KBTC

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

/*
  Flattened minimal ERC20 + Ownable implementation.
  Purpose: avoid import/version mismatch. Safe & simple for deployment.
*/

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 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    function totalSupply() external view returns (uint256);
    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);
}

contract ERC20 is Context, IERC20 {
    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 returns (string memory) { return _name; }
    function symbol() public view returns (string memory) { return _symbol; }
    function decimals() public pure returns (uint8) { return 18; }

    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 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()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked { _approve(sender, _msgSender(), currentAllowance - amount); }
        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from zero");
        require(recipient != address(0), "ERC20: transfer to zero");
        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer exceeds balance");
        unchecked { _balances[sender] = senderBalance - amount; }
        _balances[recipient] += amount;
        emit Transfer(sender, recipient, amount);
    }

    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to zero");
        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from zero");
        uint256 bal = _balances[account];
        require(bal >= amount, "ERC20: burn exceeds balance");
        unchecked { _balances[account] = bal - amount; }
        _totalSupply -= amount;
        emit Transfer(account, address(0), amount);
    }

    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from zero");
        require(spender != address(0), "ERC20: approve to zero");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
}

/* Simple Ownable that sets owner = deployer (msg.sender) — no external imports to avoid version issues */
contract Ownable is Context {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

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

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

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

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

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

/* ====== Main Token ====== */
contract KBTC is ERC20, Ownable {
    constructor() ERC20("Kongali Bitcoin", "KBTC") {
        // mint 21,000,000 * 10^18 to deployer
        _mint(_msgSender(), 21000000 * (10 ** uint256(decimals())));
    }

    // owner can mint more if desired (optional)
    function mint(address to, uint256 amount) external onlyOwner {
        _mint(to, amount);
    }

    // owner can burn from any account with approval (optional helper)
    function burnFrom(address account, uint256 amount) external {
        // require caller has allowance to burn (standard pattern)
        uint256 currentAllowance = allowance(account, _msgSender());
        require(currentAllowance >= amount, "KBTC: burn amount exceeds allowance");
        _approve(account, _msgSender(), currentAllowance - amount);
        _burn(account, amount);
    }
}