// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
pragma experimental ABIEncoderV2;

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    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;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(ERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(ERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     */
    function safeApprove(ERC20 token, address spender, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(ERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(ERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function _callOptionalReturn(ERC20 token, bytes memory data) private {

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

contract DSNote {
    event LogNote(
        bytes4 indexed sig,
        address indexed guy,
        bytes32 indexed foo,
        bytes32 indexed bar,
        uint256 wad,
        bytes fax
    ) anonymous;

    modifier note {
        bytes32 foo;
        bytes32 bar;

        assembly {
            foo := calldataload(4)
            bar := calldataload(36)
        }

        emit LogNote(msg.sig, msg.sender, foo, bar, msg.value, msg.data);

        _;
    }
}

abstract contract DSAuthority {
    function canCall(address src, address dst, bytes4 sig) public virtual view returns (bool);
}

contract Discount {
    address public owner;
    mapping(address => CustomServiceFee) public serviceFees;

    uint256 constant MAX_SERVICE_FEE = 400;

    struct CustomServiceFee {
        bool active;
        uint256 amount;
    }

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

    function isCustomFeeSet(address _user) public view returns (bool) {
        return serviceFees[_user].active;
    }

    function getCustomServiceFee(address _user) public view returns (uint256) {
        return serviceFees[_user].amount;
    }

    function setServiceFee(address _user, uint256 _fee) public {
        require(msg.sender == owner, "Only owner");
        require(_fee >= MAX_SERVICE_FEE || _fee == 0);

        serviceFees[_user] = CustomServiceFee({active: true, amount: _fee});
    }

    function disableServiceFee(address _user) public {
        require(msg.sender == owner, "Only owner");

        serviceFees[_user] = CustomServiceFee({active: false, amount: 0});
    }
}

abstract contract IFeeRecipient {
    function getFeeAddr() public view virtual returns (address);
    function changeWalletAddr(address _newWallet) public virtual;
}

abstract contract ComptrollerInterface {
    struct CompMarketState {
        uint224 index;
        uint32 block;
    }

    function claimComp(address holder) public virtual;
    function claimComp(address holder, address[] memory cTokens) public virtual;
    function claimComp(address[] memory holders, address[] memory cTokens, bool borrowers, bool suppliers) public virtual;

    function compSupplyState(address) public view virtual returns (CompMarketState memory);
    function compSupplierIndex(address,address) public view virtual returns (uint);
    function compAccrued(address) public view virtual returns (uint);

    function compBorrowState(address) public view virtual returns (CompMarketState memory);
    function compBorrowerIndex(address,address) public view virtual returns (uint);

    function enterMarkets(address[] calldata cTokens) external virtual returns (uint256[] memory);

    function exitMarket(address cToken) external virtual returns (uint256);

    function getAssetsIn(address account) external virtual view returns (address[] memory);

    function markets(address account) public virtual view returns (bool, uint256);

    function getAccountLiquidity(address account) external virtual view returns (uint256, uint256, uint256);

    function oracle() public virtual view returns (address);

    function borrowCaps(address) external virtual returns (uint256);
}

abstract contract CompoundOracleInterface {
    function getUnderlyingPrice(address cToken) external view virtual returns (uint);
}

abstract contract CEtherInterface {
    function mint() external virtual payable;
    function repayBorrow() external virtual payable;
}

contract DFSExchangeHelper {

    string public constant ERR_OFFCHAIN_DATA_INVALID = "Offchain data invalid";

    using SafeERC20 for ERC20;

    address public constant KYBER_ETH_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
    address public constant EXCHANGE_WETH_ADDRESS = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;

    IFeeRecipient public constant _feeRecipient = IFeeRecipient(0xB1a379f31374e80EEbF701d6a96dF5B716E2C246);

    address public constant DISCOUNT_ADDRESS = 0xB942bC835eE5E2eb166f8A6A171e59D247a14C9e;
    address public constant SAVER_EXCHANGE_REGISTRY = 0x60B43DF7293814Ba3B09c4b8Ba1940803A2be13E;

    address public constant ZRX_ALLOWLIST_ADDR = 0x204D84cF28fbdE05183a484B1382447D5771E316;


    function getDecimals(address _token) internal view returns (uint256) {
        if (_token == KYBER_ETH_ADDRESS) return 18;

        return ERC20(_token).decimals();
    }

    function getBalance(address _tokenAddr) internal view returns (uint balance) {
        if (_tokenAddr == KYBER_ETH_ADDRESS) {
            balance = address(this).balance;
        } else {
            balance = ERC20(_tokenAddr).balanceOf(address(this));
        }
    }

    function sendLeftover(address _srcAddr, address _destAddr, address payable _to) internal {
        // send back any leftover ether or tokens
        if (address(this).balance > 0) {
            _to.transfer(address(this).balance);
        }

        if (getBalance(_srcAddr) > 0) {
            ERC20(_srcAddr).safeTransfer(_to, getBalance(_srcAddr));
        }

        if (getBalance(_destAddr) > 0) {
            ERC20(_destAddr).safeTransfer(_to, getBalance(_destAddr));
        }
    }

    /// @notice Takes a feePercentage and sends it to wallet
    /// @param _amount Dai amount of the whole trade
    /// @param _user Address of the user
    /// @param _token Address of the token
    /// @param _dfsFeeDivider Dfs fee divider
    /// @return feeAmount Amount in Dai owner earned on the fee
    function getFee(uint256 _amount, address _user, address _token, uint256 _dfsFeeDivider) internal returns (uint256 feeAmount) {
        if (_dfsFeeDivider != 0 && Discount(DISCOUNT_ADDRESS).isCustomFeeSet(_user)) {
            _dfsFeeDivider = Discount(DISCOUNT_ADDRESS).getCustomServiceFee(_user);
        }

        if (_dfsFeeDivider == 0) {
            feeAmount = 0;
        } else {
            feeAmount = _amount / _dfsFeeDivider;

            // fee can't go over 10% of the whole amount
            if (feeAmount > (_amount / 10)) {
                feeAmount = _amount / 10;
            }

            address walletAddr = _feeRecipient.getFeeAddr();

            if (_token == KYBER_ETH_ADDRESS) {
                payable(walletAddr).transfer(feeAmount);
            } else {
                ERC20(_token).safeTransfer(walletAddr, feeAmount);
            }
        }
    }

    function sliceUint(bytes memory bs, uint256 start) internal pure returns (uint256) {
        require(bs.length >= start + 32, "slicing out of range");

        uint256 x;
        assembly {
            x := mload(add(bs, add(0x20, start)))
        }

        return x;
    }

        function writeUint256(bytes memory _b, uint256 _index, uint _input) internal pure {
        if (_b.length < _index + 32) {
            revert(ERR_OFFCHAIN_DATA_INVALID);
        }

        bytes32 input = bytes32(_input);

        _index += 32;

        // Read the bytes32 from array memory
        assembly {
            mstore(add(_b, _index), input)
        }
    }

    /// @notice Converts Kybers Eth address -> Weth
    /// @param _src Input address
    function ethToWethAddr(address _src) internal pure returns (address) {
        return _src == KYBER_ETH_ADDRESS ? EXCHANGE_WETH_ADDRESS : _src;
    }
}



interface ExchangeInterfaceV3 {
    function sell(address _srcAddr, address _destAddr, uint _srcAmount, bytes memory _additionalData) external payable returns (uint);

    function buy(address _srcAddr, address _destAddr, uint _destAmount, bytes memory _additionalData) external payable returns(uint);

    function getSellRate(address _srcAddr, address _destAddr, uint _srcAmount, bytes memory _additionalData) external view returns (uint);

    function getBuyRate(address _srcAddr, address _destAddr, uint _srcAmount, bytes memory _additionalData) external view returns (uint);
}



abstract contract TokenInterface {
	address public constant WETH_ADDRESS = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
    
    function allowance(address, address) public virtual returns (uint256);

    function balanceOf(address) public virtual returns (uint256);

    function approve(address, uint256) public virtual;

    function transfer(address, uint256) public virtual returns (bool);

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

    function deposit() public virtual payable;

    function withdraw(uint256) public virtual;
}



interface ERC20 {
    function totalSupply() external view returns (uint256 supply);

    function balanceOf(address _owner) external view returns (uint256 balance);

    function transfer(address _to, uint256 _value) external returns (bool success);

    function transferFrom(address _from, address _to, uint256 _value)
        external
        returns (bool success);

    function approve(address _spender, uint256 _value) external returns (bool success);

    function allowance(address _owner, address _spender) external view returns (uint256 remaining);

    function decimals() external view returns (uint256 digits);

    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

abstract contract DSGuard {
    function canCall(address src_, address dst_, bytes4 sig) public view virtual returns (bool);

    function permit(bytes32 src, bytes32 dst, bytes32 sig) public virtual;

    function forbid(bytes32 src, bytes32 dst, bytes32 sig) public virtual;

    function permit(address src, address dst, bytes32 sig) public virtual;

    function forbid(address src, address dst, bytes32 sig) public virtual;
}


abstract contract DSGuardFactory {
    function newGuard() public virtual returns (DSGuard guard);
}

contract ElixyrsaverLogger {
    event LogEvent(
        address indexed contractAddress,
        address indexed caller,
        string indexed logName,
        bytes data
    );

    // solhint-disable-next-line func-name-mixedcase
    function Log(address _contract, address _caller, string memory _logName, bytes memory _data)
        public
    {
        emit LogEvent(_contract, _caller, _logName, _data);
    }
}

abstract contract GasTokenInterface is ERC20 {
    function free(uint256 value) public virtual returns (bool success);

    function freeUpTo(uint256 value) public virtual returns (uint256 freed);

    function freeFrom(address from, uint256 value) public virtual returns (bool success);

    function freeFromUpTo(address from, uint256 value) public virtual returns (uint256 freed);
}

contract GasBurner {
    // solhint-disable-next-line const-name-snakecase
    GasTokenInterface public constant gasToken = GasTokenInterface(0x0000000000b3F879cb30FE243b4Dfee438691c04);

    modifier burnGas(uint _amount) {
        if (gasToken.balanceOf(address(this)) >= _amount) {
            gasToken.free(_amount);
        }

        _;
    }
}

abstract contract ILendingPool {
    function flashLoan( address payable _receiver, address _reserve, uint _amount, bytes calldata _params) external virtual;
    function deposit(address _reserve, uint256 _amount, uint16 _referralCode) external virtual payable;
	function setUserUseReserveAsCollateral(address _reserve, bool _useAsCollateral) external virtual;
	function borrow(address _reserve, uint256 _amount, uint256 _interestRateMode, uint16 _referralCode) external virtual;
	function repay( address _reserve, uint256 _amount, address payable _onBehalfOf) external virtual payable;
	function swapBorrowRateMode(address _reserve) external virtual;
    function getReserves() external virtual view returns(address[] memory);

    /// @param _reserve underlying token address
    function getReserveData(address _reserve)
        external virtual
        view
        returns (
            uint256 totalLiquidity,               // reserve total liquidity
            uint256 availableLiquidity,           // reserve available liquidity for borrowing
            uint256 totalBorrowsStable,           // total amount of outstanding borrows at Stable rate
            uint256 totalBorrowsVariable,         // total amount of outstanding borrows at Variable rate
            uint256 liquidityRate,                // current deposit APY of the reserve for depositors, in Ray units.
            uint256 variableBorrowRate,           // current variable rate APY of the reserve pool, in Ray units.
            uint256 stableBorrowRate,             // current stable rate APY of the reserve pool, in Ray units.
            uint256 averageStableBorrowRate,      // current average stable borrow rate
            uint256 utilizationRate,              // expressed as total borrows/total liquidity.
            uint256 liquidityIndex,               // cumulative liquidity index
            uint256 variableBorrowIndex,          // cumulative variable borrow index
            address aTokenAddress,                // aTokens contract address for the specific _reserve
            uint40 lastUpdateTimestamp            // timestamp of the last update of reserve data
        );

    /// @param _user users address
    function getUserAccountData(address _user)
        external virtual
        view
        returns (
            uint256 totalLiquidityETH,            // user aggregated deposits across all the reserves. In Wei
            uint256 totalCollateralETH,           // user aggregated collateral across all the reserves. In Wei
            uint256 totalBorrowsETH,              // user aggregated outstanding borrows across all the reserves. In Wei
            uint256 totalFeesETH,                 // user aggregated current outstanding fees in ETH. In Wei
            uint256 availableBorrowsETH,          // user available amount to borrow in ETH
            uint256 currentLiquidationThreshold,  // user current average liquidation threshold across all the collaterals deposited
            uint256 ltv,                          // user average Loan-to-Value between all the collaterals
            uint256 healthFactor                  // user current Health Factor
    );

    /// @param _reserve underlying token address
    /// @param _user users address
    function getUserReserveData(address _reserve, address _user)
        external virtual
        view
        returns (
            uint256 currentATokenBalance,         // user current reserve aToken balance
            uint256 currentBorrowBalance,         // user current reserve outstanding borrow balance
            uint256 principalBorrowBalance,       // user balance of borrowed asset
            uint256 borrowRateMode,               // user borrow rate mode either Stable or Variable
            uint256 borrowRate,                   // user current borrow rate APY
            uint256 liquidityRate,                // user current earn rate on _reserve
            uint256 originationFee,               // user outstanding loan origination fee
            uint256 variableBorrowIndex,          // user variable cumulative index
            uint256 lastUpdateTimestamp,          // Timestamp of the last data update
            bool usageAsCollateralEnabled         // Whether the user's current reserve is enabled as a collateral
    );

    function getReserveConfigurationData(address _reserve)
        external virtual
        view
        returns (
            uint256 ltv,
            uint256 liquidationThreshold,
            uint256 liquidationBonus,
            address rateStrategyAddress,
            bool usageAsCollateralEnabled,
            bool borrowingEnabled,
            bool stableBorrowRateEnabled,
            bool isActive
    );

    // ------------------ LendingPoolCoreData ------------------------
    function getReserveATokenAddress(address _reserve) public virtual view returns (address);
    function getReserveConfiguration(address _reserve)
        external virtual
        view
        returns (uint256, uint256, uint256, bool);
    function getUserUnderlyingAssetBalance(address _reserve, address _user)
        public virtual
        view
        returns (uint256);

    function getReserveCurrentLiquidityRate(address _reserve)
        public virtual
        view
        returns (uint256);
    function getReserveCurrentVariableBorrowRate(address _reserve)
        public virtual
        view
        returns (uint256);
    function getReserveCurrentStableBorrowRate(address _reserve)
        public virtual
        view
        returns (uint256);
    function getReserveTotalLiquidity(address _reserve)
        public virtual
        view
        returns (uint256);
    function getReserveAvailableLiquidity(address _reserve)
        public virtual
        view
        returns (uint256);
    function getReserveTotalBorrowsVariable(address _reserve)
        public virtual
        view
        returns (uint256);
    function getReserveTotalBorrowsStable(address _reserve)
        public virtual
        view
        returns (uint256);

    // ---------------- LendingPoolDataProvider ---------------------
    function calculateUserGlobalData(address _user)
        public virtual
        view
        returns (
            uint256 totalLiquidityBalanceETH,
            uint256 totalCollateralBalanceETH,
            uint256 totalBorrowBalanceETH,
            uint256 totalFeesETH,
            uint256 currentLtv,
            uint256 currentLiquidationThreshold,
            uint256 healthFactor,
            bool healthFactorBelowThreshold
        );
}

contract DSMath {
    function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x + y) >= x);
    }

    function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x - y) <= x);
    }

    function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require(y == 0 || (z = x * y) / y == x);
    }

    function div(uint256 x, uint256 y) internal pure returns (uint256 z) {
        return x / y;
    }

    function min(uint256 x, uint256 y) internal pure returns (uint256 z) {
        return x <= y ? x : y;
    }

    function max(uint256 x, uint256 y) internal pure returns (uint256 z) {
        return x >= y ? x : y;
    }

    function imin(int256 x, int256 y) internal pure returns (int256 z) {
        return x <= y ? x : y;
    }

    function imax(int256 x, int256 y) internal pure returns (int256 z) {
        return x >= y ? x : y;
    }

    uint256 constant WAD = 10**18;
    uint256 constant RAY = 10**27;

    function wmul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        z = add(mul(x, y), WAD / 2) / WAD;
    }

    function rmul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        z = add(mul(x, y), RAY / 2) / RAY;
    }

    function wdiv(uint256 x, uint256 y) internal pure returns (uint256 z) {
        z = add(mul(x, WAD), y / 2) / y;
    }

    function rdiv(uint256 x, uint256 y) internal pure returns (uint256 z) {
        z = add(mul(x, RAY), y / 2) / y;
    }

    // This famous algorithm is called "exponentiation by squaring"
    // and calculates x^n with x as fixed-point and n as regular unsigned.
    //
    // It's O(log n), instead of O(n) for naive repeated multiplication.
    //
    // These facts are why it works:
    //
    //  If n is even, then x^n = (x^2)^(n/2).
    //  If n is odd,  then x^n = x * x^(n-1),
    //   and applying the equation for even x gives
    //    x^n = x * (x^2)^((n-1) / 2).
    //
    //  Also, EVM division is flooring and
    //    floor[(n-1) / 2] = floor[n / 2].
    //
    function rpow(uint256 x, uint256 n) internal pure returns (uint256 z) {
        z = n % 2 != 0 ? x : RAY;

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

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

contract AdminAuth {

    using SafeERC20 for ERC20;

    address public owner;
    address public admin;

    modifier onlyOwner() {
        require(owner == msg.sender);
        _;
    }

    modifier onlyAdmin() {
        require(admin == msg.sender);
        _;
    }

    constructor() public {
        owner = msg.sender;
        admin = 0xac04A6f65491Df9634f6c5d640Bcc7EfFdbea326;
    }

    /// @notice Admin is set by owner first time, after that admin is super role and has permission to change owner
    /// @param _admin Address of multisig that becomes admin
    function setAdminByOwner(address _admin) public {
        require(msg.sender == owner);
        require(admin == address(0));

        admin = _admin;
    }

    /// @notice Admin is able to set new admin
    /// @param _admin Address of multisig that becomes new admin
    function setAdminByAdmin(address _admin) public {
        require(msg.sender == admin);

        admin = _admin;
    }

    /// @notice Admin is able to change owner
    /// @param _owner Address of new owner
    function setOwnerByAdmin(address _owner) public {
        require(msg.sender == admin);

        owner = _owner;
    }

    /// @notice Destroy the contract
    function kill() public onlyOwner {
        selfdestruct(payable(owner));
    }

    /// @notice  withdraw stuck funds
    function withdrawStuckFunds(address _token, uint _amount) public onlyOwner {
        if (_token == 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE) {
            payable(owner).transfer(_amount);
        } else {
            ERC20(_token).safeTransfer(owner, _amount);
        }
    }
}


contract ZrxAllowlist is AdminAuth {

    mapping (address => bool) public zrxAllowlist;
    mapping(address => bool) private nonPayableAddrs;

    constructor() public {

    }

    function setAllowlistAddr(address _zrxAddr, bool _state) public onlyOwner {
        zrxAllowlist[_zrxAddr] = _state;
    }

    function isZrxAddr(address _zrxAddr) public view returns (bool) {
        return zrxAllowlist[_zrxAddr];
    }

    function addNonPayableAddr(address _nonPayableAddr) public onlyOwner {
		nonPayableAddrs[_nonPayableAddr] = true;
	}

	function removeNonPayableAddr(address _nonPayableAddr) public onlyOwner {
		nonPayableAddrs[_nonPayableAddr] = false;
	}

	function isNonPayableAddr(address _addr) public view returns(bool) {
		return nonPayableAddrs[_addr];
	}
}

contract DFSExchangeData {

    // first is empty to keep the legacy order in place
    enum ExchangeType { _, OASIS, KYBER, UNISWAP, ZEROX }

    enum ActionType { SELL, BUY }

    struct OffchainData {
        address wrapper;
        address exchangeAddr;
        address allowanceTarget;
        uint256 price;
        uint256 protocolFee;
        bytes callData;
    }

    struct ExchangeData {
        address srcAddr;
        address destAddr;
        uint256 srcAmount;
        uint256 destAmount;
        uint256 minPrice;
        uint256 dfsFeeDivider; // service fee divider
        address user; // user to check special fee
        address wrapper;
        bytes wrapperData;
        OffchainData offchainData;
    }

    function packExchangeData(ExchangeData memory _exData) public pure returns(bytes memory) {
        return abi.encode(_exData);
    }

    function unpackExchangeData(bytes memory _data) public pure returns(ExchangeData memory _exData) {
        _exData = abi.decode(_data, (ExchangeData));
    }
}

contract SaverExchangeRegistry is AdminAuth {

	mapping(address => bool) private wrappers;

	constructor() public {

	}

	function addWrapper(address _wrapper) public onlyOwner {
		wrappers[_wrapper] = true;
	}

	function removeWrapper(address _wrapper) public onlyOwner {
		wrappers[_wrapper] = false;
	}

	function isWrapper(address _wrapper) public view returns(bool) {
		return wrappers[_wrapper];
	}
}

abstract contract OffchainWrapperInterface is DFSExchangeData {
    function takeOrder(
        ExchangeData memory _exData,
        ActionType _type
    ) virtual public payable returns (bool success, uint256);
}

contract DFSExchangeCore is DFSExchangeHelper, DSMath, DFSExchangeData {

    string public constant ERR_SLIPPAGE_HIT = "Slippage hit";
    string public constant ERR_DEST_AMOUNT_MISSING = "Dest amount missing";
    string public constant ERR_WRAPPER_INVALID = "Wrapper invalid";
    string public constant ERR_NOT_ZEROX_EXCHANGE = "Zerox exchange invalid";

    /// @notice Internal method that preforms a sell on 0x/on-chain
    /// @dev Usefull for other DFS contract to integrate for exchanging
    /// @param exData Exchange data struct
    /// @return (address, uint) Address of the wrapper used and destAmount
    function _sell(ExchangeData memory exData) internal returns (address, uint) {

        address wrapper;
        uint swapedTokens;
        bool success;

        // if selling eth, convert to weth
        if (exData.srcAddr == KYBER_ETH_ADDRESS) {
            exData.srcAddr = ethToWethAddr(exData.srcAddr);
            TokenInterface(EXCHANGE_WETH_ADDRESS).deposit{value: exData.srcAmount}();
        }

        exData.srcAmount -= getFee(exData.srcAmount, exData.user, exData.srcAddr, exData.dfsFeeDivider);

        // Try 0x first and then fallback on specific wrapper
        if (exData.offchainData.price > 0) {
            (success, swapedTokens) = takeOrder(exData, ActionType.SELL);

            if (success) {
                wrapper = exData.offchainData.exchangeAddr;
            }
        }

        // fallback to desired wrapper if 0x failed
        if (!success) {
            swapedTokens = saverSwap(exData, ActionType.SELL);
            wrapper = exData.wrapper;
        }

        // if anything is left in weth, pull it to user as eth
        if (getBalance(EXCHANGE_WETH_ADDRESS) > 0) {
            TokenInterface(EXCHANGE_WETH_ADDRESS).withdraw(
                TokenInterface(EXCHANGE_WETH_ADDRESS).balanceOf(address(this))
            );
        }

        if (exData.destAddr == EXCHANGE_WETH_ADDRESS) {
            require(getBalance(KYBER_ETH_ADDRESS) >= wmul(exData.minPrice, exData.srcAmount), ERR_SLIPPAGE_HIT);
        } else {
            require(getBalance(exData.destAddr) >= wmul(exData.minPrice, exData.srcAmount), ERR_SLIPPAGE_HIT);
        }

        return (wrapper, swapedTokens);
    }

    /// @notice Internal method that preforms a buy on 0x/on-chain
    /// @dev Usefull for other DFS contract to integrate for exchanging
    /// @param exData Exchange data struct
    /// @return (address, uint) Address of the wrapper used and srcAmount
    function _buy(ExchangeData memory exData) internal returns (address, uint) {

        address wrapper;
        uint swapedTokens;
        bool success;

        require(exData.destAmount != 0, ERR_DEST_AMOUNT_MISSING);

        exData.srcAmount -= getFee(exData.srcAmount, exData.user, exData.srcAddr, exData.dfsFeeDivider);

        // if selling eth, convert to weth
        if (exData.srcAddr == KYBER_ETH_ADDRESS) {
            exData.srcAddr = ethToWethAddr(exData.srcAddr);
            TokenInterface(EXCHANGE_WETH_ADDRESS).deposit{value: exData.srcAmount}();
        }

        if (exData.offchainData.price > 0) {
            (success, swapedTokens) = takeOrder(exData, ActionType.BUY);

            if (success) {
                wrapper = exData.offchainData.exchangeAddr;
            }
        }

        // fallback to desired wrapper if 0x failed
        if (!success) {
            swapedTokens = saverSwap(exData, ActionType.BUY);
            wrapper = exData.wrapper;
        }

        // if anything is left in weth, pull it to user as eth
        if (getBalance(EXCHANGE_WETH_ADDRESS) > 0) {
            TokenInterface(EXCHANGE_WETH_ADDRESS).withdraw(
                TokenInterface(EXCHANGE_WETH_ADDRESS).balanceOf(address(this))
            );
        }

        if (exData.destAddr == EXCHANGE_WETH_ADDRESS) {
            require(getBalance(KYBER_ETH_ADDRESS) >= exData.destAmount, ERR_SLIPPAGE_HIT);
        } else {
            require(getBalance(exData.destAddr) >= exData.destAmount, ERR_SLIPPAGE_HIT);
        }

        return (wrapper, getBalance(exData.destAddr));
    }

    /// @notice Takes order from 0x and returns bool indicating if it is successful
    /// @param _exData Exchange data
    function takeOrder(
        ExchangeData memory _exData,
        ActionType _type
    ) private returns (bool success, uint256) {
        if (!ZrxAllowlist(ZRX_ALLOWLIST_ADDR).isZrxAddr(_exData.offchainData.exchangeAddr)) {
            return (false, 0);
        }

        if (!SaverExchangeRegistry(SAVER_EXCHANGE_REGISTRY).isWrapper(_exData.offchainData.wrapper)) {
            return (false, 0);
        }

        // send src amount
        ERC20(_exData.srcAddr).safeTransfer(_exData.offchainData.wrapper, _exData.srcAmount);

        return OffchainWrapperInterface(_exData.offchainData.wrapper).takeOrder{value: _exData.offchainData.protocolFee}(_exData, _type);
    }

    /// @notice Calls wraper contract for exchage to preform an on-chain swap
    /// @param _exData Exchange data struct
    /// @param _type Type of action SELL|BUY
    /// @return swapedTokens For Sell that the destAmount, for Buy thats the srcAmount
    function saverSwap(ExchangeData memory _exData, ActionType _type) internal returns (uint swapedTokens) {
        require(SaverExchangeRegistry(SAVER_EXCHANGE_REGISTRY).isWrapper(_exData.wrapper), ERR_WRAPPER_INVALID);

        ERC20(_exData.srcAddr).safeTransfer(_exData.wrapper, _exData.srcAmount);

        if (_type == ActionType.SELL) {
            swapedTokens = ExchangeInterfaceV3(_exData.wrapper).
                    sell(_exData.srcAddr, _exData.destAddr, _exData.srcAmount, _exData.wrapperData);
        } else {
            swapedTokens = ExchangeInterfaceV3(_exData.wrapper).
                    buy(_exData.srcAddr, _exData.destAddr, _exData.destAmount, _exData.wrapperData);
        }
    }

    // solhint-disable-next-line no-empty-blocks
    receive() external virtual payable {}
}

abstract contract CTokenInterface is ERC20 {
    function mint(uint256 mintAmount) external virtual returns (uint256);

    // function mint() external virtual payable;

    function accrueInterest() public virtual returns (uint);

    function redeem(uint256 redeemTokens) external virtual returns (uint256);

    function redeemUnderlying(uint256 redeemAmount) external virtual returns (uint256);

    function borrow(uint256 borrowAmount) external virtual returns (uint256);
    function borrowIndex() public view virtual returns (uint);
    function borrowBalanceStored(address) public view virtual returns(uint);

    function repayBorrow(uint256 repayAmount) external virtual returns (uint256);

    function repayBorrow() external virtual payable;

    function repayBorrowBehalf(address borrower, uint256 repayAmount) external virtual returns (uint256);

    function repayBorrowBehalf(address borrower) external virtual payable;

    function liquidateBorrow(address borrower, uint256 repayAmount, address cTokenCollateral)
        external virtual
        returns (uint256);

    function liquidateBorrow(address borrower, address cTokenCollateral) external virtual payable;

    function exchangeRateCurrent() external virtual returns (uint256);

    function supplyRatePerBlock() external virtual returns (uint256);

    function borrowRatePerBlock() external virtual returns (uint256);

    function totalReserves() external virtual returns (uint256);

    function reserveFactorMantissa() external virtual returns (uint256);

    function borrowBalanceCurrent(address account) external virtual returns (uint256);

    function totalBorrowsCurrent() external virtual returns (uint256);

    function getCash() external virtual returns (uint256);

    function balanceOfUnderlying(address owner) external virtual returns (uint256);

    function underlying() external virtual returns (address);

    function getAccountSnapshot(address account) external virtual view returns (uint, uint, uint, uint);
}

contract DSAuthEvents {
    event LogSetAuthority(address indexed authority);
    event LogSetOwner(address indexed owner);
}


contract DSAuth is DSAuthEvents {
    DSAuthority public authority;
    address public owner;

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

    function setOwner(address owner_) public auth {
        owner = owner_;
        emit LogSetOwner(owner);
    }

    function setAuthority(DSAuthority authority_) public auth {
        authority = authority_;
        emit LogSetAuthority(address(authority));
    }

    modifier auth {
        require(isAuthorized(msg.sender, msg.sig));
        _;
    }

    function isAuthorized(address src, bytes4 sig) internal view returns (bool) {
        if (src == address(this)) {
            return true;
        } else if (src == owner) {
            return true;
        } else if (authority == DSAuthority(0)) {
            return false;
        } else {
            return authority.canCall(src, address(this), sig);
        }
    }
}

abstract contract DSProxy is DSAuth, DSNote {
    DSProxyCache public cache; // global cache for contracts

    constructor(address _cacheAddr) public {
        require(setCache(_cacheAddr));
    }

    // solhint-disable-next-line no-empty-blocks
    receive() external payable {}

    // use the proxy to execute calldata _data on contract _code
    // function execute(bytes memory _code, bytes memory _data)
    //     public
    //     payable
    //     virtual
    //     returns (address target, bytes32 response);

    function execute(address _target, bytes memory _data)
        public
        payable
        virtual
        returns (bytes32 response);

    //set new cache
    function setCache(address _cacheAddr) public virtual payable returns (bool);
}

contract DSProxyCache {
    mapping(bytes32 => address) cache;

    function read(bytes memory _code) public view returns (address) {
        bytes32 hash = keccak256(_code);
        return cache[hash];
    }

    function write(bytes memory _code) public returns (address target) {
        assembly {
            target := create(0, add(_code, 0x20), mload(_code))
            switch iszero(extcodesize(target))
                case 1 {
                    // throw if contract failed to deploy
                    revert(0, 0)
                }
        }
        bytes32 hash = keccak256(_code);
        cache[hash] = target;
    }
}

contract CarefulMath {

    /**
     * @dev Possible error codes that we can return
     */
    enum MathError {
        NO_ERROR,
        DIVISION_BY_ZERO,
        INTEGER_OVERFLOW,
        INTEGER_UNDERFLOW
    }

    /**
    * @dev Multiplies two numbers, returns an error on overflow.
    */
    function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (a == 0) {
            return (MathError.NO_ERROR, 0);
        }

        uint c = a * b;

        if (c / a != b) {
            return (MathError.INTEGER_OVERFLOW, 0);
        } else {
            return (MathError.NO_ERROR, c);
        }
    }

    /**
    * @dev Integer division of two numbers, truncating the quotient.
    */
    function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (b == 0) {
            return (MathError.DIVISION_BY_ZERO, 0);
        }

        return (MathError.NO_ERROR, a / b);
    }

    /**
    * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
    */
    function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
        if (b <= a) {
            return (MathError.NO_ERROR, a - b);
        } else {
            return (MathError.INTEGER_UNDERFLOW, 0);
        }
    }

    /**
    * @dev Adds two numbers, returns an error on overflow.
    */
    function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
        uint c = a + b;

        if (c >= a) {
            return (MathError.NO_ERROR, c);
        } else {
            return (MathError.INTEGER_OVERFLOW, 0);
        }
    }

    /**
    * @dev add a and b and then subtract c
    */
    function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
        (MathError err0, uint sum) = addUInt(a, b);

        if (err0 != MathError.NO_ERROR) {
            return (err0, 0);
        }

        return subUInt(sum, c);
    }
}

contract Exponential is CarefulMath {
    uint constant expScale = 1e18;
    uint constant doubleScale = 1e36;
    uint constant halfExpScale = expScale/2;
    uint constant mantissaOne = expScale;

    struct Exp {
        uint mantissa;
    }

    struct Double {
        uint mantissa;
    }

    /**
     * @dev Creates an exponential from numerator and denominator values.
     *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
     *            or if `denom` is zero.
     */
    function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        (MathError err1, uint rational) = divUInt(scaledNumerator, denom);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: rational}));
    }

    /**
     * @dev Adds two exponentials, returning a new exponential.
     */
    function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Subtracts two exponentials, returning a new exponential.
     */
    function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);

        return (error, Exp({mantissa: result}));
    }

    /**
     * @dev Multiply an Exp by a scalar, returning a new Exp.
     */
    function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
    }

    /**
     * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
     */
    function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(product));
    }

    /**
     * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
     */
    function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
        (MathError err, Exp memory product) = mulScalar(a, scalar);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return addUInt(truncate(product), addend);
    }

    /**
     * @dev Divide an Exp by a scalar, returning a new Exp.
     */
    function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
        (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
    }

    /**
     * @dev Divide a scalar by an Exp, returning a new Exp.
     */
    function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {
        /*
          We are doing this as:
          getExp(mulUInt(expScale, scalar), divisor.mantissa)

          How it works:
          Exp = a / b;
          Scalar = s;
          `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
        */
        (MathError err0, uint numerator) = mulUInt(expScale, scalar);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }
        return getExp(numerator, divisor.mantissa);
    }

    /**
     * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
     */
    function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {
        (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
        if (err != MathError.NO_ERROR) {
            return (err, 0);
        }

        return (MathError.NO_ERROR, truncate(fraction));
    }

    /**
     * @dev Multiplies two exponentials, returning a new exponential.
     */
    function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {

        (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);
        if (err0 != MathError.NO_ERROR) {
            return (err0, Exp({mantissa: 0}));
        }

        // We add half the scale before dividing so that we get rounding instead of truncation.
        //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
        // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
        (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);
        if (err1 != MathError.NO_ERROR) {
            return (err1, Exp({mantissa: 0}));
        }

        (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);
        // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
        assert(err2 == MathError.NO_ERROR);

        return (MathError.NO_ERROR, Exp({mantissa: product}));
    }

    /**
     * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
     */
    function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {
        return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
    }

    /**
     * @dev Multiplies three exponentials, returning a new exponential.
     */
    function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {
        (MathError err, Exp memory ab) = mulExp(a, b);
        if (err != MathError.NO_ERROR) {
            return (err, ab);
        }
        return mulExp(ab, c);
    }

    /**
     * @dev Divides two exponentials, returning a new exponential.
     *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
     *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
     */
    function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
        return getExp(a.mantissa, b.mantissa);
    }

    /**
     * @dev Truncates the given exp to a whole number value.
     *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
     */
    function truncate(Exp memory exp) pure internal returns (uint) {
        // Note: We are not using careful math here as we're performing a division that cannot fail
        return exp.mantissa / expScale;
    }

    /**
     * @dev Checks if first Exp is less than second Exp.
     */
    function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa < right.mantissa;
    }

    /**
     * @dev Checks if left Exp <= right Exp.
     */
    function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa <= right.mantissa;
    }

    /**
     * @dev Checks if left Exp > right Exp.
     */
    function greaterThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
        return left.mantissa > right.mantissa;
    }

    /**
     * @dev returns true if Exp is exactly zero
     */
    function isZeroExp(Exp memory value) pure internal returns (bool) {
        return value.mantissa == 0;
    }

    function sub_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
        return Exp({mantissa: sub_(a.mantissa, b.mantissa)});
    }

    function sub_(Double memory a, Double memory b) pure internal returns (Double memory) {
        return Double({mantissa: sub_(a.mantissa, b.mantissa)});
    }

    function sub_(uint a, uint b) pure internal returns (uint) {
        return sub_(a, b, "subtraction underflow");
    }

    function sub_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
        require(b <= a, errorMessage);
        return a - b;
    }

    function mul_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
        return Exp({mantissa: mul_(a.mantissa, b.mantissa) / expScale});
    }

    function mul_(Exp memory a, uint b) pure internal returns (Exp memory) {
        return Exp({mantissa: mul_(a.mantissa, b)});
    }

    function mul_(uint a, Exp memory b) pure internal returns (uint) {
        return mul_(a, b.mantissa) / expScale;
    }

    function mul_(Double memory a, Double memory b) pure internal returns (Double memory) {
        return Double({mantissa: mul_(a.mantissa, b.mantissa) / doubleScale});
    }

    function mul_(Double memory a, uint b) pure internal returns (Double memory) {
        return Double({mantissa: mul_(a.mantissa, b)});
    }

    function mul_(uint a, Double memory b) pure internal returns (uint) {
        return mul_(a, b.mantissa) / doubleScale;
    }

    function mul_(uint a, uint b) pure internal returns (uint) {
        return mul_(a, b, "multiplication overflow");
    }

    function mul_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
        if (a == 0 || b == 0) {
            return 0;
        }
        uint c = a * b;
        require(c / a == b, errorMessage);
        return c;
    }

    function div_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
        return Exp({mantissa: div_(mul_(a.mantissa, expScale), b.mantissa)});
    }

    function div_(Exp memory a, uint b) pure internal returns (Exp memory) {
        return Exp({mantissa: div_(a.mantissa, b)});
    }

    function div_(uint a, Exp memory b) pure internal returns (uint) {
        return div_(mul_(a, expScale), b.mantissa);
    }

    function div_(Double memory a, Double memory b) pure internal returns (Double memory) {
        return Double({mantissa: div_(mul_(a.mantissa, doubleScale), b.mantissa)});
    }

    function div_(Double memory a, uint b) pure internal returns (Double memory) {
        return Double({mantissa: div_(a.mantissa, b)});
    }

    function div_(uint a, Double memory b) pure internal returns (uint) {
        return div_(mul_(a, doubleScale), b.mantissa);
    }

    function div_(uint a, uint b) pure internal returns (uint) {
        return div_(a, b, "divide by zero");
    }

    function div_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
        require(b > 0, errorMessage);
        return a / b;
    }

    function add_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
        return Exp({mantissa: add_(a.mantissa, b.mantissa)});
    }

    function add_(Double memory a, Double memory b) pure internal returns (Double memory) {
        return Double({mantissa: add_(a.mantissa, b.mantissa)});
    }

    function add_(uint a, uint b) pure internal returns (uint) {
        return add_(a, b, "addition overflow");
    }

    function add_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
        uint c = a + b;
        require(c >= a, errorMessage);
        return c;
    }
}

contract BotRegistry is AdminAuth {

    mapping (address => bool) public botList;

    constructor() public {
        botList[0xac04A6f65491Df9634f6c5d640Bcc7EfFdbea326] = true;
    }

    function setBot(address _botAddr, bool _state) public onlyOwner {
        botList[_botAddr] = _state;
    }

}

library Address {
    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);
    }

    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");
    }

    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

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

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

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

/// @title Utlity functions for Compound contracts
contract CompoundSaverHelper is DSMath, Exponential {

    using SafeERC20 for ERC20;

    IFeeRecipient public constant feeRecipient = IFeeRecipient(0xB1a379f31374e80EEbF701d6a96dF5B716E2C246);

    address public constant DISCOUNT_ADDR = 0xB942bC835eE5E2eb166f8A6A171e59D247a14C9e;

    uint public constant MANUAL_SERVICE_FEE = 400; // 0.25% Fee
    uint public constant AUTOMATIC_SERVICE_FEE = 333; // 0.3% Fee

    address public constant ETH_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
    address public constant CETH_ADDRESS = 0x4Ddc2D193948926D02f9B1fE9e1daa0718270ED5;
    address public constant COMPTROLLER = 0x3d9819210A31b4961b30EF54bE2aeD79B9c9Cd3B;

    address public constant COMPOUND_LOGGER = 0xF1E0EFf3DFddA747058f082123473d9b03aab42C;

    address public constant BOT_REGISTRY_ADDRESS = 0x088d1fFfb9e106B7aE0dB4fC6d1877D5c1aE2276;

    /// @notice Helper method to payback the Compound debt
    /// @dev If amount is bigger it will repay the whole debt and send the extra to the _user
    /// @param _amount Amount of tokens we want to repay
    /// @param _cBorrowToken Ctoken address we are repaying
    /// @param _borrowToken Token address we are repaying
    /// @param _user Owner of the compound position we are paying back
    function paybackDebt(uint _amount, address _cBorrowToken, address _borrowToken, address payable _user) internal {
        uint wholeDebt = CTokenInterface(_cBorrowToken).borrowBalanceCurrent(address(this));

        if (_amount > wholeDebt) {
            if (_borrowToken == ETH_ADDRESS) {
                _user.transfer((_amount - wholeDebt));
            } else {
                ERC20(_borrowToken).safeTransfer(_user, (_amount - wholeDebt));
            }

            _amount = wholeDebt;
        }

        approveCToken(_borrowToken, _cBorrowToken);

        if (_borrowToken == ETH_ADDRESS) {
            CEtherInterface(_cBorrowToken).repayBorrow{value: _amount}();
        } else {
            require(CTokenInterface(_cBorrowToken).repayBorrow(_amount) == 0);
        }
    }

    /// @notice Calculates the fee amount
    /// @param _amount Amount that is converted
    /// @param _user Actuall user addr not DSProxy
    /// @param _gasCost Ether amount of gas we are spending for tx
    /// @param _cTokenAddr CToken addr. of token we are getting for the fee
    /// @return feeAmount The amount we took for the fee
    function getFee(uint _amount, address _user, uint _gasCost, address _cTokenAddr) internal returns (uint feeAmount) {
        uint fee = MANUAL_SERVICE_FEE;

        if (BotRegistry(BOT_REGISTRY_ADDRESS).botList(tx.origin)) {
            fee = AUTOMATIC_SERVICE_FEE;
        }

        address tokenAddr = getUnderlyingAddr(_cTokenAddr);

        if (Discount(DISCOUNT_ADDR).isCustomFeeSet(_user)) {
            fee = Discount(DISCOUNT_ADDR).getCustomServiceFee(_user);
        }

        feeAmount = (fee == 0) ? 0 : (_amount / fee);

        if (_gasCost != 0) {
            address oracle = ComptrollerInterface(COMPTROLLER).oracle();

            uint usdTokenPrice = CompoundOracleInterface(oracle).getUnderlyingPrice(_cTokenAddr);
            uint ethPrice = CompoundOracleInterface(oracle).getUnderlyingPrice(CETH_ADDRESS);

            uint tokenPriceInEth = wdiv(usdTokenPrice, ethPrice);

            _gasCost = wdiv(_gasCost, tokenPriceInEth);

            feeAmount = add(feeAmount, _gasCost);
        }

        // fee can't go over 20% of the whole amount
        if (feeAmount > (_amount / 5)) {
            feeAmount = _amount / 5;
        }

        address walletAddr = feeRecipient.getFeeAddr();

        if (tokenAddr == ETH_ADDRESS) {
            payable(walletAddr).transfer(feeAmount);
        } else {
            ERC20(tokenAddr).safeTransfer(walletAddr, feeAmount);
        }
    }

    /// @notice Calculates the gas cost of transaction and send it to wallet
    /// @param _amount Amount that is converted
    /// @param _gasCost Ether amount of gas we are spending for tx
    /// @param _cTokenAddr CToken addr. of token we are getting for the fee
    /// @return feeAmount The amount we took for the fee
    function getGasCost(uint _amount, uint _gasCost, address _cTokenAddr) internal returns (uint feeAmount) {
        address tokenAddr = getUnderlyingAddr(_cTokenAddr);

        if (_gasCost != 0) {
            address oracle = ComptrollerInterface(COMPTROLLER).oracle();

            uint usdTokenPrice = CompoundOracleInterface(oracle).getUnderlyingPrice(_cTokenAddr);
            uint ethPrice = CompoundOracleInterface(oracle).getUnderlyingPrice(CETH_ADDRESS);

            uint tokenPriceInEth = wdiv(usdTokenPrice, ethPrice);

            feeAmount = wdiv(_gasCost, tokenPriceInEth);
        }

        // fee can't go over 20% of the whole amount
        if (feeAmount > (_amount / 5)) {
            feeAmount = _amount / 5;
        }

        address walletAddr = feeRecipient.getFeeAddr();

        if (tokenAddr == ETH_ADDRESS) {
            payable(walletAddr).transfer(feeAmount);
        } else {
            ERC20(tokenAddr).safeTransfer(walletAddr, feeAmount);
        }
    }

    /// @notice Enters the market for the collatera and borrow tokens
    /// @param _cTokenAddrColl Collateral address we are entering the market in
    /// @param _cTokenAddrBorrow Borrow address we are entering the market in
    function enterMarket(address _cTokenAddrColl, address _cTokenAddrBorrow) internal {
        address[] memory markets = new address[](2);
        markets[0] = _cTokenAddrColl;
        markets[1] = _cTokenAddrBorrow;

        ComptrollerInterface(COMPTROLLER).enterMarkets(markets);
    }

    /// @notice Approves CToken contract to pull underlying tokens from the DSProxy
    /// @param _tokenAddr Token we are trying to approve
    /// @param _cTokenAddr Address which will gain the approval
    function approveCToken(address _tokenAddr, address _cTokenAddr) internal {
        if (_tokenAddr != ETH_ADDRESS) {
            ERC20(_tokenAddr).safeApprove(_cTokenAddr, uint(-1));
        }
    }

    /// @notice Returns the underlying address of the cToken asset
    /// @param _cTokenAddress cToken address
    /// @return Token address of the cToken specified
    function getUnderlyingAddr(address _cTokenAddress) internal returns (address) {
        if (_cTokenAddress == CETH_ADDRESS) {
            return ETH_ADDRESS;
        } else {
            return CTokenInterface(_cTokenAddress).underlying();
        }
    }

    /// @notice Returns the owner of the DSProxy that called the contract
    function getUserAddress() internal view returns (address) {
        DSProxy proxy = DSProxy(uint160(address(this)));

        return proxy.owner();
    }

    /// @notice Returns the maximum amount of collateral available to withdraw
    /// @dev Due to rounding errors the result is - 1% wei from the exact amount
    /// @param _cCollAddress Collateral we are getting the max value of
    /// @param _account Users account
    /// @return Returns the max. collateral amount in that token
    function getMaxCollateral(address _cCollAddress, address _account) public returns (uint) {
        (, uint liquidityInUsd, ) = ComptrollerInterface(COMPTROLLER).getAccountLiquidity(_account);
        uint usersBalance = CTokenInterface(_cCollAddress).balanceOfUnderlying(_account);
        address oracle = ComptrollerInterface(COMPTROLLER).oracle();

        if (liquidityInUsd == 0) return usersBalance;

        CTokenInterface(_cCollAddress).accrueInterest();

        (, uint collFactorMantissa) = ComptrollerInterface(COMPTROLLER).markets(_cCollAddress);
        Exp memory collateralFactor = Exp({mantissa: collFactorMantissa});

        (, uint tokensToUsd) = divScalarByExpTruncate(liquidityInUsd, collateralFactor);

        uint usdPrice = CompoundOracleInterface(oracle).getUnderlyingPrice(_cCollAddress);
        uint liqInToken = wdiv(tokensToUsd, usdPrice);

        if (liqInToken > usersBalance) return usersBalance;

        return sub(liqInToken, (liqInToken / 100)); // cut off 1% due to rounding issues
    }

    /// @notice Returns the maximum amount of borrow amount available
    /// @dev Due to rounding errors the result is - 1% wei from the exact amount
    /// @param _cBorrowAddress Borrow token we are getting the max value of
    /// @param _account Users account
    /// @return Returns the max. borrow amount in that token
    function getMaxBorrow(address _cBorrowAddress, address _account) public returns (uint) {
        (, uint liquidityInUsd, ) = ComptrollerInterface(COMPTROLLER).getAccountLiquidity(_account);
        address oracle = ComptrollerInterface(COMPTROLLER).oracle();

        CTokenInterface(_cBorrowAddress).accrueInterest();

        uint usdPrice = CompoundOracleInterface(oracle).getUnderlyingPrice(_cBorrowAddress);
        uint liquidityInToken = wdiv(liquidityInUsd, usdPrice);

        return sub(liquidityInToken, (liquidityInToken / 100)); // cut off 1% due to rounding issues
    }

    function isAutomation() internal view returns(bool) {
        return BotRegistry(BOT_REGISTRY_ADDRESS).botList(tx.origin);
    }
}

/// @title Contract that implements repay/boost functionality
contract CompoundSaverProxy is CompoundSaverHelper, DFSExchangeCore {

    ElixyrsaverLogger public constant logger = ElixyrsaverLogger(0x4a35CcB1cB7F8388CE640128aE4a744dff42226e);

    /// @notice Withdraws collateral, converts to borrowed token and repays debt
    /// @dev Called through the DSProxy
    /// @param _exData Exchange data
    /// @param _cAddresses Coll/Debt addresses [cCollAddress, cBorrowAddress]
    /// @param _gasCost Gas cost for specific transaction
    function repay(
        ExchangeData memory _exData,
        address[2] memory _cAddresses, // cCollAddress, cBorrowAddress
        uint256 _gasCost
    ) public payable {
        enterMarket(_cAddresses[0], _cAddresses[1]);

        address payable user = payable(getUserAddress());

        uint maxColl = getMaxCollateral(_cAddresses[0], address(this));

        uint collAmount = (_exData.srcAmount > maxColl) ? maxColl : _exData.srcAmount;

        require(CTokenInterface(_cAddresses[0]).redeemUnderlying(collAmount) == 0);

        address collToken = getUnderlyingAddr(_cAddresses[0]);
        address borrowToken = getUnderlyingAddr(_cAddresses[1]);

        uint swapAmount = 0;

        if (collToken != borrowToken) {
            _exData.srcAmount = collAmount;
            _exData.dfsFeeDivider = isAutomation() ? AUTOMATIC_SERVICE_FEE : MANUAL_SERVICE_FEE;
            _exData.user = user;

            (, swapAmount) = _sell(_exData);
            swapAmount -= getGasCost(swapAmount, _gasCost, _cAddresses[1]);
        } else {
            swapAmount = collAmount;
            swapAmount -= getGasCost(swapAmount, _gasCost, _cAddresses[1]);
        }

        paybackDebt(swapAmount, _cAddresses[1], borrowToken, user);

        // handle 0x fee
        tx.origin.transfer(address(this).balance);

        // log amount, collToken, borrowToken
        logger.Log(address(this), msg.sender, "CompoundRepay", abi.encode(_exData.srcAmount, swapAmount, collToken, borrowToken));
    }

    /// @notice Borrows token, converts to collateral, and adds to position
    /// @dev Called through the DSProxy
    /// @param _exData Exchange data
    /// @param _cAddresses Coll/Debt addresses [cCollAddress, cBorrowAddress]
    /// @param _gasCost Gas cost for specific transaction
    function boost(
        ExchangeData memory _exData,
        address[2] memory _cAddresses, // cCollAddress, cBorrowAddress
        uint256 _gasCost
    ) public payable {
        enterMarket(_cAddresses[0], _cAddresses[1]);

        address payable user = payable(getUserAddress());

        uint maxBorrow = getMaxBorrow(_cAddresses[1], address(this));
        uint borrowAmount = (_exData.srcAmount > maxBorrow) ? maxBorrow : _exData.srcAmount;

        require(CTokenInterface(_cAddresses[1]).borrow(borrowAmount) == 0);

        address collToken = getUnderlyingAddr(_cAddresses[0]);
        address borrowToken = getUnderlyingAddr(_cAddresses[1]);

        uint swapAmount = 0;

        if (collToken != borrowToken) {
            _exData.dfsFeeDivider = isAutomation() ? AUTOMATIC_SERVICE_FEE : MANUAL_SERVICE_FEE;
            _exData.user = user;

            _exData.srcAmount = borrowAmount;
            (, swapAmount) = _sell(_exData);

             swapAmount -= getGasCost(swapAmount, _gasCost, _cAddresses[1]);
        } else {
            swapAmount = borrowAmount;
            swapAmount -= getGasCost(swapAmount, _gasCost, _cAddresses[1]);
        }

        approveCToken(collToken, _cAddresses[0]);

        if (collToken != ETH_ADDRESS) {
            require(CTokenInterface(_cAddresses[0]).mint(swapAmount) == 0);
        } else {
            CEtherInterface(_cAddresses[0]).mint{value: swapAmount}(); // reverts on fail
        }

        // handle 0x fee
        tx.origin.transfer(address(this).balance);

        // log amount, collToken, borrowToken
        logger.Log(address(this), msg.sender, "CompoundBoost", abi.encode(_exData.srcAmount, swapAmount, collToken, borrowToken));
    }

}

contract ProxyPermission {
    address public constant FACTORY_ADDRESS = 0xf18Cf8abebda2804c58ff2fD01e1Ba4B406Ed883;

    /// @notice Called in the context of DSProxy to authorize an address
    /// @param _contractAddr Address which will be authorized
    function givePermission(address _contractAddr) public {
        address currAuthority = address(DSAuth(address(this)).authority());
        DSGuard guard = DSGuard(currAuthority);

        if (currAuthority == address(0)) {
            guard = DSGuardFactory(FACTORY_ADDRESS).newGuard();
            DSAuth(address(this)).setAuthority(DSAuthority(address(guard)));
        }

        guard.permit(_contractAddr, address(this), bytes4(keccak256("execute(address,bytes)")));
    }

    /// @notice Called in the context of DSProxy to remove authority of an address
    /// @param _contractAddr Auth address which will be removed from authority list
    function removePermission(address _contractAddr) public {
        address currAuthority = address(DSAuth(address(this)).authority());
        
        // if there is no authority, that means that contract doesn't have permission
        if (currAuthority == address(0)) {
            return;
        }

        DSGuard guard = DSGuard(currAuthority);
        guard.forbid(_contractAddr, address(this), bytes4(keccak256("execute(address,bytes)")));
    }

    function proxyOwner() internal returns(address) {
        return DSAuth(address(this)).owner();
    } 
}


/// @title Entry point for the FL Repay Boosts, called by DSProxy
contract CompoundFlashLoanTaker is CompoundSaverProxy, ProxyPermission, GasBurner {
    ILendingPool public constant lendingPool = ILendingPool(0x398eC7346DcD622eDc5ae82352F02bE94C62d119);

    address payable public constant COMPOUND_SAVER_FLASH_LOAN = 0x7B80E1925Ba5c583173b7F6865CECcd7Da5f7362;
    address public constant AAVE_POOL_CORE = 0x3dfd23A6c5E8BbcFc9581d2E864a68feb6a076d3;

    /// @notice Repays the position with it's own fund or with FL if needed
    /// @param _exData Exchange data
    /// @param _cAddresses cTokens addreses and exchange [cCollAddress, cBorrowAddress, exchangeAddress]
    /// @param _gasCost Gas cost for specific transaction
    function repayWithLoan(
        ExchangeData memory _exData,
        address[2] memory _cAddresses, // cCollAddress, cBorrowAddress
        uint256 _gasCost
    ) public payable burnGas(25) {
        uint maxColl = getMaxCollateral(_cAddresses[0], address(this));
        uint availableLiquidity = getAvailableLiquidity(_exData.srcAddr);

        if (_exData.srcAmount <= maxColl || availableLiquidity == 0) {
            repay(_exData, _cAddresses, _gasCost);
        } else {
            // 0x fee
            COMPOUND_SAVER_FLASH_LOAN.transfer(msg.value);

            uint loanAmount = (_exData.srcAmount - maxColl);
            if (loanAmount > availableLiquidity) loanAmount = availableLiquidity;
            bytes memory encoded = packExchangeData(_exData);
            bytes memory paramsData = abi.encode(encoded, _cAddresses, _gasCost, true, address(this));

            givePermission(COMPOUND_SAVER_FLASH_LOAN);

            lendingPool.flashLoan(COMPOUND_SAVER_FLASH_LOAN, getUnderlyingAddr(_cAddresses[0]), loanAmount, paramsData);

            removePermission(COMPOUND_SAVER_FLASH_LOAN);

            logger.Log(address(this), msg.sender, "CompoundFlashRepay", abi.encode(loanAmount, _exData.srcAmount, _cAddresses[0]));
        }
    }

    /// @notice Boosts the position with it's own fund or with FL if needed
    /// @param _exData Exchange data
    /// @param _cAddresses cTokens addreses and exchange [cCollAddress, cBorrowAddress, exchangeAddress]
    /// @param _gasCost Gas cost for specific transaction
    function boostWithLoan(
        ExchangeData memory _exData,
        address[2] memory _cAddresses, // cCollAddress, cBorrowAddress
        uint256 _gasCost
    ) public payable burnGas(20) {
        uint maxBorrow = getMaxBorrow(_cAddresses[1], address(this));
        uint availableLiquidity = getAvailableLiquidity(_exData.srcAddr);

        if (_exData.srcAmount <= maxBorrow || availableLiquidity == 0) {
            boost(_exData, _cAddresses, _gasCost);
        } else {
            // 0x fee
            COMPOUND_SAVER_FLASH_LOAN.transfer(msg.value);

            uint loanAmount = (_exData.srcAmount - maxBorrow);
            if (loanAmount > availableLiquidity) loanAmount = availableLiquidity;
            bytes memory paramsData = abi.encode(packExchangeData(_exData), _cAddresses, _gasCost, false, address(this));

            givePermission(COMPOUND_SAVER_FLASH_LOAN);

            lendingPool.flashLoan(COMPOUND_SAVER_FLASH_LOAN, getUnderlyingAddr(_cAddresses[1]), loanAmount, paramsData);

            removePermission(COMPOUND_SAVER_FLASH_LOAN);

            logger.Log(address(this), msg.sender, "CompoundFlashBoost", abi.encode(loanAmount, _exData.srcAmount, _cAddresses[1]));
        }

    }

    function getAvailableLiquidity(address _tokenAddr) internal view returns (uint liquidity) {
        if (_tokenAddr == KYBER_ETH_ADDRESS) {
            liquidity = AAVE_POOL_CORE.balance;
        } else {
            liquidity = ERC20(_tokenAddr).balanceOf(AAVE_POOL_CORE);
        }
    }
}