//------------
// Introduction to Programming Using Java: An Object-Oriented Approach
//Arnow/Weiss
//------------
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class ClockApplet extends Applet implements ActionListener {
    public void init() {
	Color backgroundColor = new Color(200,255,255);
	this.setLayout(new FlowLayout(FlowLayout.CENTER,4,1));
	clock1 = new Label("EST: 00:00:00.00", Label.CENTER);
	clock2 = new Label("GMT: 00:00:00.00", Label.CENTER);
	clock1Button = new Button(start1ButtonCommand);
	clock1Button.addActionListener(this);
	clock2Button = new Button(start2ButtonCommand);
	clock2Button.addActionListener(this);
	clock1Panel = new Panel();
	clock1Panel.setLayout(new BorderLayout(2,2));
	clock2Panel = new Panel();
	clock2Panel.setLayout(new BorderLayout(2,2));
	clock1Panel.add("West",clock1Button);
	clock1Panel.add("East",clock1);
	clock2Panel.add("West",clock2Button);
	clock2Panel.add("East",clock2);
	mainPanel = new Panel();
	mainPanel.setLayout(new BorderLayout(2,2));
	mainPanel.add("North",clock1Panel);
	mainPanel.add("South",clock2Panel);
	add(mainPanel);
	setBackground(backgroundColor);
    }
    
    public void actionPerformed(ActionEvent ae) {
	String whichButton = ae.getActionCommand();
	if (whichButton.equals(start1ButtonCommand))
	    handleStart(1);
	else if (whichButton.equals(resume1ButtonCommand))
	    handleResume(1);
	else if (whichButton.equals(stop1ButtonCommand))
	    handleStop(1);
	else if (whichButton.equals(start2ButtonCommand))
	    handleStart(2);
	else if (whichButton.equals(resume2ButtonCommand))
	    handleResume(2);
	else if (whichButton.equals(stop2ButtonCommand))
	    handleStop(2);
    }
    
    private void handleStart(int n) {
	if (n==1) {
	    clock1Button.setLabel(stop1ButtonCommand);
	    clockTicker1 = new 
		ClockThread(clock1,"EST");
	    clockTicker1.start();
	} else if (n==2) {
	    clock2Button.setLabel(stop2ButtonCommand);
	    clockTicker2 = new 
		ClockThread(clock2,"GMT");
	    clockTicker2.start();
	}
    }
    
    private void handleResume(int n) {
	if (n==1) {
	    clock1Button.setLabel(stop1ButtonCommand);
	    clockTicker1.myResume();
	} else if (n==2) {
	    clock2Button.setLabel(stop2ButtonCommand);
	    clockTicker2.myResume();
	}
    }
    private void handleStop(int n) {
	if (n==1) {
	    clock1Button.setLabel(resume1ButtonCommand);
	    clockTicker1.mySuspend();
	} else if (n==2) {
	    clock2Button.setLabel(resume2ButtonCommand);
	    clockTicker2.mySuspend();
	}
    }
    private    Panel     clock1Panel, clock2Panel, mainPanel;
    private    Button    clock1Button, clock2Button;
    private    String    start1ButtonCommand= "Start EST",
    resume1ButtonCommand= "Resume EST",
    stop1ButtonCommand= "Stop EST",
    start2ButtonCommand= "Start GMT",
    resume2ButtonCommand= "Resume GMT",
    stop2ButtonCommand= "Stop GMT";
    private    Label     clock1, clock2;
    private    ClockThread   clockTicker1,clockTicker2;
}

class ClockThread extends Thread {
    ClockThread(Label theLabel, String timeZone) {
	this.clock = theLabel;
	this.timeZone = timeZone;
    }
    
    public void run() {
	amRunning = true;
	while (true)
	    if (amRunning) {
		oneTick();
		try {
		    this.sleep(20);
		} catch (Exception e) {;}
	    }
    }
    
    public void mySuspend() {
	amRunning = false;
    }
    
    public void myResume() {
	amRunning = true;
    }
    
    private void oneTick() {
	GregorianCalendar gc = 
	    new GregorianCalendar(TimeZone.
				  getTimeZone(timeZone));
	int      h = gc.get(Calendar.HOUR);
	int      m = gc.get(Calendar.MINUTE);
	int      s = gc.get(Calendar.SECOND);
	int      ms= gc.get(Calendar.MILLISECOND);
	String  hms = leadingDigit(h," ")+":" +
	    leadingDigit(m,"0")+":" +
		leadingDigit(s,"0")+"." +
		    leadingDigit(ms/10,"0");
	clock.setText(hms);
}

    private String leadingDigit(int n, String leader) {
	if (n<10)
	    return leader+n;
	return ""+n;
    }

    private Label   clock;
    private boolean amRunning;
    private String timeZone;
}