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

public class billy extends Applet implements Runnable{
	Thread moveThread;
	private static final int MOVEPAUSE = 100;
	public boolean myGo = false;
	public boolean inTowR = false;
	public boolean inTowW = false;
	public boolean quePull = false;
	public boolean inHole = false;
	public boolean pfad = false;
	public Image offScreenImage;
	public int it = 0;
	public int theW = 420;				// width of table
	public int theH = 350;				// height of table
	public int xmin = 40;
	public int xmax = theW - xmin;
	public int ymin = 40;
	public int ymax = theH - ymin;
	public int r = 12;					// ball radius
	public int d = 2*r+1;
	public int xQ;
	public int yQ;
	public double xW = 100;				// initial ball positions
	public double yW = 50;
	public double xR = 250;
	public double yR = 120;
	public double vxW = 10;				// "velocities"
	public double vyW =  5;
	public double vxR =  0;
	public double vyR =  0;
	public int dxW;
	public int dyW;
	public int dxR;
	public int dyR;
	public int[] holeX = {xmin, xmax, xmin, xmax,(xmin+xmax)/2,(xmin+xmax)/2};
	public int[] holeY = {ymin, ymin, ymax, ymax,ymin-5,       ymax+5};
	
	public void start()  {
		if(myGo) {
			if(moveThread == null){
				moveThread = new Thread(this);
				moveThread.start();
			}
		}
	}
	
	public void stop()  {
		if(moveThread != null){
			moveThread.stop();
			try {
				moveThread.join();
			}
			catch (InterruptedException e) { }
		}
		moveThread=null;
	}
		
	public void run() {
		while (true){
			try {
				moveThread.sleep(MOVEPAUSE);
			}catch(InterruptedException e) {
			}
			repaint();
		}
	}


	public void init() {
		super.init();
		offScreenImage = createImage(500,350);

		//{{INIT_CONTROLS
		setLayout(null);
		resize(500,350);
		setBackground(new Color(16777215));
		//}}
		
		repaint();
	}

	//{{DECLARE_CONTROLS
	//}}

	public void update(Graphics g){
		Graphics offg = offScreenImage.getGraphics();
		paint(offg);
		g.drawImage(offScreenImage, 0, 0, this);
	}
		
	public void paint(Graphics g){
		if (!pfad) drawTable(g);
		if (it == 0) {
			drawTable(g);
			drawButtons(g);
			if (quePull) {
				g.setColor(Color.yellow);
				g.drawLine((int)xW+1,(int)yW,xQ+1,yQ);
				g.drawLine((int)xW-1,(int)yW,xQ-1,yQ);
				g.drawLine((int)xW,(int)yW+1,xQ,yQ+1);
				g.drawLine((int)xW,(int)yW-1,xQ,yQ-1);
				g.drawLine((int)xW,(int)yW,xQ,yQ);
			}
			it++;
		}
		if (myGo && it < 400 && it > 0) {           // moving
			xW = xW + vxW;
			yW = yW + vyW;
			xR = xR + vxR;
			yR = yR + vyR;
			if ( (xR > xmax && vxR > 0) || (xR < xmin && vxR < 0)) {
				xR = xR - vxR; 
				vxR = -vxR;
			}
			if ( (yR > ymax && vyR > 0) || (yR < ymin && vyR < 0)) {
				yR = yR - vyR;
				vyR = -vyR;
			}
			if ( (xW > xmax && vxW > 0) || (xW < xmin && vxW < 0)) {
				xW = xW - vxW;
				vxW = -vxW;
			}
			if ( (yW > ymax && vyW > 0) || (yW < ymin && vyW < 0)) {
				yW = yW - vyW;
				vyW = -vyW;
			}
			collideWithWall((int)xW,(int)yW);
			collideWithWall((int)xR,(int)yR);
			if (inHole) {
				g.setColor(Color.red);
				g.drawString("Ball im Loch",200,200);
				this.stop();
			}
			// collide the balls
			double distX = xW - xR;
			double distY = yW - yR;
			double distR = Math.sqrt(distX*distX + distY*distY);
			double relPR = distX*(vxW-vxR) + distY*(vyW-vyR);
			if (distR < d && relPR < 0) {  // collision
				double vxcm = 0.5*(vxW+vxR);
				double vycm = 0.5*(vyW+vyR);
				double vDotrW = (distX*(vxW-vxcm) + distY*(vyW-vycm)) / (distR*distR);
				double vrxW = distX*vDotrW;
				double vryW = distY*vDotrW;
				//System.out.println("Collision, v^2="+(vxR*vxR+vyR*vyR+vxW*vxW+vyW*vyW));
				vxR = vxR + 2*vrxW;
				vyR = vyR + 2*vryW;
				vxW = vxW - 2*vrxW;
				vyW = vyW - 2*vryW;
				//System.out.println("    after, v^2="+(vxR*vxR+vyR*vyR+vxW*vxW+vyW*vyW));
			}
			it++;
		}
		g.setColor(Color.white);
		if (!pfad) {
			g.fillOval((int)xW-r,(int)yW-r,d,d);
		} else {
			g.fillOval((int)xW-1,(int)yW-1,3,3);
		}
		g.setColor(Color.red);
		if (!pfad) {
			g.fillOval((int)xR-r,(int)yR-r,d,d);
		} else {
			g.fillOval((int)xR-1,(int)yR-1,3,3);
		}
		if (it == 400) {
			myGo = false;
			this.stop();
		}
		// slowing down the balls
		double vvR = Math.sqrt(vxR*vxR + vyR*vyR);
		double fR = Math.max(0,(vvR-0.1)/vvR);
		vxR = vxR*fR;
		vyR = vyR*fR;
		double vvW = Math.sqrt(vxW*vxW + vyW*vyW);
		double fW = Math.max(0,(vvW-0.1)/vvW);
		vxW = vxW*fW;
		vyW = vyW*fW;
		
	}

	public void collideWithWall(int x, int y){
		for (int i=0; i<6; i++){
			if ((int)(Math.abs(x-holeX[i])) < 10 && (int)(Math.abs(y-holeY[i])) < 10){
				inHole = true;
				myGo = false;
				this.stop();
			}
		}
	}
	
	public void drawButtons(Graphics g){
		g.setColor(Color.white);
		g.fillRect(theW,0,500-theW,350);
		g.setColor(Color.lightGray);
		g.fillRect(434,314,62,32);
		g.fill3DRect(435,315,60,30,true);          // stop button
		g.fillRect(434,4,62,32);
		g.fill3DRect(435,5,60,30,true);            // start button
		g.setColor(Color.blue);
		g.setFont(new Font("TimesRoman", Font.PLAIN, 18));
		g.drawString("Stop",445,333);
		g.drawString("Start",445,23);
	}

	public void drawTable(Graphics g){
		g.setColor(Color.green);
		g.fillRect(0,0,theW,theH);
		Color newCol = new Color(0,120,0);
		g.setColor(newCol);
		g.fillRect(xmin/2,ymin/2,theW-xmin,theH-ymin);
		newCol = new Color(0,57,0);
		g.setColor(newCol);
		g.fillRect(xmin-r,ymin-r,theW-2*xmin+2*r,theH-2*ymin+2*r);
		g.setColor(Color.black);							// holes
		g.fillOval(xmin/2-10,ymin/2-10,40,40);
		g.fillOval(xmin/2-10,theH-ymin/2-30,40,40);
		g.fillOval(theW-xmin/2-30,ymin/2-10,40,40);
		g.fillOval(theW-xmin/2-30,theH-ymin/2-30,40,40);
		g.fillOval(theW/2-20,ymin/2-15,40,40);
		g.fillOval(theW/2-20,theH-ymin/2-25,40,40);
	}
	

	public boolean handleEvent(Event evt){
		if (evt.target == this && evt.id == Event.MOUSE_DOWN) {
			osc_MouseDown(evt);
			return true;
		}
		if (evt.target == this && evt.id == Event.MOUSE_DRAG) {
			osc_MouseDrag(evt);
			return true;
		}
		if (evt.target == this && evt.id == Event.MOUSE_UP) {
			osc_MouseUp(evt);
			return true;
		}
		if (evt.id == Event.KEY_PRESS) {
			String thePressedKey = ""+(char)evt.key;
			if (thePressedKey.equalsIgnoreCase("p")) {
				pfad = !pfad;
	            repaint();
			}
		}
		return false;
	}
	
	void osc_MouseDrag(Event event) {
		if (inTowR) {
			xR = (int)(Math.min(xmax,Math.max(xmin,event.x - dxR)));
			yR = (int)(Math.min(ymax,Math.max(ymin,event.y - dyR)));
			it = 0;
			repaint();
		}
		if (inTowW) {
			xW = (Math.min(xmax,Math.max(xmin,event.x - dxW)));
			yW = (Math.min(ymax,Math.max(ymin,event.y - dyW)));
			it = 0;
			repaint();
		}
		if (quePull) {
			xQ = event.x;
			yQ = event.y;
			vxW = (double)(xW - xQ) / 10;
			vyW = (double)(yW - yQ) / 10;
			it = 0;
			repaint();
		}
	}

	void osc_MouseDown(Event event) {
		vxR = 0;
		vyR = 0;
		quePull = false;
		inHole = false;
		if (event.x > 425 && event.y > 300) {
			myGo = false;
			this.stop();
			return;
		}
		if (event.x > 425 && event.y < 50) {
			myGo = true;
			this.start();
			return;
		}
		dyR = event.y - (int)yR;
		dxR = event.x - (int)xR;
		inTowR = ((int)Math.abs(dxR) < 10 && (int)Math.abs(dyR) < 10);
		dyW = event.y - (int)yW;
		dxW = event.x - (int)xW;
		inTowW = ((int)Math.abs(dxW) < 10 && (int)Math.abs(dyW) < 10);
		if (inTowR || inTowW) return;
		// now we need to deal with the que
		quePull = true;
		xQ = event.x;
		yQ = event.y;
		repaint();
	}

	void osc_MouseUp(Event event) {
		inTowR = false;
		inTowW = false;
		quePull = false;
		inHole = false;
	}
}