//class to describe a single fish object

class Fish {
  PVector location;
  PVector velocity;
  PVector acceleration;
  float life;
  float angle;
  float angleSpeed;
  float angleFish;

  float mass =1;

  //float angle;//=0.0; //have to declare this variable because it is essentially a property of the fish 
  //dont initiate here yet..technically it is better to initiate inside constructor
  //float angleSpeed;//=random(0.1,1); 


  Fish (PVector l) {
    location = l.get();
    velocity = new PVector (random(-1, 3), random(-2, 2));
    acceleration = new PVector (0.02, -0.02);
    //float angleFish;
    angle=0;
    angleSpeed = random(0.1, 0.3);
    life = 255;
    angleFish=30;
  }

  void run() {
    update();
    display();
  }

  void applyForce(PVector hand) {
    PVector f=hand.get();
    f.div(mass);
    acceleration.add(f);
  }





  void update() {
    velocity.add(acceleration);
    location.add(velocity);
    //acceleration.mult(0);
    life-=0.9;
  }


  void display() {

    angle=angle+angleSpeed;
    float offsetHead;
    float offsetTail;

    offsetHead=sin(angle+PI)*3;
    offsetTail=sin(angle+PI/2)*5;

    //fish body outline
    fill(245, 187, 111, life);
    stroke(245, 187, 111, life);
    pushMatrix();
    translate(location.x, location.y);

    //float rotateAngle = atan2(-yspeed,xspeed);

    //!!!!!
    angleFish=atan2(velocity.y, velocity.x);
    //!!!

    rotate((angleFish)+HALF_PI);
    scale(0.65);
    beginShape();
    vertex((offsetTail), -10);
    bezierVertex((-30+offsetHead), -80, (30+offsetHead), -80, (offsetTail), -10);
    endShape();
    popMatrix();
  }

  boolean dead() {
    if (life <= 0.0) {
      return true;
    } 
    else {
      return false;
    }
  }
}

//mouse pressed will make fish swim to the left


ArrayList<Fish> fishes; 

void setup() {
  size(500,500);
  frameRate(30);
  fishes = new ArrayList<Fish> (); //create an empty array list
  }

void draw() {
  background(215,248,250);
  fishes.add(new Fish(new PVector(random(width),600)));
  //add a random fish each loop through draw
  
  /*for (int i=fishes.size()-1; i>=0; i--) {
    //Fish f = fishes.get(i);
    Fish f = (Fish)fishes.get(i); //******* we specifiy type (Fish) when we pull objects
    //if we don't specify, we are using generics which means we need to put <Fish> behind ArrayList when
    //we first delcare it at the top and when we initiate the ArrayList in setup
  f.run();
  if (f.dead()) {
    fishes.remove(i);
  }
  }*/
  
  
  //using the iterator function in arraylist
  Iterator it = fishes.iterator();
  while (it.hasNext() ) {
    Fish f = (Fish)it.next();
    f.run();
    if (f.dead()) {
      it.remove();
    }
  }
}

void mousePressed() {
  for (Fish f: fishes) {
    PVector hand = new PVector (-0.1,0);
    f.applyForce(hand);
  }
}

 
    

/*
class Hand {


  float G=100;

  PVector location;

  Hand (float x, float y) {

    location = new PVector (x, y);
  }

  PVector hand (Fish f) {
    PVector dir = PVector.sub(location, f.location);
    float d= dir.mag();
    dir.normalize();
    d=constrain (d, 5, 100);
    float force=G/(d*d);
    dir.mult(force);
    return dir;
  }
}
*/