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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

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

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @uniswap/lib/contracts/libraries/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 {
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
        // else z = 0
    }
}

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



pragma solidity >=0.6.0;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
    }

    function safeTransfer(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
    }

    function safeTransferFrom(address token, address from, address to, uint value) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
    }

    function safeTransferETH(address to, uint value) internal {
        (bool success,) = to.call{value:value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}

// File: @uniswap/v2-core/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: @uniswap/v2-core/contracts/interfaces/IUniswapV2Callee.sol



pragma solidity >=0.5.0;

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

// File: @uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router01.sol



pragma solidity >=0.6.2;

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

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        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,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

// File: @uniswap/v2-periphery/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: @uniswap/v2-periphery/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: @uniswap/v3-core/contracts/interfaces/callback/IUniswapV3SwapCallback.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Callback for IUniswapV3PoolActions#swap
/// @notice Any contract that calls IUniswapV3PoolActions#swap must implement this interface
interface IUniswapV3SwapCallback {
    /// @notice Called to `msg.sender` after executing a swap via IUniswapV3Pool#swap.
    /// @dev In the implementation you must pay the pool tokens owed for the swap.
    /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
    /// amount0Delta and amount1Delta can both be 0 if no tokens were swapped.
    /// @param amount0Delta The amount of token0 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token0 to the pool.
    /// @param amount1Delta The amount of token1 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token1 to the pool.
    /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#swap call
    function uniswapV3SwapCallback(
        int256 amount0Delta,
        int256 amount1Delta,
        bytes calldata data
    ) external;
}

// File: @uniswap/v3-periphery/contracts/interfaces/ISwapRouter.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.7.5;
pragma abicoder v2;

import '@uniswap/v3-core/contracts/interfaces/callback/IUniswapV3SwapCallback.sol';

/// @title Router token swapping functionality
/// @notice Functions for swapping tokens via Uniswap V3
interface ISwapRouter is IUniswapV3SwapCallback {
    struct ExactInputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
        uint160 sqrtPriceLimitX96;
    }

    /// @notice Swaps `amountIn` of one token for as much as possible of another token
    /// @param params The parameters necessary for the swap, encoded as `ExactInputSingleParams` in calldata
    /// @return amountOut The amount of the received token
    function exactInputSingle(ExactInputSingleParams calldata params) external payable returns (uint256 amountOut);

    struct ExactInputParams {
        bytes path;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
    }

    /// @notice Swaps `amountIn` of one token for as much as possible of another along the specified path
    /// @param params The parameters necessary for the multi-hop swap, encoded as `ExactInputParams` in calldata
    /// @return amountOut The amount of the received token
    function exactInput(ExactInputParams calldata params) external payable returns (uint256 amountOut);

    struct ExactOutputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountOut;
        uint256 amountInMaximum;
        uint160 sqrtPriceLimitX96;
    }

    /// @notice Swaps as little as possible of one token for `amountOut` of another token
    /// @param params The parameters necessary for the swap, encoded as `ExactOutputSingleParams` in calldata
    /// @return amountIn The amount of the input token
    function exactOutputSingle(ExactOutputSingleParams calldata params) external payable returns (uint256 amountIn);

    struct ExactOutputParams {
        bytes path;
        address recipient;
        uint256 deadline;
        uint256 amountOut;
        uint256 amountInMaximum;
    }

    /// @notice Swaps as little as possible of one token for `amountOut` of another along the specified path (reversed)
    /// @param params The parameters necessary for the multi-hop swap, encoded as `ExactOutputParams` in calldata
    /// @return amountIn The amount of the input token
    function exactOutput(ExactOutputParams calldata params) external payable returns (uint256 amountIn);
}

// File: contracts/Arbitrager.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

import "@uniswap/v2-periphery/contracts/interfaces/IWETH.sol";
import "@uniswap/v2-core/contracts/interfaces/IERC20.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Callee.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "@uniswap/v3-periphery/contracts/interfaces/ISwapRouter.sol";
import "@uniswap/lib/contracts/libraries/TransferHelper.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

import "./interfaces/IUniswapV2Pair.sol";
import "./libraries/UniswapV2Library.sol";
import "./libraries/ArbitragerMathLibrary.sol";

contract Arbitrager is IUniswapV2Callee, Ownable {
    IWETH public immutable weth;
    //user => token => amount
    mapping(address => uint256) public profits;

    constructor(address weth_) {
        weth = IWETH(weth_);
    }

    receive() external payable {}

    function arbitrage(
        address pullToken,
        address remainToken,
        address pairA, // address exchangeA, // flash
        address pairB // address exchangeB, // swap
    ) public {
        require(pairA != pairB, "both exchange same");
        bool pullTokenIs0 = uint160(pullToken) < uint160(remainToken);
        uint256 x;
        uint256 y;
        uint256 z;
        {
            uint256 reserveAPull;
            uint256 reserveARemain;
            uint256 reserveBpull;
            uint256 reserveBremain;

            // these are not exactly pull and remain tokens, they are swapped below if necessary
            (reserveAPull, reserveARemain, ) = IUniswapV2Pair(pairA)
                .getReserves();
            (reserveBpull, reserveBremain, ) = IUniswapV2Pair(pairB)
                .getReserves();

            // swapping if pulltoken - remaintoken is different than uniswap's 0 - 1 order.
            if (!pullTokenIs0) {
                (reserveAPull, reserveARemain) = (reserveARemain, reserveAPull);
                (reserveBpull, reserveBremain) = (reserveBremain, reserveBpull);
            }

            require(
                reserveAPull > 0 &&
                    reserveARemain > 0 &&
                    reserveBpull > 0 &&
                    reserveBremain > 0,
                "No Liquidity"
            );

            (x, y, z) = ArbitragerMathLibrary.computeProfitMaximizingTrade(
                reserveBremain,
                reserveBpull,
                reserveARemain,
                reserveAPull
            );
        }

        // emit TradeCalculated(x, y, z);
        require(x != 0, "Trade is not profitable");

        //
        // trigger flash loan
        IUniswapV2Pair(pairA).swap(
            pullTokenIs0 ? x : 0,
            pullTokenIs0 ? 0 : x,
            address(this),
            abi.encode(pairB, pullToken, remainToken, y, z)
        );

        // // store profits
        profits[remainToken] += y - z - 1;
    }

    function uniswapV2Call(
        address sender,
        uint256 amount0,
        uint256 amount1,
        bytes calldata data
    ) external override {
        bool pullTokenIs0 = amount0 > 0;
        uint256 x = pullTokenIs0 ? amount0 : amount1;

        (
            address pairB,
            address pullToken,
            address remainToken,
            uint256 y,
            uint256 z
        ) = abi.decode(data, (address, address, address, uint256, uint256));

        {
            (bool success, ) = pullToken.call(
                abi.encodeWithSignature("transfer(address,uint256)", pairB, x)
            );
            require(success, "erc20 transfer 1 failing");
        }
        IUniswapV2Pair(pairB).swap(
            pullTokenIs0 ? 0 : y,
            pullTokenIs0 ? y : 0,
            address(this),
            ""
        );

        {
            (bool success, ) = remainToken.call(
                abi.encodeWithSignature(
                    "transfer(address,uint256)",
                    msg.sender,
                    z + 1
                )
            );
            require(success, "erc20 transfer 2 failing");
        }
    }

    function normalArbitrageUniswapV2ToUniswapV3(
        address token0,
        address token1,
        IUniswapV2Router02 uniV2Router,
        ISwapRouter uniV3Router,
        uint256 amountIn
    ) external {
        require(amountIn > 0);
        //use token of this contract for arbitrager
        IERC20(token0).approve(address(uniV2Router), amountIn);
        address[] memory pathA = new address[](2);
        (pathA[0], pathA[1]) = (token0, token1);
        uint256[] memory amounts = uniV2Router.swapExactTokensForTokens(
            amountIn,
            type(uint256).max,
            pathA,
            address(this),
            block.timestamp + 60 * 15
        );

        TransferHelper.safeApprove(token1, address(uniV3Router), amounts[1]);
        ISwapRouter.ExactInputSingleParams memory params = ISwapRouter
            .ExactInputSingleParams(
                token1,
                token0,
                3000,
                address(this),
                block.timestamp + 15,
                amounts[1],
                0,
                0
            );
        uint256 amountOut = uniV3Router.exactInputSingle(params);
        require(amountOut > amountIn);
        profits[token0] += amountOut - amountIn;
    }

    function getReserves(
        address pairA,
        address pairB
    ) public view returns (uint256 reserve1, uint256 reserveA2, uint256 reserveB1, uint256 reserveB2) {
        require(pairA != pairB, "both exchange same");

        (reserve1, reserveA2, ) = IUniswapV2Pair(pairA).getReserves();
        (reserveB1, reserveB2, ) = IUniswapV2Pair(pairB).getReserves();
    }

    function withdraw(address token) external onlyOwner {
        uint256 profit = profits[token];
        profits[token] = 0; // defend reentrancy

        if (token == address(weth)) {
            weth.withdraw(profit);
            TransferHelper.safeTransferETH(msg.sender, profit);
        } else {
            TransferHelper.safeTransfer(token, msg.sender, profit);
        }
    }

    function withdraw() external onlyOwner {
        TransferHelper.safeTransferETH(msg.sender, address(this).balance);
    }

    function approveAll(address token, address sender) external onlyOwner {
        IERC20(token).approve(sender, type(uint256).max);
    }
}

// File: contracts/interfaces/IUniswapV2Pair.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
interface IUniswapV2Pair {
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
}

// File: contracts/libraries/ArbitragerMathLibrary.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

import "@uniswap/lib/contracts/libraries/Babylonian.sol";

// library containing some math for dealing with the liquidity shares of a pair, e.g. computing their exact value
// in terms of the underlying tokens
library ArbitragerMathLibrary {
    
    function calX(
        uint256 Ares0,
        uint256 Ares1,
        uint256 Bres0,
        uint256 Bres1
    ) internal pure returns (int256) {
        int256 prA = int256(Babylonian.sqrt(Ares0 * Ares1));
        int256 prB = int256(Babylonian.sqrt(Bres0 * Bres1));
        int256 x = ((((int256(Ares1) * 1000 + int256(Bres1) * 997) *
            (prA - prB)) / (prA + prB)) -
            (int256(Ares1) * 1000 - int256(Bres1) * 997)) /
            2 /
            997;
        return x;
    }

    function computeProfitMaximizingTrade(
        uint256 Ares0,
        uint256 Ares1,
        uint256 Bres0,
        uint256 Bres1
    )
        internal
        pure
        returns (
            uint256 x,
            uint256 y,
            uint256 z
        )
    {
        int256 _x = calX(Ares0, Ares1, Bres0, Bres1);
        if (_x <= 0 || x >= Bres1 || y >= Ares0) {
            return (0, 0, 0);
        }
        x = uint256(_x);

        y = ((x * 997 * Ares0)) / (Ares1 * 1000 + x * 997);
        z = ((((Bres0 * x) * 1000) / (Bres1 - x))) / 997;
    }

    function sqrt(uint256 _x) public pure returns (uint256) {
        int256 x = int256(_x);
        int256 z = (x + 1) / 2;
        int256 y = x;
        while (z - y < 0) {
            y = z;
            z = ((x / z) + z) / (2);
        }
        return uint256(y);
    }
}

// File: contracts/libraries/UniswapV2Library.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

import "../interfaces/IUniswapV2Pair.sol";

library UniswapV2Library {
    // 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 * 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 * 997;
        uint256 numerator = amountInWithFee * reserveOut;
        uint256 denominator = reserveIn * 1000 + 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 * amountOut * 1000;
        uint256 denominator = (reserveOut - amountOut) * 997;
        amountIn = (numerator / denominator) + 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);
        }
    }
}