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

public class DendriticGrowth
extends Applet implements WindowListener,MouseListener,MouseMotionListener,Runnable,ActionListener,ComponentListener {
	final static int space=0,north=1,south=2,east=3,west=4,settled=5;
	final static int size=6;
	int[][] cell;
	Button sprinkle,shake,erase;
	Image offscreen;
	Frame frame;
	boolean running=false;
	
	static public void main(String[] args) {
		main();
	}
	
	public void init() {
		main();
	}
	
	static void main() {
		DendriticGrowth dg=new DendriticGrowth();
		dg.frame=new Frame("Dendritic Growth");
		dg.frame.setSize(240,240);
		Panel panel=new Panel(new GridLayout());
		((Button)panel.add(dg.sprinkle=new Button("まく"))).addActionListener(dg);
		((Button)panel.add(dg.shake=new Button("ふる"))).addActionListener(dg);
		((Button)panel.add(dg.erase=new Button("けす"))).addActionListener(dg);
		dg.frame.add(panel,BorderLayout.NORTH);
		dg.frame.addWindowListener(dg);
		dg.addMouseListener(dg);
		dg.addMouseMotionListener(dg);
		dg.addComponentListener(dg);
		dg.frame.add(dg,BorderLayout.CENTER);
		dg.frame.show();
	}
	
	public void setCell() {
		cell=new int[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]=space;
		offscreen=createImage(getSize().width,getSize().height);
	}
	
	public void actionPerformed(ActionEvent evt) {
		if (evt.getSource()==sprinkle)
			for (int y=0;y<cell.length;y++) for (int x=0;x<cell[y].length;x++)
				if (cell[y][x]==space && Math.random()<0.1)
					cell[y][x]=random();
		if (evt.getSource()==shake)
			if (running)
				running=false;
			else
				new Thread(this).start();
		if (evt.getSource()==erase)
			setCell();
		repaint();
	}
	
	public void run() {
		running=true;
		while (running) {
			boolean allsettled=true;
			int Y=this.cell.length;
			int[][] cell=new int[Y][];
			for (int y=0;y<Y;y++) {
				int X=this.cell[y].length;
				cell[y]=new int[X];
				for (int x=0;x<X;x++) {
					if (this.cell[y][x]==space)
						if ( this.cell[(y+1)%Y][x]==north || this.cell[(y-1+Y)%Y][x]==south
						 || this.cell[y][(x-1+X)%X]==east || this.cell[y][(x+1)%X]==west)
							if (this.cell[(y+1)%Y][x]==settled || this.cell[(y-1+Y)%Y][x]==settled
							|| this.cell[y][(x-1+X)%X]==settled || this.cell[y][(x+1)%X]==settled)
								cell[y][x]=settled;
							else
						 		cell[y][x]=random();
						else
							cell[y][x]=space;
					else
						if (this.cell[y][x]==settled
						|| (this.cell[(y+1)%Y][x]==settled && this.cell[(y-1+Y)%Y][x]==settled
						&& this.cell[y][(x-1+X)%X]==settled && this.cell[y][(x+1)%X]==settled))
							cell[y][x]=settled;
						else 
							if (
								(this.cell[y][x]==north
								&& this.cell[(y-1+Y)%Y][x]==space)
								|| (this.cell[y][x]==south
								&& this.cell[(y+1)%Y][x]==space
								&& this.cell[(y+2)%Y][x]!=north)
								|| (this.cell[y][x]==west
								&& this.cell[y][(x-1+X)%X]==space
								&& this.cell[(y+1)%Y][(x-1+X)%X]!=north
								&& this.cell[(y-1+Y)%Y][(x-1+X)%X]!=south)
								|| (this.cell[y][x]==east
								&& this.cell[y][(x+1)%X]==space
								&& this.cell[(y+1)%Y][(x+1)%X]!=north
								&& this.cell[(y-1+Y)%Y][(x+1)%X]!=south
								&& this.cell[y][(x+2)%X]!=west)
							)
								cell[y][x]=space;
							else
								cell[y][x]=random();
					if (cell[y][x]!=space && cell[y][x]!=settled)
						allsettled=false;
				}
			}
			this.cell=cell;
			repaint();
			if (allsettled) break;
			try {Thread.sleep(30);} catch (InterruptedException e) {}
		}
		running=false;
	}
	
	public void update(Graphics g) {
		if (frame==null) 
			super.update(g);
		else {
			Graphics og=offscreen.getGraphics();
			for (int y=0;y<cell.length;y++) for (int x=0;x<cell[y].length;x++) {
				if (cell[y][x]==space)
					og.setColor(Color.white);
				else if (cell[y][x]==settled)
					og.setColor(Color.black);
				else
					og.setColor(Color.gray);
				og.fillOval(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);
		}
	}
	
	int random() {
		switch ((int)(Math.random()*4)) {
			case 0: return north;
			case 1: return south;
			case 2: return east;
			case 3: return west;
			default: return space;
		}
	}
	
	public void mouseClicked(MouseEvent evt) {}
	public void mouseEntered(MouseEvent evt) {}
	public void mouseExited(MouseEvent evt) {}
	public void mousePressed(MouseEvent evt) {
		try {
			cell[evt.getY()/size][evt.getX()/size]=settled;
			repaint();
		} catch (Exception e) {
		}
	}
	public void mouseReleased(MouseEvent evt) {}
	
	public void mouseDragged(MouseEvent evt) {
		mousePressed(evt);
	}
	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) {}
}