// SPDX-License-Identifier: MIT
// File: contracts/BIFI/zap/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 stable() external view returns (bool);
    function getAmountOut(uint256 amountIn, address tokenIn) external view returns (uint256);

    function initialize(address, address) external;
}

// File: contracts/BIFI/zap/Babylonian.sol


pragma solidity >=0.4.0;

// computes square roots using the babylonian method
// https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method
library Babylonian {
    // credit for this implementation goes to
    // https://github.com/abdk-consulting/abdk-libraries-solidity/blob/master/ABDKMath64x64.sol#L687
    function sqrt(uint256 x) internal pure returns (uint256) {
        if (x == 0) return 0;
        // this block is equivalent to r = uint256(1) << (BitMath.mostSignificantBit(x) / 2);
        // however that code costs significantly more gas
        uint256 xx = x;
        uint256 r = 1;
        if (xx >= 0x100000000000000000000000000000000) {
            xx >>= 128;
            r <<= 64;
        }
        if (xx >= 0x10000000000000000) {
            xx >>= 64;
            r <<= 32;
        }
        if (xx >= 0x100000000) {
            xx >>= 32;
            r <<= 16;
        }
        if (xx >= 0x10000) {
            xx >>= 16;
            r <<= 8;
        }
        if (xx >= 0x100) {
            xx >>= 8;
            r <<= 4;
        }
        if (xx >= 0x10) {
            xx >>= 4;
            r <<= 2;
        }
        if (xx >= 0x8) {
            r <<= 1;
        }
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1; // Seven iterations should be enough
        uint256 r1 = x / r;
        return (r < r1 ? r : r1);
    }
}

// File: contracts/BIFI/zap/IERC20.sol


pragma solidity >=0.6.0 <0.9.0;

/**
 * @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: contracts/BIFI/zap/SafeMath.sol


pragma solidity >=0.6.0 <0.9.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: contracts/BIFI/zap/Address.sol


pragma solidity >=0.6.2 <0.9.0;

/**
 * @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);
    }

    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: contracts/BIFI/zap/SafeERC20.sol


pragma solidity >=0.6.0 <0.9.0;




/**
 * @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/BIFI/zap/LowGasSafeMath.sol

pragma solidity >=0.7.0;

/// @title Optimized overflow and underflow safe math operations
/// @notice Contains methods for doing math operations that revert on overflow or underflow for minimal gas cost
library LowGasSafeMath {
    /// @notice Returns x + y, reverts if sum overflows uint256
    /// @param x The augend
    /// @param y The addend
    /// @return z The sum of x and y
    function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x + y) >= x);
    }

    /// @notice Returns x - y, reverts if underflows
    /// @param x The minuend
    /// @param y The subtrahend
    /// @return z The difference of x and y
    function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x - y) <= x);
    }

    /// @notice Returns x * y, reverts if overflows
    /// @param x The multiplicand
    /// @param y The multiplier
    /// @return z The product of x and y
    function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require(x == 0 || (z = x * y) / x == y);
    }

    /// @notice Returns x + y, reverts if overflows or underflows
    /// @param x The augend
    /// @param y The addend
    /// @return z The sum of x and y
    function add(int256 x, int256 y) internal pure returns (int256 z) {
        require((z = x + y) >= x == (y >= 0));
    }

    /// @notice Returns x - y, reverts if overflows or underflows
    /// @param x The minuend
    /// @param y The subtrahend
    /// @return z The difference of x and y
    function sub(int256 x, int256 y) internal pure returns (int256 z) {
        require((z = x - y) <= x == (y >= 0));
    }
}

// File: contracts/BIFI/zap/IUniswapV2Router01.sol

pragma solidity >=0.6.0 <0.9.0;
interface IUniswapRouterSolidly {


    function addLiquidity(
        address tokenA,
        address tokenB,
        bool stable,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);

    function addLiquidityETH(
        address token,
        bool stable, 
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);

    function removeLiquidity(
        address tokenA,
        address tokenB,
        bool stable, 
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);

    function removeLiquidityETH(
        address token,
        bool stable,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);

    function swapExactTokensForTokensSimple(
        uint amountIn, 
        uint amountOutMin, 
        address tokenFrom, 
        address tokenTo,
        bool stable, 
        address to, 
        uint deadline
    ) external returns (uint[] memory amounts);

    function getAmountOut(uint amountIn, address tokenIn, address tokenOut) external view returns (uint amount, bool stable);
   
    function quoteAddLiquidity(
        address tokenA,
        address tokenB,
        bool stable,
        uint amountADesired,
        uint amountBDesired
    ) external view returns (uint amountA, uint amountB, uint liquidity);

    function quoteLiquidity(uint amountA, uint reserveA, uint reserveB) external view returns (uint amountB);
    function factory() external view returns (address);
    function weth() external view returns (address);
}


// File: contracts/BIFI/zap/BeefyUniV2Zap.sol


// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// @author Wivern for Beefy.Finance
// @notice This contract adds liquidity to Uniswap V2 compatible liquidity pair pools and stake.

pragma solidity >=0.7.0;



interface IERC20Extended { 
    function decimals() external view returns (uint256);
}


interface IWETH is IERC20 {
    function deposit() external payable;
    function withdraw(uint256 wad) external;
}

interface IBeefyVaultV6 is IERC20 {
    function deposit(uint256 amount) external;
    function withdraw(uint256 shares) external;
    function want() external pure returns (address);
}

contract BeefyUniV2ZapSolidly {
    using LowGasSafeMath for uint256;
    using SafeERC20 for IERC20;
    using SafeERC20 for IBeefyVaultV6;

    
    IUniswapRouterSolidly public immutable router;
    address public immutable WETH;
    uint256 public constant minimumAmount = 1000;
    
    constructor(address _router, address _WETH) {
        router = IUniswapRouterSolidly(_router);
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH);
    }

    function beefInETH (address beefyVault, uint256 tokenAmountOutMin) external payable {
        require(msg.value >= minimumAmount, 'Beefy: Insignificant input amount');

        IWETH(WETH).deposit{value: msg.value}();

        _swapAndStake(beefyVault, tokenAmountOutMin, WETH);
    }

    function beefIn (address beefyVault, uint256 tokenAmountOutMin, address tokenIn, uint256 tokenInAmount) external {
        require(tokenInAmount >= minimumAmount, 'Beefy: Insignificant input amount');
        require(IERC20(tokenIn).allowance(msg.sender, address(this)) >= tokenInAmount, 'Beefy: Input token is not approved');

        IERC20(tokenIn).safeTransferFrom(msg.sender, address(this), tokenInAmount);

        _swapAndStake(beefyVault, tokenAmountOutMin, tokenIn);
    }

    function beefOut (address beefyVault, uint256 withdrawAmount) external {
        (IBeefyVaultV6 vault, IUniswapV2Pair pair) = _getVaultPair(beefyVault);

        IERC20(beefyVault).safeTransferFrom(msg.sender, address(this), withdrawAmount);
        vault.withdraw(withdrawAmount);

        if (pair.token0() != WETH && pair.token1() != WETH) {
            return _removeLiquidity(address(pair), msg.sender);
        }

        _removeLiquidity(address(pair), address(this));

        address[] memory tokens = new address[](2);
        tokens[0] = pair.token0();
        tokens[1] = pair.token1();

        _returnAssets(tokens);
    }

    function beefOutAndSwap(address beefyVault, uint256 withdrawAmount, address desiredToken, uint256 desiredTokenOutMin) external {
        (IBeefyVaultV6 vault, IUniswapV2Pair pair) = _getVaultPair(beefyVault);
        address token0 = pair.token0();
        address token1 = pair.token1();
        require(token0 == desiredToken || token1 == desiredToken, 'Beefy: desired token not present in liqudity pair');

        vault.safeTransferFrom(msg.sender, address(this), withdrawAmount);
        vault.withdraw(withdrawAmount);
        _removeLiquidity(address(pair), address(this));

        address swapToken = token1 == desiredToken ? token0 : token1;
        address[] memory path = new address[](2);
        path[0] = swapToken;
        path[1] = desiredToken;

        _approveTokenIfNeeded(path[0], address(router));
        router.swapExactTokensForTokensSimple(IERC20(swapToken).balanceOf(address(this)), desiredTokenOutMin, path[0], path[1], pair.stable(), address(this), block.timestamp);

        _returnAssets(path);
    }

    function _removeLiquidity(address pair, address to) private {
        IERC20(pair).safeTransfer(pair, IERC20(pair).balanceOf(address(this)));
        (uint256 amount0, uint256 amount1) = IUniswapV2Pair(pair).burn(to);

        require(amount0 >= minimumAmount, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
        require(amount1 >= minimumAmount, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
    }

    function _getVaultPair (address beefyVault) private pure returns (IBeefyVaultV6 vault, IUniswapV2Pair pair) {
        vault = IBeefyVaultV6(beefyVault);
        pair = IUniswapV2Pair(vault.want());
    }

    function _swapAndStake(address beefyVault, uint256 tokenAmountOutMin, address tokenIn) private {
        (IBeefyVaultV6 vault, IUniswapV2Pair pair) = _getVaultPair(beefyVault);

        (uint256 reserveA, uint256 reserveB,) = pair.getReserves();
        require(reserveA > minimumAmount && reserveB > minimumAmount, 'Beefy: Liquidity pair reserves too low');

        bool isInputA = pair.token0() == tokenIn;
        require(isInputA || pair.token1() == tokenIn, 'Beefy: Input token not present in liqudity pair');

        address[] memory path = new address[](2);
        path[0] = tokenIn;
        path[1] = isInputA ? pair.token1() : pair.token0();

        uint256 fullInvestment = IERC20(tokenIn).balanceOf(address(this));
        uint256 swapAmountIn;
        if (isInputA) {
            swapAmountIn = _getSwapAmount(pair, fullInvestment, reserveA, reserveB, path[0], path[1]);
        } else {
            swapAmountIn = _getSwapAmount(pair, fullInvestment, reserveB, reserveA, path[0], path[1]);
        }

        _approveTokenIfNeeded(path[0], address(router));
        uint256[] memory swapedAmounts = router
            .swapExactTokensForTokensSimple(swapAmountIn, tokenAmountOutMin, path[0], path[1], pair.stable(), address(this), block.timestamp);

        _approveTokenIfNeeded(path[1], address(router));
        (,, uint256 amountLiquidity) = router
            .addLiquidity(path[0], path[1], pair.stable(), fullInvestment.sub(swapedAmounts[0]), swapedAmounts[1], 1, 1, address(this), block.timestamp);

        _approveTokenIfNeeded(address(pair), address(vault));
        vault.deposit(amountLiquidity);

        vault.safeTransfer(msg.sender, vault.balanceOf(address(this)));
        _returnAssets(path);
    }

    function _returnAssets(address[] memory tokens) private {
        uint256 balance;
        for (uint256 i; i < tokens.length; i++) {
            balance = IERC20(tokens[i]).balanceOf(address(this));
            if (balance > 0) {
                if (tokens[i] == WETH) {
                    IWETH(WETH).withdraw(balance);
                    (bool success,) = msg.sender.call{value: balance}(new bytes(0));
                    require(success, 'Beefy: ETH transfer failed');
                } else {
                    IERC20(tokens[i]).safeTransfer(msg.sender, balance);
                }
            }
        }
    }

    function _getSwapAmount(IUniswapV2Pair pair, uint256 investmentA, uint256 reserveA, uint256 reserveB, address tokenA, address tokenB) private view returns (uint256 swapAmount) {
        uint256 halfInvestment = investmentA / 2;

        if (pair.stable()) {
            swapAmount = _getStableSwap(pair, investmentA, halfInvestment, tokenA, tokenB);
        } else {
            uint256 nominator = pair.getAmountOut(halfInvestment, tokenA);
            uint256 denominator = halfInvestment * reserveB.sub(nominator) / reserveA.add(halfInvestment);
            swapAmount = investmentA.sub(Babylonian.sqrt(halfInvestment * halfInvestment * nominator / denominator));
        }
    }

    function _getStableSwap(IUniswapV2Pair pair, uint256 investmentA, uint256 halfInvestment, address tokenA, address tokenB) private view returns (uint256 swapAmount) {
        uint out = pair.getAmountOut(halfInvestment, tokenA);
        (uint amountA, uint amountB,) = router.quoteAddLiquidity(tokenA, tokenB, pair.stable(), halfInvestment, out);
                
        amountA = amountA * 1e18 / 10**IERC20Extended(tokenA).decimals();
        amountB = amountB * 1e18 / 10**IERC20Extended(tokenB).decimals();
        out = out * 1e18 / 10**IERC20Extended(tokenB).decimals();
        halfInvestment = halfInvestment * 1e18 / 10**IERC20Extended(tokenA).decimals();
                
        uint ratio = out * 1e18 / halfInvestment * amountA / amountB; 
                
        return investmentA * 1e18 / (ratio + 1e18);
    }

    function estimateSwap(address beefyVault, address tokenIn, uint256 fullInvestmentIn) public view returns(uint256 swapAmountIn, uint256 swapAmountOut, address swapTokenOut) {
        checkWETH();
        (, IUniswapV2Pair pair) = _getVaultPair(beefyVault);

        bool isInputA = pair.token0() == tokenIn;
        require(isInputA || pair.token1() == tokenIn, 'Beefy: Input token not present in liqudity pair');

        (uint256 reserveA, uint256 reserveB,) = pair.getReserves();
        (reserveA, reserveB) = isInputA ? (reserveA, reserveB) : (reserveB, reserveA);

        swapTokenOut = isInputA ? pair.token1() : pair.token0();
        swapAmountIn = _getSwapAmount(pair, fullInvestmentIn, reserveA, reserveB, tokenIn, swapTokenOut);
        swapAmountOut = pair.getAmountOut(swapAmountIn, tokenIn); 
    }

    function checkWETH() public view returns (bool isValid) {
        isValid = WETH == router.weth();
        require(isValid, 'Beefy: WETH address not matching Router.weth()');
    }

    function _approveTokenIfNeeded(address token, address spender) private {
        if (IERC20(token).allowance(address(this), spender) == 0) {
            IERC20(token).safeApprove(spender, type(uint256).max);
        }
    }

}