package chat;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ChatServer {

    private final int port;
    private final Set<ClientHandler> connectedClients;
    private final ExecutorService threadPool;

    public ChatServer(int port) {
        this.port = port;
        this.connectedClients = Collections.synchronizedSet(new HashSet<>());
        this.threadPool = Executors.newCachedThreadPool();
    }

    public void start() {
        try (ServerSocket serverSocket = new ServerSocket(port)) {
            System.out.println("Chat server started on port " + port);

            while (true) {
                Socket clientSocket = serverSocket.accept();
                ClientHandler clientHandler = new ClientHandler(clientSocket, this);
                connectedClients.add(clientHandler);
                threadPool.execute(clientHandler);
            }
        } catch (IOException e) {
            System.err.println("Server error: " + e.getMessage());
        } finally {
            threadPool.shutdown();
        }
    }

    public void broadcast(String message, ClientHandler sender) {
        // step 1: iterate through connectedClients safely
        // step 2: skip the sender client
        // step 3: send message to remaining clients using sendMessage
    }

    public void broadcastSystemMessage(String message) {
        // step 1: iterate through all connected clients
        // step 2: send system message to each client
    }

    public void removeClient(ClientHandler clientHandler) {
        // step 1: remove client from connectedClients set
        // step 2: retrieve username from clientHandler
        // step 3: broadcast system message about user leaving
    }

    public static void main(String[] args) {
        int port = 12345;
        if (args.length > 0) {
            try {
                port = Integer.parseInt(args[0]);
            } catch (NumberFormatException e) {
                System.err.println("Invalid port. Using default: " + port);
            }
        }
        new ChatServer(port).start();
    }
}