XDEX (XDX)

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

contract XDEX {
    string public name = "XDEX";
    string public symbol = "XDX";
    uint8 public decimals = 18;
    uint256 public totalSupply;

    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor() {
        uint256 initial = 1_000_000 * 10**uint256(decimals);
        totalSupply = initial;
        balanceOf[msg.sender] = initial; // mint to deployer
        emit Transfer(address(0), msg.sender, initial);
    }

    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0), "zero addr");
        uint256 bal = balanceOf[from];
        require(bal >= value, "insufficient");
        unchecked { balanceOf[from] = bal - value; }
        balanceOf[to] += value;
        emit Transfer(from, to, value);
    }

    function transfer(address to, uint256 value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function approve(address spender, uint256 value) external returns (bool) {
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    function transferFrom(address from, address to, uint256 value) external returns (bool) {
        uint256 allowed = allowance[from][msg.sender];
        require(allowed >= value, "allowance");
        unchecked { allowance[from][msg.sender] = allowed - value; }
        _transfer(from, to, value);
        return true;
    }

    // Ownerless mint for demo/testing; REMOVE or restrict before mainnet
    function mint(address to, uint256 amount) external {
        totalSupply += amount;
        balanceOf[to] += amount;
        emit Transfer(address(0), to, amount);
    }
}