// starter file for Solar System assignment
// Kees Huizing
// 16 October 2012

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class SolarSystem extends JPanel implements ActionListener, AdjustmentListener, ChangeListener
{
    double timestep = 0.5; // simulated time that passes between frames; in days
    int delay = 20;       // interval between frames; in ms
    Timer timer;
    
    CelestialBodyExtra sun; // the center around which everything revolves

    // GUI components
    JFrame frame;        
    JPanel buttonPanel;  // holds buttons
    JScrollBar jscb;     // determines animations speed
    JSlider speedSlider;
    JButton startButton; // starts animation
    JButton stopButton;  // stops animation

    public static final double PI2 = 2 * Math.PI;
 
    public void paintComponent(Graphics g) {
        super.paintComponent(g);    // background
        int x = getWidth() / 2;     // draw in middle of panel
        int y = getHeight() / 2;
        sun.draw(g, x, y);          // from here all other bodies are drawn
    }
    
    public SolarSystem() {
        this.buildGUI();
        this.buildBodies();
    }
    
    // make planets and satellites and connect them
    void buildBodies( ) {
        CelestialBody mercury = new CelestialBody(/*fill in*/);
               
        CelestialBody[] sunSats = {mercury};
        //this.sun = new CelestialBodyExtra(sunSats, /* fill in*/);      
    }    
    
    void buildGUI() {
        this.frame = new JFrame("SolarSystem");
        this.frame.add(this, BorderLayout.CENTER);

        this.speedSlider = new JSlider();
        this.frame.add(this.speedSlider, BorderLayout.SOUTH);
        this.speedSlider.addChangeListener(this);
        
        this.buttonPanel = new JPanel();
        this.frame.add(buttonPanel, BorderLayout.NORTH);
        this.startButton = new JButton("Start");
        this.startButton.addActionListener(this);
        this.buttonPanel.add(startButton);
        this.stopButton = new JButton("Stop");
        this.stopButton.addActionListener(this);
        this.buttonPanel.add(stopButton);

        this.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.frame.setSize(600, 500);
        this.frame.setVisible(true);   
    }

    // sets timer interval, and with that the speed of the planets
    // 1 timer step moves everything the equivalent of timestep days
    public void setDelay(int delay) {
        this.timer.setDelay(delay);
    }


    public void actionPerformed(ActionEvent e) {
       //
    }

    public void adjustmentValueChanged(AdjustmentEvent e) {
        System.out.println( e.getValue() );
    }
    
    // default slider runs from 0 to 100
    public void stateChanged(ChangeEvent e) {
        // get the position of the slider
        int position = this.speedSlider.getValue();
        // update timestep
    }
    
    public static void main(String[] a) {
       new SolarSystem();
    }
}

// Simple celestial body, without satellites
class CelestialBody {
    //instance variables: size etc.
    
    // constructor

    // draw celestial body and trajectory
    // x, y central pivot point (position "sun")
    void draw(Graphics g, double x, double y) {
        // draw trajectory
        g.setColor( Color.gray );
          // etc.
        // calculate position 
        // draw body
    }
    
    // move the body for a distance corresponding to time t
    void step(double t) {
        // update angle
    }
}

// Using inheritance a simple celestial body is extended with an array of satellities
// NB Satellites are themselves also celestial bodies, so here the subclass 
// extends the superclass with an array of elements that are superclass objects. 

class CelestialBodyExtra extends CelestialBody
{
    CelestialBody[] satellites; // or use an ArrayList

    /*
    public CelestialBodyExtra(...) {
        super(...);
        // set satellites
    }
    */

    void draw(Graphics g, double x, double y) {
        // draw CelestialBody
        super.draw(g, x, y);
        // draw satellites
        // fill in
         // calculate own position
         // call draw on satellites
    }

    void step(double t) {
        // similar to draw
    }
}