#include <Adafruit_NeoPixel.h>

Adafruit_NeoPixel ledstrip(16, 12, NEO_GRB + NEO_KHZ800);

unsigned long lastChange = 0;

uint8_t hue = 0;
uint8_t colorIndex = 0; // 0–15

const uint8_t colors[16][3] = {
  {255,   0,   0},   // 1 Red
  {255,  80,   0},   // 2 Orange
  {255, 255,   0},   // 3 Yellow
  {120, 255,   0},   // 4 Lime
  {  0, 255,   0},   // 5 Green
  {  0, 255, 120},   // 6 Spring green
  {  0, 255, 255},   // 7 Cyan
  {  0, 120, 255},   // 8 Sky blue
  {  0,   0, 255},   // 9 Blue
  { 80,   0, 255},   // 10 Violet
  {150,   0, 255},   // 11 Purple
  {255,   0, 255},   // 12 Magenta
  {255,   0, 120},   // 13 Pink
  {255,  60,  60},   // 14 Rose
  {255, 200, 120},   // 15 Warm white
  {180, 200, 255}    // 16 Cool white
};

void setup() {
  ledstrip.begin();
}

void wheel(uint8_t pos, uint8_t &r, uint8_t &g, uint8_t &b) {
  if (pos < 85) {
    r = 255 - pos * 3;
    g = pos * 3;
    b = 0;
  } else if (pos < 170) {
    pos -= 85;
    r = 0;
    g = 255 - pos * 3;
    b = pos * 3;
  } else {
    pos -= 170;
    r = pos * 3;
    g = 0;
    b = 255 - pos * 3;
  }
}


void RAINBOW(int DELAY) {
    uint8_t r, g, b;

    wheel(hue, r, g, b);

    ledstrip.setPixelColor(0, Colour(r, g, b));
    ledstrip.show();

    hue++;

  delay(DELAY);
}

void loop() {
    if (millis() - lastChange >= interval) {
      lastChange = millis();

      ledstrip.setPixelColor(
        0,
        Colour(
          colors[colorIndex][0],
          colors[colorIndex][1],
          colors[colorIndex][2]
        )
      );
      ledstrip.show();

      colorIndex++;
      if (colorIndex >= 16) {
        colorIndex = 0; // back to 1
      }
    }
}