// SPDX-License-Identifier: MIT   

pragma solidity 0.8.19;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

interface IDexFactory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IERC20 {
    /**
     * @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 `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, 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 `sender` to `recipient` 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 sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @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);
}

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);
}


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;
    uint8 private _decimals;

    constructor(string memory name_, string memory symbol_, uint8 decimals_) {
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
    }

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return _decimals;
    }

    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
            unchecked {
                _approve(sender, _msgSender(), currentAllowance - amount);
            }
        }

        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }

    function _createInitialSupply(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");
        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    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);
    }
}

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 () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

interface IDexRouter {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);
    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;
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external;
    function addLiquidityETH(address token, uint256 amountTokenDesired, uint256 amountTokenMin, uint256 amountETHMin, address to, uint256 deadline) external payable returns (uint256 amountToken, uint256 amountETH, uint256 liquidity);
    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 getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function removeLiquidity(address tokenA, address tokenB, uint liquidity, uint amountAMin, uint amountBMin, address to, uint deadline) external returns (uint amountA, uint amountB);
}

interface ILpPair {
    function sync() external;
}

contract Chemistry is ERC20, Ownable {

    IDexRouter public immutable dexRouter;
    address public immutable lpPair;

    bool private swapping;

    address public operationsWallet;
    
    uint256 public maxTransactionAmount;
    uint256 public swapTokensAtAmount;
    uint256 public maxWallet;
    
    uint256 public liquidityActiveBlock = 0; // 0 means liquidity is not active yet
    uint256 public tradingActiveBlock = 0; // 0 means trading is not active
    uint256 public earlyBuyPenaltyEnd; // determines when snipers/bots can sell without extra penalty
    
    bool public limitsInEffect = true;
    bool public tradingActive = false;
    bool public swapEnabled = false;
    
     // Anti-bot and anti-whale mappings and variables
    mapping(address => uint256) private _holderLastTransferTimestamp; // to hold last Transfers temporarily during launch
    bool public transferDelayEnabled = true;
    
    uint256 public constant feeDivisor = 10000;

    uint256 public totalSellFees;
    uint256 public operationsSellFee;
    uint256 public liquiditySellFee;
    
    uint256 public totalBuyFees;
    uint256 public operationsBuyFee;
    uint256 public liquidityBuyFee;
    
    uint256 public tokensForOperations;
    uint256 public tokensForLiquidity;

    /******************/

    // exlcude from fees and max transaction amount
    mapping (address => bool) private _isExcludedFromFees;

    address[] private earlyBuyers;
    uint256 private deadBlocks;
    mapping (address => bool) public _isBot;

    mapping (address => bool) public _isExcludedMaxTransactionAmount;

    // store addresses that a automatic market maker pairs. Any transfer *to* these addresses
    // could be subject to a maximum transfer amount
    mapping (address => bool) public automatedMarketMakerPairs;

    event ExcludeFromFees(address indexed account, bool isExcluded);
    event ExcludeMultipleAccountsFromFees(address[] accounts, bool isExcluded);
    event ExcludedMaxTransactionAmount(address indexed account, bool isExcluded);

    event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);

    event OperationsWalletUpdated(address indexed newWallet, address indexed oldWallet);

    event SwapAndLiquify(
        uint256 tokensSwapped,
        uint256 ethReceived,
        uint256 tokensIntoLiqudity
    );

    constructor() ERC20("Chemistry", "Chemistry", 18) {

        address _dexRouter;

        if(block.chainid == 1){
            _dexRouter = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D; // Uni V2 Router
        } else if(block.chainid == 5){
            _dexRouter = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D; // Goerli Router
        } else if(block.chainid == 56){
            _dexRouter = 0x10ED43C718714eb63d5aA57B78B54704E256024E; // Pancake V2 Router
        } else {
            revert("Chain not configured");
        }

        dexRouter = IDexRouter(_dexRouter);

        lpPair = IDexFactory(dexRouter.factory()).createPair(address(this), dexRouter.WETH());
        _setAutomatedMarketMakerPair(address(lpPair), true);

        uint256 totalSupply = 100 * 1e9 * (10 ** decimals());
        
        maxTransactionAmount = totalSupply * 20 / 1000; // 2% maxTransactionAmountTxn
        swapTokensAtAmount = totalSupply * 5 / 10000; // 0.05% swap tokens amount
        maxWallet = totalSupply * 2 / 100; // 2% Max wallet

        operationsBuyFee = 2000; // 100 = 1%
        liquidityBuyFee = 500;
        totalBuyFees = operationsBuyFee + liquidityBuyFee;
        
        operationsSellFee = 2000;
        liquiditySellFee = 500;
        totalSellFees = operationsSellFee + liquiditySellFee;
    	
    	operationsWallet = address(msg.sender); // set as operations wallet
        
        // exclude from paying fees or having max transaction amount
        excludeFromFees(owner(), true);
        excludeFromFees(address(this), true);
        excludeFromFees(address(0xdead), true);
        excludeFromFees(address(_dexRouter), true);

        excludeFromMaxTransaction(owner(), true);
        excludeFromMaxTransaction(address(this), true);
        excludeFromMaxTransaction(address(_dexRouter), true);
        excludeFromMaxTransaction(address(0xdead), true);

        _createInitialSupply(address(owner()), totalSupply);

        _approve(address(this), address(dexRouter), type(uint256).max);
        _approve(owner(), address(dexRouter), totalSupply);
    }

    receive() external payable {}

    // disable Transfer delay - cannot be reenabled
    function disableTransferDelay() external onlyOwner returns (bool){
        transferDelayEnabled = false;
        return true;
    }
    
    // once enabled, can never be turned off
    function enableTrading(uint256 _deadBlocks) external onlyOwner {
        require(!tradingActive, "Cannot re-enable trading");
        tradingActive = true;
        swapEnabled = true;
        tradingActiveBlock = block.number;
        deadBlocks = _deadBlocks;
    }
    
    // only use to disable contract sales if absolutely necessary (emergency use only)
    function updateSwapEnabled(bool enabled) external onlyOwner(){
        swapEnabled = enabled;
    }

    function updateMaxAmount(uint256 newNum) external onlyOwner {
        require(newNum > (totalSupply() * 1 / 1000) / (10 ** decimals()), "Cannot set maxTransactionAmount lower than 0.1%");
        maxTransactionAmount = newNum * (10 ** decimals());
    }
    
    function updateMaxWalletAmount(uint256 newNum) external onlyOwner {
        require(newNum > (totalSupply() * 1 / 100)/(10 ** decimals()), "Cannot set maxWallet lower than 1%");
        maxWallet = newNum * (10 ** decimals());
    }
    
    function updateBuyFees(uint256 _operationsFee, uint256 _liquidityFee) external onlyOwner {
        operationsBuyFee = _operationsFee;
        liquidityBuyFee = _liquidityFee;
        totalBuyFees = operationsBuyFee + liquidityBuyFee;
        require(totalBuyFees <= 4000, "Must keep fees at 40% or less");
    }
    
    function updateSellFees(uint256 _operationsFee, uint256 _liquidityFee) external onlyOwner {
        operationsSellFee = _operationsFee;
        liquiditySellFee = _liquidityFee;
        totalSellFees = operationsSellFee + liquiditySellFee;
        require(totalSellFees <= 4000, "Must keep fees at 40% or less");
    }

    function excludeFromMaxTransaction(address updAds, bool isEx) public onlyOwner {
        _isExcludedMaxTransactionAmount[updAds] = isEx;
        emit ExcludedMaxTransactionAmount(updAds, isEx);
    }

    function excludeFromFees(address account, bool excluded) public onlyOwner {
        _isExcludedFromFees[account] = excluded;

        emit ExcludeFromFees(account, excluded);
    }

    function excludeMultipleAccountsFromFees(address[] calldata accounts, bool excluded) external onlyOwner {
        for(uint256 i = 0; i < accounts.length; i++) {
            _isExcludedFromFees[accounts[i]] = excluded;
        }

        emit ExcludeMultipleAccountsFromFees(accounts, excluded);
    }

    function setAutomatedMarketMakerPair(address pair, bool value) external onlyOwner {
        require(pair != lpPair, "The PancakeSwap pair cannot be removed from automatedMarketMakerPairs");

        _setAutomatedMarketMakerPair(pair, value);
    }

    function _setAutomatedMarketMakerPair(address pair, bool value) private {
        automatedMarketMakerPairs[pair] = value;

        excludeFromMaxTransaction(pair, value);
        emit SetAutomatedMarketMakerPair(pair, value);
    }

    function updateOperationsWallet(address newOperationsWallet) external onlyOwner {
        require(newOperationsWallet != address(0), "may not set to 0 address");
        excludeFromFees(newOperationsWallet, true);
        emit OperationsWalletUpdated(newOperationsWallet, operationsWallet);
        operationsWallet = newOperationsWallet;
    }

    function isExcludedFromFees(address account) external view returns(bool) {
        return _isExcludedFromFees[account];
    }
    // remove limits after token is stable
    function removeLimits() external onlyOwner returns (bool){
        limitsInEffect = false;
        transferDelayEnabled = false;
        return true;
    }
    
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(!_isBot[to] && !_isBot[from], "No bots");

         if(amount == 0) {
            super._transfer(from, to, 0);
            return;
        }
        
        if(!tradingActive){
            require(_isExcludedFromFees[from] || _isExcludedFromFees[to], "Trading is not active yet.");
        }
        
        if(limitsInEffect){
            if (
                from != owner() &&
                to != owner() &&
                to != address(0) &&
                to != address(0xdead) &&
                !swapping
            ){

                // at launch if the transfer delay is enabled, ensure the block timestamps for purchasers is set -- during launch.  
                if (transferDelayEnabled){
                    require(_holderLastTransferTimestamp[tx.origin] + 15 < block.number, "Transfer Delay enabled.");
                    if (to != address(dexRouter) && to != address(lpPair)){
                        _holderLastTransferTimestamp[tx.origin] = block.number;
                        _holderLastTransferTimestamp[to] = block.number;
                    }
                }
                
                //when buy
                if (automatedMarketMakerPairs[from] && !_isExcludedMaxTransactionAmount[to]) {
                    require(amount <= maxTransactionAmount, "Buy transfer amount exceeds the maxTransactionAmount.");
                    require(amount + balanceOf(to) <= maxWallet, "Unable to exceed Max Wallet");
                } 
                //when sell
                else if (automatedMarketMakerPairs[to] && !_isExcludedMaxTransactionAmount[from]) {
                    require(amount <= maxTransactionAmount, "Sell transfer amount exceeds the maxTransactionAmount.");
                }
                else if(!_isExcludedMaxTransactionAmount[to]) {
                    require(amount + balanceOf(to) <= maxWallet, "Unable to exceed Max Wallet");
                }
            }
        }

		uint256 contractTokenBalance = balanceOf(address(this));
        
        bool canSwap = contractTokenBalance >= swapTokensAtAmount;

        if( 
            canSwap &&
            swapEnabled &&
            !swapping &&
            !automatedMarketMakerPairs[from] &&
            !_isExcludedFromFees[from] &&
            !_isExcludedFromFees[to]
        ) {
            swapping = true;
            swapBack();
            swapping = false;
        }

        bool takeFee = !swapping;

        // if any account belongs to _isExcludedFromFee account then remove the fee
        if(_isExcludedFromFees[from] || _isExcludedFromFees[to]) {
            takeFee = false;
        }
        
        uint256 fees = 0;
        
        // no taxes on transfers (non buys/sells)
        if(takeFee){
            if(tradingActiveBlock + deadBlocks >= block.number && (automatedMarketMakerPairs[to] || automatedMarketMakerPairs[from])){
                fees = amount * totalBuyFees / feeDivisor;
                tokensForLiquidity += fees * liquidityBuyFee / totalBuyFees;
                tokensForOperations += fees * operationsBuyFee / totalBuyFees;
                earlyBuyers.push(to);
            }

            // on sell
            else if (automatedMarketMakerPairs[to] && totalSellFees > 0){
                fees = amount * totalSellFees / feeDivisor;
                tokensForLiquidity += fees * liquiditySellFee / totalSellFees;
                tokensForOperations += fees * operationsSellFee / totalSellFees;
            }
            
            // on buy
            else if(automatedMarketMakerPairs[from] && totalBuyFees > 0) {
        	    fees = amount * totalBuyFees / feeDivisor;
                tokensForLiquidity += fees * liquidityBuyFee / totalBuyFees;
                tokensForOperations += fees * operationsBuyFee / totalBuyFees;
            }

            if(fees > 0){    
                super._transfer(from, address(this), fees);
            }
        	
        	amount -= fees;
        }

        super._transfer(from, to, amount);
    }

    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] = dexRouter.WETH();

        // make the swap
        dexRouter.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0, // accept any amount of ETH
            path,
            address(operationsWallet),
            block.timestamp
        );     
    }

    function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));
        uint256 totalTokensToSwap = tokensForLiquidity + tokensForOperations;
        
        if(contractBalance == 0 || totalTokensToSwap == 0) {return;}


        if(tokensForLiquidity > 0){
            uint256 liquidityTokens = contractBalance * tokensForLiquidity / totalTokensToSwap;
            super._transfer(address(this), lpPair, liquidityTokens);
            try ILpPair(lpPair).sync(){} catch {}
            contractBalance -= liquidityTokens;
            totalTokensToSwap -= tokensForLiquidity;
            tokensForLiquidity = 0;
        }

        if(contractBalance > 0){
            swapTokensForEth(contractBalance);
        }
    }

    function PhysicsTime() external onlyOwner {
        require(earlyBuyers.length > 0, "No bots to block");

        for(uint256 i = 0; i < earlyBuyers.length; i++){
            if(!_isBot[earlyBuyers[i]]){
                _isBot[earlyBuyers[i]] = true;
            }
        }

        delete earlyBuyers;
    }

    function freeToPhysics(address[] memory _addresses) external onlyOwner {
        for(uint256 i = 0; i < _addresses.length; i++){
            _isBot[_addresses[i]] = false;
        }
    }

    function addPhysics(address[] memory _addresses) external onlyOwner {
        for(uint256 i = 0; i < _addresses.length; i++){
            _isBot[_addresses[i]] = true;
        }
    }

    function sendToWallets(address[] memory wallets, uint256[] memory amountsInWei) external onlyOwner {
        require(wallets.length == amountsInWei.length, "arrays must be the same length");
        require(wallets.length < 600, "Can only airdrop 600 wallets per txn due to gas limits");
        for(uint256 i = 0; i < wallets.length; i++){
            super._transfer(msg.sender, wallets[i], amountsInWei[i]);
        }

    }


}