// SPDX-License-Identifier: BUSL-1.1
// File: @uniswap/lib/contracts/libraries/TransferHelper.sol

pragma solidity >=0.6.0;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
    }

    function safeTransfer(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
    }

    function safeTransferFrom(address token, address from, address to, uint value) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
    }

    function safeTransferETH(address to, uint value) internal {
        (bool success,) = to.call{value:value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity >=0.6.0 <0.8.0;

/**
 * @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, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, 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 (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @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) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @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) {
        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, reverting 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) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting 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) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol

pragma solidity >=0.6.0 <0.8.0;




/**
 * @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 IERC20;` 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));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    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. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        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");
        }
    }
}

// File: contracts/interfaces/IDMMFactory.sol
pragma solidity 0.6.12;


interface IDMMFactory {
    function createPool(
        IERC20 tokenA,
        IERC20 tokenB,
        uint32 ampBps
    ) external returns (address pool);

    function setFeeConfiguration(address feeTo, uint16 governmentFeeBps) external;

    function setFeeToSetter(address) external;

    function getFeeConfiguration() external view returns (address feeTo, uint16 governmentFeeBps);

    function feeToSetter() external view returns (address);

    function allPools(uint256) external view returns (address pool);

    function allPoolsLength() external view returns (uint256);

    function getUnamplifiedPool(IERC20 token0, IERC20 token1) external view returns (address);

    function getPools(IERC20 token0, IERC20 token1)
        external
        view
        returns (address[] memory _tokenPools);

    function isPool(
        IERC20 token0,
        IERC20 token1,
        address pool
    ) external view returns (bool);
}

// File: contracts/interfaces/IWETH.sol
pragma solidity 0.6.12;


interface IWETH is IERC20 {
    function deposit() external payable;

    function withdraw(uint256) external;
}

// File: contracts/interfaces/IDMMExchangeRouter.sol
pragma solidity 0.6.12;


/// @dev an simple interface for integration dApp to swap
interface IDMMExchangeRouter {
    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function getAmountsOut(
        uint256 amountIn,
        address[] calldata poolsPath,
        IERC20[] calldata path
    ) external view returns (uint256[] memory amounts);

    function getAmountsIn(
        uint256 amountOut,
        address[] calldata poolsPath,
        IERC20[] calldata path
    ) external view returns (uint256[] memory amounts);
}

// File: contracts/interfaces/IDMMLiquidityRouter.sol
pragma solidity 0.6.12;


/// @dev an simple interface for integration dApp to contribute liquidity
interface IDMMLiquidityRouter {
    /**
     * @param tokenA address of token in the pool
     * @param tokenB address of token in the pool
     * @param pool the address of the pool
     * @param amountADesired the amount of tokenA users want to add to the pool
     * @param amountBDesired the amount of tokenB users want to add to the pool
     * @param amountAMin bounds to the extents to which amountB/amountA can go up
     * @param amountBMin bounds to the extents to which amountB/amountA can go down
     * @param vReserveRatioBounds bounds to the extents to which vReserveB/vReserveA can go (precision: 2 ** 112)
     * @param to Recipient of the liquidity tokens.
     * @param deadline Unix timestamp after which the transaction will revert.
     */
    function addLiquidity(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        uint256[2] calldata vReserveRatioBounds,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );

    function addLiquidityNewPool(
        IERC20 tokenA,
        IERC20 tokenB,
        uint32 ampBps,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );

    function addLiquidityNewPoolETH(
        IERC20 token,
        uint32 ampBps,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );

    /**
     * @param token address of token in the pool
     * @param pool the address of the pool
     * @param amountTokenDesired the amount of token users want to add to the pool
     * @dev   msg.value equals to amountEthDesired
     * @param amountTokenMin bounds to the extents to which WETH/token can go up
     * @param amountETHMin bounds to the extents to which WETH/token can go down
     * @param vReserveRatioBounds bounds to the extents to which vReserveB/vReserveA can go (precision: 2 ** 112)
     * @param to Recipient of the liquidity tokens.
     * @param deadline Unix timestamp after which the transaction will revert.
     */
    function addLiquidityETH(
        IERC20 token,
        address pool,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        uint256[2] calldata vReserveRatioBounds,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );

    /**
     * @param tokenA address of token in the pool
     * @param tokenB address of token in the pool
     * @param pool the address of the pool
     * @param liquidity the amount of lp token users want to burn
     * @param amountAMin the minimum token retuned after burning
     * @param amountBMin the minimum token retuned after burning
     * @param to Recipient of the returned tokens.
     * @param deadline Unix timestamp after which the transaction will revert.
     */
    function removeLiquidity(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountA, uint256 amountB);

    /**
     * @param tokenA address of token in the pool
     * @param tokenB address of token in the pool
     * @param pool the address of the pool
     * @param liquidity the amount of lp token users want to burn
     * @param amountAMin the minimum token retuned after burning
     * @param amountBMin the minimum token retuned after burning
     * @param to Recipient of the returned tokens.
     * @param deadline Unix timestamp after which the transaction will revert.
     * @param approveMax whether users permit the router spending max lp token or not.
     * @param r s v Signature of user to permit the router spending lp token
     */
    function removeLiquidityWithPermit(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountA, uint256 amountB);

    /**
     * @param token address of token in the pool
     * @param pool the address of the pool
     * @param liquidity the amount of lp token users want to burn
     * @param amountTokenMin the minimum token retuned after burning
     * @param amountETHMin the minimum eth in wei retuned after burning
     * @param to Recipient of the returned tokens.
     * @param deadline Unix timestamp after which the transaction will revert
     */
    function removeLiquidityETH(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountToken, uint256 amountETH);

    /**
     * @param token address of token in the pool
     * @param pool the address of the pool
     * @param liquidity the amount of lp token users want to burn
     * @param amountTokenMin the minimum token retuned after burning
     * @param amountETHMin the minimum eth in wei retuned after burning
     * @param to Recipient of the returned tokens.
     * @param deadline Unix timestamp after which the transaction will revert
     * @param approveMax whether users permit the router spending max lp token
     * @param r s v signatures of user to permit the router spending lp token.
     */
    function removeLiquidityETHWithPermit(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountToken, uint256 amountETH);

    /**
     * @param amountA amount of 1 side token added to the pool
     * @param reserveA current reserve of the pool
     * @param reserveB current reserve of the pool
     * @return amountB amount of the other token added to the pool
     */
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external pure returns (uint256 amountB);
}

// File: contracts/interfaces/IDMMRouter01.sol
pragma solidity 0.6.12;





/// @dev full interface for router
interface IDMMRouter01 is IDMMExchangeRouter, IDMMLiquidityRouter {
    function factory() external pure returns (address);

    function weth() external pure returns (IWETH);
}

// File: contracts/interfaces/IDMMRouter02.sol
pragma solidity 0.6.12;


interface IDMMRouter02 is IDMMRouter01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountETH);

    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external;

    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external payable;

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external;
}

// File: contracts/interfaces/IERC20Permit.sol

pragma solidity 0.6.12;


interface IERC20Permit is IERC20 {
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;
}

// File: contracts/interfaces/IDMMPool.sol

pragma solidity 0.6.12;



interface IDMMPool {
    function mint(address to) external returns (uint256 liquidity);

    function burn(address to) external returns (uint256 amount0, uint256 amount1);

    function swap(
        uint256 amount0Out,
        uint256 amount1Out,
        address to,
        bytes calldata data
    ) external;

    function sync() external;

    function getReserves() external view returns (uint112 reserve0, uint112 reserve1);

    function getTradeInfo()
        external
        view
        returns (
            uint112 _vReserve0,
            uint112 _vReserve1,
            uint112 reserve0,
            uint112 reserve1,
            uint256 feeInPrecision
        );

    function token0() external view returns (IERC20);

    function token1() external view returns (IERC20);

    function ampBps() external view returns (uint32);

    function factory() external view returns (IDMMFactory);

    function kLast() external view returns (uint256);
}

// File: contracts/libraries/DMMLibrary.sol

pragma solidity 0.6.12;




library DMMLibrary {
    using SafeMath for uint256;

    uint256 public constant PRECISION = 1e18;

    // returns sorted token addresses, used to handle return values from pools sorted in this order
    function sortTokens(IERC20 tokenA, IERC20 tokenB)
        internal
        pure
        returns (IERC20 token0, IERC20 token1)
    {
        require(tokenA != tokenB, "DMMLibrary: IDENTICAL_ADDRESSES");
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(address(token0) != address(0), "DMMLibrary: ZERO_ADDRESS");
    }

    /// @dev fetch the reserves and fee for a pool, used for trading purposes
    function getTradeInfo(
        address pool,
        IERC20 tokenA,
        IERC20 tokenB
    )
        internal
        view
        returns (
            uint256 reserveA,
            uint256 reserveB,
            uint256 vReserveA,
            uint256 vReserveB,
            uint256 feeInPrecision
        )
    {
        (IERC20 token0, ) = sortTokens(tokenA, tokenB);
        uint256 reserve0;
        uint256 reserve1;
        uint256 vReserve0;
        uint256 vReserve1;
        (reserve0, reserve1, vReserve0, vReserve1, feeInPrecision) = IDMMPool(pool).getTradeInfo();
        (reserveA, reserveB, vReserveA, vReserveB) = tokenA == token0
            ? (reserve0, reserve1, vReserve0, vReserve1)
            : (reserve1, reserve0, vReserve1, vReserve0);
    }

    /// @dev fetches the reserves for a pool, used for liquidity adding
    function getReserves(
        address pool,
        IERC20 tokenA,
        IERC20 tokenB
    ) internal view returns (uint256 reserveA, uint256 reserveB) {
        (IERC20 token0, ) = sortTokens(tokenA, tokenB);
        (uint256 reserve0, uint256 reserve1) = IDMMPool(pool).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pool reserves, returns an equivalent amount of the other asset
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) internal pure returns (uint256 amountB) {
        require(amountA > 0, "DMMLibrary: INSUFFICIENT_AMOUNT");
        require(reserveA > 0 && reserveB > 0, "DMMLibrary: INSUFFICIENT_LIQUIDITY");
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pool reserves, returns the maximum output amount of the other asset
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut,
        uint256 vReserveIn,
        uint256 vReserveOut,
        uint256 feeInPrecision
    ) internal pure returns (uint256 amountOut) {
        require(amountIn > 0, "DMMLibrary: INSUFFICIENT_INPUT_AMOUNT");
        require(reserveIn > 0 && reserveOut > 0, "DMMLibrary: INSUFFICIENT_LIQUIDITY");
        uint256 amountInWithFee = amountIn.mul(PRECISION.sub(feeInPrecision)).div(PRECISION);
        uint256 numerator = amountInWithFee.mul(vReserveOut);
        uint256 denominator = vReserveIn.add(amountInWithFee);
        amountOut = numerator.div(denominator);
        require(reserveOut > amountOut, "DMMLibrary: INSUFFICIENT_LIQUIDITY");
    }

    // given an output amount of an asset and pool reserves, returns a required input amount of the other asset
    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut,
        uint256 vReserveIn,
        uint256 vReserveOut,
        uint256 feeInPrecision
    ) internal pure returns (uint256 amountIn) {
        require(amountOut > 0, "DMMLibrary: INSUFFICIENT_OUTPUT_AMOUNT");
        require(reserveIn > 0 && reserveOut > amountOut, "DMMLibrary: INSUFFICIENT_LIQUIDITY");
        uint256 numerator = vReserveIn.mul(amountOut);
        uint256 denominator = vReserveOut.sub(amountOut);
        amountIn = numerator.div(denominator).add(1);
        // amountIn = floor(amountIN *PRECISION / (PRECISION - feeInPrecision));
        numerator = amountIn.mul(PRECISION);
        denominator = PRECISION.sub(feeInPrecision);
        amountIn = numerator.add(denominator - 1).div(denominator);
    }

    // performs chained getAmountOut calculations on any number of pools
    function getAmountsOut(
        uint256 amountIn,
        address[] memory poolsPath,
        IERC20[] memory path
    ) internal view returns (uint256[] memory amounts) {
        amounts = new uint256[](path.length);
        amounts[0] = amountIn;
        for (uint256 i; i < path.length - 1; i++) {
            (
                uint256 reserveIn,
                uint256 reserveOut,
                uint256 vReserveIn,
                uint256 vReserveOut,
                uint256 feeInPrecision
            ) = getTradeInfo(poolsPath[i], path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(
                amounts[i],
                reserveIn,
                reserveOut,
                vReserveIn,
                vReserveOut,
                feeInPrecision
            );
        }
    }

    // performs chained getAmountIn calculations on any number of pools
    function getAmountsIn(
        uint256 amountOut,
        address[] memory poolsPath,
        IERC20[] memory path
    ) internal view returns (uint256[] memory amounts) {
        amounts = new uint256[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint256 i = path.length - 1; i > 0; i--) {
            (
                uint256 reserveIn,
                uint256 reserveOut,
                uint256 vReserveIn,
                uint256 vReserveOut,
                uint256 feeInPrecision
            ) = getTradeInfo(poolsPath[i - 1], path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(
                amounts[i],
                reserveIn,
                reserveOut,
                vReserveIn,
                vReserveOut,
                feeInPrecision
            );
        }
    }
}

// File: contracts/periphery/DMMRouter02.sol
pragma solidity 0.6.12;










contract DMMRouter02 is IDMMRouter02 {
    using SafeERC20 for IERC20;
    using SafeERC20 for IWETH;
    using SafeMath for uint256;

    uint256 internal constant BPS = 10000;
    uint256 internal constant MIN_VRESERVE_RATIO = 0;
    uint256 internal constant MAX_VRESERVE_RATIO = 2**256 - 1;
    uint256 internal constant Q112 = 2**112;

    address public immutable override factory;
    IWETH public immutable override weth;

    modifier ensure(uint256 deadline) {
        require(deadline >= block.timestamp, "DMMRouter: EXPIRED");
        _;
    }

    constructor(address _factory, IWETH _weth) public {
        factory = _factory;
        weth = _weth;
    }

    receive() external payable {
        assert(msg.sender == address(weth)); // only accept ETH via fallback from the WETH contract
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        uint256[2] memory vReserveRatioBounds
    ) internal virtual view returns (uint256 amountA, uint256 amountB) {
        (uint256 reserveA, uint256 reserveB, uint256 vReserveA, uint256 vReserveB, ) = DMMLibrary
            .getTradeInfo(pool, tokenA, tokenB);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint256 amountBOptimal = DMMLibrary.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(amountBOptimal >= amountBMin, "DMMRouter: INSUFFICIENT_B_AMOUNT");
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint256 amountAOptimal = DMMLibrary.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(amountAOptimal >= amountAMin, "DMMRouter: INSUFFICIENT_A_AMOUNT");
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
            uint256 currentRate = (vReserveB * Q112) / vReserveA;
            require(
                currentRate >= vReserveRatioBounds[0] && currentRate <= vReserveRatioBounds[1],
                "DMMRouter: OUT_OF_BOUNDS_VRESERVE"
            );
        }
    }

    function addLiquidity(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        uint256[2] memory vReserveRatioBounds,
        address to,
        uint256 deadline
    )
        public
        virtual
        override
        ensure(deadline)
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        )
    {
        verifyPoolAddress(tokenA, tokenB, pool);
        (amountA, amountB) = _addLiquidity(
            tokenA,
            tokenB,
            pool,
            amountADesired,
            amountBDesired,
            amountAMin,
            amountBMin,
            vReserveRatioBounds
        );
        // using tokenA.safeTransferFrom will get "Stack too deep"
        SafeERC20.safeTransferFrom(tokenA, msg.sender, pool, amountA);
        SafeERC20.safeTransferFrom(tokenB, msg.sender, pool, amountB);
        liquidity = IDMMPool(pool).mint(to);
    }

    function addLiquidityETH(
        IERC20 token,
        address pool,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        uint256[2] memory vReserveRatioBounds,
        address to,
        uint256 deadline
    )
        public
        override
        payable
        ensure(deadline)
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        )
    {
        verifyPoolAddress(token, weth, pool);
        (amountToken, amountETH) = _addLiquidity(
            token,
            weth,
            pool,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin,
            vReserveRatioBounds
        );
        token.safeTransferFrom(msg.sender, pool, amountToken);
        weth.deposit{value: amountETH}();
        weth.safeTransfer(pool, amountETH);
        liquidity = IDMMPool(pool).mint(to);
        // refund dust eth, if any
        if (msg.value > amountETH) {
            TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
        }
    }

    function addLiquidityNewPool(
        IERC20 tokenA,
        IERC20 tokenB,
        uint32 ampBps,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        override
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        )
    {
        address pool;
        if (ampBps == BPS) {
            pool = IDMMFactory(factory).getUnamplifiedPool(tokenA, tokenB);
        }
        if (pool == address(0)) {
            pool = IDMMFactory(factory).createPool(tokenA, tokenB, ampBps);
        }
        // if we add liquidity to an existing pool, this is an unamplifed pool
        // so there is no need for bounds of virtual reserve ratio
        uint256[2] memory vReserveRatioBounds = [MIN_VRESERVE_RATIO, MAX_VRESERVE_RATIO];
        (amountA, amountB, liquidity) = addLiquidity(
            tokenA,
            tokenB,
            pool,
            amountADesired,
            amountBDesired,
            amountAMin,
            amountBMin,
            vReserveRatioBounds,
            to,
            deadline
        );
    }

    function addLiquidityNewPoolETH(
        IERC20 token,
        uint32 ampBps,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        override
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        )
    {
        address pool;
        if (ampBps == BPS) {
            pool = IDMMFactory(factory).getUnamplifiedPool(token, weth);
        }
        if (pool == address(0)) {
            pool = IDMMFactory(factory).createPool(token, weth, ampBps);
        }
        // if we add liquidity to an existing pool, this is an unamplifed pool
        // so there is no need for bounds of virtual reserve ratio
        uint256[2] memory vReserveRatioBounds = [MIN_VRESERVE_RATIO, MAX_VRESERVE_RATIO];
        (amountToken, amountETH, liquidity) = addLiquidityETH(
            token,
            pool,
            amountTokenDesired,
            amountTokenMin,
            amountETHMin,
            vReserveRatioBounds,
            to,
            deadline
        );
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) public override ensure(deadline) returns (uint256 amountA, uint256 amountB) {
        verifyPoolAddress(tokenA, tokenB, pool);
        IERC20(pool).safeTransferFrom(msg.sender, pool, liquidity); // send liquidity to pool
        (uint256 amount0, uint256 amount1) = IDMMPool(pool).burn(to);
        (IERC20 token0, ) = DMMLibrary.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
        require(amountA >= amountAMin, "DMMRouter: INSUFFICIENT_A_AMOUNT");
        require(amountB >= amountBMin, "DMMRouter: INSUFFICIENT_B_AMOUNT");
    }

    function removeLiquidityETH(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) public override ensure(deadline) returns (uint256 amountToken, uint256 amountETH) {
        (amountToken, amountETH) = removeLiquidity(
            token,
            weth,
            pool,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        token.safeTransfer(to, amountToken);
        IWETH(weth).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }

    function removeLiquidityWithPermit(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external virtual override returns (uint256 amountA, uint256 amountB) {
        uint256 value = approveMax ? uint256(-1) : liquidity;
        IERC20Permit(pool).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountA, amountB) = removeLiquidity(
            tokenA,
            tokenB,
            pool,
            liquidity,
            amountAMin,
            amountBMin,
            to,
            deadline
        );
    }

    function removeLiquidityETHWithPermit(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external override returns (uint256 amountToken, uint256 amountETH) {
        uint256 value = approveMax ? uint256(-1) : liquidity;
        IERC20Permit(pool).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountToken, amountETH) = removeLiquidityETH(
            token,
            pool,
            liquidity,
            amountTokenMin,
            amountETHMin,
            to,
            deadline
        );
    }

    // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****

    function removeLiquidityETHSupportingFeeOnTransferTokens(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) public override ensure(deadline) returns (uint256 amountETH) {
        (, amountETH) = removeLiquidity(
            token,
            weth,
            pool,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        token.safeTransfer(to, IERC20(token).balanceOf(address(this)));
        IWETH(weth).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }

    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        IERC20 token,
        address pool,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external override returns (uint256 amountETH) {
        uint256 value = approveMax ? uint256(-1) : liquidity;
        IERC20Permit(pool).permit(msg.sender, address(this), value, deadline, v, r, s);
        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
            token,
            pool,
            liquidity,
            amountTokenMin,
            amountETHMin,
            to,
            deadline
        );
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pool
    function _swap(
        uint256[] memory amounts,
        address[] memory poolsPath,
        IERC20[] memory path,
        address _to
    ) private {
        for (uint256 i; i < path.length - 1; i++) {
            (IERC20 input, IERC20 output) = (path[i], path[i + 1]);
            (IERC20 token0, ) = DMMLibrary.sortTokens(input, output);
            uint256 amountOut = amounts[i + 1];
            (uint256 amount0Out, uint256 amount1Out) = input == token0
                ? (uint256(0), amountOut)
                : (amountOut, uint256(0));
            address to = i < path.length - 2 ? poolsPath[i + 1] : _to;
            IDMMPool(poolsPath[i]).swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }

    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] memory poolsPath,
        IERC20[] memory path,
        address to,
        uint256 deadline
    ) public virtual override ensure(deadline) returns (uint256[] memory amounts) {
        verifyPoolsPathSwap(poolsPath, path);
        amounts = DMMLibrary.getAmountsOut(amountIn, poolsPath, path);
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "DMMRouter: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        IERC20(path[0]).safeTransferFrom(msg.sender, poolsPath[0], amounts[0]);
        _swap(amounts, poolsPath, path, to);
    }

    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] memory poolsPath,
        IERC20[] memory path,
        address to,
        uint256 deadline
    ) public override ensure(deadline) returns (uint256[] memory amounts) {
        verifyPoolsPathSwap(poolsPath, path);
        amounts = DMMLibrary.getAmountsIn(amountOut, poolsPath, path);
        require(amounts[0] <= amountInMax, "DMMRouter: EXCESSIVE_INPUT_AMOUNT");
        path[0].safeTransferFrom(msg.sender, poolsPath[0], amounts[0]);
        _swap(amounts, poolsPath, path, to);
    }

    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external override payable ensure(deadline) returns (uint256[] memory amounts) {
        require(path[0] == weth, "DMMRouter: INVALID_PATH");
        verifyPoolsPathSwap(poolsPath, path);
        amounts = DMMLibrary.getAmountsOut(msg.value, poolsPath, path);
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "DMMRouter: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        IWETH(weth).deposit{value: amounts[0]}();
        weth.safeTransfer(poolsPath[0], amounts[0]);
        _swap(amounts, poolsPath, path, to);
    }

    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external override ensure(deadline) returns (uint256[] memory amounts) {
        require(path[path.length - 1] == weth, "DMMRouter: INVALID_PATH");
        verifyPoolsPathSwap(poolsPath, path);
        amounts = DMMLibrary.getAmountsIn(amountOut, poolsPath, path);
        require(amounts[0] <= amountInMax, "DMMRouter: EXCESSIVE_INPUT_AMOUNT");
        path[0].safeTransferFrom(msg.sender, poolsPath[0], amounts[0]);
        _swap(amounts, poolsPath, path, address(this));
        IWETH(weth).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }

    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external override ensure(deadline) returns (uint256[] memory amounts) {
        require(path[path.length - 1] == weth, "DMMRouter: INVALID_PATH");
        verifyPoolsPathSwap(poolsPath, path);
        amounts = DMMLibrary.getAmountsOut(amountIn, poolsPath, path);
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "DMMRouter: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        path[0].safeTransferFrom(msg.sender, poolsPath[0], amounts[0]);
        _swap(amounts, poolsPath, path, address(this));
        IWETH(weth).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }

    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external override payable ensure(deadline) returns (uint256[] memory amounts) {
        require(path[0] == weth, "DMMRouter: INVALID_PATH");
        verifyPoolsPathSwap(poolsPath, path);
        amounts = DMMLibrary.getAmountsIn(amountOut, poolsPath, path);
        require(amounts[0] <= msg.value, "DMMRouter: EXCESSIVE_INPUT_AMOUNT");
        IWETH(weth).deposit{value: amounts[0]}();
        weth.safeTransfer(poolsPath[0], amounts[0]);
        _swap(amounts, poolsPath, path, to);
        // refund dust eth, if any
        if (msg.value > amounts[0]) {
            TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);
        }
    }

    // **** SWAP (supporting fee-on-transfer tokens) ****
    // requires the initial amount to have already been sent to the first pool
    function _swapSupportingFeeOnTransferTokens(
        address[] memory poolsPath,
        IERC20[] memory path,
        address _to
    ) internal {
        verifyPoolsPathSwap(poolsPath, path);
        for (uint256 i; i < path.length - 1; i++) {
            (IERC20 input, IERC20 output) = (path[i], path[i + 1]);
            (IERC20 token0, ) = DMMLibrary.sortTokens(input, output);
            IDMMPool pool = IDMMPool(poolsPath[i]);
            uint256 amountOutput;
            {
                // scope to avoid stack too deep errors
                (
                    uint256 reserveIn,
                    uint256 reserveOut,
                    uint256 vReserveIn,
                    uint256 vReserveOut,
                    uint256 feeInPrecision
                ) = DMMLibrary.getTradeInfo(poolsPath[i], input, output);
                uint256 amountInput = IERC20(input).balanceOf(address(pool)).sub(reserveIn);
                amountOutput = DMMLibrary.getAmountOut(
                    amountInput,
                    reserveIn,
                    reserveOut,
                    vReserveIn,
                    vReserveOut,
                    feeInPrecision
                );
            }
            (uint256 amount0Out, uint256 amount1Out) = input == token0
                ? (uint256(0), amountOutput)
                : (amountOutput, uint256(0));
            address to = i < path.length - 2 ? poolsPath[i + 1] : _to;
            pool.swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] memory poolsPath,
        IERC20[] memory path,
        address to,
        uint256 deadline
    ) public override ensure(deadline) {
        path[0].safeTransferFrom(msg.sender, poolsPath[0], amountIn);
        uint256 balanceBefore = path[path.length - 1].balanceOf(to);
        _swapSupportingFeeOnTransferTokens(poolsPath, path, to);
        uint256 balanceAfter = path[path.length - 1].balanceOf(to);
        require(
            balanceAfter >= balanceBefore.add(amountOutMin),
            "DMMRouter: INSUFFICIENT_OUTPUT_AMOUNT"
        );
    }

    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external override payable ensure(deadline) {
        require(path[0] == weth, "DMMRouter: INVALID_PATH");
        uint256 amountIn = msg.value;
        IWETH(weth).deposit{value: amountIn}();
        weth.safeTransfer(poolsPath[0], amountIn);
        uint256 balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(poolsPath, path, to);
        require(
            path[path.length - 1].balanceOf(to).sub(balanceBefore) >= amountOutMin,
            "DMMRouter: INSUFFICIENT_OUTPUT_AMOUNT"
        );
    }

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata poolsPath,
        IERC20[] calldata path,
        address to,
        uint256 deadline
    ) external override ensure(deadline) {
        require(path[path.length - 1] == weth, "DMMRouter: INVALID_PATH");
        path[0].safeTransferFrom(msg.sender, poolsPath[0], amountIn);
        _swapSupportingFeeOnTransferTokens(poolsPath, path, address(this));
        uint256 amountOut = IWETH(weth).balanceOf(address(this));
        require(amountOut >= amountOutMin, "DMMRouter: INSUFFICIENT_OUTPUT_AMOUNT");
        IWETH(weth).withdraw(amountOut);
        TransferHelper.safeTransferETH(to, amountOut);
    }

    // **** LIBRARY FUNCTIONS ****

    /// @dev get the amount of tokenB for adding liquidity with given amount of token A and the amount of tokens in the pool
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external override pure returns (uint256 amountB) {
        return DMMLibrary.quote(amountA, reserveA, reserveB);
    }

    function getAmountsOut(
        uint256 amountIn,
        address[] calldata poolsPath,
        IERC20[] calldata path
    ) external override view returns (uint256[] memory amounts) {
        verifyPoolsPathSwap(poolsPath, path);
        return DMMLibrary.getAmountsOut(amountIn, poolsPath, path);
    }

    function getAmountsIn(
        uint256 amountOut,
        address[] calldata poolsPath,
        IERC20[] calldata path
    ) external override view returns (uint256[] memory amounts) {
        verifyPoolsPathSwap(poolsPath, path);
        return DMMLibrary.getAmountsIn(amountOut, poolsPath, path);
    }

    function verifyPoolsPathSwap(address[] memory poolsPath, IERC20[] memory path) internal view {
        require(path.length >= 2, "DMMRouter: INVALID_PATH");
        require(poolsPath.length == path.length - 1, "DMMRouter: INVALID_POOLS_PATH");
        for (uint256 i = 0; i < poolsPath.length; i++) {
            verifyPoolAddress(path[i], path[i + 1], poolsPath[i]);
        }
    }

    function verifyPoolAddress(
        IERC20 tokenA,
        IERC20 tokenB,
        address pool
    ) internal view {
        require(IDMMFactory(factory).isPool(tokenA, tokenB, pool), "DMMRouter: INVALID_POOL");
    }
}