// ChatGui - a chat client program utilizing a simple GUI.  The
// program initializes the GUI with a JTextField for chat input 
// and a JTextArea for displaying messages sent and received.
// Two sockets are utilized:  a TCP socket for receiving 
// connection info and messages from the server, and a UDP 
// socket for sending messages to the server which distributes them
// to other clients.  The main loop is the receiveMessages() method,
// which loops until termination waiting on messages from the 
// server.  This loop is interrupted by a keyboard event to 
// send this user's message via the sendMessage() method.
// Run ChatGui with:
//      java ChatGui <screen_name> <server_host_name> <server_TCP_port#>

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

public class ChatGui extends JFrame {
   private JTextField enter;
   private JTextArea display;
   private Socket connectionTCPSocket;
   private BufferedReader fromServer;
   private DatagramSocket chatOutSocket;
   private int chatOutUDPPort;
   private InetAddress chatServerIP;
   private String screenName;

   public ChatGui(String args[])
   {
      super(args[0] + ": Chat Client" );

      Container c = getContentPane();
      // set up JtextField for input with ActionListener      
      enter = new JTextField();
      enter.addActionListener(
         new ActionListener() {
            public void actionPerformed( ActionEvent e )
            {
                sendMessage( e.getActionCommand() );
            }
         }
      );
      c.add( enter, BorderLayout.NORTH );
      // JTextArea for sent and received messages
      display = new JTextArea();
      c.add( new JScrollPane( display ),
             BorderLayout.CENTER );

      setSize( 400, 300 );
      show();
      enter.setEnabled( true );
      initSession(args);  // initializes sockets and "logs in" to server
   }

   // sendMessage - sends the string "message" to the server via UDP socket,
   // displays the message in the JTextArea, and finally clears the JTextField
   // input areea for the next message.
   private void sendMessage( String message )
   {
      // create a datagram consisting of the user's screen name, two separator 
      // characters and the message
     
      try {
        // write the chat message to the server via UDP socket then display locally
	
        display.append( "\n" + chatToSend ); // display in JTextArea
        enter.setText(""); //Clear the JTextField
      }
      catch(IOException ioException) {
                System.err.println ("IOException in sendMessage.");
      }
   }

   // receiveMessages - loops forever waiting on messages from server via the 
   // TCP connection.  When a message is received, display it in JTextArea
   private void receiveMessages()
   {
       //loop waiting for TCP messages from server, then display them
       while (true) {
           try { 
            
	///Get and display chat messages
           }
           catch(IOException ioException) {
                System.err.println ("IOException in receiveMessage loop.");
                break;
           }
       }
   }
   
   // initSession - initializes the two sockets with the server.  TCP port is
   // used to receive messages from the server, UDP port is used to send chat messages
   // to the server.  Recieves command line arguments: screen name, and TCP port.  Uses
   // chatServerHostName to get server IP address.  If selected screen name is already
   // in use on server, UDP port # received from server is 0, which invokes error
   // MessageDialog to inform user, then shuts down ChatGui.
   private void initSession(String args[])
   {
      screenName = args[0];
      String chatServerHostName = args[1];
      int chatServerTCPPort = Integer.parseInt(args[2]);
      DataOutputStream toServer;
      
      try {


	//  Set up TCP in/out buffers and instantiate TCP socket
	//  Send screen name and other info to server
	//  Get UDP port number from server
    
      } catch (IOException ioException) {
            ioException.printStackTrace();
      }
   }

// Execute with args: screenName, chatServerHostName, chatServerTCPPort

   public static void main( String args[] )
   {         
       if (args.length != 3) {
           System.err.println("Usage:  ChatGUI <screename> <servername> <serverport>.  Try again.");
           System.exit (-1);
       }
       ChatGui application = new ChatGui(args);      
      // The following listener responds to the close event on the window
      application.addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {            
                System.exit( 0 );
            }
         }
      );
      application.receiveMessages();
   }
}