import java.net.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;



/**
 *  UMLV Multicast Chat client v0.1
 *  @author Daniele Raffo, 9 JAN 2002
 */
public class UMLVMulticastChat implements Runnable, ActionListener {

    static final int CHATW_LINES = 500;
    static final String DEFAULT_MADDRESS = "228.45.56.1";
    static final int DEFAULT_PORT = 1777;
    static final int MAX_BUFSIZE = 1024;

    String username;

    InetAddress mAddress;
    int port;
    MulticastSocket m;

    JLabel title;
    JTextField msgline;
    JTextArea msgarea;
    int nlines = 0;


    /** Constructor. Builds the GUI for the application. */
    public UMLVMulticastChat() throws IOException {
	username = System.getProperty("user.name");

	JFrame frame = new JFrame("UMLV Multicast Chat");

	JPanel panel = new JPanel(new BorderLayout());
	panel.setPreferredSize(new Dimension(650, 500));
	title = new JLabel();
	panel.add(title, BorderLayout.NORTH);
	msgline = new JTextField();
	panel.add(msgline, BorderLayout.SOUTH);
	msgarea = new JTextArea();
	msgarea.setEditable(false);
	msgarea.setLineWrap(true);
	msgarea.setWrapStyleWord(true);
	JScrollPane scroll = new JScrollPane(msgarea,
				     JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
				     JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
	panel.add(scroll, BorderLayout.CENTER);

	Font font = new Font("Serif", Font.ITALIC, 16);
        title.setFont(font);
        msgline.setFont(font);
        msgarea.setFont(font);

	frame.getContentPane().add(panel);
        frame.pack();
        frame.setVisible(true);
        frame.addWindowListener(new WindowAdapter() {
		public void windowClosing(WindowEvent e) {
		    say("*** " + username + " disconnected ***");
		    System.exit(0);
		}
	    });

	msgline.addActionListener(this);
	msgline.requestFocus();
    }
    

    /** Main method. */
    public static void main (String[] args) throws Exception {
	System.out.println("UMLV Multicast Chat client v0.1   9 JAN 2002 \n" +
	                   "by Daniele Raffo <draffo@etudiant.univ-mlv.fr>");

	if ((args.length != 0) && (args.length != 2)) {	
	    System.out.println(
		 "Usage: java UMLVMulticastChat [<multicast address> <port>]");
	    System.exit(-1);
	}
	
	UMLVMulticastChat chat = new UMLVMulticastChat();

	if (args.length == 0) {
	    chat.mAddress = InetAddress.getByName(DEFAULT_MADDRESS);
	    chat.port = DEFAULT_PORT;
	} 
	else {
	    chat.mAddress = InetAddress.getByName(args[0]);
	    chat.port = Integer.parseInt(args[1]);
	}

	// creates the multicast socket and connects to the multicast address 
	chat.m = new MulticastSocket(chat.port);
	chat.m.joinGroup(chat.mAddress);
	chat.m.setTimeToLive(32);

	chat.title.setText("Multicast on " + chat.mAddress.getHostAddress() 
			   + ", port " + chat.port);
 	chat.say("*** " + chat.username + 
	    " connected from " + InetAddress.getLocalHost().getHostName() +
	    " (" + InetAddress.getLocalHost().getHostAddress() + 
	    ") ***");

	// creates a new thread for the reception of messages 
	Thread t = new Thread(chat);
	t.setDaemon(true);
	t.start();
    }


    /** Gets the message typed by the user and sends it to multicast. */
    public void actionPerformed(ActionEvent event) {
	say("<" + username + "> " + msgline.getText());
	msgline.setText("");
     }


    /** Sends a text to multicast. */
    public void say(String text) {
	byte[] data = new byte[MAX_BUFSIZE];
	DatagramPacket packet = 
	    new DatagramPacket(data, 0, 0, mAddress, port);

	try {
	    data = text.getBytes();
	    packet.setData(data, 0, data.length);
	    m.send(packet);
	} catch (IOException e) {
	    System.out.println(e);
	}
    }
 

    /** Waits for messages to arrive from multicast and prints them. */
    public void run() {
	byte[] data = new byte[MAX_BUFSIZE];
	DatagramPacket packet = new DatagramPacket(data, 0, data.length);

	try {
	    while (true) {
		packet.setData(data, 0, data.length);
		m.receive(packet);
		if (nlines >= CHATW_LINES) { 
		    msgarea.setText(null);
		    nlines = 0;
		}
		msgarea.append(new String(data, 0, packet.getLength()) +
			       System.getProperty("line.separator"));
		Document d = msgarea.getDocument();
		msgarea.select(d.getLength(), d.getLength());
		nlines++;
	    }
	} catch (IOException e) {
	    System.out.println(e);
	}
    }


}