#include <Adafruit_NeoPixel.h>

#define PIN            D4  // Pin connected to the NeoPixel ring
#define NUMPIXELS      16  // Number of NeoPixels in the ring
#define BUTTON_PIN     D1  // Pin connected to the button

Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  pinMode(BUTTON_PIN, INPUT);
  Serial.begin(9600); // Initialize serial communication
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
}

void loop() {
  int buttonState = digitalRead(BUTTON_PIN);

  if (buttonState == HIGH) {
    Serial.println("ON"); // Send "ON" message to serial monitor
    for (int i = 0; i < strip.numPixels(); i++) {
      strip.setPixelColor(i, strip.Color(255, 255, 255)); // Set all pixels to white
    }
    strip.show();
  } else {
    Serial.println("OFF"); // Send "OFF" message to serial monitor
    rainbow(20); // Cycle through rainbow colors with a delay
  }
}

// Fill the dots one after the other with a color wheel effect
// Speed is the delay in milliseconds between updates
void rainbow(uint8_t wait) {
  uint16_t i, j;

  for (j = 0; j < 256; j++) { // 256 colors in the wheel
    for (i = 0; i < strip.numPixels(); i++) {
      int buttonState = digitalRead(BUTTON_PIN);
      if (buttonState == HIGH) {
        Serial.println("ON"); // Send "ON" message to serial monitor
        for (int k = 0; k < strip.numPixels(); k++) {
          strip.setPixelColor(k, strip.Color(255, 255, 255)); // Set all pixels to white
        }
        strip.show();
        return; // Exit the rainbow function early
      }
      strip.setPixelColor(i, Wheel((i + j) & 255));
    }
    strip.show();
    delay(wait);
  }
}

// Input a value 0 to 255 to get a color value
// The colors are a transition r - g - b - back to r
uint32_t Wheel(byte WheelPos) {
  WheelPos = 255 - WheelPos;
  if (WheelPos < 85) {
    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else if (WheelPos < 170) {
    WheelPos -= 85;
    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  } else {
    WheelPos -= 170;
    return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  }
}