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

public class UDPMulticastServer{
	JFrame frame;
	JPanel panel;
	JButton button1,button2;
	JTextArea area;
	JScrollPane pane;
	Thread thread;
	MulticastSocket socket;

	public static void main(String[] args) {
		UDPMulticastServer u = new UDPMulticastServer();
	}
	public UDPMulticastServer(){
		frame = new JFrame("Broadcast Server");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setUndecorated(true);
		frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
		panel = new JPanel();
		panel.setLayout(null);
		area = new JTextArea();
		button1 = new JButton("Start");
		button1.setBounds(210, 10, 75, 40);
		button1.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent e){
				new StartServer();
			}
		});
		panel.add(button1);
		button2 = new JButton("Stop");
		button2.setBounds(300, 10, 75, 40);
		button2.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent ae){
				thread.interrupt();
				socket.close();
				area.append("Server is stopped\n");
				button1.setEnabled(true);
				button2.setEnabled(false);
			}
		});
		button2.setEnabled(false);
		panel.add(button2);
		pane = new JScrollPane(area);
		pane.setBounds(10, 60, 365, 250);
		panel.add(pane);
		frame.add(panel);
		frame.setSize(400, 400);
		frame.setVisible(true);
	}
	
	public class StartServer implements Runnable{
		InetAddress address;
		StartServer(){
			thread = new Thread(this);
			thread.start();
			button1.setEnabled(false);
			button2.setEnabled(true);
		}
		public void run(){
			try{
				byte[] buffer = new byte[65535];
				int port = 5000;
				String address = "224.0.0.0";
				String address1 = "235.0.0.1";
				String address2 = "235.255.0.1";
				String address3 = "224.0.255.1";
				String addresStr[] = {address, address1, address2, address3};
				try{
					socket = new MulticastSocket(port);
					InetAddress add = InetAddress.getByName(address);
					socket.joinGroup(add);
					InetAddress add1 = InetAddress.getByName(address1);
					socket.joinGroup(add1);
					InetAddress add2 = InetAddress.getByName(address2);
					socket.joinGroup(add2);
					InetAddress add3 = InetAddress.getByName(address3);
					socket.joinGroup(add3);
					InetAddress str[] = {add, add1, add2, add3};
					area.append("Server is started\n");
					while(true){
						try{
							//Receive request from client
							for(int i=0; i < str.length; i++){
							DatagramPacket packet = new DatagramPacket(buffer, buffer.length, str[i], port);
							socket.receive(packet);
							addresStr[i] = packet.getAddress().toString();
							InetAddress client = packet.getAddress();
							int client_port = packet.getPort();
							area.append("Received : '" + new String(buffer).trim() + "' from " + addresStr[i] + "\n");
							// send information to the client
							String message = "your request\n ";
							buffer = message.getBytes() ;
							packet = new DatagramPacket(buffer, buffer.length, client, client_port);
							socket.send(packet);
							}
						}
						catch(UnknownHostException ue){}
					}
				}
				catch(java.net.BindException b){}
			}
			catch (IOException e){
				System.err.println(e);
			}
		}
	}
}