// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @title MockERC20
 * @dev Simple ERC20 token for testing the AI DeFi trading agent
 * Represents a stablecoin-like asset (e.g., mock USDC)
 */
contract MockERC20 {
    string public name;
    string public symbol;
    uint8 public decimals;
    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);
    event Mint(address indexed to, uint256 amount);
    event Burn(address indexed from, uint256 amount);

    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _initialSupply
    ) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        totalSupply = _initialSupply;
        balanceOf[msg.sender] = _initialSupply;

        emit Transfer(address(0), msg.sender, _initialSupply);
    }

    function transfer(address to, uint256 amount) external returns (bool) {
        require(to != address(0), "Invalid recipient");
        require(balanceOf[msg.sender] >= amount, "Insufficient balance");

        balanceOf[msg.sender] -= amount;
        balanceOf[to] += amount;

        emit Transfer(msg.sender, to, amount);
        return true;
    }

    function approve(address spender, uint256 amount) external returns (bool) {
        require(spender != address(0), "Invalid spender");

        allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool) {
        require(from != address(0), "Invalid sender");
        require(to != address(0), "Invalid recipient");
        require(balanceOf[from] >= amount, "Insufficient balance");
        require(allowance[from][msg.sender] >= amount, "Insufficient allowance");

        balanceOf[from] -= amount;
        balanceOf[to] += amount;
        allowance[from][msg.sender] -= amount;

        emit Transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Mint new tokens (for testing/liquidity)
     */
    function mint(address to, uint256 amount) external {
        require(to != address(0), "Invalid recipient");

        totalSupply += amount;
        balanceOf[to] += amount;

        emit Mint(to, amount);
        emit Transfer(address(0), to, amount);
    }

    /**
     * @dev Burn tokens
     */
    function burn(uint256 amount) external {
        require(balanceOf[msg.sender] >= amount, "Insufficient balance");

        totalSupply -= amount;
        balanceOf[msg.sender] -= amount;

        emit Burn(msg.sender, amount);
        emit Transfer(msg.sender, address(0), amount);
    }
}