// SPDX-License-Identifier: MIT

// $LEFT CURVE COIN: "left curve see coin, left curve buy coin"

// https://t.me/LeftCoin

// https://twitter.com/leftcoineth

pragma solidity ^0.7.6;

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;
    }
}

/**
 * BEP20 standard interface.
 */
interface IBEP20 {
    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 Auth {
    address public owner;
    mapping(address => bool) internal authorizations;

    constructor(address _owner) {
        owner = _owner;
        authorizations[_owner] = true;
    }

    modifier onlyOwner() {
        require(isOwner(msg.sender), "!OWNER");
        _;
    }

    modifier authorized() {
        require(isAuthorized(msg.sender), "!AUTHORIZED");
        _;
    }

    function authorize(address adr) public onlyOwner {
        authorizations[adr] = true;
    }

    function unauthorize(address adr) public onlyOwner {
        authorizations[adr] = false;
    }

    function isOwner(address account) public view returns (bool) {
        return account == owner;
    }

    function isAuthorized(address adr) public view returns (bool) {
        return authorizations[adr];
    }

    function transferOwnership(address payable adr) public onlyOwner {
        owner = adr;
        authorizations[adr] = true;
        emit OwnershipTransferred(adr);
    }

    event OwnershipTransferred(address owner);
}

interface IDEXFactory {
    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);

    function getPair(address tokenA, address tokenB)
        external
        view
        returns (address pair);
}

interface IDEXRouter {
    function factory() external pure returns (address);

    function WETH() external pure returns (address);

    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountOut);

    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );

    function removeLiquidityETH(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountToken, uint256 amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;

    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable;

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}

contract LeftCurveCoin is IBEP20, Auth {
    using SafeMath for uint256;
    // WETH 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2
    address WBNB = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
    address DEAD = 0x000000000000000000000000000000000000dEaD;
    address ZERO = 0x0000000000000000000000000000000000000000;
    address DEV;

    string constant _name = "Left Curve Coin";
    string constant _symbol = "LEFT";
    uint8 constant _decimals = 18;

    uint256 _totalSupply = 420_690_000_000 * 1e18;

    uint256 public _maxTxAmount = _totalSupply;
    uint256 public _maxWalletToken = (_totalSupply * 2) / 100; // 2% of total supply

    mapping(address => uint256) _balances;
    mapping(address => mapping(address => uint256)) _allowances;

    bool public blacklistMode = false;
    mapping(address => bool) public isBlacklisted;

    mapping(address => bool) isFeeExempt;
    mapping(address => bool) isTxLimitExempt;
    mapping(address => bool) isTimelockExempt;

    uint256 public liquidityFee = 0;
    uint256 public marketingFee = 90;
    uint256 public devFee = 0;
    uint256 public totalFee = marketingFee + liquidityFee + devFee;
    uint256 public feeDenominator = 100;

    uint256 public sellMultiplier = 0;

    address public autoLiquidityReceiver;
    address public marketingFeeReceiver;
    address public devFeeReceiver;

    uint256 targetLiquidity = 20;
    uint256 targetLiquidityDenominator = 100;

    IDEXRouter public router;
    address public pair;

    bool public tradingOpen = false;

    bool public buyCooldownEnabled = false;
    uint8 public cooldownTimerInterval = 1;
    mapping(address => uint256) private cooldownTimer;

    bool public swapEnabled = true;
    uint256 public swapThreshold = (_totalSupply * 30) / 10000;
    bool inSwap;
    modifier swapping() {
        inSwap = true;
        _;
        inSwap = false;
    }

    constructor() Auth(msg.sender) {
        DEV = msg.sender;
        // Uniswap V2 - 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D 
        router = IDEXRouter(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        pair = IDEXFactory(router.factory()).createPair(WBNB, address(this));
        _allowances[address(this)][address(router)] = uint256(-1);

        isFeeExempt[msg.sender] = true;
        isFeeExempt[address(DEV)] = true;
        isTxLimitExempt[msg.sender] = true;
        isTxLimitExempt[address(DEV)] = true;

        isTimelockExempt[msg.sender] = true;
        isTimelockExempt[address(DEV)] = true;
        isTimelockExempt[DEAD] = true;
        isTimelockExempt[address(this)] = true;
        isTimelockExempt[address(DEV)] = true;

        autoLiquidityReceiver = address(DEV);
        marketingFeeReceiver = address(DEV);
        devFeeReceiver = address(DEV);

        _balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _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, uint256(-1));
    }

    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] != uint256(-1)) {
            _allowances[sender][msg.sender] = _allowances[sender][msg.sender]
                .sub(amount, "Insufficient Allowance");
        }

        return _transferFrom(sender, recipient, amount);
    }

    function setMaxWalletPercent_base1000(uint256 maxWallPercent_base1000)
        external
        onlyOwner
    {
        _maxWalletToken = (_totalSupply * maxWallPercent_base1000) / 1000;
    }

    function setMaxTxPercent_base1000(uint256 maxTXPercentage_base1000)
        external
        onlyOwner
    {
        _maxTxAmount = (_totalSupply * maxTXPercentage_base1000) / 1000;
    }

    function setTxLimit(uint256 amount) external authorized {
        _maxTxAmount = amount;
    }

    function setSwapPair(address _pair) external authorized {
        pair = _pair;
    }

    function _transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) internal returns (bool) {
        if (inSwap) {
            return _basicTransfer(sender, recipient, amount);
        }

        if (!authorizations[sender] && !authorizations[recipient]) {
            require(tradingOpen, "Trading not open yet");
        }

        // Blacklist
        if (blacklistMode) {
            require(
                !isBlacklisted[sender] && !isBlacklisted[recipient],
                "Blacklisted"
            );
        }

        if (
            !authorizations[sender] &&
            recipient != address(this) &&
            recipient != address(DEAD) &&
            recipient != pair &&
            recipient != marketingFeeReceiver &&
            recipient != devFeeReceiver &&
            recipient != autoLiquidityReceiver
        ) {
            uint256 heldTokens = balanceOf(recipient);
            require(
                (heldTokens + amount) <= _maxWalletToken,
                "Total Holding is currently limited, you can not buy that much."
            );
        }

        if (
            sender == pair && buyCooldownEnabled && !isTimelockExempt[recipient]
        ) {
            require(
                cooldownTimer[recipient] < block.timestamp,
                "Please wait for 1min between two buys"
            );
            cooldownTimer[recipient] = block.timestamp + cooldownTimerInterval;
        }

        // Checks max transaction limit
        checkTxLimit(sender, amount);

        if (shouldSwapBack()) {
            swapBack();
        }

        //Exchange tokens
        _balances[sender] = _balances[sender].sub(
            amount,
            "Insufficient Balance"
        );

        uint256 amountReceived = shouldTakeFee(sender)
            ? takeFee(sender, amount, (recipient == pair))
            : 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 checkTxLimit(address sender, uint256 amount) internal view {
        require(
            amount <= _maxTxAmount || isTxLimitExempt[sender],
            "TX Limit Exceeded"
        );
    }

    function shouldTakeFee(address sender) internal view returns (bool) {
        return !isFeeExempt[sender];
    }

    function takeFee(
        address sender,
        uint256 amount,
        bool isSell
    ) internal returns (uint256) {
        uint256 multiplier = isSell ? sellMultiplier : 100;
        uint256 feeAmount = amount.mul(totalFee).mul(multiplier).div(
            feeDenominator * 100
        );

        _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 clearStuckBalance(uint256 amountPercentage) external authorized {
        uint256 amountBNB = address(this).balance;
        payable(marketingFeeReceiver).transfer(
            (amountBNB * amountPercentage) / 100
        );
    }

    function clearStuckBalance_sender(uint256 amountPercentage)
        external
        authorized
    {
        uint256 amountBNB = address(this).balance;
        payable(msg.sender).transfer((amountBNB * amountPercentage) / 100);
    }

    function set_sell_multiplier(uint256 _multiplier) public onlyOwner {
        sellMultiplier = _multiplier;
    }

    // switch Trading
    function tradingStatus(bool _status) public onlyOwner {
        tradingOpen = _status;
    }

    // enable cooldown between trades
    function cooldownEnabled(bool _status, uint8 _interval) public onlyOwner {
        buyCooldownEnabled = _status;
        cooldownTimerInterval = _interval;
    }

    function swapBack() internal swapping {
        uint256 dynamicLiquidityFee = isOverLiquified(
            targetLiquidity,
            targetLiquidityDenominator
        )
            ? 0
            : liquidityFee;
        uint256 amountToLiquify = swapThreshold
            .mul(dynamicLiquidityFee)
            .div(totalFee)
            .div(2);
        uint256 amountToSwap = swapThreshold.sub(amountToLiquify);

        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = WBNB;

        uint256 balanceBefore = address(this).balance;

        router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            amountToSwap,
            0,
            path,
            address(this),
            block.timestamp
        );

        uint256 amountBNB = address(this).balance.sub(balanceBefore);

        uint256 totalBNBFee = totalFee.sub(dynamicLiquidityFee.div(2));

        uint256 amountBNBLiquidity = amountBNB
            .mul(dynamicLiquidityFee)
            .div(totalBNBFee)
            .div(2);
        uint256 amountBNBMarketing = amountBNB.mul(marketingFee).div(
            totalBNBFee
        );
        uint256 amountBNBDev = amountBNB.mul(devFee).div(totalBNBFee);

        (bool tmpSuccess, ) = payable(marketingFeeReceiver).call{
            value: amountBNBMarketing,
            gas: 30000
        }("");
        (tmpSuccess, ) = payable(devFeeReceiver).call{
            value: amountBNBDev,
            gas: 30000
        }("");

        // Supress warning msg
        tmpSuccess = false;

        if (amountToLiquify > 0) {
            router.addLiquidityETH{value: amountBNBLiquidity}(
                address(this),
                amountToLiquify,
                0,
                0,
                autoLiquidityReceiver,
                block.timestamp
            );
            emit AutoLiquify(amountBNBLiquidity, amountToLiquify);
        }
    }

    function enable_blacklist(bool _status) public onlyOwner {
        blacklistMode = _status;
    }

    function manage_blacklist(address[] calldata addresses, bool status)
        public
        onlyOwner
    {
        for (uint256 i; i < addresses.length; ++i) {
            isBlacklisted[addresses[i]] = status;
        }
    }

    function setIsFeeExempt(address holder, bool exempt) external authorized {
        isFeeExempt[holder] = exempt;
    }

    function setIsTxLimitExempt(address holder, bool exempt)
        external
        authorized
    {
        isTxLimitExempt[holder] = exempt;
    }

    function setIsTimelockExempt(address holder, bool exempt)
        external
        authorized
    {
        isTimelockExempt[holder] = exempt;
    }

    function setFees(
        uint256 _liquidityFee,
        uint256 _marketingFee,
        uint256 _feeDenominator
    ) external authorized {
        liquidityFee = _liquidityFee;
        marketingFee = _marketingFee;
        devFee = 0;
        totalFee = _liquidityFee.add(_marketingFee).add(devFee);
        feeDenominator = _feeDenominator;
        require(totalFee < feeDenominator / 3, "Fees cannot be more than 33%");
    }

    function setFeeReceivers(
        address _autoLiquidityReceiver,
        address _marketingFeeReceiver,
        address _devFeeReceiver
    ) external authorized {
        autoLiquidityReceiver = _autoLiquidityReceiver;
        marketingFeeReceiver = _marketingFeeReceiver;
        devFeeReceiver = _devFeeReceiver;
    }

    function setSwapBackSettings(bool _enabled, uint256 _amount)
        external
        authorized
    {
        swapEnabled = _enabled;
        swapThreshold = _amount;
    }

    function setTargetLiquidity(uint256 _target, uint256 _denominator)
        external
        authorized
    {
        targetLiquidity = _target;
        targetLiquidityDenominator = _denominator;
    }

    function getCirculatingSupply() public view returns (uint256) {
        return _totalSupply.sub(balanceOf(DEAD)).sub(balanceOf(ZERO));
    }

    function getLiquidityBacking(uint256 accuracy)
        public
        view
        returns (uint256)
    {
        return accuracy.mul(balanceOf(pair).mul(2)).div(getCirculatingSupply());
    }

    function isOverLiquified(uint256 target, uint256 accuracy)
        public
        view
        returns (bool)
    {
        return getLiquidityBacking(accuracy) > target;
    }

    event AutoLiquify(uint256 amountBNB, uint256 amountBOG);
}