#include <Adafruit_NeoPixel.h>

#define LED_PIN    2
#define LED_COUNT  60

Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

const int MAX_PARTICLES = 60;

struct Particle {
  float pos;
  float vel;
  uint16_t hue;
  int life;
  bool active;
  bool isCore;  // NEW: bright center flash
};

Particle particles[MAX_PARTICLES];

const float DRAG = 0.98;
const int MAX_LIFE = 60;
unsigned long lastSpawn = 0;
const unsigned long SPAWN_INTERVAL = 800;

void setup() {
  strip.begin();
  strip.show();
  randomSeed(analogRead(0));
}

void loop() {
  if (millis() - lastSpawn > SPAWN_INTERVAL) {
    spawnExplosion();
    lastSpawn = millis();
  }

  updateParticles();
  drawParticles();
  strip.show();
  delay(20);
}

void spawnExplosion() {
  int center = random(10, LED_COUNT - 10);
  uint16_t baseHue = random(0, 65535);
  int numParticles = random(15, 30);

  // Bright center spark(s)
  for (int j = 0; j < MAX_PARTICLES; j++) {
    if (!particles[j].active) {
      particles[j] = {
        (float)center,
        0.0,
        baseHue,
        4,              // Short life
        true,
        true            // Mark as core flash
      };
      break;
    }
  }

  // Flying particles
  for (int i = 0; i < numParticles; i++) {
    for (int j = 0; j < MAX_PARTICLES; j++) {
      if (!particles[j].active) {
        float velocity = (random(-100, 100) / 100.0) * 1.5;
        particles[j] = {
          (float)center,
          velocity,
          baseHue + random(-1000, 1000),
          MAX_LIFE,
          true,
          false
        };
        break;
      }
    }
  }
}

void updateParticles() {
  for (int i = 0; i < MAX_PARTICLES; i++) {
    Particle &p = particles[i];
    if (p.active) {
      p.pos += p.vel;
      p.vel *= DRAG;
      p.life--;
      if (p.life <= 0 || p.pos < 0 || p.pos >= LED_COUNT) {
        p.active = false;
      }
    }
  }
}

void drawParticles() {
  strip.clear();
  for (int i = 0; i < MAX_PARTICLES; i++) {
    Particle &p = particles[i];
    if (p.active) {
      int index = round(p.pos);
      if (index >= 0 && index < LED_COUNT) {
        uint8_t brightness = p.isCore ?
          255 : map(p.life, 0, MAX_LIFE, 0, 200);  // brighter core
        uint32_t color = strip.ColorHSV(p.hue, 255, brightness);
        strip.setPixelColor(index, color);
      }
    }
  }
}