//SPDX-License-Identifier: Unlicense
pragma solidity >=0.8.0;

// import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";
// import "@uniswap/v2-core/contracts/interfaces/IERC20.sol";
// import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol";
// import "@uniswap/v2-periphery/contracts/interfaces/IWETH.sol";
// import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
// import "@uniswap/v2-periphery/contracts/libraries/UniswapV2Library.sol";
// import "@uniswap/lib/contracts/libraries/TransferHelper.sol";
interface IUniswapV2Factory {
    event PairCreated(
        address indexed token0,
        address indexed token1,
        address pair,
        uint256
    );

    function feeTo() external view returns (address);

    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB)
        external
        view
        returns (address pair);

    function allPairs(uint256) external view returns (address pair);

    function allPairsLength() external view returns (uint256);

    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);

    function setFeeTo(address) external;

    function setFeeToSetter(address) external;
}

interface IERC20 {
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
    event Transfer(address indexed from, address indexed to, uint256 value);

    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);

    function totalSupply() external view returns (uint256);

    function balanceOf(address owner) external view returns (uint256);

    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    function approve(address spender, uint256 value) external returns (bool);

    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);
}

interface IUniswapV2Pair {
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
    event Transfer(address indexed from, address indexed to, uint256 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 (uint256);

    function balanceOf(address owner) external view returns (uint256);

    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    function approve(address spender, uint256 value) external returns (bool);

    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 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 (uint256);

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    event Mint(address indexed sender, uint256 amount0, uint256 amount1);
    event Burn(
        address indexed sender,
        uint256 amount0,
        uint256 amount1,
        address indexed to
    );
    event Swap(
        address indexed sender,
        uint256 amount0In,
        uint256 amount1In,
        uint256 amount0Out,
        uint256 amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint256);

    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 (uint256);

    function price1CumulativeLast() external view returns (uint256);

    function kLast() external view returns (uint256);

    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 skim(address to) external;

    function sync() external;

    function initialize(address, address) external;
}

interface IWETH {
    function deposit() external payable;

    function transfer(address to, uint256 value) external returns (bool);

    function withdraw(uint256) external;
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);

    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );

    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountA, uint256 amountB);

    function removeLiquidityETH(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountToken, uint256 amountETH);

    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountA, uint256 amountB);

    function removeLiquidityETHWithPermit(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountToken, uint256 amountETH);

    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external pure returns (uint256 amountB);

    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountOut);

    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountIn);

    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);

    function getAmountsIn(uint256 amountOut, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountETH);

    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        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 path,
        address to,
        uint256 deadline
    ) external;

    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable;

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}

library UniswapV2Library {
    using SafeMath for uint256;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB)
        internal
        pure
        returns (address token0, address token1)
    {
        require(tokenA != tokenB, "UniswapV2Library: IDENTICAL_ADDRESSES");
        (token0, token1) = tokenA < tokenB
            ? (tokenA, tokenB)
            : (tokenB, tokenA);
        require(token0 != address(0), "UniswapV2Library: ZERO_ADDRESS");
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(
        address factory,
        address tokenA,
        address tokenB
    ) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(
            uint160(
                uint256(
                    keccak256(
                        abi.encodePacked(
                            hex"ff",
                            factory,
                            keccak256(abi.encodePacked(token0, token1)),
                            hex"96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f" // init code hash
                        )
                    )
                )
            )
        );
    }

    // fetches and sorts the reserves for a pair
    function getReserves(
        address factory,
        address tokenA,
        address tokenB
    ) internal view returns (uint256 reserveA, uint256 reserveB) {
        (address token0, ) = sortTokens(tokenA, tokenB);
        (uint256 reserve0, uint256 reserve1, ) = IUniswapV2Pair(
            pairFor(factory, tokenA, tokenB)
        ).getReserves();
        (reserveA, reserveB) = tokenA == token0
            ? (reserve0, reserve1)
            : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) internal pure returns (uint256 amountB) {
        require(amountA > 0, "UniswapV2Library: INSUFFICIENT_AMOUNT");
        require(
            reserveA > 0 && reserveB > 0,
            "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
        );
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) internal pure returns (uint256 amountOut) {
        require(amountIn > 0, "UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT");
        require(
            reserveIn > 0 && reserveOut > 0,
            "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
        );
        uint256 amountInWithFee = amountIn.mul(997);
        uint256 numerator = amountInWithFee.mul(reserveOut);
        uint256 denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) internal pure returns (uint256 amountIn) {
        require(amountOut > 0, "UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT");
        require(
            reserveIn > 0 && reserveOut > 0,
            "UniswapV2Library: INSUFFICIENT_LIQUIDITY"
        );
        uint256 numerator = reserveIn.mul(amountOut).mul(1000);
        uint256 denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(
        address factory,
        uint256 amountIn,
        address[] memory path
    ) internal view returns (uint256[] memory amounts) {
        require(path.length >= 2, "UniswapV2Library: INVALID_PATH");
        amounts = new uint256[](path.length);
        amounts[0] = amountIn;
        for (uint256 i; i < path.length - 1; i++) {
            (uint256 reserveIn, uint256 reserveOut) = getReserves(
                factory,
                path[i],
                path[i + 1]
            );
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(
        address factory,
        uint256 amountOut,
        address[] memory path
    ) internal view returns (uint256[] memory amounts) {
        require(path.length >= 2, "UniswapV2Library: INVALID_PATH");
        amounts = new uint256[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint256 i = path.length - 1; i > 0; i--) {
            (uint256 reserveIn, uint256 reserveOut) = getReserves(
                factory,
                path[i - 1],
                path[i]
            );
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

library SafeMath {
    function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x + y) >= x, "ds-math-add-overflow");
    }

    function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x - y) <= x, "ds-math-sub-underflow");
    }

    function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require(y == 0 || (z = x * y) / y == x, "ds-math-mul-overflow");
    }
}

library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 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::safeApprove: approve failed"
        );
    }

    function safeTransfer(
        address token,
        address to,
        uint256 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::safeTransfer: transfer failed"
        );
    }

    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 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::transferFrom: transferFrom failed"
        );
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(
            success,
            "TransferHelper::safeTransferETH: ETH transfer failed"
        );
    }
}

contract PowSwap {
    using SafeMath for uint256;
    // wallet
    address internal immutable _wallet;
    // owner
    address internal immutable _owner;
    //weth
    address internal immutable WETH;

    address internal immutable _factory;

    constructor(
        address owner,
        address wallet,
        address weth,
        address factory
    ) {
        _owner = owner;
        _wallet = wallet;
        WETH = weth;
        _factory = factory;
    }

    receive() external payable {}

    function _swap(
        uint256[] memory amounts,
        address[] memory path,
        address _to
    ) internal virtual {
        for (uint256 i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0, ) = UniswapV2Library.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
                ? UniswapV2Library.pairFor(_factory, output, path[i + 2])
                : _to;
            IUniswapV2Pair(UniswapV2Library.pairFor(_factory, input, output))
                .swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }

    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path
    ) external virtual returns (uint256[] memory amounts) {
        // check owner
        require(msg.sender == _owner, "must be called by owner");

        require(path[path.length - 1] == WETH, "UniswapV2Router: INVALID_PATH");
        amounts = UniswapV2Library.getAmountsOut(_factory, amountIn, path);
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        TransferHelper.safeTransferFrom(
            path[0],
            _wallet,
            UniswapV2Library.pairFor(_factory, path[0], path[1]),
            amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(_wallet, amounts[amounts.length - 1]);
    }
}