/* Class supporting a thread maintaining timer */

import java.awt.*;

public class WatchThread extends Thread
{
	protected long lastTime;						// accumulated time before latest push of start button
	protected Label timeField;					// Display for timer
	protected long startTime; 					// Time start button is pushed
	protected long time = 0;						// Total time on timer
	protected boolean running = true;		// Whether timer is to be running (or paused)
	
	// Create thread with name "watch" and record TextField for display.
	public WatchThread(Label timeField)
	{
		super("watch");
		this.timeField = timeField;
	}
	
	// Method running timer.  Suspends until start button is pushed.  Suspend again
	//  if pause button is pushed.  Displays total running time since timer initialized.
	public void run()
	{
		while(true)
		{
			suspend();		
			running = true;
			startTime = System.currentTimeMillis();
			lastTime = time;
			while (running)
			{
				time = lastTime + (System.currentTimeMillis() - startTime);

				doze(10);
				
				timeField.setText(timeString(time));
			}
		}
	}
		
	// Set running to false in response to pause button.
	public void pause()
	{
		running = false;
	}

	// Clear total time - reset to zero.
	public void clear()
	{
		time = 0;
		timeField.setText("00 : 00 : 00");
		lastTime = 0;
		startTime = System.currentTimeMillis();
	}
	
	// Convert time to a string ready to be displayed
	String timeString(long time)
	{
		long hundredths, seconds, minutes;
		
		hundredths = Math.round(Math.floor(time/10)) % 100;
		seconds = Math.round(Math.floor(time/1000)) % 60 ;
		minutes = Math.round(Math.floor(time/(1000*60)));
		
		return digits(minutes) + " : " + 
			    digits(seconds) + " : " + digits(hundredths);

	}
	
	// Convert time to two letter string
	String digits(long time)
	{
		String dig = Long.toString(time);
		dig = "00" + dig;
		return dig.substring(dig.length()-2);
	}
	
	// Pause for interval milliseconds
	public void doze(int interval)
	{
		try {
			sleep(interval);
		} catch (InterruptedException e) {}
	}
}