/*
 * Copyright (c) 1995, 1996 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */
import java.applet.Applet;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.util.*;

public class TalkClientApplet extends Applet implements Runnable {
    Socket socket;
    DataOutputStream os;
    DataInputStream is;
    TextField portField, message;
    TextArea display;
    Button button;
    int dataPort;
    boolean trysted;
    Thread receiveThread;
    String host;
    boolean DEBUG = true;

    public void init() {
	//Get the address of the host we came from.
	host = getCodeBase().getHost();

	//Set up the UI.
	GridBagLayout gridBag = new GridBagLayout();
	GridBagConstraints c = new GridBagConstraints();
	setLayout(gridBag);

	message = new TextField("");
	c.fill = GridBagConstraints.HORIZONTAL;
	c.gridwidth = GridBagConstraints.REMAINDER;
	gridBag.setConstraints(message, c); 
	add(message);

	display = new TextArea(10, 40);
	display.setEditable(false);
	c.weightx = 1.0;
	c.weighty = 1.0;
	c.fill = GridBagConstraints.BOTH;
	gridBag.setConstraints(display, c); 
	add(display);

	Label l = new Label("Enter the port (on host " + host
			    + ") to send the request to:", 
			    Label.RIGHT);
	c.fill = GridBagConstraints.HORIZONTAL;
	c.gridwidth = 1;
	c.weightx = 0.0;
	c.weighty = 0.0;
	gridBag.setConstraints(l, c); 
	add(l);

	portField = new TextField(6);
	c.fill = GridBagConstraints.NONE;
	gridBag.setConstraints(portField, c); 
	add(portField);

	button = new Button("Connect");
	gridBag.setConstraints(button, c); 
	add(button);

	validate();
    }

    public synchronized void start() {
	if (DEBUG) {
	    System.out.println("In start() method.");
	}
	if (receiveThread == null) {
	    trysted = false;
	    portField.setEditable(true);
	    button.enable();
	    os = null;
	    is = null;
	    socket = null;
	    receiveThread = new Thread(this);
	    receiveThread.start();
	    if (DEBUG) {
	        System.out.println("  Just set everything to null and started thread.");
	    }
	} else if (DEBUG) {
	    System.out.println("  receiveThread not null! Did nothing!");
	}
    }

    public synchronized void stop() {
	if (DEBUG) {
	    System.out.println("In stop() method.");
	}
	receiveThread = null;
	trysted = false;
	portField.setEditable(true);
	button.enable();
	notify();

	try { //Close input stream.
	    if (is != null) {
	        is.close();
	        is = null;
	    }
	} catch (Exception e) {} //Ignore exceptions.

	try { //Close output stream.
	    if (os != null) {
	        os.close();
	        os = null;
	    }
	} catch (Exception e) {} //Ignore exceptions.

	try { //Close socket.
	    if (socket != null) {
	        socket.close();
	        socket = null;
	    }
	} catch (Exception e) {} //Ignore exceptions.
    }
	    
    public Insets insets() {
	return new Insets(4,4,5,5);
    }

    public void paint(Graphics g) {
        Dimension d = size();
        Color bg = getBackground();

        g.setColor(bg);
        g.draw3DRect(0, 0, d.width - 1, d.height - 1, true);
        g.draw3DRect(3, 3, d.width - 7, d.height - 7, false);
    }

    public synchronized boolean action(Event event, Object arg) {
	int port;
	
	if (DEBUG) {
	    System.out.println("In action() method.");
	}

	if (receiveThread == null) {
	    start();
	}

	if (!trysted) {
	//We need to attempt a rendezvous.

	    if (DEBUG) {
		System.out.println("  trysted = false. "
				   + "About to attempt a rendezvous.");
	    }

	    //Get the port the user entered...
	    try {
	        port = Integer.parseInt(portField.getText());
	    } catch (NumberFormatException e) {
	        //No integer entered. 
		display.appendText("Please enter an integer below.\n");
	        return true;
	    }
	    //...and rendezvous with it.
	    rendezvous(port);

	} else { //We've already rendezvoused. Just send data over.
	    if (DEBUG) {
		System.out.println("  trysted = true. "
				   + "About to send data.");
	    }
	    String str = message.getText();
	    message.selectAll();

	    try {
	        os.writeUTF(str);
	        os.flush();
	    } catch (IOException e) {
		display.appendText("ERROR: Applet couldn't write to socket.\n");
		display.appendText("...Disconnecting.\n");
		stop();
		return true;
	    } catch (NullPointerException e) {
		display.appendText("ERROR: No output stream!\n");
		display.appendText("...Disconnecting.\n");
		stop();
		return true;
	    }
	    display.appendText("Sent: " + str + "\n");
	}
	return true;
    }

    synchronized void waitForTryst() {
	//Wait for notify() call from action().
	try {
	    wait();	
	} catch (InterruptedException e) {}

	if (DEBUG) {
	    System.out.println("waitForTryst about to return. "
			       + "trysted = " + trysted + ".");
	}

	return;
    }

    public void run() {
	String received = null;

	waitForTryst();

	//OK, now we have our very own port to send messages to.
	while (Thread.currentThread() == receiveThread) {
	    try { 
	        //Wait for data from the server.
	        received = is.readUTF();

		//Display it.
	        if (received != null) {
	            display.appendText("Received: " + received + "\n");
		} else { //success but no data...
		    System.err.println("readUTF() returned no data");
		}
	    } catch (EOFException e) { //Stream has no more data.
		display.appendText("NOTE: Other applet is disconnected.\n");
		//display.appendText("...Disconnecting.\n");
		//stop();
		return;
	    } catch (NullPointerException e) { //Stream doesn't exist.
		display.appendText("NOTE: Disconnected from server.\n");
		display.appendText("...Completing disconnect.\n");
		stop();
		return;
	    } catch (IOException e) { //Perhaps a temporary problem?
		display.appendText("NOTE: Couldn't read from socket.\n");
		//display.appendText("...Disconnecting.\n");
		//stop();
		return;
	    } catch (Exception e) { //Unknown error. Throw tantrum.
		display.appendText("ERROR: Couldn't read from socket.\n");
		display.appendText("...Disconnecting.\n");
	        System.err.println("Couldn't read from socket.");
		e.printStackTrace();
		stop();
		return;
	    }
	}
    }

    private void rendezvous(int port) {
	//Try to open a socket to the port.
	try {
	    socket = new Socket(host, port);
	} catch (UnknownHostException e) {
	    display.appendText("ERROR: Can't find host: " + host + ".\n");
	    return;
	} catch (IOException e) {
	    display.appendText("ERROR: Can't open socket on rendezvous port "
	    		       + port + " (on host " + host + ").\n");
	    return;
	}

	//It should send us the data port to use.
	try {
	    is = new DataInputStream(socket.getInputStream());
	    dataPort = is.readInt();
	} catch (Exception e) {
	    display.appendText("ERROR: Created rendezvous socket but can't "
			       + "read port # from it.\n");
	    display.appendText("...Disconnecting.\n");
	    System.err.println("Applet created rendezvous socket but can't "
			       + "read port # from it:");
	    e.printStackTrace();
	    stop();
	    return;
	}

	//We don't need the rendezvous socket any more.  Close it.
	try {
	    is.close();
	    is = null;
	    socket.close();
	    socket = null;
	} catch (Exception e) {} //Ignore exceptions.

	//Try to open a socket to the data port.
        try {
            socket = new Socket(host, dataPort);
        } catch (IOException e) {
	    display.appendText("ERROR: Can't open socket on data port "
                               + port + " (on host " + host + ").\n");
	    display.appendText("...Disconnecting.\n");
	    stop();
            return;
        }   

	//Try to open streams to read and write from the socket.
        try {
            os = new DataOutputStream(socket.getOutputStream());
            is = new DataInputStream(socket.getInputStream());
        } catch (IOException e) {
	    display.appendText("ERROR: Created data socket but can't "
                               + "open stream on it.\n");
	    display.appendText("...Disconnecting.\n");
	    stop();
            return;
        }   

	if ((os != null) & (is != null)) {
	    if (DEBUG) {
		System.out.println("Successful rendezvous.");
		System.out.println("socket = " + socket);
		System.out.println("output stream = " + os);
		System.out.println("input stream = " + is);
	    }
	    //Let the main applet thread know we've successfully rendezvoused.
	    portField.setEditable(false);
	    button.disable();
	    trysted = true;
	    notify();
	} else {
	    display.appendText("ERROR: Port is valid but communication failed. "
	    		       + "Please TRY AGAIN.\n");
	}
    }

}