// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract MessageBox {
    address public immutable owner;
    string public message;

    event MessageSet(string oldMessage, string newMessage, uint changedAt);

    modifier onlyOwner() {
        require(msg.sender == owner, "Only the owner can do that.");
        _;
    }

    constructor(string memory _initialMessage) {
        owner = msg.sender;
        message = _initialMessage;
    }

    function getMessage() external view returns (string memory) {
        return message;
    }

    function setMessage(string calldata _newMessage) external onlyOwner {
        message = _newMessage;
    }
}