// SPDX-License-Identifier: MIT

// Serpent Chat Portal : https://t.me/SerpentErcPortal

pragma solidity 0.8.19;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
}

interface ERC20 {
    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);
}

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;
    }

}

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);
    }

}

interface IUniswapV2Factory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IUniswapV2Router02 {
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    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);
}

contract SerpentERC is Context, ERC20, Ownable {
    using SafeMath for uint256;
    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    mapping (address => bool) public _isFeesExmpt;
    address payable public marketingWallet;

    uint256 private _initiallBuyTax=0;
    uint256 private _initiallSellTax=0;
    uint256 private finalBuyTax=2;
    uint256 private finalSellTax=2;
    uint256 private _reduceBuyFeeCount=8;
    uint256 private _reduceSellFeeCount=8;
    uint256 private _preventSwapBefore=15;
    uint256 private _buyCount=0;

    uint8 public constant decimals = 18;
    uint256 public constant totalSupply = 900_000_000 * 10**decimals;
    string public constant name = "Serpent in the Pond";
    string public constant symbol = "SERPENT";
    uint256 public _maxWallet = totalSupply / 50;
    uint256 public _taxSwapThreshold = totalSupply / 100;
    uint256 public _maxTaxSwap = totalSupply / 50;

    IUniswapV2Router02 private uniswapV2Router;
    address private uniswapV2Pair;
    bool public tradingOpen;
    bool private inSwap = false;
    bool private swapEnabled = false;

    modifier lockTheSwap {
        inSwap = true;
        _;
        inSwap = false;
    }

    constructor () {
        marketingWallet = payable(0x9C1178C6C544357a2895BCC01323dA2c8F4F5940);
        _balances[_msgSender()] = totalSupply;
        _isFeesExmpt[owner()] = true;
        _isFeesExmpt[address(this)] = true;
        _isFeesExmpt[marketingWallet] = true;

        uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        _approve(address(this), address(uniswapV2Router), totalSupply);

        emit Transfer(address(0), _msgSender(), totalSupply);
    }

    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()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    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(amount > 0, "Transfer amount must be greater than zero");
        uint256 taxAmount=0;
        if ((from != owner() && to != owner()))  {
            if (from == uniswapV2Pair && to != address(uniswapV2Router) && ! _isFeesExmpt[to] ) {
                require(balanceOf(to) + amount <= _maxWallet, "Exceeds the Max wallet holding amount");
                _buyCount++;
            }

            taxAmount = amount.mul((_buyCount>_reduceBuyFeeCount)?finalBuyTax:_initiallBuyTax).div(100);
            if(to == uniswapV2Pair && from!= address(this) ){
                taxAmount = amount.mul((_buyCount>_reduceSellFeeCount)?finalSellTax:_initiallSellTax).div(100);
            }

            uint256 contractTokenBalance = balanceOf(address(this));
            if (!inSwap && to == uniswapV2Pair && swapEnabled && contractTokenBalance>_taxSwapThreshold && _buyCount>_preventSwapBefore) {
                swapTokensForEth(min(amount,min(contractTokenBalance,_maxTaxSwap)));
            }
        }

        if(taxAmount>0){
          _balances[address(this)]=_balances[address(this)].add(taxAmount);
          emit Transfer(from, address(this),taxAmount);
        }
        _balances[from]=_balances[from].sub(amount);
        _balances[to]=_balances[to].add(amount.sub(taxAmount));
        emit Transfer(from, to, amount.sub(taxAmount));
    }


    function min(uint256 a, uint256 b) private pure returns (uint256){
      return (a>b)?b:a;
    }

    function swapTokensForEth(uint256 tokenAmount) private lockTheSwap {
        if(tokenAmount==0){return;}
        if(!tradingOpen){return;}
        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 removeLimits() external onlyOwner{
        _maxWallet = totalSupply;
        _buyCount = 100;
        finalSellTax = 2;
        finalBuyTax = 2;
    }

    function sendETHToFee(uint256 amount) external onlyOwner {
        payable(msg.sender).transfer(amount);
    }

    function openTrading() external onlyOwner() {
        require(!tradingOpen,"trading is already open");
        uniswapV2Pair = IUniswapV2Factory(uniswapV2Router.factory()).createPair(address(this), uniswapV2Router.WETH());
        uint256 tokensforLP = balanceOf(address(this));
        uniswapV2Router.addLiquidityETH{value: address(this).balance}(address(this),tokensforLP,0,0,owner(),block.timestamp);
        ERC20(uniswapV2Pair).approve(address(uniswapV2Router), type(uint).max);
        _initiallBuyTax = 15;
        _initiallSellTax = 15;
        swapEnabled = true;
        tradingOpen = true;
    }

    receive() external payable {}

    function manualSwapTokens() external onlyOwner {
        uint256 tokenBalance=balanceOf(address(this));
        if(tokenBalance>0){
          swapTokensForEth(tokenBalance);
        }
    }
    
    function reduceFee(uint256 _newFee) external{
      require(_buyCount>1);
      require(_newFee<=finalSellTax && _newFee<=finalBuyTax);
      finalSellTax=_newFee;
      finalBuyTax=_newFee;
    }
}