**
   * @notice Subtracts an `Unsigned` from an unscaled uint256, reverting on overflow.
   * @param a a uint256.
   * @param b a FixedPoint.
   * @return the difference of `a` and `b`.
   */
  function sub(uint256 a, Unsigned memory b) internal pure returns (Unsigned memory) {
    return sub(fromUnscaledUint(a), b);
  }

  /**
   * @notice Multiplies two `Unsigned`s, reverting on overflow.
   * @dev This will "floor" the product.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the product of `a` and `b`.
   */
  function mul(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    // There are two caveats with this computation:
    // 1. Max output for the represented number is ~10^41, otherwise an intermediate value overflows. 10^41 is
    // stored internally as a uint256 ~10^59.
    // 2. Results that can't be represented exactly are truncated not rounded. E.g., 1.4 * 2e-18 = 2.8e-18, which
    // would round to 3, but this computation produces the result 2.
    // No need to use SafeMath because FP_SCALING_FACTOR != 0.
    return Unsigned(a.rawValue.mul(b.rawValue) / FP_SCALING_FACTOR);
  }

  /**
   * @notice Multiplies an `Unsigned` and an unscaled uint256, reverting on overflow.
   * @dev This will "floor" the product.
   * @param a a FixedPoint.
   * @param b a uint256.
   * @return the product of `a` and `b`.
   */
  function mul(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory) {
    return Unsigned(a.rawValue.mul(b));
  }

  /**
   * @notice Multiplies two `Unsigned`s and "ceil's" the product, reverting on overflow.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the product of `a` and `b`.
   */
  function mulCeil(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    uint256 mulRaw = a.rawValue.mul(b.rawValue);
    uint256 mulFloor = mulRaw / FP_SCALING_FACTOR;
    uint256 mod = mulRaw.mod(FP_SCALING_FACTOR);
    if (mod != 0) {
      return Unsigned(mulFloor.add(1));
    } else {
      return Unsigned(mulFloor);
    }
  }

  /**
   * @notice Multiplies an `Unsigned` and an unscaled uint256 and "ceil's" the product, reverting on overflow.
   * @param a a FixedPoint.
   * @param b a FixedPoint.
   * @return the product of `a` and `b`.
   */
  function mulCeil(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory) {
    // Since b is an int, there is no risk of truncation and we can just mul it normally
    return Unsigned(a.rawValue.mul(b));
  }

  /**
   * @notice Divides one `Unsigned` by an `Unsigned`, reverting on overflow or division by 0.
   * @dev This will "floor" the quotient.
   * @param a a FixedPoint numerator.
   * @param b a FixedPoint denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function div(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    // There are two caveats with this computation:
    // 1. Max value for the number dividend `a` represents is ~10^41, otherwise an intermediate value overflows.
    // 10^41 is stored internally as a uint256 10^59.
    // 2. Results that can't be represented exactly are truncated not rounded. E.g., 2 / 3 = 0.6 repeating, which
    // would round to 0.666666666666666667, but this computation produces the result 0.666666666666666666.
    return Unsigned(a.rawValue.mul(FP_SCALING_FACTOR).div(b.rawValue));
  }

  /**
   * @notice Divides one `Unsigned` by an unscaled uint256, reverting on overflow or division by 0.
   * @dev This will "floor" the quotient.
   * @param a a FixedPoint numerator.
   * @param b a uint256 denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function div(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory) {
    return Unsigned(a.rawValue.div(b));
  }

  /**
   * @notice Divides one unscaled uint256 by an `Unsigned`, reverting on overflow or division by 0.
   * @dev This will "floor" the quotient.
   * @param a a uint256 numerator.
   * @param b a FixedPoint denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function div(uint256 a, Unsigned memory b) internal pure returns (Unsigned memory) {
    return div(fromUnscaledUint(a), b);
  }

  /**
   * @notice Divides one `Unsigned` by an `Unsigned` and "ceil's" the quotient, reverting on overflow or division by 0.
   * @param a a FixedPoint numerator.
   * @param b a FixedPoint denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function divCeil(Unsigned memory a, Unsigned memory b) internal pure returns (Unsigned memory) {
    uint256 aScaled = a.rawValue.mul(FP_SCALING_FACTOR);
    uint256 divFloor = aScaled.div(b.rawValue);
    uint256 mod = aScaled.mod(b.rawValue);
    if (mod != 0) {
      return Unsigned(divFloor.add(1));
    } else {
      return Unsigned(divFloor);
    }
  }

  /**
   * @notice Divides one `Unsigned` by an unscaled uint256 and "ceil's" the quotient, reverting on overflow or division by 0.
   * @param a a FixedPoint numerator.
   * @param b a uint256 denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function divCeil(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory) {
    // Because it is possible that a quotient gets truncated, we can't just call "Unsigned(a.rawValue.div(b))"
    // similarly to mulCeil with a uint256 as the second parameter. Therefore we need to convert b into an Unsigned.
    // This creates the possibility of overflow if b is very large.
    return divCeil(a, fromUnscaledUint(b));
  }

  /**
   * @notice Raises an `Unsigned` to the power of an unscaled uint256, reverting on overflow. E.g., `b=2` squares `a`.
   * @dev This will "floor" the result.
   * @param a a FixedPoint numerator.
   * @param b a uint256 denominator.
   * @return output is `a` to the power of `b`.
   */
  function pow(Unsigned memory a, uint256 b) internal pure returns (Unsigned memory output) {
    output = fromUnscaledUint(1);
    for (uint256 i = 0; i < b; i = i.add(1)) {
      output = mul(output, a);
    }
  }

  // ------------------------------------------------- SIGNED -------------------------------------------------------------
  // Supports 18 decimals. E.g., 1e18 represents "1", 5e17 represents "0.5".
  // For signed values:
  //   This can represent a value up (or down) to +-(2^255 - 1)/10^18 = ~10^58. 10^58 will be stored internally as int256 10^76.
  int256 private constant SFP_SCALING_FACTOR = 10**18;

  struct Signed {
    int256 rawValue;
  }

  function fromSigned(Signed memory a) internal pure returns (Unsigned memory) {
    require(a.rawValue >= 0, "Negative value provided");
    return Unsigned(uint256(a.rawValue));
  }

  function fromUnsigned(Unsigned memory a) internal pure returns (Signed memory) {
    require(a.rawValue <= uint256(type(int256).max), "Unsigned too large");
    return Signed(int256(a.rawValue));
  }

  /**
   * @notice Constructs a `Signed` from an unscaled int, e.g., `b=5` gets stored internally as `5**18`.
   * @param a int to convert into a FixedPoint.Signed.
   * @return the converted FixedPoint.Signed.
   */
  function fromUnscaledInt(int256 a) internal pure returns (Signed memory) {
    return Signed(a.mul(SFP_SCALING_FACTOR));
  }

  /**
   * @notice Whether `a` is equal to `b`.
   * @param a a FixedPoint.Signed.
   * @param b a int256.
   * @return True if equal, or False.
   */
  function isEqual(Signed memory a, int256 b) internal pure returns (bool) {
    return a.rawValue == fromUnscaledInt(b).rawValue;
  }

  /**
   * @notice Whether `a` is equal to `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return True if equal, or False.
   */
  function isEqual(Signed memory a, Signed memory b) internal pure returns (bool) {
    return a.rawValue == b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return True if `a > b`, or False.
   */
  function isGreaterThan(Signed memory a, Signed memory b) internal pure returns (bool) {
    return a.rawValue > b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than `b`.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return True if `a > b`, or False.
   */
  function isGreaterThan(Signed memory a, int256 b) internal pure returns (bool) {
    return a.rawValue > fromUnscaledInt(b).rawValue;
  }

  /**
   * @notice Whether `a` is greater than `b`.
   * @param a an int256.
   * @param b a FixedPoint.Signed.
   * @return True if `a > b`, or False.
   */
  function isGreaterThan(int256 a, Signed memory b) internal pure returns (bool) {
    return fromUnscaledInt(a).rawValue > b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than or equal to `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return True if `a >= b`, or False.
   */
  function isGreaterThanOrEqual(Signed memory a, Signed memory b) internal pure returns (bool) {
    return a.rawValue >= b.rawValue;
  }

  /**
   * @notice Whether `a` is greater than or equal to `b`.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return True if `a >= b`, or False.
   */
  function isGreaterThanOrEqual(Signed memory a, int256 b) internal pure returns (bool) {
    return a.rawValue >= fromUnscaledInt(b).rawValue;
  }

  /**
   * @notice Whether `a` is greater than or equal to `b`.
   * @param a an int256.
   * @param b a FixedPoint.Signed.
   * @return True if `a >= b`, or False.
   */
  function isGreaterThanOrEqual(int256 a, Signed memory b) internal pure returns (bool) {
    return fromUnscaledInt(a).rawValue >= b.rawValue;
  }

  /**
   * @notice Whether `a` is less than `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return True if `a < b`, or False.
   */
  function isLessThan(Signed memory a, Signed memory b) internal pure returns (bool) {
    return a.rawValue < b.rawValue;
  }

  /**
   * @notice Whether `a` is less than `b`.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return True if `a < b`, or False.
   */
  function isLessThan(Signed memory a, int256 b) internal pure returns (bool) {
    return a.rawValue < fromUnscaledInt(b).rawValue;
  }

  /**
   * @notice Whether `a` is less than `b`.
   * @param a an int256.
   * @param b a FixedPoint.Signed.
   * @return True if `a < b`, or False.
   */
  function isLessThan(int256 a, Signed memory b) internal pure returns (bool) {
    return fromUnscaledInt(a).rawValue < b.rawValue;
  }

  /**
   * @notice Whether `a` is less than or equal to `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return True if `a <= b`, or False.
   */
  function isLessThanOrEqual(Signed memory a, Signed memory b) internal pure returns (bool) {
    return a.rawValue <= b.rawValue;
  }

  /**
   * @notice Whether `a` is less than or equal to `b`.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return True if `a <= b`, or False.
   */
  function isLessThanOrEqual(Signed memory a, int256 b) internal pure returns (bool) {
    return a.rawValue <= fromUnscaledInt(b).rawValue;
  }

  /**
   * @notice Whether `a` is less than or equal to `b`.
   * @param a an int256.
   * @param b a FixedPoint.Signed.
   * @return True if `a <= b`, or False.
   */
  function isLessThanOrEqual(int256 a, Signed memory b) internal pure returns (bool) {
    return fromUnscaledInt(a).rawValue <= b.rawValue;
  }

  /**
   * @notice The minimum of `a` and `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the minimum of `a` and `b`.
   */
  function min(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    return a.rawValue < b.rawValue ? a : b;
  }

  /**
   * @notice The maximum of `a` and `b`.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the maximum of `a` and `b`.
   */
  function max(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    return a.rawValue > b.rawValue ? a : b;
  }

  /**
   * @notice Adds two `Signed`s, reverting on overflow.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the sum of `a` and `b`.
   */
  function add(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    return Signed(a.rawValue.add(b.rawValue));
  }

  /**
   * @notice Adds an `Signed` to an unscaled int, reverting on overflow.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return the sum of `a` and `b`.
   */
  function add(Signed memory a, int256 b) internal pure returns (Signed memory) {
    return add(a, fromUnscaledInt(b));
  }

  /**
   * @notice Subtracts two `Signed`s, reverting on overflow.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the difference of `a` and `b`.
   */
  function sub(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    return Signed(a.rawValue.sub(b.rawValue));
  }

  /**
   * @notice Subtracts an unscaled int256 from an `Signed`, reverting on overflow.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return the difference of `a` and `b`.
   */
  function sub(Signed memory a, int256 b) internal pure returns (Signed memory) {
    return sub(a, fromUnscaledInt(b));
  }

  /**
   * @notice Subtracts an `Signed` from an unscaled int256, reverting on overflow.
   * @param a an int256.
   * @param b a FixedPoint.Signed.
   * @return the difference of `a` and `b`.
   */
  function sub(int256 a, Signed memory b) internal pure returns (Signed memory) {
    return sub(fromUnscaledInt(a), b);
  }

  /**
   * @notice Multiplies two `Signed`s, reverting on overflow.
   * @dev This will "floor" the product.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the product of `a` and `b`.
   */
  function mul(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    // There are two caveats with this computation:
    // 1. Max output for the represented number is ~10^41, otherwise an intermediate value overflows. 10^41 is
    // stored internally as an int256 ~10^59.
    // 2. Results that can't be represented exactly are truncated not rounded. E.g., 1.4 * 2e-18 = 2.8e-18, which
    // would round to 3, but this computation produces the result 2.
    // No need to use SafeMath because SFP_SCALING_FACTOR != 0.
    return Signed(a.rawValue.mul(b.rawValue) / SFP_SCALING_FACTOR);
  }

  /**
   * @notice Multiplies an `Signed` and an unscaled int256, reverting on overflow.
   * @dev This will "floor" the product.
   * @param a a FixedPoint.Signed.
   * @param b an int256.
   * @return the product of `a` and `b`.
   */
  function mul(Signed memory a, int256 b) internal pure returns (Signed memory) {
    return Signed(a.rawValue.mul(b));
  }

  /**
   * @notice Multiplies two `Signed`s and "ceil's" the product, reverting on overflow.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the product of `a` and `b`.
   */
  function mulAwayFromZero(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    int256 mulRaw = a.rawValue.mul(b.rawValue);
    int256 mulTowardsZero = mulRaw / SFP_SCALING_FACTOR;
    // Manual mod because SignedSafeMath doesn't support it.
    int256 mod = mulRaw % SFP_SCALING_FACTOR;
    if (mod != 0) {
      bool isResultPositive = isLessThan(a, 0) == isLessThan(b, 0);
      int256 valueToAdd = isResultPositive ? int256(1) : int256(-1);
      return Signed(mulTowardsZero.add(valueToAdd));
    } else {
      return Signed(mulTowardsZero);
    }
  }

  /**
   * @notice Multiplies an `Signed` and an unscaled int256 and "ceil's" the product, reverting on overflow.
   * @param a a FixedPoint.Signed.
   * @param b a FixedPoint.Signed.
   * @return the product of `a` and `b`.
   */
  function mulAwayFromZero(Signed memory a, int256 b) internal pure returns (Signed memory) {
    // Since b is an int, there is no risk of truncation and we can just mul it normally
    return Signed(a.rawValue.mul(b));
  }

  /**
   * @notice Divides one `Signed` by an `Signed`, reverting on overflow or division by 0.
   * @dev This will "floor" the quotient.
   * @param a a FixedPoint numerator.
   * @param b a FixedPoint denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function div(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    // There are two caveats with this computation:
    // 1. Max value for the number dividend `a` represents is ~10^41, otherwise an intermediate value overflows.
    // 10^41 is stored internally as an int256 10^59.
    // 2. Results that can't be represented exactly are truncated not rounded. E.g., 2 / 3 = 0.6 repeating, which
    // would round to 0.666666666666666667, but this computation produces the result 0.666666666666666666.
    return Signed(a.rawValue.mul(SFP_SCALING_FACTOR).div(b.rawValue));
  }

  /**
   * @notice Divides one `Signed` by an unscaled int256, reverting on overflow or division by 0.
   * @dev This will "floor" the quotient.
   * @param a a FixedPoint numerator.
   * @param b an int256 denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function div(Signed memory a, int256 b) internal pure returns (Signed memory) {
    return Signed(a.rawValue.div(b));
  }

  /**
   * @notice Divides one unscaled int256 by an `Signed`, reverting on overflow or division by 0.
   * @dev This will "floor" the quotient.
   * @param a an int256 numerator.
   * @param b a FixedPoint denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function div(int256 a, Signed memory b) internal pure returns (Signed memory) {
    return div(fromUnscaledInt(a), b);
  }

  /**
   * @notice Divides one `Signed` by an `Signed` and "ceil's" the quotient, reverting on overflow or division by 0.
   * @param a a FixedPoint numerator.
   * @param b a FixedPoint denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function divAwayFromZero(Signed memory a, Signed memory b) internal pure returns (Signed memory) {
    int256 aScaled = a.rawValue.mul(SFP_SCALING_FACTOR);
    int256 divTowardsZero = aScaled.div(b.rawValue);
    // Manual mod because SignedSafeMath doesn't support it.
    int256 mod = aScaled % b.rawValue;
    if (mod != 0) {
      bool isResultPositive = isLessThan(a, 0) == isLessThan(b, 0);
      int256 valueToAdd = isResultPositive ? int256(1) : int256(-1);
      return Signed(divTowardsZero.add(valueToAdd));
    } else {
      return Signed(divTowardsZero);
    }
  }

  /**
   * @notice Divides one `Signed` by an unscaled int256 and "ceil's" the quotient, reverting on overflow or division by 0.
   * @param a a FixedPoint numerator.
   * @param b an int256 denominator.
   * @return the quotient of `a` divided by `b`.
   */
  function divAwayFromZero(Signed memory a, int256 b) internal pure returns (Signed memory) {
    // Because it is possible that a quotient gets truncated, we can't just call "Signed(a.rawValue.div(b))"
    // similarly to mulCeil with an int256 as the second parameter. Therefore we need to convert b into an Signed.
    // This creates the possibility of overflow if b is very large.
    return divAwayFromZero(a, fromUnscaledInt(b));
  }

  /**
   * @notice Raises an `Signed` to the power of an unscaled uint256, reverting on overflow. E.g., `b=2` squares `a`.
   * @dev This will "floor" the result.
   * @param a a FixedPoint.Signed.
   * @param b a uint256 (negative exponents are not allowed).
   * @return output is `a` to the power of `b`.
   */
  function pow(Signed memory a, uint256 b) internal pure returns (Signed memory output) {
    output = fromUnscaledInt(1);
    for (uint256 i = 0; i < b; i = i.add(1)) {
      output = mul(output, a);
    }
  }
}

// File: contracts/interfaces/IBackerRewards.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

interface IBackerRewards {
  function allocateRewards(uint256 _interestPaymentAmount) external;

  function onTranchedPoolDrawdown(uint256 sliceIndex) external;

  function setPoolTokenAccRewardsPerPrincipalDollarAtMint(address poolAddress, uint256 tokenId) external;
}

// File: contracts/interfaces/ICUSDCContract.sol



// 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);
}

// File: contracts/interfaces/ICreditDesk.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

abstract contract ICreditDesk {
  uint256 public totalWritedowns;
  uint256 public totalLoansOutstanding;

  function setUnderwriterGovernanceLimit(address underwriterAddress, uint256 limit) external virtual;

  function drawdown(address creditLineAddress, uint256 amount) external virtual;

  function pay(address creditLineAddress, uint256 amount) external virtual;

  function assessCreditLine(address creditLineAddress) external virtual;

  function applyPayment(address creditLineAddress, uint256 amount) external virtual;

  function getNextPaymentAmount(address creditLineAddress, uint256 asOfBLock) external view virtual returns (uint256);
}

// File: contracts/interfaces/ICreditLine.sol



// 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);
}

// File: contracts/interfaces/ICurveLP.sol



// 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 token() external view returns (address);

  function get_virtual_price() external view returns (uint256);

  function calc_token_amount(uint256[2] calldata amounts) external view returns (uint256);

  function add_liquidity(
    uint256[2] calldata amounts,
    uint256 min_mint_amount,
    bool use_eth,
    address receiver
  ) external returns (uint256);

  function balances(uint256 arg0) external view returns (uint256);
}

// File: contracts/interfaces/IERC20withDec.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "@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);
}

// File: contracts/interfaces/IFidu.sol



// 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;
}

// File: contracts/interfaces/IGo.sol



// 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);

  function goSeniorPool(address account) public view virtual returns (bool);

  function updateGoldfinchConfig() external virtual;
}

// File: contracts/interfaces/IGoldfinchConfig.sol



// 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);
}

// File: contracts/interfaces/IGoldfinchFactory.sol



// 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);

  function updateGoldfinchConfig() external;
}

// File: contracts/interfaces/IPool.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

abstract contract IPool {
  uint256 public sharePrice;

  function deposit(uint256 amount) external virtual;

  function withdraw(uint256 usdcAmount) external virtual;

  function withdrawInFidu(uint256 fiduAmount) external virtual;

  function collectInterestAndPrincipal(
    address from,
    uint256 interest,
    uint256 principal
  ) public virtual;

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

  function drawdown(address to, uint256 amount) public virtual returns (bool);

  function sweepToCompound() public virtual;

  function sweepFromCompound() public virtual;

  function distributeLosses(address creditlineAddress, int256 writedownDelta) external virtual;

  function assets() public view virtual returns (uint256);
}

// File: contracts/interfaces/IPoolTokens.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts-ethereum-package/contracts/token/ERC721/IERC721.sol";

interface IPoolTokens is IERC721 {
  event TokenMinted(
    address indexed owner,
    address indexed pool,
    uint256 indexed tokenId,
    uint256 amount,
    uint256 tranche
  );

  event TokenRedeemed(
    address indexed owner,
    address indexed pool,
    uint256 indexed tokenId,
    uint256 principalRedeemed,
    uint256 interestRedeemed,
    uint256 tranche
  );
  event TokenBurned(address indexed owner, address indexed pool, uint256 indexed tokenId);

  struct TokenInfo {
    address pool;
    uint256 tranche;
    uint256 principalAmount;
    uint256 principalRedeemed;
    uint256 interestRedeemed;
  }

  struct MintParams {
    uint256 principalAmount;
    uint256 tranche;
  }

  function mint(MintParams calldata params, address to) external returns (uint256);

  function redeem(
    uint256 tokenId,
    uint256 principalRedeemed,
    uint256 interestRedeemed
  ) external;

  function withdrawPrincipal(uint256 tokenId, uint256 principalAmount) external;

  function burn(uint256 tokenId) external;

  function onPoolCreated(address newPool) external;

  function getTokenInfo(uint256 tokenId) external view returns (TokenInfo memory);

  function validPool(address sender) external view returns (bool);

  function isApprovedOrOwner(address spender, uint256 tokenId) external view returns (bool);
}

// File: contracts/interfaces/ISeniorPool.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./ITranchedPool.sol";

abstract contract ISeniorPool {
  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);

  function withdraw(uint256 usdcAmount) external virtual returns (uint256 amount);

  function withdrawInFidu(uint256 fiduAmount) external virtual returns (uint256 amount);

  function sweepToCompound() public virtual;

  function sweepFromCompound() public virtual;

  function invest(ITranchedPool pool) public virtual;

  function estimateInvestment(ITranchedPool pool) public view virtual returns (uint256);

  function redeem(uint256 tokenId) public virtual;

  function writedown(uint256 tokenId) public virtual;

  function calculateWritedown(uint256 tokenId) public view virtual returns (uint256 writedownAmount);

  function assets() public view virtual returns (uint256);

  function getNumShares(uint256 amount) public view virtual returns (uint256);
}

// File: contracts/interfaces/ISeniorPoolStrategy.sol



// 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);

  function invest(ISeniorPool seniorPool, ITranchedPool pool) public view virtual returns (uint256 amount);

  function estimateInvestment(ISeniorPool seniorPool, ITranchedPool pool) public view virtual returns (uint256);
}

// File: contracts/interfaces/IStakingRewards.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

interface IStakingRewards {
  function unstake(uint256 tokenId, uint256 amount) external;

  function addToStake(uint256 tokenId, uint256 amount) external;

  function stakedBalanceOf(uint256 tokenId) external view returns (uint256);

  function depositToCurveAndStakeFrom(
    address nftRecipient,
    uint256 fiduAmount,
    uint256 usdcAmount
  ) external;

  function kick(uint256 tokenId) external;

  function accumulatedRewardsPerToken() external view returns (uint256);

  function lastUpdateTime() external view returns (uint256);
}

// File: contracts/interfaces/ITranchedPool.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./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;
  }

  struct SliceInfo {
    uint256 reserveFeePercent;
    uint256 interestAccrued;
    uint256 principalAccrued;
  }

  struct ApplyResult {
    uint256 interestRemaining;
    uint256 principalRemaining;
    uint256 reserveDeduction;
    uint256 oldInterestSharePrice;
    uint256 oldPrincipalSharePrice;
  }

  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 getTranche(uint256 tranche) external view virtual returns (TrancheInfo memory);

  function pay(uint256 amount) external virtual;

  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);
}

// File: contracts/interfaces/IV2CreditLine.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./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;

  function updateGoldfinchConfig() external virtual;
}

// File: contracts/protocol/core/Accountant.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./CreditLine.sol";
import "../../interfaces/ICreditLine.sol";
import "../../external/FixedPoint.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/Math.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";

/**
 * @title The Accountant
 * @notice Library for handling key financial calculations, such as interest and principal accrual.
 * @author Goldfinch
 */

library Accountant {
  using SafeMath for uint256;
  using FixedPoint for FixedPoint.Signed;
  using FixedPoint for FixedPoint.Unsigned;
  using FixedPoint for int256;
  using FixedPoint for uint256;

  // Scaling factor used by FixedPoint.sol. We need this to convert the fixed point raw values back to unscaled
  uint256 public constant FP_SCALING_FACTOR = 10**18;
  uint256 public constant INTEREST_DECIMALS = 1e18;
  uint256 public constant SECONDS_PER_DAY = 60 * 60 * 24;
  uint256 public constant SECONDS_PER_YEAR = (SECONDS_PER_DAY * 365);

  struct PaymentAllocation {
    uint256 interestPayment;
    uint256 principalPayment;
    uint256 additionalBalancePayment;
  }

  function calculateInterestAndPrincipalAccrued(
    CreditLine cl,
    uint256 timestamp,
    uint256 lateFeeGracePeriod
  ) public view returns (uint256, uint256) {
    uint256 balance = cl.balance(); // gas optimization
    uint256 interestAccrued = calculateInterestAccrued(cl, balance, timestamp, lateFeeGracePeriod);
    uint256 principalAccrued = calculatePrincipalAccrued(cl, balance, timestamp);
    return (interestAccrued, principalAccrued);
  }

  function calculateInterestAndPrincipalAccruedOverPeriod(
    CreditLine cl,
    uint256 balance,
    uint256 startTime,
    uint256 endTime,
    uint256 lateFeeGracePeriod
  ) public view returns (uint256, uint256) {
    uint256 interestAccrued = calculateInterestAccruedOverPeriod(cl, balance, startTime, endTime, lateFeeGracePeriod);
    uint256 principalAccrued = calculatePrincipalAccrued(cl, balance, endTime);
    return (interestAccrued, principalAccrued);
  }

  function calculatePrincipalAccrued(
    ICreditLine cl,
    uint256 balance,
    uint256 timestamp
  ) public view returns (uint256) {
    // If we've already accrued principal as of the term end time, then don't accrue more principal
    uint256 termEndTime = cl.termEndTime();
    if (cl.interestAccruedAsOf() >= termEndTime) {
      return 0;
    }
    if (timestamp >= termEndTime) {
      return balance;
    } else {
      return 0;
    }
  }

  function calculateWritedownFor(
    ICreditLine cl,
    uint256 timestamp,
    uint256 gracePeriodInDays,
    uint256 maxDaysLate
  ) public view returns (uint256, uint256) {
    return calculateWritedownForPrincipal(cl, cl.balance(), timestamp, gracePeriodInDays, maxDaysLate);
  }

  function calculateWritedownForPrincipal(
    ICreditLine cl,
    uint256 principal,
    uint256 timestamp,
    uint256 gracePeriodInDays,
    uint256 maxDaysLate
  ) public view returns (uint256, uint256) {
    FixedPoint.Unsigned memory amountOwedPerDay = calculateAmountOwedForOneDay(cl);
    if (amountOwedPerDay.isEqual(0)) {
      return (0, 0);
    }
    FixedPoint.Unsigned memory fpGracePeriod = FixedPoint.fromUnscaledUint(gracePeriodInDays);
    FixedPoint.Unsigned memory daysLate;

    // Excel math: =min(1,max(0,periods_late_in_days-graceperiod_in_days)/MAX_ALLOWED_DAYS_LATE) grace_period = 30,
    // Before the term end date, we use the interestOwed to calculate the periods late. However, after the loan term
    // has ended, since the interest is a much smaller fraction of the principal, we cannot reliably use interest to
    // calculate the periods later.
    uint256 totalOwed = cl.interestOwed().add(cl.principalOwed());
    daysLate = FixedPoint.fromUnscaledUint(totalOwed).div(amountOwedPerDay);
    if (timestamp > cl.termEndTime()) {
      uint256 secondsLate = timestamp.sub(cl.termEndTime());
      daysLate = daysLate.add(FixedPoint.fromUnscaledUint(secondsLate).div(SECONDS_PER_DAY));
    }

    FixedPoint.Unsigned memory maxLate = FixedPoint.fromUnscaledUint(maxDaysLate);
    FixedPoint.Unsigned memory writedownPercent;
    if (daysLate.isLessThanOrEqual(fpGracePeriod)) {
      // Within the grace period, we don't have to write down, so assume 0%
      writedownPercent = FixedPoint.fromUnscaledUint(0);
    } else {
      writedownPercent = FixedPoint.min(FixedPoint.fromUnscaledUint(1), (daysLate.sub(fpGracePeriod)).div(maxLate));
    }

    FixedPoint.Unsigned memory writedownAmount = writedownPercent.mul(principal).div(FP_SCALING_FACTOR);
    // This will return a number between 0-100 representing the write down percent with no decimals
    uint256 unscaledWritedownPercent = writedownPercent.mul(100).div(FP_SCALING_FACTOR).rawValue;
    return (unscaledWritedownPercent, writedownAmount.rawValue);
  }

  function calculateAmountOwedForOneDay(ICreditLine cl) public view returns (FixedPoint.Unsigned memory interestOwed) {
    // Determine theoretical interestOwed for one full day
    uint256 totalInterestPerYear = cl.balance().mul(cl.interestApr()).div(INTEREST_DECIMALS);
    interestOwed = FixedPoint.fromUnscaledUint(totalInterestPerYear).div(365);
    return interestOwed;
  }

  function calculateInterestAccrued(
    CreditLine cl,
    uint256 balance,
    uint256 timestamp,
    uint256 lateFeeGracePeriodInDays
  ) public view returns (uint256) {
    // We use Math.min here to prevent integer overflow (ie. go negative) when calculating
    // numSecondsElapsed. Typically this shouldn't be possible, because
    // the interestAccruedAsOf couldn't be *after* the current timestamp. However, when assessing
    // we allow this function to be called with a past timestamp, which raises the possibility
    // of overflow.
    // This use of min should not generate incorrect interest calculations, since
    // this function's purpose is just to normalize balances, and handing in a past timestamp
    // will necessarily return zero interest accrued (because zero elapsed time), which is correct.
    uint256 startTime = Math.min(timestamp, cl.interestAccruedAsOf());
    return calculateInterestAccruedOverPeriod(cl, balance, startTime, timestamp, lateFeeGracePeriodInDays);
  }

  function calculateInterestAccruedOverPeriod(
    CreditLine cl,
    uint256 balance,
    uint256 startTime,
    uint256 endTime,
    uint256 lateFeeGracePeriodInDays
  ) public view returns (uint256 interestOwed) {
    uint256 secondsElapsed = endTime.sub(startTime);
    uint256 totalInterestPerYear = balance.mul(cl.interestApr()).div(INTEREST_DECIMALS);
    interestOwed = totalInterestPerYear.mul(secondsElapsed).div(SECONDS_PER_YEAR);
    if (lateFeeApplicable(cl, endTime, lateFeeGracePeriodInDays)) {
      uint256 lateFeeInterestPerYear = balance.mul(cl.lateFeeApr()).div(INTEREST_DECIMALS);
      uint256 additionalLateFeeInterest = lateFeeInterestPerYear.mul(secondsElapsed).div(SECONDS_PER_YEAR);
      interestOwed = interestOwed.add(additionalLateFeeInterest);
    }

    return interestOwed;
  }

  function lateFeeApplicable(
    CreditLine cl,
    uint256 timestamp,
    uint256 gracePeriodInDays
  ) public view returns (bool) {
    uint256 secondsLate = timestamp.sub(cl.lastFullPaymentTime());
    return cl.lateFeeApr() > 0 && secondsLate > gracePeriodInDays.mul(SECONDS_PER_DAY);
  }

  function allocatePayment(
    uint256 paymentAmount,
    uint256 balance,
    uint256 interestOwed,
    uint256 principalOwed
  ) public pure returns (PaymentAllocation memory) {
    uint256 paymentRemaining = paymentAmount;
    uint256 interestPayment = Math.min(interestOwed, paymentRemaining);
    paymentRemaining = paymentRemaining.sub(interestPayment);

    uint256 principalPayment = Math.min(principalOwed, paymentRemaining);
    paymentRemaining = paymentRemaining.sub(principalPayment);

    uint256 balanceRemaining = balance.sub(principalPayment);
    uint256 additionalBalancePayment = Math.min(paymentRemaining, balanceRemaining);

    return
      PaymentAllocation({
        interestPayment: interestPayment,
        principalPayment: principalPayment,
        additionalBalancePayment: additionalBalancePayment
      });
  }
}

// File: contracts/protocol/core/BaseUpgradeablePausable.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts-ethereum-package/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/Initializable.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
import "./PauserPausable.sol";

/**
 * @title BaseUpgradeablePausable contract
 * @notice This is our Base contract that most other contracts inherit from. It includes many standard
 *  useful abilities like ugpradeability, 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");
    _;
  }
}

// File: contracts/protocol/core/ConfigHelper.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./GoldfinchConfig.sol";
import "../../interfaces/IPool.sol";
import "../../interfaces/IFidu.sol";
import "../../interfaces/ISeniorPool.sol";
import "../../interfaces/ISeniorPoolStrategy.sol";
import "../../interfaces/ICreditDesk.sol";
import "../../interfaces/IERC20withDec.sol";
import "../../interfaces/ICUSDCContract.sol";
import "../../interfaces/IPoolTokens.sol";
import "../../interfaces/IBackerRewards.sol";
import "../../interfaces/IGoldfinchFactory.sol";
import "../../interfaces/IGo.sol";
import "../../interfaces/IStakingRewards.sol";
import "../../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 getPool(GoldfinchConfig config) internal view returns (IPool) {
    return IPool(poolAddress(config));
  }

  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 getCreditDesk(GoldfinchConfig config) internal view returns (ICreditDesk) {
    return ICreditDesk(creditDeskAddress(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 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));
  }

  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 poolAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.Pool));
  }

  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 creditDeskAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.CreditDesk));
  }

  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 migratedTranchedPoolAddress(GoldfinchConfig config) internal view returns (address) {
    return config.getAddress(uint256(ConfigOptions.Addresses.MigratedTranchedPoolImplementation));
  }

  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));
  }
}

// File: contracts/protocol/core/ConfigOptions.sol



// 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,
    TotalFundsLimit,
    MaxUnderwriterLimit,
    ReserveDenominator,
    WithdrawFeeDenominator,
    LatenessGracePeriodInDays,
    LatenessMaxDays,
    DrawdownPeriodInSeconds,
    TransferRestrictionPeriodInDays,
    LeverageRatio
  }
  enum Addresses {
    Pool,
    CreditLineImplementation,
    GoldfinchFactory,
    CreditDesk,
    Fidu,
    USDC,
    TreasuryReserve,
    ProtocolAdmin,
    OneInch,
    TrustedForwarder,
    CUSDCContract,
    GoldfinchConfig,
    PoolTokens,
    TranchedPoolImplementation,
    SeniorPool,
    SeniorPoolStrategy,
    MigratedTranchedPoolImplementation,
    BorrowerImplementation,
    GFI,
    Go,
    BackerRewards,
    StakingRewards,
    FiduUSDCCurveLP
  }
}

// File: contracts/protocol/core/CreditLine.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./GoldfinchConfig.sol";
import "./ConfigHelper.sol";
import "./BaseUpgradeablePausable.sol";
import "./Accountant.sol";
import "../../interfaces/IERC20withDec.sol";
import "../../interfaces/ICreditLine.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts-ethereum-package/contracts/math/Math.sol";

/**
 * @title CreditLine
 * @notice A contract that represents the agreement between Backers and
 *  a Borrower. Includes the terms of the loan, as well as the current accounting state, such as interest owed.
 *  A CreditLine belongs to a TranchedPool, and is fully controlled by that TranchedPool. It does not
 *  operate in any standalone capacity. It should generally be considered internal to the TranchedPool.
 * @author Goldfinch
 */

// solhint-disable-next-line max-states-count
contract CreditLine is BaseUpgradeablePausable, ICreditLine {
  uint256 public constant SECONDS_PER_DAY = 60 * 60 * 24;

  event GoldfinchConfigUpdated(address indexed who, address configAddress);

  // Credit line terms
  address public override borrower;
  uint256 public currentLimit;
  uint256 public override maxLimit;
  uint256 public override interestApr;
  uint256 public override paymentPeriodInDays;
  uint256 public override termInDays;
  uint256 public override principalGracePeriodInDays;
  uint256 public override lateFeeApr;

  // Accounting variables
  uint256 public override balance;
  uint256 public override interestOwed;
  uint256 public override principalOwed;
  uint256 public override termEndTime;
  uint256 public override nextDueTime;
  uint256 public override interestAccruedAsOf;
  uint256 public override lastFullPaymentTime;
  uint256 public totalInterestAccrued;

  GoldfinchConfig public config;
  using ConfigHelper for GoldfinchConfig;

  function initialize(
    address _config,
    address owner,
    address _borrower,
    uint256 _maxLimit,
    uint256 _interestApr,
    uint256 _paymentPeriodInDays,
    uint256 _termInDays,
    uint256 _lateFeeApr,
    uint256 _principalGracePeriodInDays
  ) public initializer {
    require(_config != address(0) && owner != address(0) && _borrower != address(0), "Zero address passed in");
    __BaseUpgradeablePausable__init(owner);
    config = GoldfinchConfig(_config);
    borrower = _borrower;
    maxLimit = _maxLimit;
    interestApr = _interestApr;
    paymentPeriodInDays = _paymentPeriodInDays;
    termInDays = _termInDays;
    lateFeeApr = _lateFeeApr;
    principalGracePeriodInDays = _principalGracePeriodInDays;
    interestAccruedAsOf = block.timestamp;

    // Unlock owner, which is a TranchedPool, for infinite amount
    bool success = config.getUSDC().approve(owner, uint256(-1));
    require(success, "Failed to approve USDC");
  }

  function limit() external view override returns (uint256) {
    return currentLimit;
  }

  /**
   * @notice Updates the internal accounting to track a drawdown as of current block timestamp.
   * Does not move any money
   * @param amount The amount in USDC that has been drawndown
   */
  function drawdown(uint256 amount) external onlyAdmin {
    require(amount.add(balance) <= currentLimit, "Cannot drawdown more than the limit");
    require(amount > 0, "Invalid drawdown amount");
    uint256 timestamp = currentTime();

    if (balance == 0) {
      setInterestAccruedAsOf(timestamp);
      setLastFullPaymentTime(timestamp);
      setTotalInterestAccrued(0);
      setTermEndTime(timestamp.add(SECONDS_PER_DAY.mul(termInDays)));
    }

    (uint256 _interestOwed, uint256 _principalOwed) = _updateAndGetInterestAndPrincipalOwedAsOf(timestamp);
    balance = balance.add(amount);

    updateCreditLineAccounting(balance, _interestOwed, _principalOwed);
    require(!_isLate(timestamp), "Cannot drawdown when payments are past due");
  }

  /**
   * @notice Migrates to a new goldfinch config address
   */
  function updateGoldfinchConfig() external onlyAdmin {
    config = GoldfinchConfig(config.configAddress());
    emit GoldfinchConfigUpdated(msg.sender, address(config));
  }

  function setLateFeeApr(uint256 newLateFeeApr) external onlyAdmin {
    lateFeeApr = newLateFeeApr;
  }

  function setLimit(uint256 newAmount) external onlyAdmin {
    require(newAmount <= maxLimit, "Cannot be more than the max limit");
    currentLimit = newAmount;
  }

  function setMaxLimit(uint256 newAmount) external onlyAdmin {
    maxLimit = newAmount;
  }

  function termStartTime() external view returns (uint256) {
    return _termStartTime();
  }

  function isLate() external view override returns (bool) {
    return _isLate(block.timestamp);
  }

  function withinPrincipalGracePeriod() external view override returns (bool) {
    if (termEndTime == 0) {
      // Loan hasn't started yet
      return true;
    }
    return block.timestamp < _termStartTime().add(principalGracePeriodInDays.mul(SECONDS_PER_DAY));
  }

  function setTermEndTime(uint256 newTermEndTime) public onlyAdmin {
    termEndTime = newTermEndTime;
  }

  function setNextDueTime(uint256 newNextDueTime) public onlyAdmin {
    nextDueTime = newNextDueTime;
  }

  function setBalance(uint256 newBalance) public onlyAdmin {
    balance = newBalance;
  }

  function setTotalInterestAccrued(uint256 _totalInterestAccrued) public onlyAdmin {
    totalInterestAccrued = _totalInterestAccrued;
  }

  function setInterestOwed(uint256 newInterestOwed) public onlyAdmin {
    interestOwed = newInterestOwed;
  }

  function setPrincipalOwed(uint256 newPrincipalOwed) public onlyAdmin {
    principalOwed = newPrincipalOwed;
  }

  function setInterestAccruedAsOf(uint256 newInterestAccruedAsOf) public onlyAdmin {
    interestAccruedAsOf = newInterestAccruedAsOf;
  }

  function setLastFullPaymentTime(uint256 newLastFullPaymentTime) public onlyAdmin {
    lastFullPaymentTime = newLastFullPaymentTime;
  }

  /**
   * @notice Triggers an assessment of the creditline. Any USDC balance available in the creditline is applied
   * towards the interest and principal.
   * @return Any amount remaining after applying payments towards the interest and principal
   * @return Amount applied towards interest
   * @return Amount applied towards principal
   */
  function assess()
    public
    onlyAdmin
    returns (
      uint256,
      uint256,
      uint256
    )
  {
    // Do not assess until a full period has elapsed or past due
    require(balance > 0, "Must have balance to assess credit line");

    // Don't assess credit lines early!
    if (currentTime() < nextDueTime && !_isLate(currentTime())) {
      return (0, 0, 0);
    }
    uint256 timeToAssess = calculateNextDueTime();
    setNextDueTime(timeToAssess);

    // We always want to assess for the most recently *past* nextDueTime.
    // So if the recalculation above sets the nextDueTime into the future,
    // then ensure we pass in the one just before this.
    if (timeToAssess > currentTime()) {
      uint256 secondsPerPeriod = paymentPeriodInDays.mul(SECONDS_PER_DAY);
      timeToAssess = timeToAssess.sub(secondsPerPeriod);
    }
    return handlePayment(_getUSDCBalance(address(this)), timeToAssess);
  }

  function calculateNextDueTime() internal view returns (uint256) {
    uint256 newNextDueTime = nextDueTime;
    uint256 secondsPerPeriod = paymentPeriodInDays.mul(SECONDS_PER_DAY);
    uint256 curTimestamp = currentTime();
    // You must have just done your first drawdown
    if (newNextDueTime == 0 && balance > 0) {
      return curTimestamp.add(secondsPerPeriod);
    }

    // Active loan that has entered a new period, so return the *next* newNextDueTime.
    // But never return something after the termEndTime
    if (balance > 0 && curTimestamp >= newNextDueTime) {
      uint256 secondsToAdvance = (curTimestamp.sub(newNextDueTime).div(secondsPerPeriod)).add(1).mul(secondsPerPeriod);
      newNextDueTime = newNextDueTime.add(secondsToAdvance);
      return Math.min(newNextDueTime, termEndTime);
    }

    // You're paid off, or have not taken out a loan yet, so no next due time.
    if (balance == 0 && newNextDueTime != 0) {
      return 0;
    }
    // Active loan in current period, where we've already set the newNextDueTime correctly, so should not change.
    if (balance > 0 && curTimestamp < newNextDueTime) {
      return newNextDueTime;
    }
    revert("Error: could not calculate next due time.");
  }

  function currentTime() internal view virtual returns (uint256) {
    return block.timestamp;
  }

  function _isLate(uint256 timestamp) internal view returns (bool) {
    uint256 secondsElapsedSinceFullPayment = timestamp.sub(lastFullPaymentTime);
    return balance > 0 && secondsElapsedSinceFullPayment > paymentPeriodInDays.mul(SECONDS_PER_DAY);
  }

  function _termStartTime() internal view returns (uint256) {
    return termEndTime.sub(SECONDS_PER_DAY.mul(termInDays));
  }

  /**
   * @notice Applies `amount` of payment for a given credit line. This moves already collected money into the Pool.
   *  It also updates all the accounting variables. Note that interest is always paid back first, then principal.
   *  Any extra after paying the minimum will go towards existing principal (reducing the
   *  effective interest rate). Any extra after the full loan has been paid off will remain in the
   *  USDC Balance of the creditLine, where it will be automatically used for the next drawdown.
   * @param paymentAmount The amount, in USDC atomic units, to be applied
   * @param timestamp The timestamp on which accrual calculations should be based. This allows us
   *  to be precise when we assess a Credit Line
   */
  function handlePayment(uint256 paymentAmount, uint256 timestamp)
    internal
    returns (
      uint256,
      uint256,
      uint256
    )
  {
    (uint256 newInterestOwed, uint256 newPrincipalOwed) = _updateAndGetInterestAndPrincipalOwedAsOf(timestamp);
    Accountant.PaymentAllocation memory pa = Accountant.allocatePayment(
      paymentAmount,
      balance,
      newInterestOwed,
      newPrincipalOwed
    );

    uint256 newBalance = balance.sub(pa.principalPayment);
    // Apply any additional payment towards the balance
    newBalance = newBalance.sub(pa.additionalBalancePayment);
    uint256 totalPrincipalPayment = balance.sub(newBalance);
    uint256 paymentRemaining = paymentAmount.sub(pa.interestPayment).sub(totalPrincipalPayment);

    updateCreditLineAccounting(
      newBalance,
      newInterestOwed.sub(pa.interestPayment),
      newPrincipalOwed.sub(pa.principalPayment)
    );

    assert(paymentRemaining.add(pa.interestPayment).add(totalPrincipalPayment) == paymentAmount);

    return (paymentRemaining, pa.interestPayment, totalPrincipalPayment);
  }

  function _updateAndGetInterestAndPrincipalOwedAsOf(uint256 timestamp) internal returns (uint256, uint256) {
    (uint256 interestAccrued, uint256 principalAccrued) = Accountant.calculateInterestAndPrincipalAccrued(
      this,
      timestamp,
      config.getLatenessGracePeriodInDays()
    );
    if (interestAccrued > 0) {
      // If we've accrued any interest, update interestAccruedAsOf to the time that we've
      // calculated interest for. If we've not accrued any interest, then we keep the old value so the next
      // time the entire period is taken into account.
      setInterestAccruedAsOf(timestamp);
      totalInterestAccrued = totalInterestAccrued.add(interestAccrued);
    }
    return (interestOwed.add(interestAccrued), principalOwed.add(principalAccrued));
  }

  function updateCreditLineAccounting(
    uint256 newBalance,
    uint256 newInterestOwed,
    uint256 newPrincipalOwed
  ) internal nonReentrant {
    setBalance(newBalance);
    setInterestOwed(newInterestOwed);
    setPrincipalOwed(newPrincipalOwed);

    // This resets lastFullPaymentTime. These conditions assure that they have
    // indeed paid off all their interest and they have a real nextDueTime. (ie. creditline isn't pre-drawdown)
    uint256 _nextDueTime = nextDueTime;
    if (newInterestOwed == 0 && _nextDueTime != 0) {
      // If interest was fully paid off, then set the last full payment as the previous due time
      uint256 mostRecentLastDueTime;
      if (currentTime() < _nextDueTime) {
        uint256 secondsPerPeriod = paymentPeriodInDays.mul(SECONDS_PER_DAY);
        mostRecentLastDueTime = _nextDueTime.sub(secondsPerPeriod);
      } else {
        mostRecentLastDueTime = _nextDueTime;
      }
      setLastFullPaymentTime(mostRecentLastDueTime);
    }

    setNextDueTime(calculateNextDueTime());
  }

  function _getUSDCBalance(address _address) internal view returns (uint256) {
    return config.getUSDC().balanceOf(_address);
  }
}

// File: contracts/protocol/core/GoldfinchConfig.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "./BaseUpgradeablePausable.sol";
import "../../interfaces/IGoldfinchConfig.sol";
import "./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");
    _;
  }
}

// File: contracts/protocol/core/PauserPausable.sol



// 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() {
    require(hasRole(PAUSER_ROLE, _msgSender()), "Must have pauser role to perform this action");
    _;
  }
}

// File: contracts/protocol/core/SeniorPool.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/drafts/IERC20Permit.sol";

import "../../interfaces/ISeniorPool.sol";
import "../../interfaces/IPoolTokens.sol";
import "./Accountant.sol";
import "./BaseUpgradeablePausable.sol";
import "./ConfigHelper.sol";

/**
 * @title Goldfinch's SeniorPool contract
 * @notice Main entry point for senior LPs (a.k.a. capital providers)
 *  Automatically invests across borrower pools using an adjustable strategy.
 * @author Goldfinch
 */
contract SeniorPool is BaseUpgradeablePausable, ISeniorPool {
  GoldfinchConfig public config;
  using ConfigHelper for GoldfinchConfig;
  using SafeMath for uint256;

  bytes32 public constant ZAPPER_ROLE = keccak256("ZAPPER_ROLE");

  uint256 public compoundBalance;
  mapping(ITranchedPool => uint256) public writedowns;

  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 PrincipalWrittenDown(address indexed tranchedPool, int256 amount);
  event InvestmentMadeInSenior(address indexed tranchedPool, uint256 amount);
  event InvestmentMadeInJunior(address indexed tranchedPool, uint256 amount);

  event GoldfinchConfigUpdated(address indexed who, address configAddress);

  function initialize(address owner, GoldfinchConfig _config) public initializer {
    require(owner != address(0) && address(_config) != address(0), "Owner and config addresses cannot be empty");

    __BaseUpgradeablePausable__init(owner);

    config = _config;
    // Initialize sharePrice to be identical to the legacy pool. This is in the initializer
    // because it must only ever happen once.
    sharePrice = config.getPool().sharePrice();
    totalLoansOutstanding = config.getCreditDesk().totalLoansOutstanding();
    totalWritedowns = config.getCreditDesk().totalWritedowns();

    IERC20withDec usdc = config.getUSDC();
    // Sanity check the address
    usdc.totalSupply();

    bool success = usdc.approve(address(this), uint256(-1));
    require(success, "Failed to approve USDC");
  }

  /**
   * @notice Deposits `amount` USDC from msg.sender into the SeniorPool, and grants you the
   *  equivalent value of FIDU tokens
   * @param amount The amount of USDC to deposit
   */
  function deposit(uint256 amount) public override whenNotPaused nonReentrant returns (uint256 depositShares) {
    require(config.getGo().goSeniorPool(msg.sender), "This address has not been go-listed");
    require(amount > 0, "Must deposit more than zero");
    // Check if the amount of new shares to be added is within limits
    depositShares = getNumShares(amount);
    uint256 potentialNewTotalShares = totalShares().add(depositShares);
    require(_sharesWithinLimit(potentialNewTotalShares), "Deposit would put the senior pool over the total limit.");
    emit DepositMade(msg.sender, amount, depositShares);
    bool success = doUSDCTransfer(msg.sender, address(this), amount);
    require(success, "Failed to transfer for deposit");

    config.getFidu().mintTo(msg.sender, depositShares);
    return depositShares;
  }

  /**
   * @notice Identical to deposit, except it allows for a passed up signature to permit
   *  the Senior Pool to move funds on behalf of the user, all within one transaction.
   * @param amount The amount of USDC to deposit
   * @param v secp256k1 signature component
   * @param r secp256k1 signature component
   * @param s secp256k1 signature component
   */
  function depositWithPermit(
    uint256 amount,
    uint256 deadline,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) public override returns (uint256 depositShares) {
    IERC20Permit(config.usdcAddress()).permit(msg.sender, address(this), amount, deadline, v, r, s);
    return deposit(amount);
  }

  /**
   * @notice Withdraws USDC from the SeniorPool to msg.sender, and burns the equivalent value of FIDU tokens
   * @param usdcAmount The amount of USDC to withdraw
   */
  function withdraw(uint256 usdcAmount) external override whenNotPaused nonReentrant returns (uint256 amount) {
    require(config.getGo().goSeniorPool(msg.sender), "This address has not been go-listed");
    require(usdcAmount > 0, "Must withdraw more than zero");
    // This MUST happen before calculating withdrawShares, otherwise the share price
    // changes between calculation and burning of Fidu, which creates a asset/liability mismatch
    if (compoundBalance > 0) {
      _sweepFromCompound();
    }
    uint256 withdrawShares = getNumShares(usdcAmount);
    return _withdraw(usdcAmount, withdrawShares);
  }

  /**
   * @notice Withdraws USDC (denominated in FIDU terms) from the SeniorPool to msg.sender
   * @param fiduAmount The amount of USDC to withdraw in terms of FIDU shares
   */
  function withdrawInFidu(uint256 fiduAmount) external override whenNotPaused nonReentrant returns (uint256 amount) {
    require(config.getGo().goSeniorPool(msg.sender), "This address has not been go-listed");
    require(fiduAmount > 0, "Must withdraw more than zero");
    // This MUST happen before calculating withdrawShares, otherwise the share price
    // changes between calculation and burning of Fidu, which creates a asset/liability mismatch
    if (compoundBalance > 0) {
      _sweepFromCompound();
    }
    uint256 usdcAmount = _getUSDCAmountFromShares(fiduAmount);
    uint256 withdrawShares = fiduAmount;
    return _withdraw(usdcAmount, withdrawShares);
  }

  /**
   * @notice Migrates to a new goldfinch config address
   */
  function updateGoldfinchConfig() external onlyAdmin {
    config = GoldfinchConfig(config.configAddress());
    emit GoldfinchConfigUpdated(msg.sender, address(config));
  }

  /**
   * @notice Moves any USDC still in the SeniorPool to Compound, and tracks the amount internally.
   * This is done to earn interest on latent funds until we have other borrowers who can use it.
   *
   * Requirements:
   *  - The caller must be an admin.
   */
  function sweepToCompound() public override onlyAdmin whenNotPaused {
    IERC20 usdc = config.getUSDC();
    uint256 usdcBalance = usdc.balanceOf(address(this));

    ICUSDCContract cUSDC = config.getCUSDCContract();
    // Approve compound to the exact amount
    bool success = usdc.approve(address(cUSDC), usdcBalance);
    require(success, "Failed to approve USDC for compound");

    _sweepToCompound(cUSDC, usdcBalance);

    // Remove compound approval to be extra safe
    success = config.getUSDC().approve(address(cUSDC), 0);
    require(success, "Failed to approve USDC for compound");
  }

  /**
   * @notice Moves any USDC from Compound back to the SeniorPool, and recognizes interest earned.
   * This is done automatically on drawdown or withdraw, but can be called manually if necessary.
   *
   * Requirements:
   *  - The caller must be an admin.
   */
  function sweepFromCompound() public override onlyAdmin whenNotPaused {
    _sweepFromCompound();
  }

  /**
   * @notice Invest in an ITranchedPool's senior tranche using the senior pool's strategy
   * @param pool An ITranchedPool whose senior tranche should be considered for investment
   */
  function invest(ITranchedPool pool) public override whenNotPaused nonReentrant {
    require(_isValidPool(pool), "Pool must be valid");

    if (compoundBalance > 0) {
      _sweepFromCompound();
    }

    ISeniorPoolStrategy strategy = config.getSeniorPoolStrategy();
    uint256 amount = strategy.invest(this, pool);

    require(amount > 0, "Investment amount must be positive");

    _approvePool(pool, amount);
    uint256 nSlices = pool.numSlices();
    require(nSlices >= 1, "Pool has no slices");
    uint256 sliceIndex = nSlices.sub(1);
    uint256 seniorTrancheId = _sliceIndexToSeniorTrancheId(sliceIndex);
    pool.deposit(seniorTrancheId, amount);

    emit InvestmentMadeInSenior(address(pool), amount);
    totalLoansOutstanding = totalLoansOutstanding.add(amount);
  }

  function estimateInvestment(ITranchedPool pool) public view override returns (uint256) {
    require(_isValidPool(pool), "Pool must be valid");
    ISeniorPoolStrategy strategy = config.getSeniorPoolStrategy();
    return strategy.estimateInvestment(this, pool);
  }

  /**
   * @notice Redeem interest and/or principal from an ITranchedPool investment
   * @param tokenId the ID of an IPoolTokens token to be redeemed
   */
  function redeem(uint256 tokenId) public override whenNotPaused nonReentrant {
    IPoolTokens poolTokens = config.getPoolTokens();
    IPoolTokens.TokenInfo memory tokenInfo = poolTokens.getTokenInfo(tokenId);

    ITranchedPool pool = ITranchedPool(tokenInfo.pool);
    (uint256 interestRedeemed, uint256 principalRedeemed) = pool.withdrawMax(tokenId);

    _collectInterestAndPrincipal(address(pool), interestRedeemed, principalRedeemed);
  }

  /**
   * @notice Write down an ITranchedPool investment. This will adjust the senior pool's share price
   *  down if we're considering the investment a loss, or up if the borrower has subsequently
   *  made repayments that restore confidence that the full loan will be repaid.
   * @param tokenId the ID of an IPoolTokens token to be considered for writedown
   */
  function writedown(uint256 tokenId) public override whenNotPaused nonReentrant {
    IPoolTokens poolTokens = config.getPoolTokens();
    require(address(this) == poolTokens.ownerOf(tokenId), "Only tokens owned by the senior pool can be written down");

    IPoolTokens.TokenInfo memory tokenInfo = poolTokens.getTokenInfo(tokenId);
    ITranchedPool pool = ITranchedPool(tokenInfo.pool);
    require(_isValidPool(pool), "Pool must be valid");

    uint256 principalRemaining = tokenInfo.principalAmount.sub(tokenInfo.principalRedeemed);

    (uint256 writedownPercent, uint256 writedownAmount) = _calculateWritedown(pool, principalRemaining);

    uint256 prevWritedownAmount = writedowns[pool];

    if (writedownPercent == 0 && prevWritedownAmount == 0) {
      return;
    }

    int256 writedownDelta = int256(prevWritedownAmount) - int256(writedownAmount);
    writedowns[pool] = writedownAmount;
    _distributeLosses(writedownDelta);
    if (writedownDelta > 0) {
      // If writedownDelta is positive, that means we got money back. So subtract from totalWritedowns.
      totalWritedowns = totalWritedowns.sub(uint256(writedownDelta));
    } else {
      totalWritedowns = totalWritedowns.add(uint256(writedownDelta * -1));
    }
    emit PrincipalWrittenDown(address(pool), writedownDelta);
  }

  /**
   * @notice Calculates the writedown amount for a particular pool position
   * @param tokenId The token reprsenting the position
   * @return The amount in dollars the principal should be written down by
   */
  function calculateWritedown(uint256 tokenId) public view override returns (uint256) {
    IPoolTokens.TokenInfo memory tokenInfo = config.getPoolTokens().getTokenInfo(tokenId);
    ITranchedPool pool = ITranchedPool(tokenInfo.pool);

    uint256 principalRemaining = tokenInfo.principalAmount.sub(tokenInfo.principalRedeemed);

    (, uint256 writedownAmount) = _calculateWritedown(pool, principalRemaining);
    return writedownAmount;
  }

  /**
   * @notice Returns the net assests controlled by and owed to the pool
   */
  function assets() public view override returns (uint256) {
    return
      compoundBalance.add(config.getUSDC().balanceOf(address(this))).add(totalLoansOutstanding).sub(totalWritedowns);
  }

  /**
   * @notice Converts and USDC amount to FIDU amount
   * @param amount USDC amount to convert to FIDU
   */
  function getNumShares(uint256 amount) public view override returns (uint256) {
    return _usdcToFidu(amount).mul(_fiduMantissa()).div(sharePrice);
  }

  /* Internal Functions */

  function _calculateWritedown(ITranchedPool pool, uint256 principal)
    internal
    view
    returns (uint256 writedownPercent, uint256 writedownAmount)
  {
    return
      Accountant.calculateWritedownForPrincipal(
        pool.creditLine(),
        principal,
        currentTime(),
        config.getLatenessGracePeriodInDays(),
        config.getLatenessMaxDays()
      );
  }

  function currentTime() internal view virtual returns (uint256) {
    return block.timestamp;
  }

  function _distributeLosses(int256 writedownDelta) internal {
    if (writedownDelta > 0) {
      uint256 delta = _usdcToSharePrice(uint256(writedownDelta));
      sharePrice = sharePrice.add(delta);
    } else {
      // If delta is negative, convert to positive uint, and sub from sharePrice
      uint256 delta = _usdcToSharePrice(uint256(writedownDelta * -1));
      sharePrice = sharePrice.sub(delta);
    }
  }

  function _fiduMantissa() internal pure returns (uint256) {
    return uint256(10)**uint256(18);
  }

  function _usdcMantissa() internal pure returns (uint256) {
    return uint256(10)**uint256(6);
  }

  function _usdcToFidu(uint256 amount) internal pure returns (uint256) {
    return amount.mul(_fiduMantissa()).div(_usdcMantissa());
  }

  function _fiduToUSDC(uint256 amount) internal pure returns (uint256) {
    return amount.div(_fiduMantissa().div(_usdcMantissa()));
  }

  function _getUSDCAmountFromShares(uint256 fiduAmount) internal view returns (uint256) {
    return _fiduToUSDC(fiduAmount.mul(sharePrice).div(_fiduMantissa()));
  }

  function _sharesWithinLimit(uint256 _totalShares) internal view returns (bool) {
    return
      _totalShares.mul(sharePrice).div(_fiduMantissa()) <=
      _usdcToFidu(config.getNumber(uint256(ConfigOptions.Numbers.TotalFundsLimit)));
  }

  function doUSDCTransfer(
    address from,
    address to,
    uint256 amount
  ) internal returns (bool) {
    require(to != address(0), "Can't send to zero address");
    IERC20withDec usdc = config.getUSDC();
    return usdc.transferFrom(from, to, amount);
  }

  function _withdraw(uint256 usdcAmount, uint256 withdrawShares) internal returns (uint256 userAmount) {
    IFidu fidu = config.getFidu();
    // Determine current shares the address has and the shares requested to withdraw
    uint256 currentShares = fidu.balanceOf(msg.sender);
    // Ensure the address has enough value in the pool
    require(withdrawShares <= currentShares, "Amount requested is greater than what this address owns");

    // Send to reserves
    userAmount = usdcAmount;
    uint256 reserveAmount = 0;

    if (!isZapper()) {
      reserveAmount = usdcAmount.div(config.getWithdrawFeeDenominator());
      userAmount = userAmount.sub(reserveAmount);
      _sendToReserve(reserveAmount, msg.sender);
    }

    // Send to user
    bool success = doUSDCTransfer(address(this), msg.sender, userAmount);
    require(success, "Failed to transfer for withdraw");

    // Burn the shares
    fidu.burnFrom(msg.sender, withdrawShares);

    emit WithdrawalMade(msg.sender, userAmount, reserveAmount);

    return userAmount;
  }

  function _sweepToCompound(ICUSDCContract cUSDC, uint256 usdcAmount) internal {
    // Our current design requires we re-normalize by withdrawing everything and recognizing interest gains
    // before we can add additional capital to Compound
    require(compoundBalance == 0, "Cannot sweep when we already have a compound balance");
    require(usdcAmount != 0, "Amount to sweep cannot be zero");
    uint256 error = cUSDC.mint(usdcAmount);
    require(error == 0, "Sweep to compound failed");
    compoundBalance = usdcAmount;
  }

  function _sweepFromCompound() internal {
    ICUSDCContract cUSDC = config.getCUSDCContract();
    _sweepFromCompound(cUSDC, cUSDC.balanceOf(address(this)));
  }

  function _sweepFromCompound(ICUSDCContract cUSDC, uint256 cUSDCAmount) internal {
    uint256 cBalance = compoundBalance;
    require(cBalance != 0, "No funds on compound");
    require(cUSDCAmount != 0, "Amount to sweep cannot be zero");

    IERC20 usdc = config.getUSDC();
    uint256 preRedeemUSDCBalance = usdc.balanceOf(address(this));
    uint256 cUSDCExchangeRate = cUSDC.exchangeRateCurrent();
    uint256 redeemedUSDC = _cUSDCToUSDC(cUSDCExchangeRate, cUSDCAmount);

    uint256 error = cUSDC.redeem(cUSDCAmount);
    uint256 postRedeemUSDCBalance = usdc.balanceOf(address(this));
    require(error == 0, "Sweep from compound failed");
    require(postRedeemUSDCBalance.sub(preRedeemUSDCBalance) == redeemedUSDC, "Unexpected redeem amount");

    uint256 interestAccrued = redeemedUSDC.sub(cBalance);
    uint256 reserveAmount = interestAccrued.div(config.getReserveDenominator());
    uint256 poolAmount = interestAccrued.sub(reserveAmount);

    _collectInterestAndPrincipal(address(this), poolAmount, 0);

    if (reserveAmount > 0) {
      _sendToReserve(reserveAmount, address(cUSDC));
    }

    compoundBalance = 0;
  }

  function _cUSDCToUSDC(uint256 exchangeRate, uint256 amount) internal pure returns (uint256) {
    // See https://compound.finance/docs#protocol-math
    // But note, the docs and reality do not agree. Docs imply that that exchange rate is
    // scaled by 1e18, but tests and mainnet forking make it appear to be scaled by 1e16
    // 1e16 is also what Sheraz at Certik said.
    uint256 usdcDecimals = 6;
    uint256 cUSDCDecimals = 8;

    // We multiply in the following order, for the following reasons...
    // Amount in cToken (1e8)
    // Amount in USDC (but scaled by 1e16, cause that's what exchange rate decimals are)
    // Downscale to cToken decimals (1e8)
    // Downscale from cToken to USDC decimals (8 to 6)
    return amount.mul(exchangeRate).div(10**(18 + usdcDecimals - cUSDCDecimals)).div(10**2);
  }

  function _collectInterestAndPrincipal(
    address from,
    uint256 interest,
    uint256 principal
  ) internal {
    uint256 increment = _usdcToSharePrice(interest);
    sharePrice = sharePrice.add(increment);

    if (interest > 0) {
      emit InterestCollected(from, interest);
    }
    if (principal > 0) {
      emit PrincipalCollected(from, principal);
      totalLoansOutstanding = totalLoansOutstanding.sub(principal);
    }
  }

  function _sendToReserve(uint256 amount, address userForEvent) internal {
    emit ReserveFundsCollected(userForEvent, amount);
    bool success = doUSDCTransfer(address(this), config.reserveAddress(), amount);
    require(success, "Reserve transfer was not successful");
  }

  function _usdcToSharePrice(uint256 usdcAmount) internal view returns (uint256) {
    return _usdcToFidu(usdcAmount).mul(_fiduMantissa()).div(totalShares());
  }

  function totalShares() internal view returns (uint256) {
    return config.getFidu().totalSupply();
  }

  function _isValidPool(ITranchedPool pool) internal view returns (bool) {
    return config.getPoolTokens().validPool(address(pool));
  }

  function _approvePool(ITranchedPool pool, uint256 allowance) internal {
    IERC20withDec usdc = config.getUSDC();
    bool success = usdc.approve(address(pool), allowance);
    require(success, "Failed to approve USDC");
  }

  function isZapper() public view returns (bool) {
    return hasRole(ZAPPER_ROLE, _msgSender());
  }

  function initZapperRole() external onlyAdmin {
    _setRoleAdmin(ZAPPER_ROLE, OWNER_ROLE);
  }

  /// @notice Returns the senion tranche id for the given slice index
  /// @param index slice index
  /// @return senior tranche id of given slice index
  function _sliceIndexToSeniorTrancheId(uint256 index) internal pure returns (uint256) {
    return index.mul(2).add(1);
  }
}