/**
 *
 * Applet Life
 * <applet code="Life.class" width=460 height=340>
 * </applet>
 */

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

public class Life extends Applet implements Runnable {
    static final int W = 45;
    static final int H = 30;
    static final int DX = 10;
    static final int DY = 10;
    static final int MARGIN = 5;
    static final int HSKIP = 5;
    static final int VSKIP = 5;
    static final int BUTTONH = 20;
    static final int BUTTONW = 80;
    static final long DT = 500;

    Color fg = Color.blue;
    Color bg = Color.lightGray;

    Button stepButton;
    Button startButton;
    Button stopButton;
    Button eraseButton;

    byte[][] a0 = new byte[W][H];
    byte[][] a1 = new byte[W][H];
    byte[][] a  = a0;                   // Matrix on current step
    byte[][] n  = a1;                   // Matrix on next step

    Thread lifeThread;
    boolean terminate = false;

    public void init() {
        requestFocus();
        setBackground(bg);
        setFont(new Font("TimesRoman", Font.BOLD, 14));
        setLayout(null);

        stepButton = new Button("Step");
        add(stepButton);
        int y = MARGIN + DY * H + VSKIP;
        int x = MARGIN;
        stepButton.reshape(x, y, BUTTONW, BUTTONH);
        x += BUTTONW + HSKIP;

        startButton = new Button("Start");
        add(startButton);
        startButton.reshape(x, y, BUTTONW, BUTTONH);
        x += BUTTONW + HSKIP;

        stopButton = new Button("Stop");
        add(stopButton);
        stopButton.reshape(x, y, BUTTONW, BUTTONH);
        x += BUTTONW + HSKIP;

        eraseButton = new Button("Erase");
        add(eraseButton);
        eraseButton.reshape(x, y, BUTTONW, BUTTONH);
        x += BUTTONW + HSKIP;

        for (int i = 0; i < W; i++) {
            for (int j = 0; j < H; j++) {
                a[i][j] = 0;
            }
        }
        //  Planer
        //   *
        //    *
        //  ***
        // a[6][5] = 1;
        // a[7][6] = 1;
        // a[5][7] = 1;
        // a[6][7] = 1;
        // a[7][7] = 1;

        // S-pentamino
        // **
        //  **
        //  *
        a[5][5] = 1;
        a[6][5] = 1;
        a[6][6] = 1;
        a[6][7] = 1;
        a[7][6] = 1;

        stepButton.enable(true);
        startButton.enable(true);
        stopButton.enable(false);
        eraseButton.enable(true);
    }

    public boolean mouseDown(Event evt, int x, int y) {
        if (lifeThread != null) return false;
        int i;
        int j;

        i = (x - MARGIN) / DX;
        j = (y - MARGIN) / DY;

        if (0 <= i && i < W && 0 <= j && j < H) {
            if ((evt.modifiers & Event.META_MASK) != 0) {
                // Right button
                a[i][j] = (byte)0;
            } else if ((evt.modifiers & Event.ALT_MASK) != 0) {
                // Middle button
                a[i][j] = (byte)(1 - a[i][j]);
            } else {
                // Left button
                a[i][j] = (byte)1;
            }
            repaintCell(i, j);
            return true;
        }
        return false;
    }

    public void update(Graphics g) { paint(g); }

    public void paint(Graphics g) {
        g.setColor(Color.blue);
        g.drawRect(MARGIN, MARGIN, W * DX, H * DY);
        for (int x = 0; x < W; x++) {
            int left = MARGIN + DX * x + 1;
            for (int y = 0; y < H; y++) {
                int top = MARGIN + DY * y + 1;
                if (a[x][y] != 0) {
                    g.setColor(fg);
                    g.fillOval(left + 1, top + 1, DX - 3, DY - 3);
                } else {
                    g.setColor(bg);
                    g.fillRect(left, top, DX - 1, DY - 1);
                }
            }
        }
    }

    void repaintCell(int x, int y) {
        repaint(DT - 10, MARGIN + x * DX, MARGIN + y * DY, DX + 1, DY + 1);
    }

    synchronized void onStep() {
        // System.out.println("Step");
        byte[][] n = new byte[W][H];
        int sum = 0;
        for (int x = 0; x < W; x++) {
            for (int y = 0; y < H; y++) {
                int k = numNeibours(x, y);
                if (k <= 1) {
                    n[x][y] = 0;
                } else if (k == 2) {
                    n[x][y] = a[x][y];
                } else if (k == 3) {
                    n[x][y] = 1;
                } else {
                    n[x][y] = 0;
                }
                // if (n[x][y] != a[x][y]) repaintCell(x, y);
                sum += k;
            }
        }

        // Swap two matrices
        byte[][] tmp = n;
        a = n;
        n = tmp;

        if (sum == 0) {
           terminate = true;
        }
        a = n;

        repaint(DT - 10);
    }

    int numNeibours(int x, int y) {
        int x0 = x - 1;
        if (x0 < 0) x0 = W - 1;
        int x1 = x + 1;
        if (x1 >= W) x1 = 0;

        int y0 = y - 1;
        if (y0 < 0) y0 = H - 1;
        int y1 = y + 1;
        if (y1 >= H) y1 = 0;

        int n = 0;
        if (a[x0][y0] == 1) n++;
        if (a[x0][y] == 1) n++;
        if (a[x0][y1] == 1) n++;

        if (a[x][y0] == 1) n++;
        if (a[x][y1] == 1) n++;

        if (a[x1][y0] == 1) n++;
        if (a[x1][y] == 1) n++;
        if (a[x1][y1] == 1) n++;
        return n;
    }

    void onStart() {
        // System.out.println("Start");

        stepButton.enable(false);
        startButton.enable(false);
        stopButton.enable(true);
        eraseButton.enable(false);

        if (lifeThread != null) return;

        terminate = false;
        lifeThread = new Thread(this, "lifeThread");
        lifeThread.start();
    }

    void onStop() {
        terminate = true;
    }

    synchronized void onErase() {
        for (int x = 0; x < W; x++) {
            for (int y = 0; y < H; y++) {
                a[x][y] = 0;
            }
        }
        repaint();
    }

    public void stop() {
        onStop();
    }

    public boolean action(Event e, Object arg) {
        Object source = e.target;
        requestFocus();
        if (source == startButton) {
            onStart();
        } else if (source == stopButton) {
            onStop();
        } else if (source == stepButton) {
            onStep();
        } else if (source == eraseButton) {
            onErase();
        } else {
            return true;
        }
        return false;
    }

    public void run() {
        while (!terminate) {
            onStep();
            try {
                lifeThread.sleep(DT);
            } catch (InterruptedException e) {

            }
        }

        lifeThread = null;
        stepButton.enable(true);
        startButton.enable(true);
        stopButton.enable(false);
        eraseButton.enable(true);
    }

    public static void main(String[] args) {
        class MyFrame extends Frame {

            MyFrame(String headline) { super(headline); }

            public boolean action(Event e, Object arg) {
                if (e.target instanceof MenuItem) {
                    // We have only one "Quit" menu item...
                    System.exit(0);
                }
                return false;
            }

            public boolean handleEvent(Event e) {
                if (e.id == Event.WINDOW_DESTROY) {
                    System.exit(0);
                }
                return super.handleEvent(e);
            }
        };
        Frame f = new MyFrame("Python");

        f.setFont(new Font("Helvetica", Font.PLAIN, 14));
        MenuBar mb = new MenuBar();
        f.setMenuBar(mb);
        Menu fileMenu = new Menu("File");
        fileMenu.add(new MenuItem("Quit"));
        mb.add(fileMenu);

        f.resize(
            2*MARGIN + W * DX
            + 16,   // ???
            2*MARGIN + H * DY + VSKIP + BUTTONH
            + 24    // ???
            + 36    // Menu bar width
        );

        Life l = new Life();
        f.add("Center", l);

        l.init();
        l.start();

        f.show();
    }
}