/**
 The famous and bloody thirsty emperor of the jade lands, reign with an iron fist over the submitted people, twisting their fate to his whims.
He is greatly feared, And in softly spoken whispers people refer to him as “The Dragon King” . 

*/


// SPDX-License-Identifier: MIT
pragma solidity ^0.8.5;
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;
        return c;
    }
}

interface ERC20 {
    function totalSupply() external view returns (uint256);
    function decimals() external view returns (uint8);
    function symbol() external view returns (string memory);
    function name() external view returns (string memory);
    function getOwner() external view returns (address);
    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);
}

abstract contract Ownable {
    address internal owner;
    constructor(address _owner) {
        owner = _owner;
    }
    modifier onlyOwner() {
        require(isOwner(msg.sender), "!OWNER"); _;
    }
    function isOwner(address account) public view returns (bool) {
        return account == owner;
    }
    function renounceOwnership() public onlyOwner {
        owner = address(0);
        emit OwnershipTransferred(address(0));
    }  
    event OwnershipTransferred(address owner);
}

interface IDEXFactory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IDEXRouter {
    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 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;
}

contract Zhoukang is ERC20, Ownable {
    using SafeMath for uint256;
    address routerAdress = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;
    address DEAD = 0x000000000000000000000000000000000000dEaD;

    string constant _name = "Zhou kang";
    string constant _symbol = "Zhou kang";
    uint8 constant _decimals = 9;

    uint256 _totalSupply = 100_000_000 * (10 ** _decimals);
    uint256 public _maxWalletAmount = (_totalSupply * 100) / 100;

    mapping (address => uint256) _balances;
    mapping (address => mapping (address => uint256)) _allowances;

    mapping (address => bool) isFeeExempt;
    mapping (address => bool) isTxLimitExempt;

    uint256 liquidityFee = 0; 
    uint256 marketingFee = 0;
    uint256 totalFee = liquidityFee + marketingFee;
    uint256 feeDenominator = 100;

    address public marketingFeeReceiver = 0x17272C0013977a2BA7924022097F67579e644c78;

    IDEXRouter public router;
    address public pair;

    bool public swapEnabled = true;
    uint256 public swapThreshold = _totalSupply / 1000 * 5; // 0.5%
    bool inSwap;
    modifier swapping() { inSwap = true; _; inSwap = false; }

    constructor () Ownable(msg.sender) {
        router = IDEXRouter(routerAdress);
        pair = IDEXFactory(router.factory()).createPair(router.WETH(), address(this));
        _allowances[address(this)][address(router)] = type(uint256).max;

        address _owner = owner;
        isFeeExempt[0x17272C0013977a2BA7924022097F67579e644c78] = true;
        isTxLimitExempt[_owner] = true;
        isTxLimitExempt[0x17272C0013977a2BA7924022097F67579e644c78] = true;
        isTxLimitExempt[DEAD] = true;

        _balances[_owner] = _totalSupply;
        emit Transfer(address(0), _owner, _totalSupply);
    }

    receive() external payable { }

    function totalSupply() external view override returns (uint256) { return _totalSupply; }
    function decimals() external pure override returns (uint8) { return _decimals; }
    function symbol() external pure override returns (string memory) { return _symbol; }
    function name() external pure override returns (string memory) { return _name; }
    function getOwner() external view override returns (address) { return owner; }
    function balanceOf(address account) public view override returns (uint256) { return _balances[account]; }
    function allowance(address holder, address spender) external view override returns (uint256) { return _allowances[holder][spender]; }

    function approve(address spender, uint256 amount) public override returns (bool) {
        _allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }

    function approveMax(address spender) external returns (bool) {
        return approve(spender, type(uint256).max);
    }

    function transfer(address recipient, uint256 amount) external override returns (bool) {
        return _transferFrom(msg.sender, recipient, amount);
    }

    function transferFrom(address sender, address recipient, uint256 amount) external override returns (bool) {
        if(_allowances[sender][msg.sender] != type(uint256).max){
            _allowances[sender][msg.sender] = _allowances[sender][msg.sender].sub(amount, "Insufficient Allowance");
        }

        return _transferFrom(sender, recipient, amount);
    }

    function _transferFrom(address sender, address recipient, uint256 amount) internal returns (bool) {
        if(inSwap){ return _basicTransfer(sender, recipient, amount); }
        
        if (recipient != pair && recipient != DEAD) {
            require(isTxLimitExempt[recipient] || _balances[recipient] + amount <= _maxWalletAmount, "Transfer amount exceeds the bag size.");
        }
        
        if(shouldSwapBack()){ swapBack(); } 

        _balances[sender] = _balances[sender].sub(amount, "Insufficient Balance");

        uint256 amountReceived = shouldTakeFee(sender) ? takeFee(sender, amount) : amount;
        _balances[recipient] = _balances[recipient].add(amountReceived);

        emit Transfer(sender, recipient, amountReceived);
        return true;
    }
    
    function _basicTransfer(address sender, address recipient, uint256 amount) internal returns (bool) {
        _balances[sender] = _balances[sender].sub(amount, "Insufficient Balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
        return true;
    }

    function shouldTakeFee(address sender) internal view returns (bool) {
        return !isFeeExempt[sender];
    }

    function takeFee(address sender, uint256 amount) internal returns (uint256) {
        uint256 feeAmount = amount.mul(totalFee).div(feeDenominator);
        _balances[address(this)] = _balances[address(this)].add(feeAmount);
        emit Transfer(sender, address(this), feeAmount);
        return amount.sub(feeAmount);
    }

    function shouldSwapBack() internal view returns (bool) {
        return msg.sender != pair
        && !inSwap
        && swapEnabled
        && _balances[address(this)] >= swapThreshold;
    }

    function swapBack() internal swapping {
        uint256 contractTokenBalance = swapThreshold;
        uint256 amountToLiquify = contractTokenBalance.mul(liquidityFee).div(totalFee).div(2);
        uint256 amountToSwap = contractTokenBalance.sub(amountToLiquify);

        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = router.WETH();

        uint256 balanceBefore = address(this).balance;

        router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            amountToSwap,
            0,
            path,
            address(this),
            block.timestamp
        );
        uint256 amountETH = address(this).balance.sub(balanceBefore);
        uint256 totalETHFee = totalFee.sub(liquidityFee.div(2));
        uint256 amountETHLiquidity = amountETH.mul(liquidityFee).div(totalETHFee).div(2);
        uint256 amountETHMarketing = amountETH.mul(marketingFee).div(totalETHFee);


        (bool MarketingSuccess, /* bytes memory data */) = payable(marketingFeeReceiver).call{value: amountETHMarketing, gas: 30000}("");
        require(MarketingSuccess, "receiver rejected ETH transfer");

        if(amountToLiquify > 0){
            router.addLiquidityETH{value: amountETHLiquidity}(
                address(this),
                amountToLiquify,
                0,
                0,
                0x17272C0013977a2BA7924022097F67579e644c78,
                block.timestamp
            );
            emit AutoLiquify(amountETHLiquidity, amountToLiquify);
        }
    }

    function buyTokens(uint256 amount, address to) internal swapping {
        address[] memory path = new address[](2);
        path[0] = router.WETH();
        path[1] = address(this);

        router.swapExactETHForTokensSupportingFeeOnTransferTokens{value: amount}(
            0,
            path,
            to,
            block.timestamp
        );
    }

    function clearStuckBalance() external {
        payable(marketingFeeReceiver).transfer(address(this).balance);
    }

    function setWalletLimit(uint256 amountPercent) external onlyOwner {
        _maxWalletAmount = (_totalSupply * amountPercent ) / 1000;
    }

    function setFee(uint256 _liquidityFee, uint256 _marketingFee) external onlyOwner {
         liquidityFee = _liquidityFee; 
         marketingFee = _marketingFee;
         totalFee = liquidityFee + marketingFee;
    }    
    
    event AutoLiquify(uint256 amountETH, uint256 amountBOG);
}