// ============================================
// 13주차 실습: 나만의 파티클 이펙트
// ============================================

// --- Particle 클래스 ---
class Particle {
  constructor(x, y) {
    this.position = createVector(x, y);
    this.velocity = createVector(random(-1, 1), random(-2, 0));
    this.acceleration = createVector(0, 0.05);
    this.lifespan = 255;
  }

  update() {
    this.velocity.add(this.acceleration);
    this.position.add(this.velocity);
    this.lifespan -= 2;
  }

  display() {
    stroke(0, this.lifespan);
    fill(127, this.lifespan);
    ellipse(this.position.x, this.position.y, 12);
  }

  isDead() {
    return this.lifespan < 0;
  }
}

// --- 여기에 Emitter 클래스를 만들어보세요! (단계 2) ---
// class Emitter {
//   ...
// }

// --- 메인 코드 ---
let particles = [];

function setup() {
  createCanvas(640, 360);
}

function draw() {
  background(220);

  // 마우스 위치에서 파티클 생성
  particles.push(new Particle(mouseX, mouseY));

  // 역순 순회로 업데이트 + 표시 + 소멸
  for (let i = particles.length - 1; i >= 0; i--) {
    particles[i].update();
    particles[i].display();
    if (particles[i].isDead()) {
      particles.splice(i, 1);
    }
  }

  // 파티클 수 표시
  fill(0);
  noStroke();
  text("파티클 수: " + particles.length, 10, 20);
}

// 불꽃놀이 시스템
let fireworks = [];

function setup() {
  createCanvas(640, 360);
  colorMode(HSB, 255);
}

function draw() {
  background(0, 0, 0, 25);

  // 랜덤으로 불꽃놀이 발사
  if (random(1) < 0.05) {
    fireworks.push(new Firework());
  }

  for (let i = fireworks.length - 1; i >= 0; i--) {
    fireworks[i].update();
    fireworks[i].display();
    if (fireworks[i].isDone()) {
      fireworks.splice(i, 1);
    }
  }
}

function mousePressed() {
  fireworks.push(new Firework(mouseX));
}

class Firework {
  constructor(x) {
    this.hue = random(255);
    this.rocket = new Particle(x || random(width), height);
    this.rocket.velocity = createVector(random(-2, 2), random(-12, -8));
    this.exploded = false;
    this.fragments = [];
  }

  update() {
    if (!this.exploded) {
      this.rocket.applyForce(createVector(0, 0.15));
      this.rocket.update();

      if (this.rocket.velocity.y >= 0) {
        this.explode();
      }
    }

    for (let i = this.fragments.length - 1; i >= 0; i--) {
      this.fragments[i].applyForce(createVector(0, 0.05));
      this.fragments[i].update();
      if (this.fragments[i].isDead()) {
        this.fragments.splice(i, 1);
      }
    }
  }

  explode() {
    this.exploded = true;
    for (let i = 0; i < 40; i++) {
      let f = new Particle(this.rocket.position.x, this.rocket.position.y);
      f.velocity = p5.Vector.random2D().mult(random(2, 7));
      f.hue = this.hue;
      this.fragments.push(f);
    }
  }

  display() {
    if (!this.exploded) {
      // 발사체: 흰색 점
      push();
      noStroke();
      fill(0, 0, 255);
      ellipse(this.rocket.position.x, this.rocket.position.y, 4);
      pop();
    }

    for (let f of this.fragments) {
      push();
      noStroke();
      fill(f.hue, 255, 255, f.lifespan);
      let size = map(f.lifespan, 0, 255, 0, 6);
      ellipse(f.position.x, f.position.y, size);
      pop();
    }
  }

  isDone() {
    return this.exploded && this.fragments.length === 0;
  }
}

class Particle {
  constructor(x, y) {
    this.position = createVector(x, y);
    this.velocity = createVector(0, 0);
    this.acceleration = createVector(0, 0);
    this.lifespan = 255;
    this.hue = 0;
  }

  applyForce(force) {
    this.acceleration.add(force);
  }

  update() {
    this.velocity.add(this.acceleration);
    this.position.add(this.velocity);
    this.acceleration.mult(0);
    this.lifespan -= 4;
  }

  isDead() {
    return this.lifespan < 0;
  }
}

// ============================================
// 13주차 실습 완성 예제
// 다중 Emitter + HSB 색상 + 크기 변화
// ============================================

let emitters = [];

function setup() {
  createCanvas(640, 360);
  colorMode(HSB, 255);
}

function draw() {
  background(0, 0, 30, 40);

  for (let emitter of emitters) {
    emitter.run();
  }

  // 안내 텍스트
  fill(0, 0, 255);
  noStroke();
  text("클릭: 파티클 방출 효과 생성 | 드래그: 연속 생성 | 'c': 초기화", 10, 20);

  let totalParticles = 0;
  for (let e of emitters) {
    totalParticles += e.particles.length;
  }
  text("Emitter: " + emitters.length + " | 파티클: " + totalParticles, 10, 40);
}

function mousePressed() {
  emitters.push(new Emitter(mouseX, mouseY));
}

function mouseDragged() {
  // 드래그하면 연속으로 Emitter 생성 (5프레임마다)
  if (frameCount % 5 === 0) {
    emitters.push(new Emitter(mouseX, mouseY));
  }
}

function keyPressed() {
  if (key === 'c' || key === 'C') {
    emitters = [];
  }
}

// --- Particle 클래스 ---
class Particle {
  constructor(x, y, hue) {
    this.position = createVector(x, y);
    this.velocity = createVector(random(-1.5, 1.5), random(-2.5, -0.5));
    this.acceleration = createVector(0, 0);
    this.lifespan = 255;
    this.hue = hue;
  }

  applyForce(force) {
    this.acceleration.add(force);
  }

  update() {
    this.velocity.add(this.acceleration);
    this.position.add(this.velocity);
    this.acceleration.mult(0);
    this.lifespan -= 2;
  }

  display() {
    noStroke();
    // 기본 Hue에서 약간 변화하며 사라짐
    let h = (this.hue + map(this.lifespan, 0, 255, 30, 0)) % 255;
    fill(h, 220, 255, this.lifespan);
    // 수명에 따라 크기 변화
    let size = map(this.lifespan, 0, 255, 1, 14);
    ellipse(this.position.x, this.position.y, size);
  }

  isDead() {
    return this.lifespan < 0;
  }
}

// --- Emitter 클래스 ---
class Emitter {
  constructor(x, y) {
    this.origin = createVector(x, y);
    this.particles = [];
    this.hue = random(255); // 각 Emitter마다 고유 색상
  }

  addParticle() {
    this.particles.push(
      new Particle(this.origin.x, this.origin.y, this.hue)
    );
  }

  run() {
    this.addParticle();

    let gravity = createVector(0, 0.05);

    for (let i = this.particles.length - 1; i >= 0; i--) {
      this.particles[i].applyForce(gravity);
      this.particles[i].update();
      this.particles[i].display();

      if (this.particles[i].isDead()) {
        this.particles.splice(i, 1);
      }
    }
  }
}