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

pragma solidity ^0.5.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

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

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

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

pragma solidity ^0.5.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

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

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

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

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

pragma solidity ^0.5.0;

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

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

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

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

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

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

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

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

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

pragma solidity ^0.5.0;

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

        return c;
    }

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

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

        return c;
    }

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

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

        return c;
    }

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

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

        return c;
    }

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

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

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.5.5;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * This test is non-exhaustive, and there may be false-negatives: during the
     * execution of a contract's constructor, its address will be reported as
     * not containing a contract.
     *
     * IMPORTANT: It is unsafe to assume that an address for which this
     * function returns false is an externally-owned account (EOA) and not a
     * contract.
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        // 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 != 0x0 && codehash != accountHash);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

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

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol

pragma solidity ^0.5.0;




/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 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(IERC20 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));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "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");
        }
    }
}

// File: @openzeppelin/contracts/utils/ReentrancyGuard.sol

pragma solidity ^0.5.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 */
contract ReentrancyGuard {
    // counter to allow mutex lock with only one SSTORE operation
    uint256 private _guardCounter;

    constructor () internal {
        // The counter starts at one to prevent changing it from zero to a non-zero
        // value, which is a more expensive operation.
        _guardCounter = 1;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _guardCounter += 1;
        uint256 localCounter = _guardCounter;
        _;
        require(localCounter == _guardCounter, "ReentrancyGuard: reentrant call");
    }
}

// File: contracts/protocol/interfaces/IWETH.sol

/*
 * Copyright 2020 DMM Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


pragma solidity ^0.5.0;

interface IWETH {

    function deposit() external payable;

    function withdraw(uint wad) external;

}

// File: contracts/utils/AddressUtil.sol

/*

  Copyright 2017 Loopring Project Ltd (Loopring Foundation).

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/


pragma solidity ^0.5.11;


/// @title Utility Functions for addresses
/// @author Daniel Wang - <daniel@loopring.org>
/// @author Brecht Devos - <brecht@loopring.org>
library AddressUtil
{
    using AddressUtil for *;

    function isContract(
        address addr
    )
    internal
    view
    returns (bool)
    {
        uint32 size;
        assembly {size := extcodesize(addr)}
        return (size > 0);
    }

    function toPayable(
        address addr
    )
    internal
    pure
    returns (address payable)
    {
        return address(uint160(addr));
    }

    // Works like address.send but with a customizable gas limit
    // Make sure your code is safe for reentrancy when using this function!
    function sendETH(
        address to,
        uint amount
    )
    internal
    returns (bool success) {
        if (amount == 0) {
            return true;
        }

        address payable recipient = to.toPayable();
        require(address(this).balance >= amount, "AddressUtil::sendETH: INSUFFICIENT_BALANCE");

        /* solium-disable-next-line */
        (success,) = recipient.call.value(amount)("");
    }

    // Works like address.transfer but with a customizable gas limit
    // Make sure your code is safe for reentrancy when using this function!
    function sendETHAndVerify(
        address to,
        uint amount
    )
    internal
    returns (bool success)
    {
        success = to.sendETH(amount);
        require(success, "TRANSFER_FAILURE");
    }
}

// File: contracts/external/uniswap/interfaces/IUniswapV2Pair.sol

pragma solidity ^0.5.0;

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/uniswap/libs/UniswapV2Library.sol

pragma solidity ^0.5.0;



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, bytes32 initCodeHash) 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)),
            // Taken from the UniswapV2Pair.json "bytecode" field
            //                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// init code hash
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB, bytes32 initCodeHash) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB, initCodeHash)).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;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(
        uint amountIn,
        uint reserveIn,
        uint reserveOut
    ) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(997);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(
        uint amountOut,
        uint reserveIn,
        uint reserveOut
    ) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(
        address factory,
        uint amountIn,
        address[] memory path,
        bytes32 initCodeHash
    ) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1], initCodeHash);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(
        address factory,
        uint amountOut,
        address[] memory path,
        bytes32 initCodeHash
    ) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i], initCodeHash);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

// File: contracts/external/farming/v1/IDMGYieldFarmingV1.sol

/*
 * Copyright 2020 DMM Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


pragma solidity ^0.5.0;

/**
 * The interface for DMG "Yield Farming" - A process through which users may earn DMG by locking up their mTokens in
 * Uniswap pools, and staking the Uniswap pool's equity token in this contract.
 *
 * Yield farming in the DMM Ecosystem entails "rotation periods" in which a season is active, in order to incentivize
 * deposits of underlying tokens into the protocol.
 */
interface IDMGYieldFarmingV1 {

    // ////////////////////
    // Events
    // ////////////////////

    event GlobalProxySet(address indexed proxy, bool isTrusted);

    event TokenAdded(address indexed token, address indexed underlyingToken, uint8 underlyingTokenDecimals, uint16 points);
    event TokenRemoved(address indexed token);

    event FarmSeasonBegun(uint indexed seasonIndex, uint dmgAmount);
    event FarmSeasonEnd(uint indexed seasonIndex, address dustRecipient, uint dustyDmgAmount);

    event DmgGrowthCoefficientSet(uint coefficient);
    event RewardPointsSet(address indexed token, uint16 points);

    event Approval(address indexed user, address indexed spender, bool isTrusted);

    event BeginFarming(address indexed owner, address indexed token, uint depositedAmount);
    event EndFarming(address indexed owner, address indexed token, uint withdrawnAmount, uint earnedDmgAmount);

    event WithdrawOutOfSeason(address indexed owner, address indexed token, address indexed recipient, uint amount);

    // ////////////////////
    // Admin Functions
    // ////////////////////

    /**
     * Sets the `proxy` as a trusted contract, allowing it to interact with the user, on the user's behalf.
     *
     * @param proxy     The address that can interact on the user's behalf.
     * @param isTrusted True if the proxy is trusted or false if it's not (should be removed).
     */
    function approveGloballyTrustedProxy(address proxy, bool isTrusted) external;

    /**
     * @return  true if the provided `proxy` is globally trusted and may interact with the yield farming contract on a
     *          user's behalf or false otherwise.
     */
    function isGloballyTrustedProxy(address proxy) external view returns (bool);

    /**
     * @param token                     The address of the token to be supported for farming.
     * @param underlyingToken           The token to which this token is pegged. IE a Uniswap-V2 LP equity token for
     *                                  DAI-mDAI has an underlying token of DAI.
     * @param underlyingTokenDecimals   The number of decimals that the `underlyingToken` has.
     * @param points                    The amount of reward points for the provided token.
     */
    function addAllowableToken(address token, address underlyingToken, uint8 underlyingTokenDecimals, uint16 points) external;

    /**
     * @param token     The address of the token that will be removed from farming.
     */
    function removeAllowableToken(address token) external;

    /**
     * Changes the reward points for the provided token. Reward points are a weighting system that enables certain
     * tokens to accrue DMG faster than others, allowing the protocol to prioritize certain deposits.
     */
    function setRewardPointsByToken(address token, uint16 points) external;

    /**
     * Sets the DMG growth coefficient to use the new parameter provided. This variable is used to define how much
     * DMG is earned every second, for each point accrued.
     */
    function setDmgGrowthCoefficient(uint dmgGrowthCoefficient) external;

    /**
     * Begins the farming process so users that accumulate DMG by locking tokens can start for this rotation. Calling
     * this function increments the currentSeasonIndex, starting a new season. This function reverts if there is
     * already an active season.
     *
     * @param dmgAmount The amount of DMG that will be used to fund this campaign.
     */
    function beginFarmingSeason(uint dmgAmount) external;

    /**
     * Ends the active farming process if the admin calls this function. Otherwise, anyone may call this function once
     * all DMG have been drained from the contract.
     *
     * @param dustRecipient The recipient of any leftover DMG in this contract, when the campaign finishes.
     */
    function endActiveFarmingSeason(address dustRecipient) external;

    // ////////////////////
    // Misc Functions
    // ////////////////////

    /**
     * @return  The tokens that the farm supports.
     */
    function getFarmTokens() external view returns (address[] memory);

    /**
     * @return  True if the provided token is supported for farming, or false if it's not.
     */
    function isSupportedToken(address token) external view returns (bool);

    /**
     * @return  True if there is an active season for farming, or false if there isn't one.
     */
    function isFarmActive() external view returns (bool);

    /**
     * The address that acts as a "secondary" owner with quicker access to function calling than the owner. Typically,
     * this is the DMMF.
     */
    function guardian() external view returns (address);

    /**
     * @return The DMG token.
     */
    function dmgToken() external view returns (address);

    /**
     * @return  The growth coefficient for earning DMG while farming. Each unit represents how much DMG is earned per
     *          point
     */
    function dmgGrowthCoefficient() external view returns (uint);

    /**
     * @return  The amount of points that the provided token earns for each unit of token deposited. Defaults to `1`
     *          if the provided `token` does not exist or does not have a special weight. This number is `2` decimals.
     */
    function getRewardPointsByToken(address token) external view returns (uint16);

    /**
     * @return  The number of decimals that the underlying token has.
     */
    function getTokenDecimalsByToken(address token) external view returns (uint8);

    /**
     * @return  The index into the array returned from `getFarmTokens`, plus 1. 0 if the token isn't found. If the
     *          index returned is non-zero, subtract 1 from it to get the real index into the array.
     */
    function getTokenIndexPlusOneByToken(address token) external view returns (uint);

    // ////////////////////
    // User Functions
    // ////////////////////

    /**
     * Approves the spender from `msg.sender` to transfer funds into the contract on the user's behalf. If `isTrusted`
     * is marked as false, removes the spender.
     */
    function approve(address spender, bool isTrusted) external;

    /**
     * True if the `spender` can transfer tokens on the user's behalf to this contract.
     */
    function isApproved(address user, address spender) external view returns (bool);

    /**
     * Begins a farm by transferring `amount` of `token` from `user` to this contract and adds it to the balance of
     * `user`. `user` must be either 1) msg.sender or 2) a wallet who has approved msg.sender as a proxy; else this
     * function reverts. `funder` must fit into the same criteria as `user`; else this function reverts
     */
    function beginFarming(address user, address funder, address token, uint amount) external;

    /**
     * Ends a farm by transferring all of `token` deposited by `from` to `recipient`, from this contract, as well as
     * all earned DMG for farming `token` to `recipient`. `from` must be either 1) msg.sender or 2) an approved
     * proxy; else this function reverts.
     *
     * @return  The amount of `token` withdrawn and the amount of DMG earned for farming. Both values are sent to
     *          `recipient`.
     */
    function endFarmingByToken(address from, address recipient, address token) external returns (uint, uint);

    /**
     * Withdraws all of `msg.sender`'s tokens from the farm to `recipient`. This function reverts if there is an active
     * farm. `user` must be either 1) msg.sender or 2) an approved proxy; else this function reverts.
     */
    function withdrawAllWhenOutOfSeason(address user, address recipient) external;

    /**
     * Withdraws all of `user` `token` from the farm to `recipient`. This function reverts if there is an active farm and the token is NOT removed.
     * `user` must be either 1) msg.sender or 2) an approved proxy; else this function reverts.
     *
     * @return The amount of tokens sent to `recipient`
     */
    function withdrawByTokenWhenOutOfSeason(
        address user,
        address recipient,
        address token
    ) external returns (uint);

    /**
     * @return  The amount of DMG that this owner has earned in the active farm. If there are no active season, this
     *          function returns `0`.
     */
    function getRewardBalanceByOwner(address owner) external view returns (uint);

    /**
     * @return  The amount of DMG that this owner has earned in the active farm for the provided token. If there is no
     *          active season, this function returns `0`.
     */
    function getRewardBalanceByOwnerAndToken(address owner, address token) external view returns (uint);

    /**
     * @return  The amount of `token` that this owner has deposited into this contract. The user may withdraw this
     *          non-zero balance by invoking `endFarming` or `endFarmingByToken` if there is an active farm. If there is
     *          NO active farm, the user may withdraw his/her funds by invoking
     */
    function balanceOf(address owner, address token) external view returns (uint);

    /**
     * @return  The most recent timestamp at which the `owner` deposited `token` into the yield farming contract for
     *          the current season. If there is no active season, this function returns `0`.
     */
    function getMostRecentDepositTimestampByOwnerAndToken(address owner, address token) external view returns (uint64);

    /**
     * @return  The most recent indexed amount of DMG earned by the `owner` for the deposited `token` which is being
     *          farmed for the most-recent season. If there is no active season, this function returns `0`.
     */
    function getMostRecentIndexedDmgEarnedByOwnerAndToken(address owner, address token) external view returns (uint);

}

// File: contracts/external/farming/DMGYieldFarmingRouter.sol

/*
 * Copyright 2020 DMM Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


pragma solidity ^0.5.0;









contract DMGYieldFarmingRouter is Ownable, ReentrancyGuard {

    using AddressUtil for address payable;
    using SafeERC20 for IERC20;
    using UniswapV2Library for *;

    address public dmgYieldFarming;
    address public uniswapV2Factory;
    address public weth;
    bytes32 public initCodeHash;

    // Used to prevent stack too deep errors.
    struct UniswapParams {
        address tokenA;
        address tokenB;
        uint liquidity;
        uint amountAMin;
        uint amountBMin;
    }

    modifier ensureDeadline(uint deadline) {
        require(deadline >= block.timestamp, "DMGYieldFarmingFundingProxy: EXPIRED");
        _;
    }

    modifier ensurePairIsSupported(address tokenA, address tokenB) {
        require(
            IDMGYieldFarmingV1(dmgYieldFarming).isSupportedToken(UniswapV2Library.pairFor(uniswapV2Factory, tokenA, tokenB, initCodeHash)),
            "DMGYieldFarmingFundingProxy: TOKEN_UNSUPPORTED"
        );
        _;
    }

    constructor(
        address _dmgYieldFarming,
        address _uniswapV2Factory,
        address _weth
    ) public {
        dmgYieldFarming = _dmgYieldFarming;
        uniswapV2Factory = _uniswapV2Factory;
        weth = _weth;
        initCodeHash = bytes32(0x96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f);
    }

    function() external payable {
        require(
            msg.sender == weth,
            "DMGYieldFarmingFundingProxy::default: INVALID_SENDER"
        );
    }

    function getPair(
        address tokenA,
        address tokenB
    ) public view returns (address) {
        return UniswapV2Library.pairFor(uniswapV2Factory, tokenA, tokenB, initCodeHash);
    }

    function setInitCodeHash(
        bytes32 _initCodeHash
    )
    public
    onlyOwner {
        initCodeHash = _initCodeHash;
    }

    function enableTokens(
        address[] calldata tokens,
        address[] calldata spenders
    )
    external
    nonReentrant {
        require(
            tokens.length == spenders.length,
            "DMGYieldFarmingFundingProxy::enableTokens: INVALID_LENGTH"
        );

        for (uint i = 0; i < tokens.length; i++) {
            IERC20(tokens[i]).safeApprove(spenders[i], uint(- 1));
        }
    }

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        uint deadline
    )
    public
    nonReentrant
    ensureDeadline(deadline) {
        _verifyTokensAreSupported(tokenA, tokenB);

        address _uniswapV2Factory = uniswapV2Factory;

        UniswapParams memory params = UniswapParams({
        tokenA : tokenA,
        tokenB : tokenB,
        liquidity : 0,
        amountAMin : amountAMin,
        amountBMin : amountBMin
        });

        (uint amountA, uint amountB) = _getAmounts(
            params,
            amountADesired,
            amountBDesired,
            _uniswapV2Factory
        );

        address pair = UniswapV2Library.pairFor(uniswapV2Factory, params.tokenA, params.tokenB, initCodeHash);
        uint liquidity = _doTokenTransfersAndMintLiquidity(params, pair, amountA, amountB);

        IDMGYieldFarmingV1(dmgYieldFarming).beginFarming(msg.sender, address(this), pair, liquidity);
    }

    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        uint deadline
    )
    public payable
    nonReentrant
    ensureDeadline(deadline) {
        UniswapParams memory params = UniswapParams({
        tokenA : token,
        tokenB : weth,
        liquidity : 0,
        amountAMin : amountTokenMin,
        amountBMin : amountETHMin
        });

        _verifyTokensAreSupported(token, params.tokenB);

        address _uniswapV2Factory = uniswapV2Factory;

        (uint amountToken, uint amountETH) = _getAmounts(
            params,
            amountTokenDesired,
            msg.value,
            _uniswapV2Factory
        );

        address pair = UniswapV2Library.pairFor(_uniswapV2Factory, token, params.tokenB, initCodeHash);

        uint liquidity = _doTokenTransfersWithEthAndMintLiquidity(params, pair, amountToken, amountETH);

        // refund dust eth, if any
        if (msg.value > amountETH) {
            require(
                msg.sender.sendETH(msg.value - amountETH),
                "DMGYieldFarmingFundingProxy::addLiquidityETH: ETH_TRANSFER_FAILURE"
            );
        }

        IDMGYieldFarmingV1(dmgYieldFarming).beginFarming(msg.sender, address(this), pair, liquidity);
    }

    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        uint deadline,
        bool isInSeason
    )
    public
    nonReentrant
    ensureDeadline(deadline) {
        _verifyTokensAreSupported(tokenA, tokenB);

        UniswapParams memory params = UniswapParams({
        tokenA : tokenA,
        tokenB : tokenB,
        liquidity : liquidity,
        amountAMin : amountAMin,
        amountBMin : amountBMin
        });

        _removeLiquidity(params, msg.sender, msg.sender, isInSeason);
    }

    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        uint deadline,
        bool isInSeason
    )
    public
    nonReentrant
    ensureDeadline(deadline) {
        UniswapParams memory params = UniswapParams({
        tokenA : token,
        tokenB : weth,
        liquidity : liquidity,
        amountAMin : amountTokenMin,
        amountBMin : amountETHMin
        });

        _verifyTokensAreSupported(params.tokenA, params.tokenB);

        (uint amountToken, uint amountETH) = _removeLiquidity(params, msg.sender, address(this), isInSeason);

        IERC20(params.tokenA).safeTransfer(msg.sender, amountToken);
        IWETH(params.tokenB).withdraw(amountETH);
        require(
            msg.sender.sendETH(amountETH),
            "DMGYieldFarmingFundingProxy::addLiquidityETH: ETH_TRANSFER_FAILURE"
        );
    }

    function _verifyTokensAreSupported(
        address tokenA,
        address tokenB
    ) internal view {
        require(
            IDMGYieldFarmingV1(dmgYieldFarming).isSupportedToken(UniswapV2Library.pairFor(uniswapV2Factory, tokenA, tokenB, initCodeHash)),
            "DMGYieldFarmingFundingProxy::_verifyTokensAreSupported: TOKEN_UNSUPPORTED"
        );
    }

    function _removeLiquidity(
        UniswapParams memory params,
        address farmer,
        address liquidityRecipient,
        bool isInSeason
    )
    internal returns (uint amountA, uint amountB) {
        address pair = UniswapV2Library.pairFor(uniswapV2Factory, params.tokenA, params.tokenB, initCodeHash);
        uint liquidity;
        if (isInSeason) {
            (uint _liquidity, uint dmgEarned) = IDMGYieldFarmingV1(dmgYieldFarming).endFarmingByToken(farmer, address(this), pair);
            liquidity = _liquidity;
            // Forward the DMG along to the farmer
            IERC20(IDMGYieldFarmingV1(dmgYieldFarming).dmgToken()).safeTransfer(farmer, dmgEarned);
        } else {
            liquidity = IDMGYieldFarmingV1(dmgYieldFarming).withdrawByTokenWhenOutOfSeason(
                farmer,
                address(this),
                pair
            );
        }

        IERC20(pair).safeTransfer(pair, liquidity);
        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(liquidityRecipient);
        (address token0,) = UniswapV2Library.sortTokens(params.tokenA, params.tokenB);
        (amountA, amountB) = params.tokenA == token0 ? (amount0, amount1) : (amount1, amount0);

        require(amountA >= params.amountAMin, 'DMGYieldFarmingFundingProxy::removeLiquidity: INSUFFICIENT_A_AMOUNT');
        require(amountB >= params.amountBMin, 'DMGYieldFarmingFundingProxy::removeLiquidity: INSUFFICIENT_B_AMOUNT');
    }

    function _getAmounts(
        UniswapParams memory params,
        uint amountADesired,
        uint amountBDesired,
        address uniswapV2Factory
    )
    internal view returns (uint amountA, uint amountB) {
        (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(uniswapV2Factory, params.tokenA, params.tokenB, initCodeHash);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(
                    amountBOptimal >= params.amountBMin,
                    "DMGYieldFarmingFundingProxy::_getAmounts: INSUFFICIENT_B_AMOUNT"
                );

                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(
                    amountAOptimal >= params.amountAMin,
                    "DMGYieldFarmingFundingProxy::_getAmounts: INSUFFICIENT_A_AMOUNT"
                );

                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }

    function _doTokenTransfersAndMintLiquidity(
        UniswapParams memory params,
        address pair,
        uint amountA,
        uint amountB
    ) internal returns (uint) {
        IERC20(params.tokenA).safeTransferFrom(msg.sender, pair, amountA);
        IERC20(params.tokenB).safeTransferFrom(msg.sender, pair, amountB);

        return IUniswapV2Pair(pair).mint(address(this));
    }

    function _doTokenTransfersWithEthAndMintLiquidity(
        UniswapParams memory params,
        address pair,
        uint amountToken,
        uint amountETH
    ) internal returns (uint) {
        IERC20(params.tokenA).safeTransferFrom(msg.sender, pair, amountToken);
        IWETH(params.tokenB).deposit.value(amountETH)();
        IERC20(params.tokenB).safeTransfer(pair, amountETH);

        return IUniswapV2Pair(pair).mint(address(this));
    }

}

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