// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// 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;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "../../periphery/interfaces/IWETH.sol";
import '../../lib/utils/TransferHelper.sol';
import "../interface/IFunPool.sol";
import "../interface/IFunFactory.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "../interface/IFunToken.sol";

contract FunPool is IFunPool, Pausable, Ownable {
    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    address public override WETH;
    mapping(address => uint) private locked;

    address public operatorAddress;

    mapping(address => address) public token1Addresses;

    mapping(address => uint256) private _liquidity0;
    mapping(address => uint256) private _liquidity1;
    mapping(address => uint256) private _liquidity1Virtual;
    mapping(address => uint256) public swapLimits;
    mapping(address => uint256) public fees;
    mapping(address => uint8) public status;// 0,1,2,3

    uint256 constant private X = 1E6;
    uint256 public feeRate = 1E4;

    address public funFactory;
    address public uniSwapV2Router02;

    constructor(address _WETH, address _funFactory, address _uniSwapV2Router02){
        WETH = _WETH;
        funFactory = _funFactory;
        operatorAddress = msg.sender;
        uniSwapV2Router02 = _uniSwapV2Router02;
    }

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

    modifier lock(address token0) {
        require(locked[token0] == 0, 'LOCKED');
        locked[token0] = 1;
        _;
        locked[token0] = 0;
    }

    modifier statusCheck(address token0){
        require(status[token0] == 1, 'Error: status != 1');
        _;
    }

    modifier onlyOperator(){
        require(msg.sender == operatorAddress, 'caller is not the operator');
        _;
    }

    function setOperatorAddress(address newAddress) onlyOwner public {
        require(newAddress != address(0), 'Error newAddress');
        operatorAddress = newAddress;
    }

    function emergencyWithdrawEther() public onlyOwner {
        payable(msg.sender).transfer(address(this).balance);
    }

    function emergencyWithdrawErc20(address _tokenAddress) public onlyOwner {
        IERC20 token = IERC20(_tokenAddress);
        token.safeTransfer(msg.sender, token.balanceOf(address(this)));
    }

    function setFeeRate(uint256 _feeRate) onlyOwner public {
        require(_feeRate < X, 'Error: _feeRate >= X');
        feeRate = _feeRate;
    }

    function pause() public onlyOwner {
        _pause();
    }

    function unpause() public onlyOwner {
        _unpause();
    }

    function addLiquidity(address token0,
        address token1,
        uint256 liquidity0,
        uint256 liquidity1,
        uint256 swapLimit,
        uint256 fee) override virtual public {
        require(status[token0] == 0,'Error: status != 0');
        require(msg.sender == funFactory, 'No authority');
        require(token0 != address(0), 'token0 zero');
        require(token1Addresses[token0] == address(0), 'Added');
        require(liquidity0 >= 20 && liquidity1 >= 20, 'liquidity low');
        require(_liquidity0[token0] == 0 && _liquidity1[token0] == 0, 'liquidity added');
        _liquidity0[token0] = liquidity0;
        _liquidity1[token0] = _liquidity1Virtual[token0] = liquidity1;
        if (token1 == address(0)) token1 = WETH;
        token1Addresses[token0] = token1;
        swapLimits[token0] = swapLimit;
        fees[token0] = fee;
        status[token0] = 1;
        emit LiquidityAdded(token0, token1, liquidity0, liquidity1);
        emit Status(token0, token1, 1);
    }

    function getLiquidity(address token0) override virtual public view returns (uint256 liquidity0, uint256 liquidity1){
        liquidity0 = _liquidity0[token0];
        liquidity1 = _liquidity1[token0];
    }

    function tokenPrice(address token0) override virtual public view returns (uint256){
        require(_liquidity0[token0] > 0 && _liquidity1[token0] > 0, 'Liquidity 0');
        return _liquidity1[token0] * 1E18 / _liquidity0[token0];
    }

    function buyGain(address token0, uint256 cost) override virtual public view returns (uint256){
        (uint256 amount,,,) = _buyGain(token0, cost);
        return amount;
    }

    function _buyGain(address token0, uint256 cost) internal virtual view returns (uint256 amount, uint256 price, uint256 fee, uint256 k){
        (uint256 liquidity0, uint256 liquidity1) = getLiquidity(token0);
        require(liquidity0 > 0, 'Insufficient liquidity');
        require(cost > 0, 'Overflow');
        k = liquidity0 * liquidity1;
        fee = cost * feeRate / X;
        amount = liquidity0 - k / (liquidity1 + (cost - fee));
        // amount = cost * _liquidity0[token0] / (_liquidity1[token0] + cost)
        price = (cost - fee) * 1E18 / amount;
        require(amount > 0 && amount < liquidity0, 'Insufficient liquidity');
    }

    function buyExactGain(address token0, uint256 gain) override virtual public view returns (uint256){
        (uint256 cost,,,) = _buyExactGain(token0, gain);
        return cost;
    }

    function _buyExactGain(address token0, uint256 gain) internal virtual view returns (uint256 cost, uint256 price, uint256 fee, uint256 k){
        (uint256 liquidity0, uint256 liquidity1) = getLiquidity(token0);
        require(liquidity0 > 0, 'Insufficient liquidity');
        require(gain > 0, 'Overflow');
        k = liquidity0 * liquidity1;
        cost = k / (liquidity0 - gain) - liquidity1 + 1;
        cost = cost * X / (X - feeRate);
        fee = cost * feeRate / X;
        price = (cost - fee) * 1E18 / gain;
        require(cost > 0 && cost < liquidity1, 'Insufficient liquidity');
    }

    function buy(address token0, address to, uint256 cost, uint256 amountOutMin) whenNotPaused() override virtual external payable {
        address token1 = token1Addresses[token0];
        require(token1 != address(0), 'Not found!');
        if (token1 == WETH) {
            if (msg.value > 0) cost = msg.value;
            else if (cost > 0) {
                IERC20(WETH).transferFrom(msg.sender, address(this), cost);
                IWETH(WETH).withdraw(cost);
            }
        }
        _buy(token0, token1, to, amountOutMin, cost);
        endCheck(token0, token1);
    }

    function _buy(address token0, address token1, address to, uint256 amountOutMin, uint256 cost) statusCheck(token0) lock(token0) internal virtual returns (uint256) {
        (uint256 amount,,uint256 fee,) = _buyGain(token0, cost);
        require(amount >= amountOutMin, 'LT amountOutMin');
        IERC20(token0).safeTransfer(to, amount);
        _liquidity0[token0] -= amount;
        _liquidity1[token0] += (cost - fee);
        if (token1 == WETH) {
            IWETH(WETH).deposit{value: (cost - fee)}();
            if (fee > 0) TransferHelper.safeTransferETH(IFunFactory(funFactory).feeTo(), fee);
        } else {
            IERC20(token1).safeTransferFrom(msg.sender, address(this), cost);
            if (fee > 0) IERC20(token1).safeTransfer(IFunFactory(funFactory).feeTo(), fee);
        }
        uint256 newPrice = _liquidity1[token0] * 1E18 / _liquidity0[token0];
        emit Buy(to, token0, token1, newPrice, cost, amount, fee, block.timestamp);
        return amount;
    }

    function buyCostForExactGain(address token0, address to, uint256 gain, uint256 amountInMax) whenNotPaused() override virtual external payable {
        address token1 = token1Addresses[token0];
        require(token1 != address(0), 'Not found!');
        if (token1 == WETH) {
            if (msg.value > 0) amountInMax = msg.value;
            else if (amountInMax > 0) {
                IERC20(WETH).transferFrom(msg.sender, address(this), amountInMax);
                IWETH(WETH).withdraw(amountInMax);
            }
        }
        _buyCostForExactGain(token0, token1, to, gain, amountInMax);
        endCheck(token0, token1);
    }

    function _buyCostForExactGain(address token0, address token1, address to, uint256 gain, uint256 amountInMax) statusCheck(token0) lock(token0) internal virtual returns (uint256) {
        (uint256 cost,,uint256 fee,) = _buyExactGain(token0, gain);
        require(cost <= amountInMax, 'GT amountInMax');
        IERC20(token0).safeTransfer(to, gain);
        _liquidity0[token0] -= gain;
        _liquidity1[token0] += (cost - fee);
        if (token1 == WETH) {
            IWETH(WETH).deposit{value: (cost - fee)}();
            if (fee > 0) TransferHelper.safeTransferETH(IFunFactory(funFactory).feeTo(), fee);
            if (amountInMax > cost) TransferHelper.safeTransferETH(msg.sender, amountInMax - cost);
        } else {
            IERC20(token1).safeTransferFrom(msg.sender, address(this), amountInMax);
            if (fee > 0) IERC20(token1).safeTransfer(IFunFactory(funFactory).feeTo(), fee);
            if (amountInMax > cost) IERC20(token1).safeTransfer(msg.sender, amountInMax - cost);
        }
        uint256 newPrice = _liquidity1[token0] * 1E18 / _liquidity0[token0];
        emit Buy(to, token0, token1, newPrice, cost, gain, fee, block.timestamp);
        return cost;
    }


    function sellGain(address token0, uint256 amount) override virtual public view returns (uint256){
        (uint256 gain,,,) = _sellGain(token0, amount);
        return gain;
    }

    function _sellGain(address token0, uint256 amount) internal virtual view returns (uint256 gain, uint256 price, uint256 fee, uint256 k){
        (uint256 liquidity0, uint256 liquidity1) = getLiquidity(token0);
        require(liquidity0 > 0, 'Insufficient liquidity');
        require(amount > 0, 'Overflow');
        k = liquidity0 * liquidity1;
        gain = liquidity1 - k / (liquidity0 + amount);
        // gain = amount * _liquidity1[token0] / (_liquidity0[token0] + amount);
        fee = gain * feeRate / X;
        gain = gain * (X - feeRate) / X;
        price = gain * 1E18 / amount;
        require(gain > 0 && gain < liquidity1, 'Insufficient liquidity');
    }

    function sellExactGain(address token0, uint256 gain) override virtual public view returns (uint256){
        (uint256 amount,,,) = _sellExactGain(token0, gain);
        return amount;
    }

    function _sellExactGain(address token0, uint256 gain) internal virtual view returns (uint256 amount, uint256 price, uint256 fee, uint256 k){
        (uint256 liquidity0, uint256 liquidity1) = getLiquidity(token0);
        require(liquidity0 > 0, 'Insufficient liquidity');
        require(gain > 0, 'Overflow');
        k = liquidity0 * liquidity1;
        uint256 _gain = gain * X / (X - feeRate);
        amount = k / (liquidity1 - _gain) - liquidity0 + 1;
        fee = _gain * feeRate / X;
        price = gain * 1E18 / amount;
        require(amount > 0 && amount < liquidity0, 'Insufficient liquidity');
    }

    function sell(address token0, address to, uint256 amount, uint256 amountOutMin) whenNotPaused() override virtual external {
        address token1 = token1Addresses[token0];
        require(token1 != address(0), 'Not found!');
        _sell(token0, token1, to, amount, amountOutMin);
    }

    function _sell(address token0, address token1, address to, uint256 amount, uint256 amountOutMin) statusCheck(token0) lock(token0) internal virtual returns (uint256){
        (uint256 gain,,uint256 fee,) = _sellGain(token0, amount);
        require(gain >= amountOutMin, 'LT amountOutMin');
        IERC20(token0).safeTransferFrom(msg.sender, address(this), amount);
        _liquidity0[token0] += amount;
        _liquidity1[token0] -= (gain + fee);
        require(gain + fee <= IERC20(token1).balanceOf(address(this)), 'Insufficient token1');
        if (token1 == WETH) {
            IWETH(WETH).withdraw(gain + fee);
            TransferHelper.safeTransferETH(to, gain);
            if (fee > 0) TransferHelper.safeTransferETH(IFunFactory(funFactory).feeTo(), fee);
        } else {
            IERC20(token1).safeTransfer(to, gain);
            if (fee > 0) IERC20(token1).safeTransfer(IFunFactory(funFactory).feeTo(), fee);
        }
        uint256 newPrice = _liquidity1[token0] * 1E18 / _liquidity0[token0];
        emit Sell(to, token0, token1, newPrice, gain, amount, fee, block.timestamp);
        return gain;
    }

    function sellCostForExactGain(address token0, address to, uint256 gain, uint256 amountInMax) whenNotPaused() override virtual external {
        address token1 = token1Addresses[token0];
        require(token1 != address(0), 'Not found!');
        _sellCostForExactGain(token0, token1, to, gain, amountInMax);
    }

    function _sellCostForExactGain(address token0, address token1, address to, uint256 gain, uint256 amountInMax) statusCheck(token0) lock(token0) internal virtual returns (uint256){
        (uint256 amount,,uint256 fee,) = _sellExactGain(token0, gain);
        require(amount <= amountInMax, 'GT amountInMax');
        IERC20(token0).safeTransferFrom(msg.sender, address(this), amountInMax);
        if (amountInMax > amount) IERC20(token0).safeTransfer(msg.sender, amountInMax - amount);
        _liquidity0[token0] += amount;
        _liquidity1[token0] -= (gain + fee);
        require(gain + fee <= IERC20(token1).balanceOf(address(this)), 'Insufficient token1');
        if (token1 == WETH) {
            IWETH(WETH).withdraw(gain + fee);
            TransferHelper.safeTransferETH(to, gain);
            if (fee > 0) TransferHelper.safeTransferETH(IFunFactory(funFactory).feeTo(), fee);
        } else {
            IERC20(token1).safeTransfer(to, gain);
            if (fee > 0) IERC20(token1).safeTransfer(IFunFactory(funFactory).feeTo(), fee);
        }
        uint256 newPrice = _liquidity1[token0] * 1E18 / _liquidity0[token0];
        emit Sell(to, token0, token1, newPrice, gain, amount, fee, block.timestamp);
        return amount;
    }

    function endCheck(address token0, address token1) internal virtual {
        if (_liquidity1[token0] - _liquidity1Virtual[token0] >= swapLimits[token0]) {
            status[token0] = 2;
            emit Status(token0, token1, 2);
        }
    }

    function addSwapLiquidity(address token0) onlyOperator virtual external {
        require(status[token0] == 2, 'Error: status != 2');
        address token1 = token1Addresses[token0];
        require(token1 != address(0), 'Not found!');
        uint256 token0Balance = IERC20(token0).balanceOf(address(this));
        uint256 token1Balance = _liquidity1[token0] - _liquidity1Virtual[token0];
        if (!IFunToken(token0).status()) IFunToken(token0).setStatus(true);
        uint256 fee = fees[token0];
        uint256 token1Amount = token1Balance - fee;
        IERC20(token0).approve(uniSwapV2Router02, token0Balance);
        if (token1 == WETH) {
            IWETH(WETH).withdraw(token1Balance);
            TransferHelper.safeTransferETH(msg.sender, fee);
            IUniswapV2Router02(uniSwapV2Router02).addLiquidityETH{value: token1Amount}(token0, token0Balance, token0Balance, token1Amount, msg.sender, block.timestamp);
        } else {
            IERC20(token1).safeTransfer(msg.sender, fee);
            IERC20(token1).approve(uniSwapV2Router02, token1Amount);
            IUniswapV2Router02(uniSwapV2Router02).addLiquidity(token0, token1, token0Balance, token1Amount, token0Balance, token1Amount, msg.sender, block.timestamp);
        }
        _liquidity0[token0] = 0;
        _liquidity1[token0] = 0;
        _liquidity1Virtual[token0] = 0;
        status[token0] = 3;
        emit Status(token0, token1, 3);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

pragma solidity >=0.8.0;

interface IFunFactory {
    event TokenCreated(address indexed token, address indexed creator, string id);

    event SetSupportToken(
        address indexed token1,
        bool isSupport,
        uint256 liquidity0,
        uint256 liquidity1,
        uint256 swapLimit,
        uint256 fee
    );

    event SetFunPool(address indexed poolAddress);

    function feeTo() external view returns (address);

    function allTokens(uint256) external view returns (address token);

    function allTokenLength() external view returns (uint256);

    function setFeeTo(address) external;
}

pragma solidity >=0.8.0;

interface IFunPool {

    event LiquidityAdded(
        address indexed token0,
        address token1,
        uint256 liquidity0,
        uint256 liquidity1
    );

    event Buy(
        address indexed to,
        address indexed token0,
        address token1,
        uint256 newPrice,
        uint256 costIn,
        uint256 amount,
        uint256 fee,
        uint256 timestamp
    );

    event Sell(
        address indexed to,
        address indexed token0,
        address token1,
        uint256 newPrice,
        uint256 gainOut,
        uint256 amount,
        uint256 fee,
        uint256 timestamp
    );

    event Status(
        address indexed token0,
        address token1,
        uint8 status
    );

    function WETH() external view returns (address);

    function addLiquidity(address token0, address token1, uint256 liquidity0, uint256 liquidity1, uint256 swapLimit, uint256 fee) external;

    function getLiquidity(address token0) external view returns (uint256 liquidity0, uint256 liquidity1);

    function tokenPrice(address token0) external view returns (uint256);

    function buyGain(address token0, uint256 cost) external view returns (uint256);

    function buyExactGain(address token0, uint256 gain) external view returns (uint256);

    function buy(address token0, address to, uint256 cost, uint256 amountOutMin) external payable;

    function buyCostForExactGain(address token0, address to, uint256 gain, uint256 amountInMax) external payable;

    function sellGain(address token0, uint256 amount0) external view returns (uint256);

    function sellExactGain(address token0, uint256 gain) external view returns (uint256);

    function sell(address token0, address to, uint256 amount, uint256 amountOutMin) external;

    function sellCostForExactGain(address token0, address to, uint256 gain, uint256 amountInMax) external;
}

pragma solidity >=0.8.0;

interface IFunToken {

    function status() view external returns (bool);

    function setStatus(bool status) external;
}

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);
}

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;
}

pragma solidity >=0.5.0;

interface IWETH {
    function deposit() external payable;

    function transfer(address to, uint256 value) external returns (bool);

    function withdraw(uint256) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing 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);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/Pausable.sol)

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

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

pragma solidity >=0.6.0;

// helper methods for interacting with ERC20.sol 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: 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: 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: TRANSFER_FROM_FAILED');
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}

{
  "compilationTarget": {
    "contracts/BakeFun/core/FunPool.sol": "FunPool"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs",
    "useLiteralContent": true
  },
  "optimizer": {
    "enabled": true,
    "runs": 999999
  },
  "remappings": []
}