// Original version j.n.magee 11/11/96
// Revised b.s.logan 14/02/2002

import java.awt.*;
import java.applet.*;

public class Garden extends Applet {

    Button goButton = new Button(" Go ");
    Turnstile west;
    Turnstile east;
    Counter counter;
    NumberCanvas counterD = new NumberCanvas("Counter");
    NumberCanvas westD = new NumberCanvas("West",Color.green);
    NumberCanvas eastD = new NumberCanvas("East",Color.green);;
    public final static int MAX = 20;


    public void init() {
        super.init();
        // Set up Button
        Panel p0 = new Panel();
        p0.add(goButton);
        goButton.setFont(new Font("Helvetica", Font.BOLD, 24));
        Panel p1= new Panel();
        p1.setLayout(new BorderLayout());
        p1.add("Center", p0);
        // Set up Display
        Panel p2 = new Panel();
        counterD.resize(150, 100);
        westD.resize(100, 100);
        eastD.resize(100, 100);
        p2.add(westD);
        p2.add(counterD);
        p2.add(eastD);
        // Arrange Applet display
        setLayout(new BorderLayout());
        add("Center", p2);
        add("South", p1);
    }

    public boolean handleEvent(Event event) {
        if (((event.id == event.ACTION_EVENT) &&
	     event.target == goButton) &&
            ((west == null && east == null) ||
	     (!west.isAlive() && !east.isAlive()))) {
		counter = new Counter(counterD);
		west = new Turnstile(westD, counter);
		east = new Turnstile(eastD, counter);
		west.start();
		east.start();
		return true;
        } else
            return super.handleEvent(event);
    }

}

class Counter {

    int value = 0;
    NumberCanvas display;

    Counter(NumberCanvas n) {
        display = n;
        display.setvalue(value);
    }

    void increment() {
        value = value + 1;       //write[v+1]
        display.setvalue(value);
    }
}

class Turnstile extends Thread {

  NumberCanvas display;
  Counter people;

    Turnstile(NumberCanvas n, Counter c) {
	display = n; 
	people = c;
    }

    public void run() {
	try{
	    display.setvalue(0);
	    for (int i=1; i <= Garden.MAX; i++) {
		Thread.sleep(500); //0.5 second
		display.setvalue(i);
		people.increment();
	    }
	} catch (InterruptedException e) {}
    }
}