// SPDX-License-Identifier: MIT
pragma solidity ^0.8.25;

// 💡🔗⚙️🚀🌐💡🔗
// 🔗                                      🔗
// 🔗  Quantum Token: Future in Your Hands! 🔗
// 🔗                                      🔗
// 💡🔗⚙️🚀🌐💡🔗

// "Step into the future of finance with Quantum Token."

// 🌐 Connect with innovation and endless possibilities! 🚀

// Import ReentrancyGuard from OpenZeppelin
abstract contract ReentrancyGuard {
    bool private _notEntered;

    constructor() {
        _notEntered = true;
    }

    modifier nonReentrant() {
        require(_notEntered, "ReentrancyGuard: reentrant call");
        _notEntered = false;
        _;
        _notEntered = true;
    }
}

// Import ERC20 and Ownable contracts
abstract contract ERC20 {
    function totalSupply() public view virtual returns (uint256);
    function balanceOf(address account) public view virtual returns (uint256);
    function transfer(address recipient, uint256 amount) public virtual returns (bool);
    function allowance(address owner, address spender) public view virtual returns (uint256);
    function approve(address spender, uint256 amount) public virtual returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) public virtual returns (bool);
    
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

abstract contract Ownable {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor() {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

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

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

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

    function renounceOwnership() public virtual onlyOwner {
        revert("Renouncing ownership is not allowed");
    }
}

contract Quantum is ERC20, Ownable, ReentrancyGuard {
    string public name = "Quantum";
    string public symbol = "Quantum";
    uint8 public decimals = 18;
    uint256 private _totalSupply;

    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;

    constructor() {
        _totalSupply = 1_000_000_000 * 10 ** uint256(decimals); // 1 billion tokens
        _balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public override nonReentrant returns (bool) {
        require(recipient != address(0), "ERC20: transfer to the zero address");
        require(_balances[msg.sender] >= amount, "ERC20: transfer amount exceeds balance");

        _balances[msg.sender] -= amount;
        _balances[recipient] += amount;
        emit Transfer(msg.sender, recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public override returns (bool) {
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public override nonReentrant returns (bool) {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");
        require(_balances[sender] >= amount, "ERC20: transfer amount exceeds balance");
        require(_allowances[sender][msg.sender] >= amount, "ERC20: transfer amount exceeds allowance");

        _balances[sender] -= amount;
        _balances[recipient] += amount;
        _allowances[sender][msg.sender] -= amount;
        emit Transfer(sender, recipient, amount);
        return true;
    }
}

{
  "compilationTarget": {
    "Quantum.sol": "Quantum"
  },
  "evmVersion": "cancun",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}