// File: RAMBE.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.21;
import {Ownable2Step} from "@openzeppelin/contracts/access/Ownable2Step.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {ERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import {IUniswapV2Factory} from "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";
import {IUniswapV2Router02} from "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";

/// @title ERC20 with buy and sell fees
contract RAMBE is ERC20, Ownable2Step {
    /// custom errors
    error CannotRemoveMainPair();
    error ZeroAddressNotAllowed();
    error FeesLimitExceeds();
    error SenderIsBlacklisted();
    error ReceiverIsBlacklisted();
    error CannotBlacklistLPPair();
    error UpdateBoolValue();
    error CannotClaimNativeToken();
    error ERC20TokenClaimFailed();
    
    /// @notice Max limit on Buy / Sell fees
    uint256 public constant MAX_FEE_LIMIT = 10; 
    /// @notice max total supply 1 billion tokens (18 decimals)
    uint256 private maxSupply = 1e9 * 1e18; 
    /// @notice swap threshold at which collected fees tokens are swapped for ether, autoLP
    uint256 public swapTokensAtAmount = 1e3 * 1e18;
    /// @notice check if it's a swap tx
    bool private inSwap = false;
    
    /// @notice struct buy fees variable
    /// marketing: marketing fees
    /// autoLP: liquidity fees
    struct BuyFees {
        uint16 marketing;
        uint16 autoLP;
    }
    /// @notice struct sell fees variable
    /// marketing: marketing fees
    /// autoLP: liquidity fees
    struct SellFees {
        uint16 marketing;
        uint16 autoLP;
    }
    
    /// @notice buyFees variable
    BuyFees public buyFee;
    /// @notice sellFees variable
    SellFees public sellFee;
    
    /// @notice totalBuyFees
    uint256 private totalBuyFee;
    /// @notice totalSellFees
    uint256 private totalSellFee;
    
    /// @notice marketingWallet
    address public marketingWallet;
    /// @notice uniswap V2 router address
    IUniswapV2Router02 public immutable uniswapV2Router;
    /// @notice uniswap V2 Pair address
    address public uniswapV2Pair;
    
    /// @notice mapping to manager liquidity pairs
    mapping(address => bool) public isAutomatedMarketMaker;
    /// @notice mapping to manage excluded address from/to fees
    mapping(address => bool) public  isExcludedFromFees;
    /// @notice mapping to manage blacklisted users
    mapping(address => bool)public  isBlacklisted;

    //// EVENTS //// 
    event BuyFeesUpdated(uint16 indexed marketingFee, uint16 indexed liquidityFee);
    event SellFeesUpdated(uint16 indexed marketingFee, uint16 indexed liquidityFee);
    event FeesSwapped(uint256 indexed ethForLiquidity, uint256 indexed tokensForLiquidity,  uint256 indexed ethForMarketing);

    
    /// @dev create an erc20 token using openzeppeling ERC20, Ownable2Step
    /// uses uniswap router and factory interface
    /// set uniswap router, create pair, initialize buy, sell fees, marketingWallet values
    /// excludes the token, marketingWallet and owner address from fees
    /// and mint all the supply to owner wallet.
    constructor () ERC20("Harambe Token", "RAMBE"){
      uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
      uniswapV2Pair = IUniswapV2Factory(uniswapV2Router.factory()).createPair(address(this), uniswapV2Router.WETH());
      isAutomatedMarketMaker[uniswapV2Pair] = true;

      buyFee.marketing = 4;
      buyFee.autoLP = 1;
      totalBuyFee = 5;

      sellFee.marketing = 4;
      sellFee.autoLP = 1;
      totalSellFee = 5;
      
      marketingWallet = 0xa0E13E7CA54274173931349e4c3DA1223d4F701d;

      isExcludedFromFees[address(this)] = true;
      isExcludedFromFees[marketingWallet] = true;
      isExcludedFromFees[owner()] = true;
      _mint(msg.sender, maxSupply);
    }

    /// modifier  ///
     modifier lockTheSwap {
        inSwap = true;
        _;
        inSwap = false;
    }
    
    /// receive external ether
    receive () external payable {}

    /// @dev owner can claim other erc20 tokens, if accidently sent by someone
    /// @param _token: token address to be rescued
    /// @param _amount: amount to rescued
    /// Requirements --
    /// Cannot claim native token
    function claimOtherERC20 (address _token, uint256 _amount) external onlyOwner {
        if(_token == address(this)) {
            revert CannotClaimNativeToken();
        }
        IERC20 tkn = IERC20(_token);
        bool success = tkn.transfer(owner(), _amount);
        if(!success){
            revert ERC20TokenClaimFailed();
        }
    }
    
    /// @dev exclude or include a user from/to fees
    /// @param user: user address
    /// @param value: boolean value. true means excluded. false means included
    /// Requirements --
    /// zero address not allowed
    /// if a user is excluded already, can't exlude him again
    function excludeFromFees (address user, bool value) external onlyOwner {
        if(user == address(0)){
           revert  ZeroAddressNotAllowed();
        }
        if(isExcludedFromFees[user] == value){
           revert UpdateBoolValue();
        }
        isExcludedFromFees[user] = value;
    }
    

    /// @dev blacklist or unblacklist users
    /// @param account: address to be blacklisted or unblacklisted
    /// @param value: boolean value, true means blacklisted, false means unblacklisted
    /// Requirements --
    /// address should not be zero
    /// Can not blacklist pairs
    /// can not blacklist already blacklisted address and vice versa
    function manageBlacklistAddress(address account, bool value) external onlyOwner {
        if(account == address(0)){
            revert ZeroAddressNotAllowed();
        }
        if(isAutomatedMarketMaker[account]){
            revert CannotBlacklistLPPair();
        }
        if(isBlacklisted[account] == value){
            revert UpdateBoolValue();
        }
        isBlacklisted[account] = value;
    }

    /// @dev add or remove new pairs
    /// @param _newPair: address to be added or removed as pair
    /// @param value: boolean value, true means blacklisted, false means unblacklisted
    /// Requirements --
    /// address should not be zero
    /// Can not remove main pair
    /// can not add already added pairs  and vice versa
    function manageLiquidityPairs (address _newPair, bool value) external onlyOwner {
        if(_newPair == address(0)){
            revert ZeroAddressNotAllowed();
        }
        if(_newPair == uniswapV2Pair){
            revert CannotRemoveMainPair();
        }
        if(isAutomatedMarketMaker[_newPair] == value){
            revert UpdateBoolValue();
        }
        isAutomatedMarketMaker[_newPair] = value;
        
    }
    
    /// @dev update marketing fee wallet
    /// @param _newMarketingWallet: new marketing wallet address
    /// Requirements -
    /// Address should not be zero
    function updateMarketingWallet(address _newMarketingWallet) external onlyOwner {
        if(_newMarketingWallet == address(0)){
            revert ZeroAddressNotAllowed();
        }
        marketingWallet = _newMarketingWallet;
    }

    /// @dev update buy fees
    /// @param _marketing: marketing fees
    /// @param _autoLP: liquidity fees
    /// Requirements --
    /// total Buy fees must be less than equals to MAX_FEE_LIMIT (10%);
    function updateBuyFees (uint16 _marketing, uint16 _autoLP) external onlyOwner {
        if(_marketing + _autoLP > MAX_FEE_LIMIT){
            revert FeesLimitExceeds();
        }
        buyFee.marketing = _marketing;
        buyFee.autoLP = _autoLP;
        totalBuyFee = _marketing + _autoLP;
        emit BuyFeesUpdated(_marketing, _autoLP);

    }
    
    /// @dev update sell fees
    /// @param _marketing: marketing fees
    /// @param _autoLP: liquidity fees
    /// Requirements --
    /// total Sell fees must be less than equals to MAX_FEE_LIMIT (10%);
    function updateSellFees (uint16 _marketing, uint16 _autoLP) external onlyOwner {
        if(_marketing + _autoLP > MAX_FEE_LIMIT){
            revert FeesLimitExceeds();
        }
        sellFee.marketing = _marketing;
        sellFee.autoLP = _autoLP;
        totalSellFee = _marketing + _autoLP;
        emit SellFeesUpdated(_marketing, _autoLP);

    }

    /// @notice manage transfers, fees
    /// see {ERC20 - _transfer}
    /// requirements -- 
    /// from or to should not be zero
    /// from or to should not be blacklisted
    function _transfer (address from, address to, uint256 amount) internal override {
       if(from == address(0)){
        revert ZeroAddressNotAllowed();
       } 
       if(to == address(0)){
        revert ZeroAddressNotAllowed();
       }
       if(isBlacklisted[from]){
        revert SenderIsBlacklisted();
       }
       if(isBlacklisted[to]){
        revert ReceiverIsBlacklisted();
       }
       if(amount == 0){
        super._transfer(from, to, 0);
        return;
       }
       uint256 contractBalance = balanceOf(address(this)); 
       bool canSwapped = contractBalance >= swapTokensAtAmount;
       if(canSwapped && !isAutomatedMarketMaker[from] && !inSwap && !isExcludedFromFees[from] && !isExcludedFromFees[to]){
          if(contractBalance > swapTokensAtAmount * 20){
             contractBalance = swapTokensAtAmount * 20;
            }
        swapAndLiquify(contractBalance);
       }
       
       bool takeFee = true;
       if(isExcludedFromFees[from] || isExcludedFromFees[to]){
        takeFee = false;
       }
       uint256 fees = 0;
       if(takeFee){
        if(isAutomatedMarketMaker[from] && totalBuyFee > 0){
            fees = (amount * totalBuyFee) / 100;
        }
        if(isAutomatedMarketMaker[to] && totalSellFee > 0){
            fees = (amount * totalSellFee) / 100;
        }
        super._transfer(from, address(this), fees);
        amount = amount - fees;
       }
     super._transfer(from, to, amount);
    }
    
    /// @notice swap the collected fees to eth / add liquidity
    /// after conversion, it sends eth to marketing wallet, add auto liquidity
    /// @param tokenAmount: tokens to be swapped appropriately as per fee structure
    function swapAndLiquify (uint256 tokenAmount) private lockTheSwap {
        if(totalBuyFee + totalSellFee == 0){
            swapTokensForEth(tokenAmount);
            bool m;
           (m,) = payable(marketingWallet).call{value: address(this).balance}("");
        } else {
        uint256 marketingTokens = ((buyFee.marketing + sellFee.marketing) * tokenAmount) / (totalBuyFee + totalSellFee);
        uint256 liquidityTokens = tokenAmount - marketingTokens;
        uint256 liquidityTokensHalf = liquidityTokens / 2;
        uint256 swapTokens = tokenAmount - liquidityTokensHalf;
        uint256 ethBalanceBeforeSwap = address(this).balance;
        swapTokensForEth(swapTokens);
        uint256 ethBalanceAfterSwap = address(this).balance - ethBalanceBeforeSwap;
        uint256 ethForLiquidity = (liquidityTokensHalf * ethBalanceAfterSwap) /swapTokens;
        if(ethForLiquidity > 0 && liquidityTokensHalf > 0){
            addLiquidity(liquidityTokensHalf, ethForLiquidity);
        }
        bool success;
        uint256 marketingEth = address(this).balance;
        if(marketingEth > 0){
          (success,) = payable(marketingWallet).call{value: marketingEth}("");
        }
        emit FeesSwapped(ethForLiquidity, liquidityTokensHalf, marketingEth);
        }

    }

    /// @notice manages tokens conversion to eth
    /// @param tokenAmount: tokens to be converted to eth
    function swapTokensForEth(uint256 tokenAmount) private {
        // generate the uniswap pair path of token -> weth
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();
        
        if(allowance(address(this), address(uniswapV2Router)) < tokenAmount){
        _approve(address(this), address(uniswapV2Router), type(uint256).max);
        }

        // make the swap
        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0, // accept any amount of ETH
            path,
            address(this),
            block.timestamp
        );
    }
    
    /// @notice manage autoLP (liquidity addition)
    /// @param tokenAmount: tokens to be added to liquidity
    /// @param ethAmount: eth to be added to liquidity
    function addLiquidity(uint256 tokenAmount, uint256 ethAmount) private {

        // add the liquidity
        uniswapV2Router.addLiquidityETH{value: ethAmount}(
            address(this),
            tokenAmount,
            0, // slippage is unavoidable
            0, // slippage is unavoidable
            owner(), // LP tokens recevier
            block.timestamp
        );
    }


}


// 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-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: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the default value returned by this function, unless
     * it's overridden.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(address from, address to, uint256 amount) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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);
}

// File: @openzeppelin/contracts/access/Ownable2Step.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable2Step.sol)

pragma solidity ^0.8.0;

import "./Ownable.sol";

/**
 * @dev Contract module which provides 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} and {acceptOwnership}.
 *
 * This module is used through inheritance. It will make available all functions
 * from parent (Ownable).
 */
abstract contract Ownable2Step is Ownable {
    address private _pendingOwner;

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

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

    /**
     * @dev Starts the ownership transfer of the contract to a new account. Replaces the pending transfer if there is one.
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual override onlyOwner {
        _pendingOwner = newOwner;
        emit OwnershipTransferStarted(owner(), newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`) and deletes any pending owner.
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual override {
        delete _pendingOwner;
        super._transferOwnership(newOwner);
    }

    /**
     * @dev The new owner accepts the ownership transfer.
     */
    function acceptOwnership() public virtual {
        address sender = _msgSender();
        require(pendingOwner() == sender, "Ownable2Step: caller is not the new owner");
        _transferOwnership(sender);
    }
}

// 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: @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: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// 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);
    }
}