// This is part of the program used in lab exercise 02
// This part does not include the code generated by Netbeans
// Please read the slides and watch the video for explanation
//
// This file is for reference only.  It is your responsibility
// to write a functional program.
// 
// Yung-Hsiang Lu, ECE Purdue
//
public class BallPanel extends JPanel {

    public BallPanel(int width, int height,
		     JLabel location, JLabel direction) {
        bpWidth = width;
        bpHeight = height;
        // ball's initial location is near the center
        bpBallX = width / 2;
        bpBallY = height / 2;
        do {
            bpBallVX = Math.random();
        } while (bpBallVX < 0.1);
        bpBallVY = Math.sqrt(1 - bpBallVX * bpBallVX);
        bpPaddleHeight = height / 7;
        bpPaddleTop = bpPaddleHeight;
        setSize(width, height);
        // System.out.println("width and height " + width + " " + height);
        bpLocationLabel = location;
        bpDirectionLabel = direction;
    }

    public void setPaddle(int top) {
        if (top < bpPaddleTop) {
            bpPaddleTop--;
        }
        if (top > bpPaddleTop) {
            bpPaddleTop++;
        }
        if (bpPaddleTop < 0) {
            bpPaddleTop = 0;
        }
        if (bpPaddleTop >= (bpHeight - bpPaddleHeight)) {
            bpPaddleTop = bpHeight - bpPaddleHeight;
        }
        repaint(); // draw the new paddle's location
    }

    public void paintComponent(Graphics gfx) {
        // System.out.println("paintComponent");
        // update labels
        bpLocationLabel.setText("location " + (int) bpBallX + " , " + (int) bpBallY);
        int vx = (int) (bpBallVX * 1000);
        int vy = (int) (bpBallVY * 1000);
        bpDirectionLabel.setText("direction " + vx + " , " + vy);
        // erase everything
        gfx.setColor(bpBackgroundColor);
        gfx.fillRect(0, 0, bpWidth - 1, bpHeight - 1);
        // draw ball
        gfx.setColor(bpBallColor);
        gfx.fillOval((int) bpBallX, (int) bpBallY,
		     bpBallSize, bpBallSize);
        // draw paddle
        gfx.setColor(bpPaddleColor);
        gfx.fillRect(0, bpPaddleTop,
		     bpPaddleWidth, bpPaddleHeight);
        // update ball's location
        bpBallX += bpBallVX;
        bpBallY += bpBallVY;
        // check whether the ball hits a wall
        if (bpBallX < 0) {
            bpBallX = 0;
            bpBallVX = -bpBallVX;
        }
        if (bpBallX > (bpWidth - bpBallSize)) {
            bpBallX = bpWidth - bpBallSize;
            bpBallVX = -bpBallVX;
        }
        if (bpBallY < 0) {
            bpBallY = 0;
            bpBallVY = -bpBallVY;
        }
        if (bpBallY > (bpHeight - bpBallSize)) {
            bpBallY = bpHeight - bpBallSize;
            bpBallVY = -bpBallVY;
        }
    }
    // all attributes start with "bp" (BallPanel)
    private int bpWidth;
    private int bpHeight;
    private Color bpBackgroundColor = Color.white;
    private Color bpBallColor = Color.black;
    private Color bpPaddleColor = Color.green;
    private int bpBallSize = 10;
    private double bpBallX;
    private double bpBallY;
    private double bpBallVX; // (VX, VY) is a unit vector
    private double bpBallVY;
    private int bpPaddleHeight;
    private int bpPaddleTop;
    private int bpPaddleWidth = 5;
    private JLabel bpLocationLabel;
    private JLabel bpDirectionLabel;
}    

class UpdatePanelThread extends Thread {

    public UpdatePanelThread(BallPanel bp) {
        uptPanel = bp;
    }

    public void setDelay(int delay) {
        uptDelay = delay; // does not have to be sychronized
    }

    public void run() {
        while (uptDelay > 0) {
            uptPanel.repaint();
            try {
                sleep(uptDelay);
            } catch (InterruptedException ie) {
		// do nothing here
            }
        }
    }
    BallPanel uptPanel;
    int uptDelay; // negative to stop updating
}

public class NewJFrame extends javax.swing.JFrame {

    /** Creates new form NewJFrame */
    public NewJFrame() {
        initComponents();
        njfBP = new BallPanel(jPanel1.getWidth(), jPanel1.getHeight(),
			      locationLabel, directionLabel);
        jPanel1.add(njfBP);
        njfThread = new UpdatePanelThread(njfBP);
        int sliderValue = speedSlider.getValue();
        speedLabel.setText("Speed " + sliderValue);
        njfThread.setDelay(speedSlider.getMaximum() + 1 - sliderValue);
        njfThread.start();
    }
    private void initComponents() {
	int sliderValue = speedSlider.getValue();
        speedLabel.setText("Speed " + sliderValue);
        njfThread.setDelay(speedSlider.getMaximum() + 1 - sliderValue);
    }

    private void speedSliderStateChanged(javax.swing.event.ChangeEvent evt) {
        int sliderValue = speedSlider.getValue();
        speedLabel.setText("Speed " + sliderValue);
        njfThread.setDelay(speedSlider.getMaximum() + 1 - sliderValue);
    }

    BallPanel njfBP;
    UpdatePanelThread njfThread;
}