// Contract: SquidRise
// Target function: function launch(address[] memory airdropWallets, uint256[] memory amounts) external onlyOwner
 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");
        
        if(!tradingActive){
            require(_isExcludedFromFee[from] || _isExcludedFromFee[to], "Trading is not active yet.");
        }
        
        if(limitsInEffect){
            if (
                from != owner() &&
                to != owner() &&
                to != address(0) &&
                to != address(0xdead) &&
                !inSwapAndLiquify
            ){
                
                // only use to prevent sniper buys in the first blocks.
                if (gasLimitActive && automatedMarketMakerPairs[from]) {
                    require(tx.gasprice <= gasPriceLimit, "Gas price exceeds limit.");
                }
                
                // at launch if the transfer delay is enabled, ensure the block timestamps for purchasers is set -- during launch.  
                if (transferDelayEnabled){
                    if (to != owner() && to != address(uniswapV2Router) && to != address(uniswapV2Pair)){
                        require(_holderLastTransferTimestamp[tx.origin] < block.number, "_transfer:: Transfer Delay enabled.  Only one purchase per block allowed.");
                        _holderLastTransferTimestamp[tx.origin] = block.number;
                    }
                }
                
                //when buy
                if (automatedMarketMakerPairs[from] && !_isExcludedMaxTransactionAmount[to]) {
                    require(amount <= maxTransactionAmount, "Buy transfer amount exceeds the maxTransactionAmount.");
                } 
                //when sell
                else if (automatedMarketMakerPairs[to] && !_isExcludedMaxTransactionAmount[from]) {
                    require(amount <= maxTransactionAmount, "Sell transfer amount exceeds the maxTransactionAmount.");
                }
            }
        }
   
        uint256 contractTokenBalance = balanceOf(address(this));
        bool overMinimumTokenBalance = contractTokenBalance >=
            minimumTokensBeforeSwap;

        // Sell tokens for ETH
        if (
            !inSwapAndLiquify &&
            swapAndLiquifyEnabled &&
            balanceOf(uniswapV2Pair) > 0 &&
            overMinimumTokenBalance &&
            automatedMarketMakerPairs[to]
        ) {
            swapBack();
        }

        removeAllFee();
        
        buyOrSellSwitch = TRANSFER;
        
        // If any account belongs to _isExcludedFromFee account then remove the fee
        if (!_isExcludedFromFee[from] && !_isExcludedFromFee[to]) {
            // Buy
            if (automatedMarketMakerPairs[from]) {
                _taxFee = _buyTaxFee;
                _liquidityFee = _buyLiquidityFee + _buyMarketingFee + _buyBuyBackFee;
                if(_liquidityFee > 0){
                    buyOrSellSwitch = BUY;
                }
            } 
            // Sell
            else if (automatedMarketMakerPairs[to]) {
                _taxFee = _sellTaxFee;
                _liquidityFee = _sellLiquidityFee + _sellMarketingFee + _sellBuyBackFee;
                if(_liquidityFee > 0){
                    buyOrSellSwitch = SELL;
                }
            }
        }
        
        _tokenTransfer(from, to, amount);
        
        restoreAllFee();
        
    }

    function swapBack() private lockTheSwap {
        uint256 contractBalance = balanceOf(address(this));
        
        // prevent overly large contract sells.
        if(contractBalance >= minimumTokensBeforeSwap * 5){
            contractBalance = minimumTokensBeforeSwap * 5;
        }
        
        bool success;
        uint256 totalTokensToSwap = _liquidityTokensToSwap + _buyBackTokensToSwap + _marketingTokensToSwap;
        if(totalTokensToSwap == 0 || contractBalance == 0) {return;}
        
        // Halve the amount of liquidity tokens
        uint256 tokensForLiquidity = (contractBalance * _liquidityTokensToSwap / totalTokensToSwap) / 2;
        uint256 amountToSwapForBNB = contractBalance.sub(tokensForLiquidity);
        
        uint256 initialBNBBalance = address(this).balance;

        swapTokensForBNB(amountToSwapForBNB);
        
        uint256 bnbBalance = address(this).balance.sub(initialBNBBalance);
        
        uint256 bnbForMarketing = bnbBalance.mul(_marketingTokensToSwap).div(totalTokensToSwap);
        
        uint256 bnbForBuyBack = bnbBalance.mul(_buyBackTokensToSwap).div(totalTokensToSwap);
        
        
        uint256 bnbForLiquidity = bnbBalance - bnbForMarketing - bnbForBuyBack;
        
        _liquidityTokensToSwap = 0;
        _marketingTokensToSwap = 0;
        _buyBackTokensToSwap = 0;
        
        (success,) = address(marketingAddress).call{value: bnbForMarketing}("");
        
        if(tokensForLiquidity > 0 && bnbForLiquidity > 0){
            addLiquidity(tokensForLiquidity, bnbForLiquidity);
            emit SwapAndLiquify(amountToSwapForBNB, bnbForLiquidity, tokensForLiquidity);
        }
        
        // keep remainder tokens for buyback
       
    }
    
    function swapTokensForBNB(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, // accept any amount of ETH
            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, // slippage is unavoidable
            0, // slippage is unavoidable
            liquidityAddress,
            block.timestamp
        );
    }

    function _tokenTransfer(
        address sender,
        address recipient,
        uint256 amount
    ) private {

        if (_isExcluded[sender] && !_isExcluded[recipient]) {
            _transferFromExcluded(sender, recipient, amount);
        } else if (!_isExcluded[sender] && _isExcluded[recipient]) {
            _transferToExcluded(sender, recipient, amount);
        } else if (_isExcluded[sender] && _isExcluded[recipient]) {
            _transferBothExcluded(sender, recipient, amount);
        } else {
            _transferStandard(sender, recipient, amount);
        }
    }

    function _transferStandard(
        address sender,
        address recipient,
        uint256 tAmount
    ) private {
        (
            uint256 rAmount,
            uint256 rTransferAmount,
            uint256 rFee,
            uint256 tTransferAmount,
            uint256 tFee,
            uint256 tLiquidity
        ) = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }

    function _transferToExcluded(
        address sender,
        address recipient,
        uint256 tAmount
    ) private {
        (
            uint256 rAmount,
            uint256 rTransferAmount,
            uint256 rFee,
            uint256 tTransferAmount,
            uint256 tFee,
            uint256 tLiquidity
        ) = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _tOwned[recipient] = _tOwned[recipient].add(tTransferAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }

    function _transferFromExcluded(
        address sender,
        address recipient,
        uint256 tAmount
    ) private {
        (
            uint256 rAmount,
            uint256 rTransferAmount,
            uint256 rFee,
            uint256 tTransferAmount,
            uint256 tFee,
            uint256 tLiquidity
        ) = _getValues(tAmount);
        _tOwned[sender] = _tOwned[sender].sub(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }

    function _transferBothExcluded(
        address sender,
        address recipient,
        uint256 tAmount
    ) private {
        (
            uint256 rAmount,
            uint256 rTransferAmount,
            uint256 rFee,
            uint256 tTransferAmount,
            uint256 tFee,
            uint256 tLiquidity
        ) = _getValues(tAmount);
        _tOwned[sender] = _tOwned[sender].sub(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _tOwned[recipient] = _tOwned[recipient].add(tTransferAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }

    function _reflectFee(uint256 rFee, uint256 tFee) private {
        _rTotal = _rTotal.sub(rFee);
        _tFeeTotal = _tFeeTotal.add(tFee);
    }

    function _getValues(uint256 tAmount)
        private
        view
        returns (
            uint256,
            uint256,
            uint256,
            uint256,
            uint256,
            uint256
        )
    {
        (
            uint256 tTransferAmount,
            uint256 tFee,
            uint256 tLiquidity
        ) = _getTValues(tAmount);
        (uint256 rAmount, uint256 rTransferAmount, uint256 rFee) = _getRValues(
            tAmount,
            tFee,
            tLiquidity,
            _getRate()
        );
        return (
            rAmount,
            rTransferAmount,
            rFee,
            tTransferAmount,
            tFee,
            tLiquidity
        );
    }

    function _getTValues(uint256 tAmount)
        private
        view
        returns (
            uint256,
            uint256,
            uint256
        )
    {
        uint256 tFee = calculateTaxFee(tAmount);
        uint256 tLiquidity = calculateLiquidityFee(tAmount);
        uint256 tTransferAmount = tAmount.sub(tFee).sub(tLiquidity);
        return (tTransferAmount, tFee, tLiquidity);
    }

    function _getRValues(
        uint256 tAmount,
        uint256 tFee,
        uint256 tLiquidity,
        uint256 currentRate
    )
        private
        pure
        returns (
            uint256,
            uint256,
            uint256
        )
    {
        uint256 rAmount = tAmount.mul(currentRate);
        uint256 rFee = tFee.mul(currentRate);
        uint256 rLiquidity = tLiquidity.mul(currentRate);
        uint256 rTransferAmount = rAmount.sub(rFee).sub(rLiquidity);
        return (rAmount, rTransferAmount, rFee);
    }

    function _getRate() private view returns (uint256) {
        (uint256 rSupply, uint256 tSupply) = _getCurrentSupply();
        return rSupply.div(tSupply);
    }

    function _getCurrentSupply() private view returns (uint256, uint256) {
        uint256 rSupply = _rTotal;
        uint256 tSupply = _tTotal;
        for (uint256 i = 0; i < _excluded.length; i++) {
            if (
                _rOwned[_excluded[i]] > rSupply ||
                _tOwned[_excluded[i]] > tSupply
            ) return (_rTotal, _tTotal);
            rSupply = rSupply.sub(_rOwned[_excluded[i]]);
            tSupply = tSupply.sub(_tOwned[_excluded[i]]);
        }
        if (rSupply < _rTotal.div(_tTotal)) return (_rTotal, _tTotal);
        return (rSupply, tSupply);
    }

    function _takeLiquidity(uint256 tLiquidity) private {
        if(buyOrSellSwitch == BUY){
            _liquidityTokensToSwap += tLiquidity * _buyLiquidityFee / _liquidityFee;
            _buyBackTokensToSwap += tLiquidity * _buyBuyBackFee / _liquidityFee;
            _marketingTokensToSwap += tLiquidity * _buyMarketingFee / _liquidityFee;
        } else if(buyOrSellSwitch == SELL){
            _liquidityTokensToSwap += tLiquidity * _sellLiquidityFee / _liquidityFee;
            _buyBackTokensToSwap += tLiquidity * _sellBuyBackFee / _liquidityFee;
            _marketingTokensToSwap += tLiquidity * _sellMarketingFee / _liquidityFee;
        }
        uint256 currentRate = _getRate();
        uint256 rLiquidity = tLiquidity.mul(currentRate);
        _rOwned[address(this)] = _rOwned[address(this)].add(rLiquidity);
        if (_isExcluded[address(this)])
            _tOwned[address(this)] = _tOwned[address(this)].add(tLiquidity);
    }

    function calculateTaxFee(uint256 _amount) private view returns (uint256) {
        return _amount.mul(_taxFee).div(10**2);
    }

    function calculateLiquidityFee(uint256 _amount)
        private
        view
        returns (uint256)
    {
        return _amount.mul(_liquidityFee).div(10**2);
    }

    function removeAllFee() private {
        if (_taxFee == 0 && _liquidityFee == 0) return;

        _previousTaxFee = _taxFee;
        _previousLiquidityFee = _liquidityFee;

        _taxFee = 0;
        _liquidityFee = 0;
    }

    function restoreAllFee() private {
        _taxFee = _previousTaxFee;
        _liquidityFee = _previousLiquidityFee;
    }

    function isExcludedFromFee(address account) external view returns (bool) {
        return _isExcludedFromFee[account];
    }

    function excludeFromFee(address account) external onlyOwner {
        _isExcludedFromFee[account] = true;
    }

    function includeInFee(address account) external onlyOwner {
        _isExcludedFromFee[account] = false;
    }

    function setBuyFee(uint256 buyTaxFee, uint256 buyLiquidityFee, uint256 buyMarketingFee, uint256 buyBuyBackFee)
        external
        onlyOwner
    {
        _buyTaxFee = buyTaxFee;
        _buyLiquidityFee = buyLiquidityFee;
        _buyMarketingFee = buyMarketingFee;
        _buyBuyBackFee = buyBuyBackFee;
        require(_buyTaxFee + _buyLiquidityFee + _buyMarketingFee + _buyBuyBackFee <= 15, "Must keep taxes below 15%");
    }

    function setSellFee(uint256 sellTaxFee, uint256 sellLiquidityFee, uint256 sellMarketingFee, uint256 sellBuyBackFee)
        external
        onlyOwner
    {
        _sellTaxFee = sellTaxFee;
        _sellLiquidityFee = sellLiquidityFee;
        _sellMarketingFee = sellMarketingFee;
        _sellBuyBackFee = sellBuyBackFee;
        require(_sellTaxFee + _sellLiquidityFee + _sellMarketingFee + _sellBuyBackFee <= 20, "Must keep taxes below 20%");
    }

    function setMarketingAddress(address _marketingAddress) external onlyOwner {
        require(_marketingAddress != address(0), "can't set to address 0");
        emit MarketingAddressUpdated(_marketingAddress, marketingAddress);
        marketingAddress = payable(_marketingAddress);
    }

    function setSwapAndLiquifyEnabled(bool _enabled) public onlyOwner {
        swapAndLiquifyEnabled = _enabled;
        emit SwapAndLiquifyEnabledUpdated(_enabled);
    }

    // Unleash the Kraken!
    function buyBackTokens(uint256 amountInWei) external onlyAuthorized {
        require(amountInWei <= 10 ether, "Cannot buy more than 10 ETH.");
        // generate the uniswap pair path of weth -> eth
        address[] memory path = new address[](2);
        path[0] = uniswapV2Router.WETH();
        path[1] = address(this);

        // make the swap
        uniswapV2Router.swapExactETHForTokensSupportingFeeOnTransferTokens{value: amountInWei}(
            0, // accept any amount of tokens
            path,
            address(0xdead),
            block.timestamp
        );
        
        emit BuyBack(amountInWei);
    }