/**

https://www.hkex4200.com/
https://twitter.com/hkex4200
https://t.me/HKEXportal

*/

/**

 /$$   /$$ /$$   /$$ /$$$$$$$$ /$$   /$$ /$$   /$$  /$$$$$$   /$$$$$$   /$$$$$$ 
| $$  | $$| $$  /$$/| $$_____/| $$  / $$| $$  | $$ /$$__  $$ /$$$_  $$ /$$$_  $$
| $$  | $$| $$ /$$/ | $$      |  $$/ $$/| $$  | $$|__/  \ $$| $$$$\ $$| $$$$\ $$
| $$$$$$$$| $$$$$/  | $$$$$    \  $$$$/ | $$$$$$$$  /$$$$$$/| $$ $$ $$| $$ $$ $$
| $$__  $$| $$  $$  | $$__/     >$$  $$ |_____  $$ /$$____/ | $$\ $$$$| $$\ $$$$
| $$  | $$| $$\  $$ | $$       /$$/\  $$      | $$| $$      | $$ \ $$$| $$ \ $$$
| $$  | $$| $$ \  $$| $$$$$$$$| $$  \ $$      | $$| $$$$$$$$|  $$$$$$/|  $$$$$$/
|__/  |__/|__/  \__/|________/|__/  |__/      |__/|________/ \______/  \______/ 
                                                                                

*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.18;

abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return payable(msg.sender);
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this;
        return msg.data;
    }
}

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    function owner() public view returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

interface IUniswapV2Router02 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        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;
}

interface IUniswapV2Pair {
    function sync() external;
}

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IERC20 {

    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


contract HKEX is Context, IERC20, Ownable {
    using SafeMath for uint256;
    IUniswapV2Router02 public uniswapV2Router;

    address public uniswapV2Pair;
    mapping (address => uint256) private balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    mapping (address => bool) private _isExcludedFromFee;

    string private constant _name = "HKEX4200";
    string private constant _symbol = "HKEX";
    uint8 private constant _decimals = 9;
    uint256 private _tTotal =  100000000000  * 10**_decimals;
    bool public tradingActive = false;
    uint256 private liquidityFee;
    uint256 private marketingFee;
    BuyFees public buyFee;
    SellFees public sellFee;
    bool private swapping;
    uint256 public _maxWalletAmount = 2000000000 * 10**_decimals;
    uint256 public _maxTxAmount =  2000000000 * 10**_decimals;
    uint256 public swapTokenAtAmount = 2000000000 * 10**_decimals;
    uint256 public forceSwapCount;
    address public liquidityReceiver;
    address public marketingWallet;
    struct BuyFees{uint256 liquidity;uint256 marketing;}
    struct SellFees{uint256 liquidity;uint256 marketing;}

    event SwapAndLiquify(uint256 tokensSwapped, uint256 ethReceived, uint256 tokensIntoLiquidity);

    constructor (address marketingAddress, address liquidityAddress) {
        marketingWallet = marketingAddress;
        liquidityReceiver = liquidityAddress;

        balances[_msgSender()] = _tTotal;
        IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        address _uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH());
        buyFee.liquidity = 1;
        buyFee.marketing = 14;
        sellFee.liquidity = 1;
        sellFee.marketing = 14;

        uniswapV2Router = _uniswapV2Router;
        uniswapV2Pair = _uniswapV2Pair;
        
        _isExcludedFromFee[msg.sender] = true;
        _isExcludedFromFee[address(this)] = true;
        _isExcludedFromFee[address(0x00)] = true;
        _isExcludedFromFee[address(0xdead)] = true;

        
        emit Transfer(address(0), _msgSender(), _tTotal);
    }

    function name() public pure returns (string memory) {return _name;}
    function symbol() public pure returns (string memory) {return _symbol;}
    function decimals() public pure returns (uint8) {return _decimals;}
    function totalSupply() public view override returns (uint256) {return _tTotal;}
    function balanceOf(address account) public view override returns (uint256) {return balances[account];}
    function transfer(address recipient, uint256 amount) public override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()] - amount);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }
    
    function excludeFromFees(address account, bool excluded) public onlyOwner {
        _isExcludedFromFee[address(account)] = excluded;
    }

    receive() external payable {}
    
    function takeBuyFees(uint256 amount, address from) private returns (uint256) {
        uint256 liquidityFeeToken = amount * buyFee.liquidity / 100; 
        uint256 marketingFeeTokens = amount * buyFee.marketing / 100;

        balances[address(this)] += liquidityFeeToken + marketingFeeTokens;
        emit Transfer (from, address(this), marketingFeeTokens + liquidityFeeToken);
        return (amount -liquidityFeeToken -marketingFeeTokens);
    }

    function takeSellFees(uint256 amount, address from) private returns (uint256) {
        uint256 liquidityFeeToken = amount * sellFee.liquidity / 100; 
        uint256 marketingFeeTokens = amount * sellFee.marketing / 100;

        balances[address(this)] += liquidityFeeToken + marketingFeeTokens;
        emit Transfer (from, address(this), marketingFeeTokens + liquidityFeeToken );
        return (amount -liquidityFeeToken -marketingFeeTokens);
    }

    function startTrade() external onlyOwner {
        tradingActive = true;
    }

    function adjustFees(uint256 _buyMarketingFee, uint256 _buyLiquidityFee, uint256 _sellMarketingFee, uint256 _sellLiquidityFee) public onlyOwner {
        buyFee.liquidity = _buyLiquidityFee;
        buyFee.marketing = _buyMarketingFee;
        sellFee.liquidity = _sellLiquidityFee;
        sellFee.marketing = _sellMarketingFee;
    }

    function updateMaxTransactions(uint256 _maxTx, uint256 _maxWallet) public onlyOwner {
        require(_maxTx + _maxWallet > _tTotal / 10000, "Should be bigger than 0,1%");
        _maxTxAmount = _maxTx;
        _maxWalletAmount = _maxWallet;
    }

    function _approve(address owner, address spender, uint256 amount) private {
        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);
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) private {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(amount > 0, "Transfer amount must be greater than zero");
        
        balances[from] -= amount;
        uint256 transferAmount = amount;
        
        bool takeFee;

        if(!_isExcludedFromFee[from] && !_isExcludedFromFee[to]){
            takeFee = true;
        }

        if (!tradingActive) {
                    require(
                        _isExcludedFromFee[from] || _isExcludedFromFee[to],
                        "Trading is not active."
                    );
                }

        if(takeFee){
            if(to != uniswapV2Pair){
                require(amount <= _maxTxAmount, "Transfer Amount exceeds the maxTxnsAmount");
                require(balanceOf(to) + amount <= _maxWalletAmount, "Transfer amount exceeds the maxWalletAmount.");
                transferAmount = takeBuyFees(amount, to);
            }

            if(from != uniswapV2Pair){
                require(amount <= _maxTxAmount, "Transfer Amount exceeds the maxTxnsAmount");
                transferAmount = takeSellFees(amount, from);
                forceSwapCount += 1;

               if (balanceOf(address(this)) >= swapTokenAtAmount && !swapping) {
                    swapping = true;
                    swapBack(swapTokenAtAmount);
                    swapping = false;
                    forceSwapCount = 0;
              }

                if (forceSwapCount > 5 && !swapping) {
                    swapping = true;
                    swapBack(balanceOf(address(this)));
                    swapping = false;
                    forceSwapCount = 0;
              }
            }

            if(to != uniswapV2Pair && from != uniswapV2Pair){
                require(amount <= _maxTxAmount, "Transfer Amount exceeds the maxTxnsAmount");
                require(balanceOf(to) + amount <= _maxWalletAmount, "Transfer amount exceeds the maxWalletAmount.");
            }
        }
        
        balances[to] += transferAmount;
        emit Transfer(from, to, transferAmount);
    }
   
    function swapBack(uint256 amount) private {
        uint256 contractBalance = amount;
        uint256 liquidityTokens = contractBalance * (buyFee.liquidity + sellFee.liquidity) / (buyFee.marketing + buyFee.liquidity + sellFee.marketing + sellFee.liquidity);
        uint256 marketingTokens = contractBalance * (buyFee.marketing + sellFee.marketing) / (buyFee.marketing + buyFee.liquidity + sellFee.marketing + sellFee.liquidity);
        uint256 totalTokensToSwap = liquidityTokens + marketingTokens;
        
        uint256 tokensForLiquidity = liquidityTokens.div(2);
        uint256 amountToSwapForETH = contractBalance.sub(tokensForLiquidity);
        uint256 initialETHBalance = address(this).balance;
        swapTokensForEth(amountToSwapForETH); 
        uint256 ethBalance = address(this).balance.sub(initialETHBalance);
        
        uint256 ethForLiquidity = ethBalance.mul(liquidityTokens).div(totalTokensToSwap);
        addLiquidity(tokensForLiquidity, ethForLiquidity);
        payable(marketingWallet).transfer(address(this).balance);
    }

    function swapTokensForEth(uint256 tokenAmount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();

        _approve(address(this), address(uniswapV2Router), tokenAmount);

        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            address(this),
            block.timestamp
        );
    }

    function addLiquidity(uint256 tokenAmount, uint256 ethAmount) private {
        _approve(address(this), address(uniswapV2Router), tokenAmount);

        uniswapV2Router.addLiquidityETH {value: ethAmount} (
            address(this),
            tokenAmount,
            0,
            0,
            liquidityReceiver,
            block.timestamp
        );
    }
}