// File: contracts/DeSwapRouter.sol



pragma solidity =0.6.6;

import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";
import "@uniswap/lib/contracts/libraries/TransferHelper.sol";

import "./interfaces/IUniswapV2Router02.sol";
import "./libraries/DeSwapLibrary.sol";
import "./libraries/SafeMath.sol";
import "./interfaces/IERC20.sol";
import "./interfaces/IWETH.sol";

contract DeSwapRouter is IUniswapV2Router02 {
    using SafeMath for uint256;

    address public immutable override factory;
    address public immutable override WBNB;

    mapping(address => bool) public isWhitelisted;

    modifier ensure(uint256 deadline) {
        require(deadline >= block.timestamp, "UniswapV2Router: EXPIRED");
        _;
    }

    constructor(address _factory, address _WBNB) public {
        factory = _factory;
        WBNB = _WBNB;
    }

    receive() external payable {
        assert(msg.sender == WBNB); // only accept ETH via fallback from the WBNB contract
    }

    function whitelist(address addr, bool _whitelist) external {
        require(
            IUniswapV2Factory(factory).feeToSetter() == msg.sender,
            "UniswapV2Router: Only feeToSetter"
        );
        isWhitelisted[addr] = _whitelist;
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin
    ) internal virtual returns (uint256 amountA, uint256 amountB) {
        // create the pair if it doesn't exist yet
        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
        }
        (uint256 reserveA, uint256 reserveB) = DeSwapLibrary.getReserves(
            factory,
            tokenA,
            tokenB
        );
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint256 amountBOptimal = DeSwapLibrary.quote(
                amountADesired,
                reserveA,
                reserveB
            );
            if (amountBOptimal <= amountBDesired) {
                require(
                    amountBOptimal >= amountBMin,
                    "UniswapV2Router: INSUFFICIENT_B_AMOUNT"
                );
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint256 amountAOptimal = DeSwapLibrary.quote(
                    amountBDesired,
                    reserveB,
                    reserveA
                );
                assert(amountAOptimal <= amountADesired);
                require(
                    amountAOptimal >= amountAMin,
                    "UniswapV2Router: INSUFFICIENT_A_AMOUNT"
                );
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        virtual
        override
        ensure(deadline)
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        )
    {
        (amountA, amountB) = _addLiquidity(
            tokenA,
            tokenB,
            amountADesired,
            amountBDesired,
            amountAMin,
            amountBMin
        );
        address pair = DeSwapLibrary.pairFor(factory, tokenA, tokenB);
        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
        liquidity = IUniswapV2Pair(pair).mint(to);
    }

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        virtual
        override
        ensure(deadline)
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        )
    {
        (amountToken, amountETH) = _addLiquidity(
            token,
            WBNB,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin
        );
        address pair = DeSwapLibrary.pairFor(factory, token, WBNB);
        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
        IWETH(WBNB).deposit{value: amountETH}();
        assert(IWETH(WBNB).transfer(pair, amountETH));
        liquidity = IUniswapV2Pair(pair).mint(to);
        // refund dust eth, if any
        if (msg.value > amountETH)
            TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        public
        virtual
        override
        ensure(deadline)
        returns (uint256 amountA, uint256 amountB)
    {
        address pair = DeSwapLibrary.pairFor(factory, tokenA, tokenB);
        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
        (uint256 amount0, uint256 amount1) = IUniswapV2Pair(pair).burn(to);
        (address token0, ) = DeSwapLibrary.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0
            ? (amount0, amount1)
            : (amount1, amount0);
        require(
            amountA >= amountAMin,
            "UniswapV2Router: INSUFFICIENT_A_AMOUNT"
        );
        require(
            amountB >= amountBMin,
            "UniswapV2Router: INSUFFICIENT_B_AMOUNT"
        );
    }

    function removeLiquidityETH(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        public
        virtual
        override
        ensure(deadline)
        returns (uint256 amountToken, uint256 amountETH)
    {
        (amountToken, amountETH) = removeLiquidity(
            token,
            WBNB,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, amountToken);
        IWETH(WBNB).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, 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 virtual override returns (uint256 amountA, uint256 amountB) {
        address pair = DeSwapLibrary.pairFor(factory, tokenA, tokenB);
        uint256 value = approveMax ? uint256(-1) : liquidity;
        IUniswapV2Pair(pair).permit(
            msg.sender,
            address(this),
            value,
            deadline,
            v,
            r,
            s
        );
        (amountA, amountB) = removeLiquidity(
            tokenA,
            tokenB,
            liquidity,
            amountAMin,
            amountBMin,
            to,
            deadline
        );
    }

    function removeLiquidityETHWithPermit(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    )
        external
        virtual
        override
        returns (uint256 amountToken, uint256 amountETH)
    {
        address pair = DeSwapLibrary.pairFor(factory, token, WBNB);
        uint256 value = approveMax ? uint256(-1) : liquidity;
        IUniswapV2Pair(pair).permit(
            msg.sender,
            address(this),
            value,
            deadline,
            v,
            r,
            s
        );
        (amountToken, amountETH) = removeLiquidityETH(
            token,
            liquidity,
            amountTokenMin,
            amountETHMin,
            to,
            deadline
        );
    }

    // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) public virtual override ensure(deadline) returns (uint256 amountETH) {
        (, amountETH) = removeLiquidity(
            token,
            WBNB,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(
            token,
            to,
            IERC20(token).balanceOf(address(this))
        );
        IWETH(WBNB).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }

    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external virtual override returns (uint256 amountETH) {
        address pair = DeSwapLibrary.pairFor(factory, token, WBNB);
        uint256 value = approveMax ? uint256(-1) : liquidity;
        IUniswapV2Pair(pair).permit(
            msg.sender,
            address(this),
            value,
            deadline,
            v,
            r,
            s
        );
        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
            token,
            liquidity,
            amountTokenMin,
            amountETHMin,
            to,
            deadline
        );
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pair
    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, ) = DeSwapLibrary.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
                ? DeSwapLibrary.pairFor(factory, output, path[i + 2])
                : _to;
            IUniswapV2Pair(DeSwapLibrary.pairFor(factory, input, output)).swap(
                amount0Out,
                amount1Out,
                to,
                new bytes(0)
            );
        }
    }

    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    )
        external
        virtual
        override
        ensure(deadline)
        returns (uint256[] memory amounts)
    {
        if (!isWhitelisted[msg.sender])
            amounts = DeSwapLibrary.getAmountsOut(factory, amountIn, path);
        else
            amounts = DeSwapLibrary.getAmountsOutWhitelist(
                factory,
                amountIn,
                path
            );
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        TransferHelper.safeTransferFrom(
            path[0],
            msg.sender,
            DeSwapLibrary.pairFor(factory, path[0], path[1]),
            amounts[0]
        );
        _swap(amounts, path, to);
    }

    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    )
        external
        virtual
        override
        ensure(deadline)
        returns (uint256[] memory amounts)
    {
        if (!isWhitelisted[msg.sender])
            amounts = DeSwapLibrary.getAmountsIn(factory, amountOut, path);
        else
            amounts = DeSwapLibrary.getAmountsInWhitelist(
                factory,
                amountOut,
                path
            );
        require(
            amounts[0] <= amountInMax,
            "UniswapV2Router: EXCESSIVE_INPUT_AMOUNT"
        );
        TransferHelper.safeTransferFrom(
            path[0],
            msg.sender,
            DeSwapLibrary.pairFor(factory, path[0], path[1]),
            amounts[0]
        );
        _swap(amounts, path, to);
    }

    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    )
        external
        payable
        virtual
        override
        ensure(deadline)
        returns (uint256[] memory amounts)
    {
        require(path[0] == WBNB, "UniswapV2Router: INVALID_PATH");
        if (!isWhitelisted[msg.sender])
            amounts = DeSwapLibrary.getAmountsOut(factory, msg.value, path);
        else
            amounts = DeSwapLibrary.getAmountsOutWhitelist(
                factory,
                msg.value,
                path
            );
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        IWETH(WBNB).deposit{value: amounts[0]}();
        assert(
            IWETH(WBNB).transfer(
                DeSwapLibrary.pairFor(factory, path[0], path[1]),
                amounts[0]
            )
        );
        _swap(amounts, path, to);
    }

    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    )
        external
        virtual
        override
        ensure(deadline)
        returns (uint256[] memory amounts)
    {
        require(path[path.length - 1] == WBNB, "UniswapV2Router: INVALID_PATH");

        if (!isWhitelisted[msg.sender])
            amounts = DeSwapLibrary.getAmountsIn(factory, amountOut, path);
        else
            amounts = DeSwapLibrary.getAmountsInWhitelist(
                factory,
                amountOut,
                path
            );
        require(
            amounts[0] <= amountInMax,
            "UniswapV2Router: EXCESSIVE_INPUT_AMOUNT"
        );
        TransferHelper.safeTransferFrom(
            path[0],
            msg.sender,
            DeSwapLibrary.pairFor(factory, path[0], path[1]),
            amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WBNB).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }

    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    )
        external
        virtual
        override
        ensure(deadline)
        returns (uint256[] memory amounts)
    {
        require(path[path.length - 1] == WBNB, "UniswapV2Router: INVALID_PATH");

        if (!isWhitelisted[msg.sender])
            amounts = DeSwapLibrary.getAmountsOut(factory, amountIn, path);
        else
            amounts = DeSwapLibrary.getAmountsOutWhitelist(
                factory,
                amountIn,
                path
            );
        require(
            amounts[amounts.length - 1] >= amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        TransferHelper.safeTransferFrom(
            path[0],
            msg.sender,
            DeSwapLibrary.pairFor(factory, path[0], path[1]),
            amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WBNB).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }

    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata path,
        address to,
        uint256 deadline
    )
        external
        payable
        virtual
        override
        ensure(deadline)
        returns (uint256[] memory amounts)
    {
        require(path[0] == WBNB, "UniswapV2Router: INVALID_PATH");
        if (!isWhitelisted[msg.sender])
            amounts = DeSwapLibrary.getAmountsIn(factory, amountOut, path);
        else
            amounts = DeSwapLibrary.getAmountsInWhitelist(
                factory,
                amountOut,
                path
            );

        require(
            amounts[0] <= msg.value,
            "UniswapV2Router: EXCESSIVE_INPUT_AMOUNT"
        );
        IWETH(WBNB).deposit{value: amounts[0]}();
        assert(
            IWETH(WBNB).transfer(
                DeSwapLibrary.pairFor(factory, path[0], path[1]),
                amounts[0]
            )
        );
        _swap(amounts, 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 pair
    function _swapSupportingFeeOnTransferTokens(
        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, ) = DeSwapLibrary.sortTokens(input, output);
            IUniswapV2Pair pair = IUniswapV2Pair(
                DeSwapLibrary.pairFor(factory, input, output)
            );
            uint256 amountInput;
            uint256 amountOutput;
            {
                // scope to avoid stack too deep errors
                (uint256 reserve0, uint256 reserve1, ) = pair.getReserves();
                (uint256 reserveInput, uint256 reserveOutput) = input == token0
                    ? (reserve0, reserve1)
                    : (reserve1, reserve0);
                amountInput = IERC20(input).balanceOf(address(pair)).sub(
                    reserveInput
                );
                amountOutput = !isWhitelisted[msg.sender]
                    ? DeSwapLibrary.getAmountOut(
                        amountInput,
                        reserveInput,
                        reserveOutput
                    )
                    : DeSwapLibrary.getAmountOutWhitelist(
                        amountInput,
                        reserveInput,
                        reserveOutput
                    );
            }
            (uint256 amount0Out, uint256 amount1Out) = input == token0
                ? (uint256(0), amountOutput)
                : (amountOutput, uint256(0));
            address to = i < path.length - 2
                ? DeSwapLibrary.pairFor(factory, output, path[i + 2])
                : _to;
            pair.swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external virtual override ensure(deadline) {
        TransferHelper.safeTransferFrom(
            path[0],
            msg.sender,
            DeSwapLibrary.pairFor(factory, path[0], path[1]),
            amountIn
        );
        uint256 balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >=
                amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
    }

    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable virtual override ensure(deadline) {
        require(path[0] == WBNB, "UniswapV2Router: INVALID_PATH");
        uint256 amountIn = msg.value;
        IWETH(WBNB).deposit{value: amountIn}();
        assert(
            IWETH(WBNB).transfer(
                DeSwapLibrary.pairFor(factory, path[0], path[1]),
                amountIn
            )
        );
        uint256 balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >=
                amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
    }

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external virtual override ensure(deadline) {
        require(path[path.length - 1] == WBNB, "UniswapV2Router: INVALID_PATH");
        TransferHelper.safeTransferFrom(
            path[0],
            msg.sender,
            DeSwapLibrary.pairFor(factory, path[0], path[1]),
            amountIn
        );
        _swapSupportingFeeOnTransferTokens(path, address(this));
        uint256 amountOut = IERC20(WBNB).balanceOf(address(this));
        require(
            amountOut >= amountOutMin,
            "UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT"
        );
        IWETH(WBNB).withdraw(amountOut);
        TransferHelper.safeTransferETH(to, amountOut);
    }

    // **** LIBRARY FUNCTIONS ****
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) public pure virtual override returns (uint256 amountB) {
        return DeSwapLibrary.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) public pure virtual override returns (uint256 amountOut) {
        return DeSwapLibrary.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) public pure virtual override returns (uint256 amountIn) {
        return DeSwapLibrary.getAmountIn(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint256 amountIn, address[] memory path)
        public
        view
        virtual
        override
        returns (uint256[] memory amounts)
    {
        return DeSwapLibrary.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint256 amountOut, address[] memory path)
        public
        view
        virtual
        override
        returns (uint256[] memory amounts)
    {
        return DeSwapLibrary.getAmountsIn(factory, amountOut, path);
    }

    function getAmountOutWhitelist(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) public pure returns (uint256 amountOut) {
        return
            DeSwapLibrary.getAmountOutWhitelist(
                amountIn,
                reserveIn,
                reserveOut
            );
    }

    function getAmountInWhitelist(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) public pure returns (uint256 amountIn) {
        return
            DeSwapLibrary.getAmountInWhitelist(
                amountOut,
                reserveIn,
                reserveOut
            );
    }

    function getAmountsOutWhitelist(uint256 amountIn, address[] memory path)
        public
        view
        returns (uint256[] memory amounts)
    {
        return DeSwapLibrary.getAmountsOutWhitelist(factory, amountIn, path);
    }

    function getAmountsInWhitelist(uint256 amountOut, address[] memory path)
        public
        view
        returns (uint256[] memory amounts)
    {
        return DeSwapLibrary.getAmountsInWhitelist(factory, amountOut, path);
    }
}

// File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol



pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    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(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

// File: @uniswap/lib/contracts/libraries/TransferHelper.sol



// SPDX-License-Identifier: GPL-3.0-or-later

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,
        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');
    }
}

// File: contracts/interfaces/IUniswapV2Router02.sol



pragma solidity >=0.6.2;

import './IUniswapV2Router01.sol';

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

// File: contracts/libraries/DeSwapLibrary.sol



pragma solidity >=0.5.0;

import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol";

import "./SafeMath.sol";

library DeSwapLibrary {
    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, "DeSwapLibrary: IDENTICAL_ADDRESSES");
        (token0, token1) = tokenA < tokenB
            ? (tokenA, tokenB)
            : (tokenB, tokenA);
        require(token0 != address(0), "DeSwapLibrary: 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(
            uint256(
                keccak256(
                    abi.encodePacked(
                        hex"ff",
                        factory,
                        keccak256(abi.encodePacked(token0, token1)),
                        hex"4cfdbd9412c313201c8e2f145161c99a6e59be6a7331cdc65348046ecc260bb9" // 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, "DeSwapLibrary: INSUFFICIENT_AMOUNT");
        require(
            reserveA > 0 && reserveB > 0,
            "DeSwapLibrary: 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, "DeSwapLibrary: INSUFFICIENT_INPUT_AMOUNT");
        require(
            reserveIn > 0 && reserveOut > 0,
            "DeSwapLibrary: 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, "DeSwapLibrary: INSUFFICIENT_OUTPUT_AMOUNT");
        require(
            reserveIn > 0 && reserveOut > 0,
            "DeSwapLibrary: 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, "DeSwapLibrary: 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, "DeSwapLibrary: 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);
        }
    }

    // WHITELISTED ADDRESS TRADING VALUES
    function getAmountOutWhitelist(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) internal pure returns (uint256 amountOut) {
        require(amountIn > 0, "DeSwapLibrary: INSUFFICIENT_INPUT_AMOUNT");
        require(
            reserveIn > 0 && reserveOut > 0,
            "DeSwapLibrary: INSUFFICIENT_LIQUIDITY"
        );
        uint256 amountInWithFee = amountIn.mul(1000);
        uint256 numerator = amountInWithFee.mul(reserveOut);
        uint256 denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    function getAmountInWhitelist(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) internal pure returns (uint256 amountIn) {
        require(amountOut > 0, "DeSwapLibrary: INSUFFICIENT_OUTPUT_AMOUNT");
        require(
            reserveIn > 0 && reserveOut > 0,
            "DeSwapLibrary: INSUFFICIENT_LIQUIDITY"
        );
        uint256 numerator = reserveIn.mul(amountOut).mul(1000);
        uint256 denominator = reserveOut.sub(amountOut).mul(1000);
        amountIn = (numerator / denominator).add(1);
    }

    function getAmountsOutWhitelist(
        address factory,
        uint256 amountIn,
        address[] memory path
    ) internal view returns (uint256[] memory amounts) {
        require(path.length >= 2, "DeSwapLibrary: 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] = getAmountOutWhitelist(
                amounts[i],
                reserveIn,
                reserveOut
            );
        }
    }

    function getAmountsInWhitelist(
        address factory,
        uint256 amountOut,
        address[] memory path
    ) internal view returns (uint256[] memory amounts) {
        require(path.length >= 2, "DeSwapLibrary: 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] = getAmountInWhitelist(
                amounts[i],
                reserveIn,
                reserveOut
            );
        }
    }
}

// File: contracts/libraries/SafeMath.sol



pragma solidity =0.6.6;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

// File: contracts/interfaces/IERC20.sol



pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint 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 (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);
}

// File: contracts/interfaces/IWETH.sol



pragma solidity >=0.5.0;

interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

// File: contracts/interfaces/IUniswapV2Router01.sol



pragma solidity >=0.6.2;

interface IUniswapV2Router01 {
    function factory() external pure returns (address);

    function WBNB() 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);
}

// File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol



pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}