#include <Adafruit_NeoPixel.h>
#define NUM_LEDS 3
#define DATA_PIN 6
#define BRIGHTNESS 255     // Max brightness (change as needed)
#define CYCLE_TIME 30000   // 30 seconds, in milliseconds

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

unsigned long startTime;

void setup() {
  strip.begin();
  strip.setBrightness(BRIGHTNESS);
  strip.show();
  startTime = millis();
}

// Helper function: get color for a given step
uint32_t redSpectrumColor(float t) {
  // t in [0, 1]; cycle through reds and oranges
  // We'll interpolate between deep red, orange-red, yellow-red, then back to deep red
  float r, g, b;
  if (t < 0.5) {
    // Fade from (255,0,0) to (255,110,0): red to orangey
    r = 150 + (255-150)*(t/0.5); // 150 to 255
    g = 0   + (90-0)*(t/0.5);    // 0 to 90
    b = 0;
  } else {
    // Fade from (255,90,0) back to (150,0,0)
    r = 255 - (255-150)*((t-0.5)/0.5);
    g = 90  - (90-0)*((t-0.5)/0.5);
    b = 0;
  }
  return strip.Color((int)r, (int)g, (int)b);
}

// Helper function: calculates delay via a sine wave mapped to 0.1s (fast) to 0.6s (slow)
unsigned int rotatingDelay(unsigned long ellapsed) {
  float cyclePosition = (ellapsed % CYCLE_TIME) / (float)CYCLE_TIME;
  // This creates a value oscillating between 0 and 1, slow-fast-slow-fast
  float wave = (sin(2 * 3.14159 * cyclePosition - 3.14159/2) + 1) / 2; // [0..1], slowest at wave=1, fastest at wave=0
  // Map to delay: 100ms (fast) to 600ms (slow)
  unsigned int minDelay = 100;
  unsigned int maxDelay = 200;
  return (unsigned int)(minDelay + (maxDelay-minDelay) * wave);
}

void loop() {
  static int ledIndex = 0;
  unsigned long now = millis();
  unsigned long elapsed = (now - startTime) % CYCLE_TIME;
  float colorPhase = ((float)elapsed) / CYCLE_TIME; // [0..1]

  // Show only one LED at a time, with color from the red spectrum function
  strip.clear();
  strip.setPixelColor(ledIndex, redSpectrumColor(colorPhase));
  strip.show();

  // Wait based on current cycle position (slows down and speeds up)
  delay(rotatingDelay(elapsed));

  // Move the 'blade'
  ledIndex = (ledIndex + 1) % NUM_LEDS;
}