import java.applet.Applet;
import java.applet.*;
import java.awt.*;
import java.awt.Color;
import java.net.URL;
import java.awt.event.*;

/**User defined class (ImageAndSound) extended from the Applet class to implements musics and images.
   Also, the methods of the following interfaces (ActionListener, AdjustmentListener, ItemListener)
   are defined in the ImageAndSound class
*/


public class ImageAndSound extends Applet implements ActionListener, AdjustmentListener, ItemListener {

	private int INIT_Y = 50;
	private int PACE = 40; // adjustable by scrollbar 'speed'

	private Image image[];
	private int totalImage = 2;
	private int x_pos = 1,		// x position of the image
			y_pos = INIT_Y,	// y position of the image
			sleepTime = 40;   // milliseconds to sleep
	private AudioClip music;
	private Button b_play_sound;
	private Button b_stop_resume;
	private Choice c_music_list; //droplist for choosing music
	private Scrollbar speed;  //scrollbar used for controlling the speed of movement of the image
	private Label l_speed;
	private boolean tag = false; //tag for toggle two images
	private boolean interrupted = false; //indicate if thread if interrupted

	Panel soundPanel;
	Panel speedPanel;

	private work thread;
	private URL myurl;
	
	/**This method is called after the applet instance is first created by 
	   the browser.  This will initialize the user interface panel for the applet and 
	   display it on the browser
	*/
	public void init() {

	   //Returns the URL of my applet. 
			myurl = getCodeBase();

		//for debug use. message can be found in the Java console
		System.out.println("myurl: " + myurl);

		//set the applet layout
		this.setBackground(new Color(175, 160, 105));
		setLayout(new BorderLayout());

		b_play_sound = new Button("Play Music");
		b_stop_resume = new Button("  Stop ");
		//Register action listener for the play button
		b_play_sound.addActionListener(this);
		//Register action listener for the Stop button
		b_stop_resume.addActionListener(this);

		// initialize music list
		c_music_list = new Choice();
		c_music_list.add("Space Music");
		c_music_list.add("Yahoo!");
		c_music_list.add("Chirp");
		c_music_list.add("Hi");
		c_music_list.select(0);
		music = getAudioClip(myurl, "Sound/" + "spacemusic.au");
		//Register action listener for the drop down listbox
		c_music_list.addItemListener(this);

		// set the layout of soundPanel
		soundPanel = new Panel(new FlowLayout());
		soundPanel.setBackground(Color.lightGray);
		soundPanel.setSize(433, 50);
		soundPanel.add(c_music_list);
		soundPanel.add(b_play_sound);
		soundPanel.add(b_stop_resume);

		// set the layout of the speed scrollbar
		l_speed = new Label("Speed of Animation ");
		l_speed.setSize(200, 15);
		speed = new Scrollbar(Scrollbar.HORIZONTAL, PACE, 10, 0, 600);
		speed.setSize(300, 24);
		speed.setUnitIncrement(30);
		//Register action listener for scrollbar
		speed.addAdjustmentListener(this);

		// set the layout of the speedPanel
		speedPanel = new Panel(new BorderLayout());
		speedPanel.setBackground(Color.lightGray);
		speedPanel.add("West", l_speed);
		speedPanel.add("Center", speed);

		// add soundPanel and speedPanel to applet
		add("North", soundPanel);
		add("South", speedPanel);
		
		//get images
		image = new Image[totalImage];
		for (int i=0; i<totalImage; i++)
			image[i] = getImage(myurl, "Image/" + "title" + i + ".gif");

	}
   /**The start method is called after init is completed, but before the 
      first invocation of paint.  This method is called everything
      the applet is stopped and restarted. Also, it is used
      to repaint() the image on different positions
   */
	public void start() {

		//always start from the initial position
		x_pos = 1;
		y_pos = INIT_Y;
		interrupted = false;
		
		//instantiate work class for repainting this applet
		thread = new work(this);
		//Start execution of a thread
		thread.start();

	}
	/**The stop method is called everything the user leaves the page
	   containing the applet or minimizes the browser. It is used
	   as a destructor for the class
	 */
	public void stop()  {
		System.out.println("applet stopped");

		// make sure the thread will stop after this applet is unloaded
		interrupted = true;

		//stop music if it's existing
		if (music != null)
			music.stop();

	}
	/**This is where user-level drawing is placed.  It is invoked by the browser
	  after init and start have completed, and again whenever the browser
	  needs to be redrawn.  Therefore, this method will draw the images at different
	  location.
	  @param Graphics Object
	*/
	public void paint( Graphics g) {

		// toggle between two images title0.gif and title1.gif
		if (tag)
			g.drawImage(image[0], x_pos, y_pos, this);
		else  g.drawImage(image[1], x_pos, y_pos, this);

		tag = !tag;
		
		// display the images line by line
		if (x_pos > 490)
		{
			x_pos = 1;
		
			if (y_pos > 180 )
				y_pos = INIT_Y;
			else  
				y_pos += 20;
				
		}
		else	
			x_pos += PACE;
		

	}
	/**Implements the method from the ActionListener Interface
	  This listerner applies to buttons and actionperfomed is invoked
	  when the user clicks on the button.
	  @param ActionEvent Object
	*/
	public void actionPerformed(ActionEvent ae) {

		Object obj=	ae.getSource();		
		System.out.println("Action Performed, source = " + obj.toString());

		if ( obj == b_play_sound)
			music.play();
		
		if (obj == b_stop_resume)
		{
			if (interrupted)
			{
				b_stop_resume.setLabel("Stop ");
				interrupted = false;
				// new instant of work to resume moving images
				thread = new work(this);
				thread.start();
			}
			else
			{
				b_stop_resume.setLabel("Resume ");	
				this.stop();
			}
				
						
		}
			
	}
	/**Implements the method for AdjustmentListener interface
	  This listener applies to scrollbars and adjustmentvaluechanged
	  is invoked when the scrollbar is moved.  Therefore, this 
	  method will adjust the pace of the multimedia image
	  @param AdjustmentEvent Object
	*/

	public void adjustmentValueChanged( AdjustmentEvent event) {
		
		// adjust PACE based on the speed scrollbar
		if (event.getSource() == speed)
			PACE = speed.getValue();

	}

    /**Implements the method for ItemListener interface.
	  This listerner applies to List box and is invoked when an item is 
	  changed.  Therefore, this method will capture the
      selected song.
	  @param ItemEvent Object
	*/
	public void itemStateChanged(ItemEvent ie) {

		System.out.println("itemStateChanged: " + ie.getSource());

		if (ie.getSource() == c_music_list)
		{
		  // for debug use only
		  System.out.println("c_music_list.getSelectedIndex() = " + c_music_list.getSelectedIndex());
		  System.out.println("c_music_list.getSelectedItem() = " + c_music_list.getSelectedItem());

		  switch (c_music_list.getSelectedIndex()) {
			case 0:
				music = getAudioClip(myurl, "Sound/" + "spacemusic.au");
				break;
			case 1:
				music = getAudioClip(myurl, "Sound/" + "yahoo1.au");
				break;	
			case 2:
				music = getAudioClip(myurl, "Sound/" +                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 "chirp.au");
				break;
			case 3:
				music = getAudioClip(myurl, "Sound/" + "hi.au");
				break;
		  }
		  System.out.println("music: " + music.toString());

		}
	}
	/**
	  Method to determine if the process is interrupted
	*/
	public boolean is_interrupted() {
		System.out.println("is_interrupted called: " + interrupted);
		return interrupted;
	}

}