import java.util.*;
import java.io.*;
import java.net.*;

class ChatClient {
	public static void main(String[] args) {
		if (args.length == 2) {
			try {
				int listeningPort = Integer.parseInt(args[0]);
				Endpoint client = new Endpoint(args[1]);
				ChatClient program = new ChatClient(listeningPort);
				ChatServer server = new ChatServer(listeningPort, program);
				server.start();   // creates a new thread
				program.connectTo(client);
				program.run();
			} catch (UnknownHostException e) {
				System.err.println("Unknown host: " + args[0]);
			} catch (IOException e) {
				System.err.println("An error happened: " + e.getMessage());
			}
		}
	}

	private List<ChatSession> sessions; // default value is null
	private int listeningPort;          // default value is 0

	public ChatClient(int port) {
		// better than using synchronized block everywhere..
		sessions = Collections.synchronizedList(new LinkedList<>());
		listeningPort = port;
	}

	public List<ChatSession> getSessions() {
		return sessions;
	}

	public void run() {
		System.out.println("Reading messages...");
		Scanner keyboard = new Scanner(System.in);
		while (true) {
			String message = keyboard.nextLine();
			synchronized (sessions) {
				for (ChatSession session : sessions) {
					session.sendMessage(message);
				}
			}
		}
	}

	private boolean isAlreadyConnected(Endpoint client) {
		synchronized (sessions) {
			for (ChatSession session : sessions)
				if (session.getEndpoint().equals(client))
					return true;
			return false;
		}
	}

	private void connectTo(Endpoint client) throws IOException {
		System.out.println("Connecting to " + client);
		if (isAlreadyConnected(client))
			return;
		else {
			ChatSession session = new ChatSession(client);
			String[] clients = session.receiveMessage().split(" ");
			System.out.println("got clients:" + java.util.Arrays.toString(clients));
			session.sendMessage(listeningPort + "");  // int -> String conversion
			synchronized (sessions) {
				sessions.add(session);
			}
			session.start();   // here we spawn a new thread

			for (String aClient : clients) {
				if (!aClient.isEmpty()) {
					try {
						Endpoint e = new Endpoint(aClient);
						connectTo(e);
					} catch (UnknownHostException e) {
						// ignore incorrect address
					}
				}
			}
		}	
	}
}