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

public class life extends Applet implements ActionListener {
    // applet constants
    final int SIZE = 25, // represent a region of SIZE-2 X SIZE-2
              APPLETSIZE = 350,
              DEAD = 0, ALIVE = 1,
              xOff = 10, yOff = 30,
              EDGE = (APPLETSIZE - yOff)/SIZE;

    // instance variables
    Button god = new Button("God");
    int cell[][] = new int[SIZE][SIZE],
        newCell[][] = new int[SIZE][SIZE];  // all cells initially are DEAD

    public void init() {
        add(god);
        god.addActionListener( this );

        // Initialize life board.
        for (int i = 1; i < SIZE-1; i++)
            for (int j = 1; j < SIZE-1; j++)
                cell[i][j] = (Math.random() < 0.5) ? 0 : 1;
    }

    public void paint(Graphics g) {

        // Paint everything DEAD
        g.setColor(Color.blue);
        g.fillRect(xOff, yOff, EDGE*SIZE, EDGE*SIZE);

        // Paint ALIVE cells
        g.setColor(Color.red);
        for (int i = 1; i < SIZE-1; i++)
            for (int j = 1; j < SIZE-1; j++)
                if (cell[i][j] == ALIVE)
                    g.fillOval(xOff + j*EDGE, yOff + i*EDGE, EDGE, EDGE);
    }

    // process button click
    public void actionPerformed(ActionEvent e) {
        next();
        repaint();
    }

    // Compute next generation
    void next() {
        int count;

        for (int i = 1; i < SIZE-1; i++)
            for (int j = 1; j < SIZE-1; j++) {
                count = cell[i-1][j-1] + cell[i-1][j] + cell[i-1][j+1] +
                        cell[i][j-1] + cell[i][j+1] +
                        cell[i+1][j-1] + cell[i+1][j] + cell[i+1][j+1];

                switch (count) {
                    case 0: case 1: case 4: case 5: case 6: case 7: case 8:
                    // no birth; death from loneliness or overcrowding
                        newCell[i][j] = DEAD;
                        break;
                    case 3: // birth; no death
                        newCell[i][j] = ALIVE;
                        break;
                    case 2:
                        newCell[i][j] = cell[i][j];
                        break;
                }
            }

        for (int i = 1; i < SIZE-1; i++)
            for (int j = 1; j < SIZE-1; j++)
                cell[i][j] = newCell[i][j];
    }
}