/*Created by Alec Jacobson
 *March 19, 2007
 */
import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.applet.*;
/*three body chaos with one to nine satellites with
 *the "same" starting location
 */
public class ThreeBodyBufferedApplet extends  BufferedApplet //the class that does the "painting"
{   /*all these instances may or may not be used depending
     *on the input of the user*/
  int amount =  10;
  Position[] moon = new Position[amount];
  int count = 0;
  int h,w;
  Thread runner = null;
  boolean clear = true;
  boolean mouse_down = false;
  boolean mouse_dragged = false;
  boolean mouse_click_not_drag = false;
  int curr_mx, curr_my;
  int prev_mx, prev_my;
  boolean initialized = false;
  public void initialize(){      
    for(int j = 0; j<amount;j++)
    {
        moon[j] = new Position();
    }
    initialized = true;
  } 

  public void render(Graphics g) 
    {   
      if(!initialized) initialize();

      if(w!=bounds().width||h!=bounds().height){
        w = bounds().width;
        h = bounds().height;
        Position.sunAPosX = w/4;
        Position.sunBPosX = 3*w/4;
        Position.sunAPosY = h/2;
        Position.sunBPosY = h/2;
      }


      Graphics2D g2 = (Graphics2D) g;
      if(clear){
        g2.setColor(Color.BLACK);
        g2.fillRect(0,0,w,h);
        clear = false;
      }

      if(mouse_down){
        g2.setColor(Color.WHITE);
        g2.drawLine(prev_mx,prev_my,curr_mx,curr_my);
      }
      else{
        if(mouse_click_not_drag){
          g2.setColor(Color.BLACK);
          g2.drawLine(prev_mx,prev_my,curr_mx,curr_my);
          mouse_click_not_drag = false;
        }
        for(int j = 0; j < amount; j++)
        {   
          g2.setColor(moon[j].crayon);
          int[][] box = moon[j].drawPosition();
          g2.drawLine(box[0][0],box[0][1],box[1][0],box[1][1]);
        }
      }
  
  /*This all paints two black dots as the Suns everytime so
   *they stay on top
   */
    int side = Position.side;
    g2.setColor(Color.RED);
    g2.fillOval(Position.sunAPosX-side*2,Position.sunAPosY-side*2, 4*side, 4*side);
    g2.setColor(Color.BLUE);
    g2.fillOval(Position.sunBPosX-side*2,Position.sunBPosY-side*2, 4*side, 4*side);
    g2.setColor(Color.WHITE);
    g2.drawOval(Position.sunAPosX-side*2,Position.sunAPosY-side*2, 4*side, 4*side);
    g2.drawOval(Position.sunBPosX-side*2,Position.sunBPosY-side*2, 4*side, 4*side);
    sleep_amount = 1;
    animating = true;
  }
  
  public boolean mouseDown(Event e, int x, int y) {
    mouse_down = true;
    prev_mx = x;
    prev_my = y;
    curr_mx = x;
    curr_my = y;
    return true;
  }
  public boolean mouseDrag(Event e, int x, int y) {
    mouse_dragged = true;
    curr_mx = x;
    curr_my = y;
    clear = true;
    return true;
  }

  public boolean mouseUp(Event e, int x, int y) {
    mouse_down = false;
    if(mouse_dragged){
      for(int i = 0; i < moon.length; i++){
        moon[i].satPosX = prev_mx+0.0001*Math.random();
        moon[i].satPosY = prev_my+0.0001*Math.random();
        moon[i].satVelX = 10*(prev_mx-x);
        moon[i].satVelY = 10*(prev_my-y);
      }
      clear = true;
    }else{
      mouse_click_not_drag = true;
    }
    mouse_dragged = false;
    return true;
  }
}





class Position //finds position of the satellites
{   double time = 0.00005;
    //most everything is spilt into X & Y componenets
    static int sunAPosX = 225;//suns' positions
    static int sunAPosY = 150;
    static int sunBPosX = 375;
    static int sunBPosY = 150;
    static int side=1;//for size of suns
    double gravCon = .667;//the gravitational constant adjusted for scale
    double sunAMass = 6000000;//the satMass would be 1
    double sunBMass = 6000000;

    int r = (int)(256*Math.random());
    int g = (int)(256*Math.random());
    int b = (int)(256*Math.random());
    Color crayon = new Color(r, g, b);
    double satPosX = 299+0.0001*Math.random();//creating "same" original positions
    double satPosY = 125+0.0001*Math.random();
    double satVelX = 0;// satellite velocity is nothing
    double satVelY = 0;
    private double satToSunAPosX;//distances to suns, don't need to be set to anything now
    private double satToSunAPosY;
    private double satToSunBPosX;
    private double satToSunBPosY;
    private double radToSunA;
    private double radToSunB;
    private double accSunAX;//acceleration due to each sun
    private double accSunAY;
    private double accSunBX;
    private double accSunBY; 
    private double satDispAccX;//displacement of satellite from acc or vel
    private double satDispAccY;
    private double satDispVelX;
    private double satDispVelY;
    private double satDispX;//total displacement
    private double satDispY;
    int[][] box = new int[2][2];//an array for the satellites current displacement, two vectors in a box
    
    public int[][] drawPosition()//gets new position
  {   box[0][0]= (int)satPosX;//first vector is its past location
      box[0][1]= (int)satPosY;
      //the math to find next position
      satToSunAPosX = satPosX - sunAPosX;
      satToSunAPosY = satPosY - sunAPosY;
      satToSunBPosX = satPosX - sunBPosX;
      satToSunBPosY = satPosY - sunBPosY;
      radToSunA = Math.sqrt(satToSunAPosX*satToSunAPosX+satToSunAPosY*satToSunAPosY);
      radToSunB = Math.sqrt(satToSunBPosX*satToSunBPosX+satToSunBPosY*satToSunBPosY);
      accSunAX = satToSunAPosX*(gravCon*sunAMass)/(radToSunA*radToSunA);
      accSunAY = satToSunAPosY*(gravCon*sunAMass)/(radToSunA*radToSunA);
      accSunBX = satToSunBPosX*(gravCon*sunBMass)/(radToSunB*radToSunB);
      accSunBY = satToSunBPosY*(gravCon*sunBMass)/(radToSunB*radToSunB);
      satDispAccX = -1*(accSunAX*time*time+satPosX+accSunBX*time*time+satPosX);
      satDispAccY = -1*(accSunAY*time*time+satPosY+accSunBY*time*time+satPosY);
      satDispVelX = time*satVelX+satPosX;
      satDispVelY = time*satVelY+satPosY;
      satDispX = satDispVelX+satPosX+satDispAccX;
      satDispY = satDispVelY+satPosY+satDispAccY;
      box[1][0]= (int)satPosX;//second vector is new location
      box[1][1]= (int)satPosY;
      satVelX = satDispX/time;
      satVelY = satDispY/time;
      satPosX = satPosX+satDispX;
      satPosY = satPosY+satDispY;
      return box;//box of vectors for drawing line from first to second vectors
  }
}