Greeter

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

contract Greeter {
    string private greeting;
    address public owner;
    uint256 public totalGreetings;
    
    event GreetingChanged(string newGreeting, uint256 timestamp);
    event GreetingSent(address indexed sender, string message, uint256 timestamp, uint256 chainId);
    
    constructor() {
        owner = msg.sender;
        greeting = unicode"Good Morning! ☀️";
    }
    
    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }
    
    function setGreeting(string memory _newGreeting) external onlyOwner {
        require(bytes(_newGreeting).length > 0, "Empty greeting");
        greeting = _newGreeting;
        emit GreetingChanged(_newGreeting, block.timestamp);
    }
    
    function getGreeting() external view returns (string memory) {
        return greeting;
    }
    
    function sayGM() external {
        totalGreetings++;
        emit GreetingSent(msg.sender, greeting, block.timestamp, block.chainid);
    }
    
    function sayGM(string memory _customGreeting) external {
        require(bytes(_customGreeting).length > 0, "Empty greeting");
        totalGreetings++;
        emit GreetingSent(msg.sender, _customGreeting, block.timestamp, block.chainid);
    }
    
    function transferOwnership(address _newOwner) external onlyOwner {
        require(_newOwner != address(0), "Invalid address");
        owner = _newOwner;
    }
    
    function getChainId() external view returns (uint256) {
        return block.chainid;
    }
    
    function getStats() external view returns (string memory currentGreeting, uint256 totalTxns, uint256 chainId) {
        return (greeting, totalGreetings, block.chainid);
    }
}