final float BALL_AMOUNT = 5000;
final int SHOOTING_COOLDOWN = 10;
final float PROJECTILE_RADIUS = 10;
final float VELOCITY_MAGNITUDE = 2;
final float HEADING_LINE_LENGTH = 50;
final float USER_TERMINAL_VELOCITY = 6;
final float USER_DECELERATION_MAGNITUDE = 0.1;
final float USER_ACCELERATION_MAGNITUDE = 0.25;

ArrayList<Projectile> projectiles = new ArrayList<Projectile>();
ArrayList<Wall> walls = new ArrayList<Wall>();

PVector mouse;
int dragIndex = -1;
boolean dragType = false;

PVector userPosition, userVelocity;

void setup() {
  fullScreen(P3D);

  mouse = new PVector(width, height/2);

  userPosition = new PVector(width/2, height/2);
  userVelocity = new PVector(0, 0);

  // walls.add(new Wall(
  //   new PVector(width/2, 0),
  //   new PVector(width, height/2)
  // ));
  // walls.add(new Wall(
  //   new PVector(width, height/2),
  //   new PVector(width/2, height)
  // ));
  // walls.add(new Wall(
  //   new PVector(width/2, height),
  //   new PVector(0, height/2)
  // ));
  // walls.add(new Wall(
  //   new PVector(0, height/2),
  //   new PVector(width/2, 0)
  // ));

  walls.add(new Wall(
    new PVector(100, 100),
    new PVector(width-100, 100)
  ));
  walls.add(new Wall(
    new PVector(width-100, 100),
    new PVector(width-100, height-100)
  ));
  walls.add(new Wall(
    new PVector(width-100, height-100),
    new PVector(100, height-100)
  ));
  walls.add(new Wall(
    new PVector(100, height-100),
    new PVector(100, 100)
  ));

  // for (int i = 0; i < 20; i++) {
  //   walls.add(new Wall(
  //     new PVector(random(width), random(height)),
  //     new PVector(random(width), random(height))
  //   ));
  // }

  // final PVector center = new PVector(width/2, height/2);
  // final float INCREMENT = TWO_PI / BALL_AMOUNT;
  // for (float a = 0; a < TWO_PI; a+=INCREMENT) {
  //   PVector v = new PVector(
  //     cos(a) * HEADING_LINE_LENGTH,
  //     sin(a) * HEADING_LINE_LENGTH
  //   );
  //   projectiles.add(new Projectile(
  //     PVector.add(center, v),
  //     PVector.mult(PVector.div(v, v.mag()), VELOCITY_MAGNITUDE)
  //   ));
  // }
}

void draw() {
  background(0);

  for (Wall w : walls)
    w.show();

  for (int i = projectiles.size()-1; i >= 0; i--) {
    Projectile p = projectiles.get(i);
    p.show();
    p.move();
  }

  // mouse = new PVector(width, height / 2);
  mouse = new PVector(mouseX, mouseY);
  stroke(255,0,0);
  fill(255,0,0);
  ellipse(userPosition.x, userPosition.y, PROJECTILE_RADIUS*2, PROJECTILE_RADIUS*2);

  // Handle 'mouseDrag' when pressing LMB
  if (dragIndex != -1) {
    Wall w = walls.get(dragIndex);
    if (dragType)
      w.end = mouse.copy();
    else
      w.start = mouse.copy();
  }

  // Handle 'shooting' when pressing RMB
  if (mousePressed && mouseButton == RIGHT && frameCount % SHOOTING_COOLDOWN == 0 && !mouse.equals(userPosition)) {
    PVector baseVelocity = PVector.sub(mouse, userPosition);
    baseVelocity.setMag(VELOCITY_MAGNITUDE);
    baseVelocity.add(userVelocity);
    projectiles.add(new Projectile(
      userPosition,
      baseVelocity
    ));
  }

  // Display user heading
  PVector userHeading = PVector.sub(mouse, userPosition);
  userHeading.setMag(HEADING_LINE_LENGTH);
  PVector temp = PVector.add(userPosition, userHeading);
  float headingFromOrigin = userHeading.heading();
  PVector arrowLeft = PVector.fromAngle(headingFromOrigin-(4*PI)/5);
  PVector arrowRight = PVector.fromAngle(headingFromOrigin+(4*PI)/5);
  arrowLeft.setMag(HEADING_LINE_LENGTH / 3);
  arrowRight.setMag(HEADING_LINE_LENGTH / 3);
  arrowLeft.add(temp);
  arrowRight.add(temp);
  if (!mouse.equals(userPosition)) {
    stroke(255);
    noFill();
    line(userPosition.x, userPosition.y, temp.x, temp.y);
    line(temp.x, temp.y, arrowLeft.x, arrowLeft.y);
    line(temp.x, temp.y, arrowRight.x, arrowRight.y);
  }

  // Handle user movement
  float decel = userVelocity.mag()-USER_DECELERATION_MAGNITUDE;
  if (decel < 0)
    decel = 0;
  userVelocity.setMag(decel);
  PVector nPos = PVector.add(userPosition, userVelocity);
  boolean xZero = nPos.x < 0;
  if (xZero || nPos.x > width) {
    nPos.x = (xZero) ? 0 : width;
    userVelocity.x = 0;
  }
  boolean yZero = nPos.y < 0;
  if (yZero || nPos.y > height) {
    nPos.y = (yZero) ? 0 : height;
    userVelocity.y = 0;
  }
  userPosition = nPos.copy();

  if (keyPressed)
    userMovement(key, headingFromOrigin);

  // saveFrame("Y:\\Stash\\ProcessingAnimations\\Reflections\\frame-#####.png");
}