class ParticleController
{
  
  LinkedList particles;
  int jitterRadius = 5;
  void addParticles( int amt){
   for(int i = 0; i < amt; i++){
    addRandomParticle();
   } 
  }
  void addParticles(int amt, int x, int y,Vec2D v){
   for (int i = 0; i < amt; i++){
      addParticle(jitter(x),jitter(y),v); 
   } 
  }
  
  int jitter(int loc){
    int jit = int(random(-1*jitterRadius,jitterRadius));
    return loc + jit;
  }
  void addParticle(int x, int y){
    particles.add(new Particle(x,y));
  }
  void addParticle(int xi, int yi,Vec2D v){
    particles.add(new Particle(xi,yi,v));
  }
  void addRandomParticle(){
    int x = int(random(0,width));
    int y = int(random(0,height));
    addParticle(x,y);
  }
  
  ParticleController(){
    particles = new LinkedList();
  }
  void update(){
    repulseParticles();
    for(Iterator it = particles.iterator(); it.hasNext();){
      Particle p = (Particle)it.next();
      
      p.update();
      
      if(p.isDead){
       it.remove(); 
      }
    }
  }
  void repulseParticles(){
   for(Iterator i1 = particles.iterator(); i1.hasNext();){
    
    Particle p1 = (Particle)i1.next();
    int i = particles.indexOf(p1) +1;
    int s= particles.size();
    if ( i == s){
      return;
    }
    for(Iterator i2 = particles.subList(i,particles.size()-1).iterator(); i2.hasNext();){
      Particle p2 = (Particle)i2.next();
      Vec2D dir = p1.sub(p2);
      float distSqrd = p1.distanceToSquared(p2);
      if(distSqrd > 0.0){
        dir.normalize();
        float F = 1.0/distSqrd;
        p1.acceleration.addSelf( dir.scale(F /p1.mass));
        p2.acceleration.subSelf(dir.scale(F /p2.mass));
      }
      
    }
    
    
   } 
  }
  
 
 void draw(){
    for(Iterator it = particles.iterator(); it.hasNext();){
      Particle p = (Particle)it.next();
      
      p.draw();
    }
 } 
}