// define gravity

float gravity = 0.98;
int lastSecond;
int spawnNum;

// define a array to manage balls

ArrayList<Ball> balls = new ArrayList<Ball>();
Paddle paddle = new Paddle(new PVector(300,240));

void setup(){
  
  // Initialize screen resolution
  
  size(600, 480); 
  noStroke();
  
  lastSecond = second();
  
  // spwan a new ball at beginning
  
  SpawnNewBall(1);
  
}


void draw(){
  
   background(0); 
   
   // show total balls
   fill(255);
   textSize(18);
   text("Total balls:" + balls.size(), 10, 30); 
   
   //// if time has passed 1 second
   
   if(lastSecond != second()){
   
     
     
     lastSecond = second();
     
     // chance to spawn new ball
     
     if(random(0,100) < 50){
       
       // spawn new ball
       SpawnNewBall(int(random(1,3 + spawnNum)));
       spawnNum++;
       
     }
     
   }
   
   // Draw Paddle
  
   paddle.SetPosition(new PVector(mouseX,450));
   paddle.Update();
   
   // draw balls
   
   
   for (int i = balls.size() - 1; i >= 0; i--) {
     
     Ball ball = balls.get(i);
     
     ball.Update();
     
     // check if the ball hits paddle
     if(CheckWithin(ball.position.x, paddle.position.x - paddle.size.x / 2, paddle.position.x + paddle.size.x / 2) &&
     CheckWithin(ball.position.y, paddle.position.y - paddle.size.y / 2, paddle.position.y + paddle.size.y / 2)){
       
       // if it hits the paddle
       
       ball.SetVelocity(new PVector(ball.velocity.x, abs(ball.velocity.y) * -1));
       
     }
     
     
     // check if the ball fell under
     
     if(ball.position.y > height + 50){
     
       // destory the ball
       
       balls.remove(ball);
       ball = null;
     }
     

     
   }

}


void SpawnNewBall(int num){
  
  // spawn new balls based on given number
  
  for(int i=0; i< num; i++){
    
    
    
    balls.add(new Ball(new PVector(random(0 ,width), random(-200,0)), new PVector(random(-10,10),0), 20));
    
  }
}


boolean CheckWithin(float val, float min, float max){
  
  if(val >= min && val <= max){
  
    return true;
  }
  
  
  return false;
  
}

class Ball{
  
  PVector position, velocity;
  color myColor;
  float size;
  
  
  Ball(PVector _pos, PVector _vel, float _size){
    
    // Ball constructor
    
    position = _pos;
    velocity = _vel;
    size = _size;
    
    SetRandomColor();
    
  }
  
  void Update(){
    
    // adds gravity
    velocity.y += 0.98;

    // apply velocity to the ball
    
    position.add(velocity);
    
        
    // collision detect
    
    CollisionDetect();
    
    // draw ball on the sceen
    
    fill(myColor);
    arc(position.x, position.y, size, size, 0, 2 * PI);
    
  }
  
  
  void CollisionDetect(){
  
    // check x bounds
    
    if(position.x + size > width ){
      // hits bounds
      
      velocity.x = -1 * abs(velocity.x);

      
    } else if(position.x - size < 0){
      
      velocity.x = 1 * abs(velocity.x);
      
    }
  
  }
  
  
  void SetRandomColor(){
  
    myColor = color(int(random(5,255)),int(random(5,255)),int(random(5,255)));
    
    
    
  }
  
  void SetVelocity(PVector velo){
      
    velocity = velo;
      
  }
  
}

class Paddle{
  
  color woodColor = color(163, 110, 32);
  color myColor = color(226, 35, 24);
  PVector position;
  PVector size = new PVector(200,50);
  
  Paddle(PVector pos){
    
    position = pos;
    
  }
  
  void Update(){
    
    
    
    noStroke();
    
    // Draw handle
    fill(woodColor);
    rect(position.x - 25, position.y, 50, 80);
    
    // Draw wood
    
    arc(position.x, position.y, size.x, size.y, 0, 2 * PI);
      
    // Draw paddle
    fill(myColor);
    arc(position.x, position.y, size.x - 20, size.y - 10, 0, 2 * PI);
    
  }
  
  
  void SetPosition(PVector pos){
    
    position = pos;
    
  }
  
}