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

public class BallisticDeposition
extends Applet implements WindowListener,MouseListener,MouseMotionListener,Runnable,ActionListener,ComponentListener {
	final static int size=6;
	boolean[][] cell;
	Button fall,stop,erase;
	Image offscreen;
	Frame frame;
	boolean running=false;
	boolean falling=false;
	boolean state=true;
	
	static public void main(String[] args) {
		main();
	}
	
	public void init() {
		main();
	}
	
	static void main() {
		BallisticDeposition bd=new BallisticDeposition();
		bd.frame=new Frame("Ballistic Deposition");
		bd.frame.setSize(240,350);
		Panel panel=new Panel(new GridLayout());
		((Button)panel.add(bd.fall=new Button("ふる"))).addActionListener(bd);
		((Button)panel.add(bd.stop=new Button("やむ"))).addActionListener(bd);
		((Button)panel.add(bd.erase=new Button("けす"))).addActionListener(bd);
		bd.frame.add(panel,BorderLayout.NORTH);
		bd.frame.addWindowListener(bd);
		bd.setBackground(Color.white);
		bd.addMouseListener(bd);
		bd.addMouseMotionListener(bd);
		bd.addComponentListener(bd);
		bd.frame.add(bd,BorderLayout.CENTER);
		bd.frame.show();
	}
	
	public void setCell() {
		running=false;
		falling=false;
		cell=new boolean[getSize().height/size][getSize().width/size];
		for (int y=0;y<cell.length;y++) for (int x=0;x<cell[y].length;x++)
			cell[y][x]=(y==cell.length-1);
		offscreen=createImage(getSize().width,getSize().height);
		repaint();
	}
	
	public void actionPerformed(ActionEvent evt) {
		if (evt.getSource()==fall) {
			falling=true;
			if (!running)
				new Thread(this).start();
		}
		if (evt.getSource()==stop)
			falling=false;
		if (evt.getSource()==erase)
			setCell();
		repaint();
	}
	
	public void run() {
		running=true;
		while (running) {
			boolean calmed=!falling;
			int Y=this.cell.length;
			boolean[][] cell=new boolean[Y][];
			{
				int X=this.cell[0].length;
				cell[0]=new boolean[X];
				for (int x=0;x<X;x++)
					cell[0][x]=falling?Math.random()<0.03:false;
			}
			for (int y=1;y<Y-1;y++) {
				int X=this.cell[y].length;
				cell[y]=new boolean[X];
				for (int x=0;x<X;x++)
					if (this.cell[y][x])
						if (!this.cell[y+1][x] && !this.cell[y][(x+1)%X] && !this.cell[y][(x-1+X)%X])
							calmed=(cell[y][x]=false);
						else
							cell[y][x]=true;
					else
						if (this.cell[y-1][x] && !this.cell[y-1][(x+1)%X] && !this.cell[y-1][(x-1+X)%X])
							calmed=!(cell[y][x]=true);
						else
							cell[y][x]=false;
			}
			cell[Y-1]=this.cell[Y-1];
			this.cell=cell;
			repaint();
			if (calmed)
				break;
			try {Thread.sleep(100);} catch (InterruptedException e) {}
		}
		running=false;
	}
	
	public void update(Graphics g) {
		if (frame==null) 
			super.update(g);
		else {
			Graphics og=offscreen.getGraphics();
			og.setColor(Color.gray);
			for (int y=0;y<cell.length;y++) for (int x=0;x<cell[y].length;x++)
				if (cell[y][x])
					og.fillOval(x*size,y*size,size,size);
				else
					og.clearRect(x*size,y*size,size,size);
			g.drawImage(offscreen,0,0,this);
		}
	}
	
	public void paint(Graphics g) {
		if (frame==null)
			super.paint(g);
		else {
			if (offscreen==null) {
				setCell();
				update(g);
			}
			g.drawImage(offscreen,0,0,this);
		}
	}
	
	public void mouseClicked(MouseEvent evt) {}
	public void mouseEntered(MouseEvent evt) {}
	public void mouseExited(MouseEvent evt) {}
	public void mousePressed(MouseEvent evt) {
		running=false;
		try {
			state=!cell[evt.getY()/size][evt.getX()/size];
		} catch (Exception e) {
		}
		mouseDragged(evt);
	}
	public void mouseReleased(MouseEvent evt) {
		if (!running)
			new Thread(this).start();
	}
	
	public void mouseDragged(MouseEvent evt) {
		try {
			cell[evt.getY()/size][evt.getX()/size]=state;
			repaint();
		} catch (Exception e) {
		}
	}
	public void mouseMoved(MouseEvent evt) {}
	
	public void windowOpened(WindowEvent evt) {}
	public void windowActivated(WindowEvent evt) {}
	public void windowDeactivated(WindowEvent evt) {}
	public void windowIconified(WindowEvent evt) {}
	public void windowDeiconified(WindowEvent evt) {}
	public void windowClosing(WindowEvent evt) {
		frame.dispose();
	}
	public void windowClosed(WindowEvent evt) {}
	
	public void componentResized(ComponentEvent evt) {
		setCell();
	}
	public void componentMoved(ComponentEvent evt) {}
	public void componentShown(ComponentEvent evt) {}
	public void componentHidden(ComponentEvent evt) {}
}