#include <Adafruit_NeoPixel.h>

#define PIN            A3
#define NUM_LEDS       60
#define MAX_SPARKS     12

Adafruit_NeoPixel strip(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);

struct Spark {
  float pos;          // Sub-pixel position
  float velocity;     // Speed/Direction
  float brightness;   // Current intensity (0.0 to 1.0)
  float decay;        // How fast it dies
  bool active = false;
};

Spark sparks[MAX_SPARKS];

void setup() {
  strip.begin();
  strip.show();
}

void createSpark() {
  for (int i = 0; i < MAX_SPARKS; i++) {
    if (!sparks[i].active) {
      sparks[i].pos = random(0, NUM_LEDS * 100) / 100.0;
      sparks[i].velocity = (random(-50, 50) / 1000.0); // Micro-movement
      sparks[i].brightness = 1.0;
      sparks[i].decay = random(5, 15) / 100.0; // Fast decay
      sparks[i].active = true;
      break;
    }
  }
}

void loop() {
  if (random(0, 10) > 7) createSpark(); 

  strip.clear();

  for (int i = 0; i < MAX_SPARKS; i++) {
    if (sparks[i].active) {
      sparks[i].pos += sparks[i].velocity;
      sparks[i].brightness -= sparks[i].decay;

      if (sparks[i].brightness <= 0) {
        sparks[i].active = false;
        continue;
      }

      float p = sparks[i].pos;
      int led1 = (int)p;
      int led2 = led1 + 1;
      float weight2 = p - led1;
      float weight1 = 1.0 - weight2;

      // --- ENHANCED BRIGHTNESS MATH ---
      float b = sparks[i].brightness;
      
      // Red stays high longest
      uint8_t r = 255 * pow(b, 0.5); 
      // Green drops off to create orange/red tones
      uint8_t g = 255 * pow(b, 1.5); 
      // Blue only exists at the very peak (White-hot core)
      uint8_t bl = 255 * pow(b, 3.5); 

      if (led1 >= 0 && led1 < NUM_LEDS) addBuffer(led1, r * weight1, g * weight1, bl * weight1);
      if (led2 >= 0 && led2 < NUM_LEDS) addBuffer(led2, r * weight2, g * weight2, bl * weight2);
    }
  }

  strip.show();
  delay(8); // Slightly faster refresh for "sharper" movement
}

void addBuffer(int i, uint8_t r, uint8_t g, uint8_t b) {
  uint32_t oldColor = strip.getPixelColor(i);
  uint8_t oldR = (oldColor >> 16) & 0xFF;
  uint8_t oldG = (oldColor >> 8) & 0xFF;
  uint8_t oldB = oldColor & 0xFF;

  // Saturated addition: ensures overlapping sparks create "White" hot-spots
  int newR = qadd8(oldR, r);
  int newG = qadd8(oldG, g);
  int newB = qadd8(oldB, b);
  
  strip.setPixelColor(i, newR, newG, newB);
}

// Helper for saturated addition (caps at 255)
uint8_t qadd8(uint8_t a, uint8_t b) {
  int res = a + b;
  return (res > 255) ? 255 : (uint8_t)res;
}