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

/* Java Pong
	by C. Neustaedter
	August 16, 2001


	the following keys control the game:

	a - move bottom paddle left
	d - move bottom paddle right

	left arrow - move top paddle left
	right arrow - move top paddle right
	
	1 - toggle top paddle to computer controlled
	2 - toggle bottom paddle to computer controlled

	+ speed up ball
	-  slow down ball

*/

public class PongGame extends Applet implements Runnable
{
	Thread t;
	private Image bufferImage;
	private Graphics buffer;
	private int width, height;

	// fields for both paddles
	private int p1x, p1y, p2x, p2y, pwidth, pheight, pspeed, p1score, p2score;
	private Color p1color, p2color;	
	
	private int p1move,  p2move; 

	// fields for the ball
	private int ballx, bally, ballspeedx, ballspeedy, ballsize;
	private Color ballcolor;

	private String message; 

	private boolean pause;  // true if the game is paused, false if the game is not paused
	private boolean ai1;       // if player 1 is controlled by the computer
	private boolean ai2;       // if player 2 is controlled by the computer

	private Font myFont;

	public void init()
	{
		myFont = new Font("Helvetica", Font.BOLD, 24);
		setFont(myFont);
		pause =true;
		ai1 = false;  // player 1 not controlled by computer
		ai2 = false;  // player 2 not controlled by computer

		t=new Thread(this);
		t.start();
		width=size().width;
		height=size().height;
		bufferImage = createImage(width, height);
		buffer=bufferImage.getGraphics();

		p1x=p2x=width/2;
		p1y=30;
		p2y=height-30;
		pwidth=75;
		pheight=10;

		pspeed=4;		
		p1move = 0;		
		p2move = 0;		
		message = "Click to Start";

		p1score=0;
		p2score=0;
		p1color=Color.yellow;
		p2color=Color.red;

		ballx=width/2;
		bally = height/2;
		ballspeedx=ballspeedy=2;
		ballsize=10;
		ballcolor=Color.blue;

	}

	public void run()
	{
		while(true)
		{
			repaint();
			try{
				t.sleep(5);
			}catch(InterruptedException e) { ; }


		if (!pause)
		{

			// --------PADDLE MOVEMENT
			
			if (!ai1)  // if not computer controlled
				p1x += p1move;

			else  // computer controlled
				p1x = ballx-30;

			if (!ai2)  // if not computer controlled
				p2x += p2move;

			else	// computer controlled
				p2x = ballx-30;


			// --------KEEP PADDLE ON THE SCREEN

			if (p1x < 0)   // gone off the left side
				p1x = 0;
			if (p1x+pwidth > width) // gone off the right side
				p1x = width - pwidth;

			if (p2x < 0)   // gone off the left side
				p2x = 0;
			if (p2x+pwidth > width) // gone off the right side
				p2x = width - pwidth;

			// -------BALL MOVEMENT ----------------

			ballx += ballspeedx;
			bally += ballspeedy;


			if (ballx+ballsize > width)  // ball hits the right wall
				ballspeedx *= -1;  // reverse the x direction

			if (ballx < 0)  // ball hits the left wall
				ballspeedx *= -1;

			if (bally < 0) // ball hits top wall, goal for p2
			{
				// move ball back to the middle
				ballx=width/2;
				bally=height/2;

				ballspeedy *=-1;	// reverse direction
				p2score++;  // p2 gets a point
			}

			if (bally > height) // ball hits bottom wall, goal for p1
			{
				// move ball back to the middle
				ballx=width/2;
				bally=height/2;

				p1score+=1;
				ballspeedy *=-1;	// reverse direction						
			}

			if ((ballx > p2x) && (ballx < p2x + pwidth) && (bally+ballsize >p2y)
				&& (bally < p2y +pheight))
			// ball hits bottom paddle, confusing
				ballspeedy *= -1;

			if ((ballx > p1x) && (ballx < p1x + pwidth) && (bally < p1y + pheight) 
				&& (bally > p1y))
			// ball hits top paddle, still confusing
				ballspeedy *= -1;
		}

		}


	}

	public void paint (Graphics g)
	{
		buffer.setColor(Color.black);
		buffer.fillRect(0,0,width,height);
		
		buffer.setColor(p1color);
		buffer.fillRect(p1x, p1y, pwidth, pheight);		//draw paddle1 (p1)

		buffer.setColor(p2color);
		buffer.fillRect(p2x, p2y, pwidth, pheight);		//draw paddle2 (p2)

		buffer.setColor(ballcolor);
		buffer.fillOval(ballx, bally, ballsize, ballsize);		// draw ball

		buffer.setColor(Color.red);
		buffer.drawString(Integer.toString(p2score), width-30, height/2);	
		// draw p2 score

		buffer.setColor(Color.yellow);
		buffer.drawString( Integer.toString(p1score), 20, height/2);
		// draw p1 score

		buffer.setColor(Color.green);
		buffer.drawString(message, 130, height /2);  

		g.drawImage(bufferImage, 0, 0, this);
		// copy buffer to applet

	}	

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

	public boolean keyDown(Event e, int key)
	{
		if (key == 1006)  		// left arrow key
			p1move = pspeed * -1;
		if (key == 1007) 		// right arrow key
			p1move = pspeed;

		if (key == 97)     		// a key
			p2move=pspeed * -1;

		if (key == 100)
			p2move= pspeed;	// d key

		if (key == 112)  // p key
			if (pause == true)
				pause = false;
			else	
				pause = true;

		if (key == 49) // 1 key, computer control
			if (ai1 == true)
				ai1 = false;
			else
				ai1 = true;

		if (key == 50) // 2 key, computer control
			if (ai2 == true)
				ai2 = false;
			else
				ai2 = true;

		if (key == 61) // +/= key
		{
			ballspeedx*=2;
			ballspeedy*=2;
		}

		if (key == 45) // - key
		{
			// reset the speed
			if (ballspeedx / 2 >= 2)
			{
				ballspeedx/=2;
				ballspeedy/=2;
			}

		}

				

		return true;
	}

	public boolean keyUp(Event e, int key)
	{
		if (key == 1006)  		// left arrow key
			p1move = 0;
		if (key == 1007) 		// right arrow key
			p1move = 0;

		if (key == 97)     		// a key
			p2move=0;

		if (key == 100)
			p2move= 0;	// d key
		return true;
	}
	public boolean lostFocus(Event e, Object obj)
	{
		message = "Click to Start";
		pause = true;
		return super.lostFocus(e, obj);
	}

	public boolean gotFocus(Event e, Object obj)
	{
		message = "";
		pause = false;
		return super.gotFocus(e, obj);
	}
}