class Circle {
    float x,y; //location
    float dia; //diameter
    float exSpd; //expansion speed
    color c; //color of each circle

  Circle (float x_, float y_) {
    dia = 10; //starting diameter, also dot for moving, and dot for bounce-back
    x = x_; //x position
    y = y_; //y position
    c = color(random(255), random(255), random(255)); //randomize color of circle
  }
  
  void display(float exSpd_) {
    exSpd = exSpd_;
    stroke(c); //random color
    strokeWeight(4);
    fill(255);
    ellipse(x,y,dia,dia); //displays the circle
    dia += exSpd; //expands the circle at rate pre-defined
    noStroke();
    fill(c);
    ellipse(x,y,10,10); //displays a solid circle in the center of expanding one
   }
  
  float diameter() { //sends diamter expansion data to the main draw loop for storing in an array
    return dia;
  }
}

ArrayList circles;
//Circle[] circles = new Circle[0]; //object array
float[] expandSpeed = new float[0]; //speed array
float[] xCoord = new float[0]; //x coordinates array
float[] yCoord = new float[0]; //y coordinates array
float[] diaArray = new float[0]; //diameters array
int iter; //counter to keep track of current interation
float x,y,dia;

void setup() {
  size(400,400);
  smooth();
  circles = new ArrayList(); //create blank arraylist
}

void draw() {
  background(255);
  
  for(int i = 0; i < circles.size(); i++) { //loop for the current number of objects
    iter = i; //iteration counter equals i
    Circle circle = (Circle) circles.get(i); //get object from ArrayList position i
    circle.display(expandSpeed[i]); //display the object Array
    diaArray[i] = circle.diameter(); //fill the diameter array to that it updates with display
    
    if (circle.diameter() < 13) { //if circle gets too small, expand
      expandSpeed[i] = 1;
    }
    
    x = xCoord[iter]; //pull the current iteration of x coordinates
    y = yCoord[iter]; //pull the current iteration of y coordinates
    dia = diaArray[iter]; //pull the current iteration of diameter data
    
    for(int h = 0; h < diaArray.length-1; h++) { //for each indice currently holding object/xy/diameter data
	  if (h != iter) { //NOT including the iteration that was pulled before this loop
	      float distance = dist(x,y,xCoord[h],yCoord[h]); //get distance between current iteration and all other points

	      if(distance < dia/2+diaArray[h]/2) { //if that distance is greater than current radius plus all other radi
                  expandSpeed[h] = -1; //reverse current iteration
                  expandSpeed[iter] = -1; //and all other colliding iterations
	      }
	  }
      }
   }
}


void mousePressed() {
  float xCoord_ = mouseX; //add place to xCoord array and input current mouseX data
  xCoord = (float[]) append(xCoord, xCoord_); 
  
  float yCoord_ = mouseY; //add place to yCoord array and input current mouseY data
  yCoord = (float[]) append(yCoord, yCoord_);
  
  float diaArray_ = 10; //add place to diameter Array and input dumb placeholder data
  diaArray = (float[]) append(diaArray, diaArray_);
  
  float expandSpeed_ = .2; //add place to expnasion speed Array and input the speed
  expandSpeed = (float[]) append(expandSpeed, expandSpeed_);
  
  circles.add(new Circle(mouseX,mouseY)); //add new object to object arrayList
}

void keyPressed() {
  if (circles.size() > 0) {
  circles.remove(circles.size()-1);
  xCoord = shorten(xCoord);
  yCoord = shorten(yCoord);
  diaArray = shorten(diaArray);
  expandSpeed = shorten(expandSpeed);
  }
}