import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;						// for JSlider events (ChangeListener)
import java.util.Random;

public class BouncingBallsWithJSliders			// this class is the same as BouncingBallsWithRebound but adds JSliders to control the number of balls and speed
{
	private static int number=25, delay=30;		// the number of balls and the Timer's delay will be determined by JSliders in the SliderPanel and this will affect how GraphicsPanel works
	private static GraphicsPanel gp;			// declared here so that SliderPanel can reference gp

	public static void main(String[] args)
	{
		JFrame frame=new JFrame();
		frame.setSize(540,540);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		SliderPanel sp=new SliderPanel();		
		gp=new GraphicsPanel();
		JPanel p1=new JPanel(new BorderLayout());			// add two JPanels now, put the SliderPanel to the right of the GraphicsPanel
		p1.add(gp,BorderLayout.CENTER);
		p1.add(sp,BorderLayout.EAST);
		frame.add(p1);
		frame.setVisible(true);
	}
	
	public static class SliderPanel extends JPanel implements ChangeListener	// will implement two JSliders to control number of balls and speed of animation
	{
		private JSlider numberSlider, speedSlider;			// our two JSliders
		
		public SliderPanel()
		{
			numberSlider=new JSlider(JSlider.VERTICAL,1,50,25);		// both JSliders will be vertical, number of balls ranges from 1-50 starting at 25
			speedSlider=new JSlider(JSlider.VERTICAL,0,20,11);		// speed ranges from 0 to 20 starting at 11, but we will take this int and do 3*(21-int), so for instance
			numberSlider.addChangeListener(this);					//     starting at all gives us a delay of 3*(21-11) = 30
			speedSlider.addChangeListener(this);				// both JSliders ChangeListeners will be handled in this class
			add(numberSlider);										// add both  JSliders to this JPanel
			add(speedSlider);
		}
		
		public void stateChanged(ChangeEvent e)						// A JSlider was moved
		{
			if(e.getSource()==numberSlider) 						// if numberSlider was moved, get its new position, subtract the current number of balls from this 
				gp.resetNumber(numberSlider.getValue()-number);		//    and send this change to gp's resetNumber method
			else if(e.getSource()==speedSlider)						// otherwise the speedSlider was moved
			{
				delay=3*(21-speedSlider.getValue());				// reset delay accordinatly
				gp.resetSpeed();									// and call gp's resetSpeed which resets the Timer's delay
			}
		}
	}
	public static class GraphicsPanel extends JPanel implements ActionListener
	{
		private BouncingBall[] balls;
		private Random generator;
		private Timer t;
		
		public GraphicsPanel()
		{
			generator=new Random();
			balls=new BouncingBall[50];								// change this to 50 to allow for more balls to be added, we start with number=25
			for(int i=0;i<number;i++)
				balls[i]=new BouncingBall(500,500,generator);
			t=new Timer(delay,this);
			t.start();
		}
		
		public void actionPerformed(ActionEvent e)
		{
			for(int i=0;i<number;i++)
			{
				balls[i].move();							 	
				for(int j=0;j<number;j++)						
					if(i!=j&&balls[i].collide(balls[j]))		
					{
						balls[i].rebound();						
						balls[j].rebound();						
					}
			}
			repaint();
		}
		
		public void paintComponent(Graphics g)
		{
			super.paintComponent(g);
			g.setColor(Color.white);
			g.fillRect(0,0,540,540);
			for(int i=0;i<number;i++)
				balls[i].draw(g);
		}
		
		public void resetSpeed()							// new method, resets the Timer with the new delay
		{
			t.stop();
			t.setDelay(delay);
			t.start();
		}
		
		public void resetNumber(int temp)					// new method, if the number has increased from what it was, add new balls
		{
			if(temp>0)
				for(int i=0;i<temp;i++)						// number of new balls will be slider's new position - current number, which is passed in as temp
					balls[i+number]=new BouncingBall(500,500,generator);	
			number+=temp;									// whether temp is positive or not, reset number based on the value of temp (if temp is negative, this reduces
		}													//	  number so that the next actionPerformed will move fewer balls and paintComponent will draw fewer balls)
	}
}