pragma solidity ^0.5.17;
pragma experimental ABIEncoderV2;

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

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

        return c;
    }

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

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

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

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

        return c;
    }

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

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

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

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

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


/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

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

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

// File: contracts/external/Require.sol


/**
 * @title Require
 * @author dYdX
 *
 * Stringifies parameters to pretty-print revert messages. Costs more gas than regular require()
 */
library Require {

    // ============ Constants ============

    uint256 constant ASCII_ZERO = 48; // '0'
    uint256 constant ASCII_RELATIVE_ZERO = 87; // 'a' - 10
    uint256 constant ASCII_LOWER_EX = 120; // 'x'
    bytes2 constant COLON = 0x3a20; // ': '
    bytes2 constant COMMA = 0x2c20; // ', '
    bytes2 constant LPAREN = 0x203c; // ' <'
    byte constant RPAREN = 0x3e; // '>'
    uint256 constant FOUR_BIT_MASK = 0xf;

    // ============ Library Functions ============

    function that(
        bool must,
        bytes32 file,
        bytes32 reason
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason)
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        uint256 payloadA
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        RPAREN
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        uint256 payloadA,
        uint256 payloadB
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        COMMA,
                        stringify(payloadB),
                        RPAREN
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        address payloadA
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        RPAREN
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        address payloadA,
        uint256 payloadB
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        COMMA,
                        stringify(payloadB),
                        RPAREN
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        address payloadA,
        uint256 payloadB,
        uint256 payloadC
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        COMMA,
                        stringify(payloadB),
                        COMMA,
                        stringify(payloadC),
                        RPAREN
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        bytes32 payloadA
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        RPAREN
                    )
                )
            );
        }
    }

    function that(
        bool must,
        bytes32 file,
        bytes32 reason,
        bytes32 payloadA,
        uint256 payloadB,
        uint256 payloadC
    )
    internal
    pure
    {
        if (!must) {
            revert(
                string(
                    abi.encodePacked(
                        stringifyTruncated(file),
                        COLON,
                        stringifyTruncated(reason),
                        LPAREN,
                        stringify(payloadA),
                        COMMA,
                        stringify(payloadB),
                        COMMA,
                        stringify(payloadC),
                        RPAREN
                    )
                )
            );
        }
    }

    // ============ Private Functions ============

    function stringifyTruncated(
        bytes32 input
    )
    private
    pure
    returns (bytes memory)
    {
        // put the input bytes into the result
        bytes memory result = abi.encodePacked(input);

        // determine the length of the input by finding the location of the last non-zero byte
        for (uint256 i = 32; i > 0; ) {
            // reverse-for-loops with unsigned integer
            /* solium-disable-next-line security/no-modify-for-iter-var */
            i--;

            // find the last non-zero byte in order to determine the length
            if (result[i] != 0) {
                uint256 length = i + 1;

                /* solium-disable-next-line security/no-inline-assembly */
                assembly {
                    mstore(result, length) // r.length = length;
                }

                return result;
            }
        }

        // all bytes are zero
        return new bytes(0);
    }

    function stringify(
        uint256 input
    )
    private
    pure
    returns (bytes memory)
    {
        if (input == 0) {
            return "0";
        }

        // get the final string length
        uint256 j = input;
        uint256 length;
        while (j != 0) {
            length++;
            j /= 10;
        }

        // allocate the string
        bytes memory bstr = new bytes(length);

        // populate the string starting with the least-significant character
        j = input;
        for (uint256 i = length; i > 0; ) {
            // reverse-for-loops with unsigned integer
            /* solium-disable-next-line security/no-modify-for-iter-var */
            i--;

            // take last decimal digit
            bstr[i] = byte(uint8(ASCII_ZERO + (j % 10)));

            // remove the last decimal digit
            j /= 10;
        }

        return bstr;
    }

    function stringify(
        address input
    )
    private
    pure
    returns (bytes memory)
    {
        uint256 z = uint256(input);

        // addresses are "0x" followed by 20 bytes of data which take up 2 characters each
        bytes memory result = new bytes(42);

        // populate the result with "0x"
        result[0] = byte(uint8(ASCII_ZERO));
        result[1] = byte(uint8(ASCII_LOWER_EX));

        // for each byte (starting from the lowest byte), populate the result with two characters
        for (uint256 i = 0; i < 20; i++) {
            // each byte takes two characters
            uint256 shift = i * 2;

            // populate the least-significant character
            result[41 - shift] = char(z & FOUR_BIT_MASK);
            z = z >> 4;

            // populate the most-significant character
            result[40 - shift] = char(z & FOUR_BIT_MASK);
            z = z >> 4;
        }

        return result;
    }

    function stringify(
        bytes32 input
    )
    private
    pure
    returns (bytes memory)
    {
        uint256 z = uint256(input);

        // bytes32 are "0x" followed by 32 bytes of data which take up 2 characters each
        bytes memory result = new bytes(66);

        // populate the result with "0x"
        result[0] = byte(uint8(ASCII_ZERO));
        result[1] = byte(uint8(ASCII_LOWER_EX));

        // for each byte (starting from the lowest byte), populate the result with two characters
        for (uint256 i = 0; i < 32; i++) {
            // each byte takes two characters
            uint256 shift = i * 2;

            // populate the least-significant character
            result[65 - shift] = char(z & FOUR_BIT_MASK);
            z = z >> 4;

            // populate the most-significant character
            result[64 - shift] = char(z & FOUR_BIT_MASK);
            z = z >> 4;
        }

        return result;
    }

    function char(
        uint256 input
    )
    private
    pure
    returns (byte)
    {
        // return ASCII digit (0-9)
        if (input < 10) {
            return byte(uint8(input + ASCII_ZERO));
        }

        // return ASCII letter (a-f)
        return byte(uint8(input + ASCII_RELATIVE_ZERO));
    }
}

// File: contracts/external/Decimal.sol

/**
 * @title Decimal
 * @author dYdX
 *
 * Library that defines a fixed-point number with 18 decimal places.
 */
library Decimal {
    using SafeMath for uint256;

    // ============ Constants ============

    uint256 constant BASE = 10**18;

    // ============ Structs ============


    struct D256 {
        uint256 value;
    }

    // ============ Static Functions ============

    function zero()
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: 0 });
    }

    function one()
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: BASE });
    }

    function from(
        uint256 a
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: a.mul(BASE) });
    }

    function ratio(
        uint256 a,
        uint256 b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: getPartial(a, BASE, b) });
    }

    // ============ Self Functions ============

    function add(
        D256 memory self,
        uint256 b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.add(b.mul(BASE)) });
    }

    function sub(
        D256 memory self,
        uint256 b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.sub(b.mul(BASE)) });
    }

    function sub(
        D256 memory self,
        uint256 b,
        string memory reason
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.sub(b.mul(BASE), reason) });
    }

    function mul(
        D256 memory self,
        uint256 b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.mul(b) });
    }

    function div(
        D256 memory self,
        uint256 b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.div(b) });
    }

    function pow(
        D256 memory self,
        uint256 b
    )
    internal
    pure
    returns (D256 memory)
    {
        if (b == 0) {
            return from(1);
        }

        D256 memory temp = D256({ value: self.value });
        for (uint256 i = 1; i < b; i++) {
            temp = mul(temp, self);
        }

        return temp;
    }

    function add(
        D256 memory self,
        D256 memory b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.add(b.value) });
    }

    function sub(
        D256 memory self,
        D256 memory b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.sub(b.value) });
    }

    function sub(
        D256 memory self,
        D256 memory b,
        string memory reason
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: self.value.sub(b.value, reason) });
    }

    function mul(
        D256 memory self,
        D256 memory b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: getPartial(self.value, b.value, BASE) });
    }

    function div(
        D256 memory self,
        D256 memory b
    )
    internal
    pure
    returns (D256 memory)
    {
        return D256({ value: getPartial(self.value, BASE, b.value) });
    }

    function equals(D256 memory self, D256 memory b) internal pure returns (bool) {
        return self.value == b.value;
    }

    function greaterThan(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) == 2;
    }

    function lessThan(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) == 0;
    }

    function greaterThanOrEqualTo(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) > 0;
    }

    function lessThanOrEqualTo(D256 memory self, D256 memory b) internal pure returns (bool) {
        return compareTo(self, b) < 2;
    }

    function isZero(D256 memory self) internal pure returns (bool) {
        return self.value == 0;
    }

    function asUint256(D256 memory self) internal pure returns (uint256) {
        return self.value.div(BASE);
    }

    // ============ Core Methods ============

    function getPartial(
        uint256 target,
        uint256 numerator,
        uint256 denominator
    )
    private
    pure
    returns (uint256)
    {
        return target.mul(numerator).div(denominator);
    }

    function compareTo(
        D256 memory a,
        D256 memory b
    )
    private
    pure
    returns (uint256)
    {
        if (a.value == b.value) {
            return 1;
        }
        return a.value > b.value ? 2 : 0;
    }
}

// File: contracts/Constants.sol


library Constants {
    /* Chain */
    uint256 private constant CHAIN_ID = 1; // Mainnet

    /* Bootstrapping */
    uint256 private constant BOOTSTRAPPING_PERIOD = 56; // 14 days
    uint256 private constant BOOTSTRAPPING_PRICE = 11e17; // ESG price == 1.10 * sXAU

    /* Oracle */
    address private constant sXAU = address(0x261EfCdD24CeA98652B9700800a13DfBca4103fF);
    uint256 private constant ORACLE_RESERVE_MINIMUM = 1e18;

    /* Bonding */
    uint256 private constant INITIAL_STAKE_MULTIPLE = 1e6; // 100 ESG -> 100M ESGS

    /* Epoch */
    struct EpochStrategy {
        uint256 offset;
        uint256 start;
        uint256 period;
    }

    uint256 private constant EPOCH_START = 1609027200; // 2020-12-27T00:00:00+00:00
    uint256 private constant EPOCH_OFFSET = 0;
    uint256 private constant EPOCH_PERIOD = 21600; // 6 hours

    /* Governance */
    uint256 private constant GOVERNANCE_PERIOD = 9; // 9 epochs
    uint256 private constant GOVERNANCE_EXPIRATION = 2; // 2 + 1 epochs
    uint256 private constant GOVERNANCE_QUORUM = 20e16; // 20%
    uint256 private constant GOVERNANCE_PROPOSAL_THRESHOLD = 5e15; // 0.5%
    uint256 private constant GOVERNANCE_SUPER_MAJORITY = 66e16; // 66%
    uint256 private constant GOVERNANCE_EMERGENCY_DELAY = 6; // 6 epochs

    /* DAO */
    uint256 private constant ADVANCE_INCENTIVE = 1e17; // 0.1 ESG
    uint256 private constant DAO_EXIT_LOCKUP_EPOCHS = 20; // 5 days

    /* Pool */
    uint256 private constant POOL_EXIT_LOCKUP_EPOCHS = 8; // 2 days

    /* Market */
    uint256 private constant COUPON_EXPIRATION = 120; // 30 days
    uint256 private constant DEBT_RATIO_CAP = 35e16; // 35%

    /* Regulator */
    uint256 private constant SUPPLY_CHANGE_LIMIT = 1e17; // 10%
    uint256 private constant COUPON_SUPPLY_CHANGE_LIMIT = 6e16; // 6%
    uint256 private constant ORACLE_POOL_RATIO = 20; // 20%
    uint256 private constant TREASURY_RATIO = 250; // 2.5%, until TREASURY_ADDRESS is set, this portion is sent to LP

    // TODO: vote on recipient
    address private constant TREASURY_ADDRESS = address(0x0000000000000000000000000000000000000000);

    function getSXAUAddress() internal pure returns (address) {
        return sXAU;
    }

    function getOracleReserveMinimum() internal pure returns (uint256) {
        return ORACLE_RESERVE_MINIMUM;
    }

    function getCurrentEpochStrategy() internal pure returns (EpochStrategy memory) {
        return EpochStrategy({
            offset: EPOCH_OFFSET,
            start: EPOCH_START,
            period: EPOCH_PERIOD
        });
    }

    function getInitialStakeMultiple() internal pure returns (uint256) {
        return INITIAL_STAKE_MULTIPLE;
    }

    function getBootstrappingPeriod() internal pure returns (uint256) {
        return BOOTSTRAPPING_PERIOD;
    }

    function getBootstrappingPrice() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: BOOTSTRAPPING_PRICE});
    }

    function getGovernancePeriod() internal pure returns (uint256) {
        return GOVERNANCE_PERIOD;
    }

    function getGovernanceExpiration() internal pure returns (uint256) {
        return GOVERNANCE_EXPIRATION;
    }

    function getGovernanceQuorum() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: GOVERNANCE_QUORUM});
    }

    function getGovernanceProposalThreshold() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: GOVERNANCE_PROPOSAL_THRESHOLD});
    }

    function getGovernanceSuperMajority() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: GOVERNANCE_SUPER_MAJORITY});
    }

    function getGovernanceEmergencyDelay() internal pure returns (uint256) {
        return GOVERNANCE_EMERGENCY_DELAY;
    }

    function getAdvanceIncentive() internal pure returns (uint256) {
        return ADVANCE_INCENTIVE;
    }

    function getDAOExitLockupEpochs() internal pure returns (uint256) {
        return DAO_EXIT_LOCKUP_EPOCHS;
    }

    function getPoolExitLockupEpochs() internal pure returns (uint256) {
        return POOL_EXIT_LOCKUP_EPOCHS;
    }

    function getCouponExpiration() internal pure returns (uint256) {
        return COUPON_EXPIRATION;
    }

    function getDebtRatioCap() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: DEBT_RATIO_CAP});
    }

    function getSupplyChangeLimit() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: SUPPLY_CHANGE_LIMIT});
    }

    function getCouponSupplyChangeLimit() internal pure returns (Decimal.D256 memory) {
        return Decimal.D256({value: COUPON_SUPPLY_CHANGE_LIMIT});
    }

    function getOraclePoolRatio() internal pure returns (uint256) {
        return ORACLE_POOL_RATIO;
    }

    function getTreasuryRatio() internal pure returns (uint256) {
        return TREASURY_RATIO;
    }

    function getChainId() internal pure returns (uint256) {
        return CHAIN_ID;
    }

    function getTreasuryAddress() internal pure returns (address) {
        return TREASURY_ADDRESS;
    }
}

// File: contracts/token/IGold.sol


contract IGold is IERC20 {
    function burn(uint256 amount) public;
    function burnFrom(address account, uint256 amount) public;
    function mint(address account, uint256 amount) public returns (bool);
}

// File: contracts/oracle/IDAO.sol


contract IDAO {
    function epoch() external view returns (uint256);
}

// File: contracts/oracle/PoolState.sol


contract PoolAccount {
    enum Status {
        Frozen,
        Fluid,
        Locked
    }

    struct State {
        uint256 staged;
        uint256 claimable;
        uint256 bonded;
        uint256 phantom;
        uint256 fluidUntil;
    }
}

contract PoolStorage {
    struct Provider {
        IDAO dao;
        IGold gold;
        IERC20 univ2;
    }

    struct Balance {
        uint256 staged;
        uint256 claimable;
        uint256 bonded;
        uint256 phantom;
    }

    struct State {
        Balance balance;
        Provider provider;
        bool paused;

        mapping(address => PoolAccount.State) accounts;
    }
}

contract PoolState {
    PoolStorage.State _state;
}

// File: contracts/oracle/PoolGetters.sol



contract PoolGetters is PoolState {
    using SafeMath for uint256;

    /**
     * Global
     */

    function sXAU() public view returns (address) {
        return Constants.getSXAUAddress();
    }

    function dao() public view returns (IDAO) {
        return _state.provider.dao;
    }

    function gold() public view returns (IGold) {
        return _state.provider.gold;
    }

    function univ2() public view returns (IERC20) {
        return _state.provider.univ2;
    }

    function totalBonded() public view returns (uint256) {
        return _state.balance.bonded;
    }

    function totalStaged() public view returns (uint256) {
        return _state.balance.staged;
    }

    function totalClaimable() public view returns (uint256) {
        return _state.balance.claimable;
    }

    function totalPhantom() public view returns (uint256) {
        return _state.balance.phantom;
    }

    function totalRewarded(IGold gold) public view returns (uint256) {
        return gold.balanceOf(address(this)).sub(totalClaimable());
    }

    function paused() public view returns (bool) {
        return _state.paused;
    }

    /**
     * Account
     */

    function balanceOfStaged(address account) public view returns (uint256) {
        return _state.accounts[account].staged;
    }

    function balanceOfClaimable(address account) public view returns (uint256) {
        return _state.accounts[account].claimable;
    }

    function balanceOfBonded(address account) public view returns (uint256) {
        return _state.accounts[account].bonded;
    }

    function balanceOfPhantom(address account) public view returns (uint256) {
        return _state.accounts[account].phantom;
    }


    function balanceOfRewarded(address account, IGold gold) public view returns (uint256) {
        uint256 totalBonded = totalBonded();
        if (totalBonded == 0) {
            return 0;
        }

        uint256 totalRewardedWithPhantom = totalRewarded(gold).add(totalPhantom());
        uint256 balanceOfRewardedWithPhantom = totalRewardedWithPhantom
        .mul(balanceOfBonded(account))
        .div(totalBonded);

        uint256 balanceOfPhantom = balanceOfPhantom(account);
        if (balanceOfRewardedWithPhantom > balanceOfPhantom) {
            return balanceOfRewardedWithPhantom.sub(balanceOfPhantom);
        }
        return 0;
    }

    function statusOf(address account, uint256 epoch) public view returns (PoolAccount.Status) {
        return epoch >= _state.accounts[account].fluidUntil ?
        PoolAccount.Status.Frozen :
        PoolAccount.Status.Fluid;
    }
}

// File: contracts/oracle/PoolSetters.sol



contract PoolSetters is PoolState, PoolGetters {
    using SafeMath for uint256;

    /**
     * Global
     */

    function pause() internal {
        _state.paused = true;
    }

    /**
     * Account
     */

    function incrementBalanceOfBonded(address account, uint256 amount) internal {
        _state.accounts[account].bonded = _state.accounts[account].bonded.add(amount);
        _state.balance.bonded = _state.balance.bonded.add(amount);
    }

    function decrementBalanceOfBonded(address account, uint256 amount, string memory reason) internal {
        _state.accounts[account].bonded = _state.accounts[account].bonded.sub(amount, reason);
        _state.balance.bonded = _state.balance.bonded.sub(amount, reason);
    }

    function incrementBalanceOfStaged(address account, uint256 amount) internal {
        _state.accounts[account].staged = _state.accounts[account].staged.add(amount);
        _state.balance.staged = _state.balance.staged.add(amount);
    }

    function decrementBalanceOfStaged(address account, uint256 amount, string memory reason) internal {
        _state.accounts[account].staged = _state.accounts[account].staged.sub(amount, reason);
        _state.balance.staged = _state.balance.staged.sub(amount, reason);
    }

    function incrementBalanceOfClaimable(address account, uint256 amount) internal {
        _state.accounts[account].claimable = _state.accounts[account].claimable.add(amount);
        _state.balance.claimable = _state.balance.claimable.add(amount);
    }

    function decrementBalanceOfClaimable(address account, uint256 amount, string memory reason) internal {
        _state.accounts[account].claimable = _state.accounts[account].claimable.sub(amount, reason);
        _state.balance.claimable = _state.balance.claimable.sub(amount, reason);
    }

    function incrementBalanceOfPhantom(address account, uint256 amount) internal {
        _state.accounts[account].phantom = _state.accounts[account].phantom.add(amount);
        _state.balance.phantom = _state.balance.phantom.add(amount);
    }

    function decrementBalanceOfPhantom(address account, uint256 amount, string memory reason) internal {
        _state.accounts[account].phantom = _state.accounts[account].phantom.sub(amount, reason);
        _state.balance.phantom = _state.balance.phantom.sub(amount, reason);
    }

    function unfreeze(address account, uint256 epoch) internal {
        _state.accounts[account].fluidUntil = epoch.add(Constants.getPoolExitLockupEpochs());
    }
}

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


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

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

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

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

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

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

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

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

    function initialize(address, address) external;
}

// File: contracts/external/UniswapV2Library.sol




library UniswapV2Library {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }
}

// File: contracts/oracle/Pool.sol








contract Pool is PoolSetters {
    using SafeMath for uint256;

    constructor(address gold, address univ2) public {
        _state.provider.dao = IDAO(msg.sender);
        _state.provider.gold = IGold(gold);
        _state.provider.univ2 = IERC20(univ2);
    }

    address private constant UNISWAP_FACTORY = address(0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f);

    function addLiquidity(uint256 goldAmount) internal returns (uint256, uint256) {
        (address gold, address sXAU) = (address(_state.provider.gold), sXAU());
        (uint reserveA, uint reserveB) = getReserves(gold, sXAU);

        uint256 sXAUAmount = (reserveA == 0 && reserveB == 0) ?
        goldAmount :
        UniswapV2Library.quote(goldAmount, reserveA, reserveB);

        address pair = address(_state.provider.univ2);
        IERC20(gold).transfer(pair, goldAmount);
        IERC20(sXAU).transferFrom(msg.sender, pair, sXAUAmount);
        return (sXAUAmount, IUniswapV2Pair(pair).mint(address(this)));
    }

    // overridable for testing
    function getReserves(address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(UniswapV2Library.pairFor(UNISWAP_FACTORY, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    bytes32 private constant FILE = "Pool";

    event Deposit(address indexed account, uint256 value);
    event Withdraw(address indexed account, uint256 value);
    event Claim(address indexed account, uint256 value);
    event Bond(address indexed account, uint256 start, uint256 value);
    event Unbond(address indexed account, uint256 start, uint256 value, uint256 newClaimable);
    event Provide(address indexed account, uint256 value, uint256 lessSXAU, uint256 newUniv2);

    function deposit(uint256 value) external onlyFrozen(msg.sender) notPaused {
        _state.provider.univ2.transferFrom(msg.sender, address(this), value);
        incrementBalanceOfStaged(msg.sender, value);

        balanceCheck();

        emit Deposit(msg.sender, value);
    }

    function withdraw(uint256 value) external onlyFrozen(msg.sender) {
        _state.provider.univ2.transfer(msg.sender, value);
        decrementBalanceOfStaged(msg.sender, value, "Pool: insufficient staged balance");

        balanceCheck();

        emit Withdraw(msg.sender, value);
    }

    function claim(uint256 value) external onlyFrozen(msg.sender) {
        _state.provider.gold.transfer(msg.sender, value);
        decrementBalanceOfClaimable(msg.sender, value, "Pool: insufficient claimable balance");

        balanceCheck();

        emit Claim(msg.sender, value);
    }

    function unfreeze(address account) internal {
        super.unfreeze(account, _state.provider.dao.epoch());
    }

    function bond(uint256 value) external notPaused {
        unfreeze(msg.sender);

        uint256 totalRewardedWithPhantom = totalRewarded(_state.provider.gold).add(totalPhantom());
        uint256 newPhantom = totalBonded() == 0 ?
        totalRewarded(_state.provider.gold) == 0 ? Constants.getInitialStakeMultiple().mul(value) : 0 :
        totalRewardedWithPhantom.mul(value).div(totalBonded());

        incrementBalanceOfBonded(msg.sender, value);
        incrementBalanceOfPhantom(msg.sender, newPhantom);
        decrementBalanceOfStaged(msg.sender, value, "Pool: insufficient staged balance");

        balanceCheck();

        emit Bond(msg.sender, _state.provider.dao.epoch().add(1), value);
    }

    function unbond(uint256 value) external {
        unfreeze(msg.sender);

        uint256 balanceOfBonded = balanceOfBonded(msg.sender);
        Require.that(
            balanceOfBonded > 0,
            FILE,
            "insufficient bonded balance"
        );

        uint256 newClaimable = balanceOfRewarded(msg.sender, _state.provider.gold).mul(value).div(balanceOfBonded);
        uint256 lessPhantom = balanceOfPhantom(msg.sender).mul(value).div(balanceOfBonded);

        incrementBalanceOfStaged(msg.sender, value);
        incrementBalanceOfClaimable(msg.sender, newClaimable);
        decrementBalanceOfBonded(msg.sender, value, "Pool: insufficient bonded balance");
        decrementBalanceOfPhantom(msg.sender, lessPhantom, "Pool: insufficient phantom balance");

        balanceCheck();

        emit Unbond(msg.sender, _state.provider.dao.epoch().add(1), value, newClaimable);
    }

    function provide(uint256 value) external onlyFrozen(msg.sender) notPaused {
        Require.that(
            totalBonded() > 0,
            FILE,
            "insufficient total bonded"
        );

        Require.that(
            totalRewarded(_state.provider.gold) > 0,
            FILE,
            "insufficient total rewarded"
        );

        Require.that(
            balanceOfRewarded(msg.sender, _state.provider.gold) >= value,
            FILE,
            "insufficient rewarded balance"
        );

        (uint256 lessSXAU, uint256 newUniv2) = addLiquidity(value);

        uint256 totalRewardedWithPhantom = totalRewarded(_state.provider.gold).add(totalPhantom()).add(value);
        uint256 newPhantomFromBonded = totalRewardedWithPhantom.mul(newUniv2).div(totalBonded());

        incrementBalanceOfBonded(msg.sender, newUniv2);
        incrementBalanceOfPhantom(msg.sender, value.add(newPhantomFromBonded));


        balanceCheck();

        emit Provide(msg.sender, value, lessSXAU, newUniv2);
    }

    function emergencyWithdraw(address token, uint256 value) external onlyDao {
        IERC20(token).transfer(address(_state.provider.dao), value);
    }

    function emergencyPause() external onlyDao {
        pause();
    }

    function balanceCheck() private {
        Require.that(
            _state.provider.univ2.balanceOf(address(this)) >= totalStaged().add(totalBonded()),
            FILE,
            "Inconsistent UNI-V2 balances"
        );
    }

    modifier onlyFrozen(address account) {
        Require.that(
            statusOf(account, _state.provider.dao.epoch()) == PoolAccount.Status.Frozen,
            FILE,
            "Not frozen"
        );

        _;
    }

    modifier onlyDao() {
        Require.that(
            msg.sender == address(_state.provider.dao),
            FILE,
            "Not dao"
        );

        _;
    }

    modifier notPaused() {
        Require.that(
            !paused(),
            FILE,
            "Paused"
        );

        _;
    }
}

{
  "compilationTarget": {
    "Pool.sol": "Pool"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}