//SPDX-License-Identifier: MIT
pragma solidity 0.8.15;

interface IERC20 {
	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 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 Auth {
	address internal owner;
	constructor(address _owner) { owner = _owner; }
	modifier onlyOwner() { require(msg.sender == owner, "Only contract owner can call this function"); _; }
	function transferOwnership(address payable newOwner) external onlyOwner { owner = newOwner;	emit OwnershipTransferred(newOwner); }
	event OwnershipTransferred(address owner);
}

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 WETH() external pure returns (address);
	function factory() 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 J is IERC20, Auth {
	string constant _name = "Last Dragon Slayer"; 
	string constant _symbol = "J"; 
	uint8 constant _decimals = 9;
	uint256 constant _totalSupply = 1_000_000_000_000 * 10**_decimals;
	mapping (address => uint256) _balances;
	mapping (address => mapping (address => uint256)) _allowances;
	uint256 private _tradingOpenBlock;
	mapping (address => bool) private _isLiqPool;

	uint8 private fee_taxRateMaxLimit; uint8 private fee_taxRateBuy; uint8 private fee_taxRateSell;

	uint256 private lim_maxTxAmount; uint256 private lim_maxWalletAmount;
	uint256 private lim_taxSwapMin; uint256 private lim_taxSwapMax;

	address private _liquidityPool;

	mapping(address => bool) private exm_noFees;
	mapping(address => bool) private exm_noLimits;
	
	bool private _inTaxSwap = false;
	address private constant _uniswapV2RouterAddress = address(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
	address private _wethAddress = address(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);
	IUniswapV2Router02 private _uniswapV2Router;
	modifier lockTaxSwap { _inTaxSwap = true; _; _inTaxSwap = false; }

	event TokensBurned(address burnedFrom, uint256 tokenAmount);
	event TaxRatesChanged(uint8 taxRateBuy, uint8 taxRateSell);
	event LimitsIncreased(uint256 maxTransaction, uint256 maxWalletSize);
	event TaxSwapSettingsChanged(uint256 taxSwapMin, uint256 taxSwapMax);
	event WalletExemptionsSet(address wallet, bool noFees, bool noLimits);

	constructor() Auth(msg.sender) {
		_tradingOpenBlock = type(uint256).max; 
		fee_taxRateMaxLimit = 7;
		lim_maxTxAmount = _totalSupply;
		lim_maxWalletAmount = _totalSupply;
		lim_taxSwapMin = _totalSupply * 10 / 10000;
		lim_taxSwapMax = _totalSupply * 50 / 10000;
		_uniswapV2Router = IUniswapV2Router02(_uniswapV2RouterAddress);

		exm_noFees[owner] = true;
		exm_noFees[address(this)] = true;
		exm_noFees[_uniswapV2RouterAddress] = true;

		exm_noLimits[owner] = true;
		exm_noLimits[address(this)] = true;
		exm_noLimits[_uniswapV2RouterAddress] = true;
	}
	
	receive() external payable {}
	
	function totalSupply() external pure 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 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 transfer(address recipient, uint256 amount) external override returns (bool) {
		require(_checkTradingOpen(), "Trading not open");
		return _transferFrom(msg.sender, recipient, amount);
	}

	function transferFrom(address sender, address recipient, uint256 amount) external override returns (bool) {
		require(_checkTradingOpen(), "Trading not open");
		if (_allowances[sender][msg.sender] != type(uint256).max){
			_allowances[sender][msg.sender] = _allowances[sender][msg.sender] - amount;
		}
		return _transferFrom(sender, recipient, amount);
	}

	function addLP() external onlyOwner {
		require(!_tradingOpen(), "trading already open");
		require(_liquidityPool == address(0), "LP already added");

		_balances[address(this)] = _totalSupply / 2;
		emit Transfer(address(0), address(this), _balances[address(this)]);

		_balances[owner] = _totalSupply - _balances[address(this)];
		emit Transfer(address(0), owner, _balances[owner]);

		_wethAddress = _uniswapV2Router.WETH(); //override the WETH address from router
		_liquidityPool = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _wethAddress);

		_isLiqPool[_liquidityPool] = true;

		uint256 _contractETHBalance = address(this).balance;
		require(_contractETHBalance >= 0, "no eth");		
		uint256 _contractTokenBalance = balanceOf(address(this));
		require(_contractTokenBalance > 0, "no tokens");

		_approveRouter(_contractTokenBalance);
		_addLiquidity(_contractTokenBalance, _contractETHBalance, false);
	}

	function _approveRouter(uint256 _tokenAmount) internal {
		if ( _allowances[address(this)][_uniswapV2RouterAddress] < _tokenAmount ) {
			_allowances[address(this)][_uniswapV2RouterAddress] = type(uint256).max;
			emit Approval(address(this), _uniswapV2RouterAddress, type(uint256).max);
		}
	}

	function _addLiquidity(uint256 _tokenAmount, uint256 _ethAmountWei, bool autoburn) internal {
		address lpTokenRecipient = address(0);
		if ( !autoburn ) { lpTokenRecipient = owner; }
		_uniswapV2Router.addLiquidityETH{value: _ethAmountWei} ( address(this), _tokenAmount, 0, 0, lpTokenRecipient, block.timestamp );
	}

	function openTrading() external onlyOwner {
		require(!_tradingOpen(), "trading already open");
		require(_liquidityPool != address(0), "LP not initialized");
		_openTrading();
	}

	function _openTrading() internal {
		lim_maxTxAmount     = 100 * _totalSupply / 10000 + 10**_decimals; 
		lim_maxWalletAmount = 100 * _totalSupply / 10000 + 10**_decimals;
		fee_taxRateBuy = 4;
		fee_taxRateSell = 4;
		_tradingOpenBlock = block.number + 134;
	}

	function tradingOpen() external view returns (bool) {
		if (_tradingOpen() && block.number >= _tradingOpenBlock + 10) { return _tradingOpen(); }
		else { return false; }
	}

	function _transferFrom(address sender, address recipient, uint256 amount) internal returns (bool) {
		require(sender!=address(0) && recipient!=address(0), "Zero address not allowed");

		if ( !_inTaxSwap && _isLiqPool[recipient] ) { _swapTaxAndLiquify();	}

		if ( sender != address(this) && recipient != address(this) && sender != owner ) { require(_checkLimits(sender, recipient, amount), "TX exceeds limits"); }
		uint256 _taxAmount = _calculateTax(sender, recipient, amount);
		uint256 _transferAmount = amount - _taxAmount;
		_balances[sender] = _balances[sender] - amount;
		if ( _taxAmount > 0 ) { _balances[address(this)] = _balances[address(this)] + _taxAmount; }
		_balances[recipient] = _balances[recipient] + _transferAmount;
		emit Transfer(sender, recipient, amount);
		return true;
	}
	
	function _checkLimits(address sender, address recipient, uint256 transferAmount) internal view returns (bool) {
		bool limitCheckPassed = true;
		if ( _tradingOpen() && !exm_noLimits[recipient] && !exm_noLimits[sender] ) {
			if ( transferAmount > lim_maxTxAmount ) { limitCheckPassed = false; }
			else if ( !_isLiqPool[recipient] && (_balances[recipient] + transferAmount > lim_maxWalletAmount) ) { limitCheckPassed = false; }
		}
		return limitCheckPassed;
	}

	function _tradingOpen() private view returns (bool) {
		bool result = false;
		if (block.number >= _tradingOpenBlock) { result = true; }
		return result;
	}

	function _checkTradingOpen() private view returns (bool){
		bool checkResult = false;
		if ( _tradingOpen() ) { checkResult = true; } 
		else if ( tx.origin == owner ) { checkResult = true; } 
		return checkResult;
	}

	function _calculateTax(address sender, address recipient, uint256 amount) internal view returns (uint256) {
		uint256 taxAmount;
		if ( !_tradingOpen() || exm_noFees[sender] || exm_noFees[recipient] ) { taxAmount = 0; }
		else if ( _isLiqPool[sender] ) { taxAmount = amount * fee_taxRateBuy / 100; }
		else if ( _isLiqPool[recipient] ) { taxAmount = amount * fee_taxRateSell / 100; }
		else { taxAmount = 0; }
		return taxAmount;
	}

	function getExemptions(address wallet) external view returns(bool noFees, bool noLimits) {
		return (exm_noFees[wallet], exm_noLimits[wallet]);
	}

	function setExemptions(address wallet, bool noFees, bool noLimits) external onlyOwner {
		exm_noFees[wallet] = noFees;
		exm_noLimits[wallet] = noLimits;
		emit WalletExemptionsSet(wallet, noFees, noLimits);
	}

	function getFeeSettings() external view returns(uint8 taxRateMaxLimit, uint8 taxRateBuy, uint8 taxRateSell) {
		return (fee_taxRateMaxLimit, fee_taxRateBuy, fee_taxRateSell);
	}

	function setTaxRates(uint8 newBuyTax, uint8 newSellTax) external onlyOwner {
		require( newBuyTax+newSellTax <= 2*fee_taxRateMaxLimit, "Tax too high");
		fee_taxRateBuy = newBuyTax;
		fee_taxRateSell = newSellTax;
		emit TaxRatesChanged(newBuyTax, newSellTax);
	}

	function getWallets() external view returns(address contractOwner, address liquidityPool) {
		return (owner, _liquidityPool);
	}

	function getLimits() external view returns(uint256 maxTxAmount, uint256 maxWalletAmount, uint256 taxSwapMin, uint256 taxSwapMax) {
		return (lim_maxTxAmount, lim_maxWalletAmount, lim_taxSwapMin, lim_taxSwapMax);
	}

	function increaseLimits(uint16 maxTxAmtPermile, uint16 maxWalletAmtPermile) external onlyOwner {
		uint256 newTxAmt = _totalSupply * maxTxAmtPermile / 1000 + 1;
		require(newTxAmt >= lim_maxTxAmount, "tx limit too low");
		lim_maxTxAmount = newTxAmt;
		uint256 newWalletAmt = _totalSupply * maxWalletAmtPermile / 1000 + 1;
		require(newWalletAmt >= lim_maxWalletAmount, "wallet limit too low");
		lim_maxWalletAmount = newWalletAmt;
		emit LimitsIncreased(lim_maxTxAmount, lim_maxWalletAmount);
	}

	function setTaxSwapLimits(uint32 minValue, uint32 minDivider, uint32 maxValue, uint32 maxDivider) external onlyOwner {
		lim_taxSwapMin = _totalSupply * minValue / minDivider;
		lim_taxSwapMax = _totalSupply * maxValue / maxDivider;
		require(lim_taxSwapMax > lim_taxSwapMin);
		emit TaxSwapSettingsChanged(lim_taxSwapMin, lim_taxSwapMax);
	}

	function _swapTaxAndLiquify() private lockTaxSwap {
		uint256 _taxTokensAvailable = balanceOf(address(this));

		if ( _taxTokensAvailable >= lim_taxSwapMin && _tradingOpen() ) {
			if ( _taxTokensAvailable >= lim_taxSwapMax ) { _taxTokensAvailable = lim_taxSwapMax; }
			uint256 _tokensForLP = _taxTokensAvailable / 2;
			uint256 _tokensToSwap = _taxTokensAvailable - _tokensForLP;
			if (_tokensToSwap >= 10**_decimals) {
				uint256 _ethPreSwap = address(this).balance;
				_swapTaxTokensForEth(_tokensToSwap);
				uint256 _ethSwapped = address(this).balance - _ethPreSwap;
				if ( _ethSwapped > 0 ) {
					_approveRouter(_tokensForLP);
					_addLiquidity(_tokensForLP, _ethSwapped, false);
				}
			}
		}
	}

	function _swapTaxTokensForEth(uint256 _tokenAmount) private {
		_approveRouter(_tokenAmount);
		address[] memory path = new address[](2);
		path[0] = address(this);
		path[1] = _wethAddress;
		_uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(_tokenAmount,0,path,address(this),block.timestamp);
	}

	function recoverBalance() external onlyOwner {
		uint256 _stuckEthBalance = address(this).balance;
        require (_stuckEthBalance > 0);
		address payable recipient = payable(owner);
		recipient.transfer(_stuckEthBalance);
	}

	function manualSwap(uint8 swapPercent) external onlyOwner {
		uint256 taxTokenBalance = balanceOf(address(this));
		require(taxTokenBalance > 0, "No tokens");
		uint256 tokensToSwap = taxTokenBalance * swapPercent / 100;
		_swapTaxTokensForEth(tokensToSwap);
	}

	function burnTokens(uint256 amount) external {
		uint256 _tokensAvailable = balanceOf(msg.sender);
		require(amount <= _tokensAvailable, "Token balance too low");
		_balances[msg.sender] -= amount;
		_balances[address(0)] += amount;
		emit Transfer(msg.sender, address(0), amount);
		emit TokensBurned(msg.sender, amount);
	}
}