import java.net.ServerSocket;
import java.net.Socket;

import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.PrintWriter;
import java.io.IOException;

import java.util.ArrayList;
import java.util.Iterator;

class ClientThread extends Thread {
    private static int numberOfClients = 0;
    private static ArrayList allClients = new ArrayList();

    private final int clientNumber = ++numberOfClients;
    private final Socket socket;
    private final BufferedReader in;
    private final PrintWriter out;

    public ClientThread(Socket s) throws IOException {
	socket = s;
	in = new BufferedReader(
	         new InputStreamReader(
		     socket.getInputStream()));
	out = new PrintWriter(
	          new BufferedWriter(
		      new OutputStreamWriter(
		          socket.getOutputStream())), true);
	// true: PrintWriter is line buffered

	System.out.println("Klienttråd " + clientNumber +
			   " skapad.");
	out.println("Välkommen. Du är klient nummer " +
		    clientNumber + ".");

	allClients.add(this);

	// If any of the above calls throw an 
	// exception, the caller is responsible for
	// closing the socket. Otherwise the thread
	// will close it.
	start(); // Starts the thread, and calls run()
    }

    public void run() {
	try {
	    while (true) {
		String inline = in.readLine();
		System.out.println("Klienttråd " + clientNumber +
				   " tog emot: " + inline);
		// Not: inline == "quit"
		if (inline == null || inline.equals("quit"))
		    break;
		out.println("Du sa '" + inline + "'");
		Iterator i = allClients.iterator();
		while (i.hasNext()) {
		    ClientThread t = (ClientThread)i.next();
		    if (t != this)
			t.out.println("Från klient " + clientNumber +
				      ": " + inline);
		}
	    }
	    System.out.println("Klienttråd " + clientNumber +
			       ": Avslutar...");
	}
	catch(IOException e) {
	    System.out.println("Klienttråd " + clientNumber +
			       ": I/O-fel");
	}
	finally {
	    try {
		socket.close();
	    }
	    catch(IOException e) {
		System.out.println("Klienttråd " + clientNumber +
				   ": Socketen ej stängd");
	    }
	    allClients.remove(allClients.indexOf(this));
	}
    } // run
} // class ClientThread

public class MultiServer {
    public static final int PORT = 2000;
    public static void main(String[] args) throws IOException {
	ServerSocket s = new ServerSocket(PORT);
	System.out.println("Server-socketen: " + s);
	System.out.println("Servern lyssnar...");

	try {
	    while(true) {
		// Blocks until a connection occurs:
		Socket socket = s.accept();
		System.out.println("Uppkoppling accepterad.");
		System.out.println("Den nya socketen: " + socket);
		try {
		    ClientThread t = new ClientThread(socket);
		    System.out.println("Ny tråd skapad.");
		    System.out.println("Den nya tråden: " + t);
		}
		catch(IOException e) {
		    // If the constructor fails, close the socket,
		    // otherwise the thread will close it:
		    socket.close();
		}
	    }
	}
	finally {
	    s.close();
	}
    } // main
} // MultiServer