// FlipFlop.java
// Raja Sooriamurthi
//
// An applet using the JDK 1.1 event model 
// to play the game of "Lights Out" 
//
// 1999/11/03  Initial version

/*
<applet code=FlipFlop.class height=500 width=500></applet>
*/

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

public class FlipFlop extends Applet {

    int gameSize   = 6;    
    int numButtons = gameSize*gameSize;
    int buttonSize = 65; 
    
    private boolean[] state;
    private Button[]  buttons;

    public void init() {

        // all initialized to false
        state   = new boolean[numButtons]; 
        buttons = new Button[numButtons];

        setLayout (new BorderLayout());
   
        Panel p0 = new Panel();
        p0.setLayout(new FlowLayout(FlowLayout.CENTER));
        Button startButton = new Button("Start");
        startButton.setBackground(Color.blue);
        startButton.setForeground(Color.yellow);

        startButton.addActionListener (new StartButtonL());

        p0.add(startButton);
        // *** "North" is case sensitive !!
        add("North", p0);

        Panel p1 = new Panel();
        p1.setLayout(new GridLayout(gameSize, gameSize));
        for (int i = 0; i < numButtons; i++) {
            buttons[i] = new Button(Integer.toString(i));
            buttons[i].setSize (buttonSize, buttonSize);
            buttons[i].addActionListener (new ButtonL());
            p1.add(buttons[i]);
            show(i);
        }
        // *** "Center" is case sensitive !!
        add("Center", p1);

        setSize (gameSize*buttonSize, 
                 gameSize*buttonSize + p0.getSize().height);
        setBackground (Color.cyan); 
        repaint();
    }

    // *********************************
    // A listener for the "start" button
    // *********************************

    class StartButtonL implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            for (int i=0; i<numButtons; i++) 
                if (Math.random() > 0.5) click(i);
        }
    }

    // ****************************
    // Listners for each button
    // ****************************

    class ButtonL implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            int i = Integer.parseInt (e.getActionCommand());
            click (i);
        }
    }

    // *************************
    // Click
    // *************************
    // Click toggles button i as well as each of its
    // neighbors on its four sides -if- they exist

    private void click (int i) {
        // toggle the clicked button
      System.out.println ("Clicked " + i);
        toggle(i);
        // toggle the left
        if (i%gameSize != 0)           toggle(i-1);
        // toggle the right
        if (i%gameSize < gameSize-1)   toggle(i+1);
        // toggle the below
        if (i >= gameSize)             toggle(i-gameSize);
        // toggle the above
        if (i < numButtons-gameSize)   toggle(i+gameSize);
        repaint();
    }
    
    // *************************
    //     toggle
    // *************************

    private void toggle (int i) {
            state[i] = !state[i];
            show (i);
    }

    // *************************
    //     show
    // *************************

    private void show (int i) {
        buttons[i].setBackground (state[i] ? Color.red: Color.green);
    }
}