#include <Adafruit_NeoPixel.h>

#define PIN 2
#define NUM_PIXELS 32
#define NUM_PER_RING 16

#define LEFT_BTN 3
#define RIGHT_BTN 4

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUM_PIXELS, PIN, NEO_GRB + NEO_KHZ800);

int offset = 0;
int speed = 50;
int speedStep = 1;
int minSpeed = 5;
int maxSpeed = 100;
int direction = 1;

int colorIndex = 0;

// ----- Rotation color palette -----
uint32_t colors[] = {
  Adafruit_NeoPixel::Color(255,   0,   0), // red
  Adafruit_NeoPixel::Color(0,   255,   0), // green
  Adafruit_NeoPixel::Color(0,     0, 255), // blue
  Adafruit_NeoPixel::Color(255, 255,   0), // yellow
  Adafruit_NeoPixel::Color(255,   0, 255), // purple
  Adafruit_NeoPixel::Color(0,   255, 255), // cyan
  Adafruit_NeoPixel::Color(255, 255, 255)  // white
};
int totalColors = sizeof(colors) / sizeof(colors[0]);


void setup() {
  pixels.begin();

  pinMode(LEFT_BTN, INPUT_PULLUP);
  pinMode(RIGHT_BTN, INPUT_PULLUP);
}

void loop() {

  // -------- BUTTON CONTROL --------
  if (digitalRead(LEFT_BTN) == LOW) {
    direction = -1;          // rotate left
  }
  if (digitalRead(RIGHT_BTN) == LOW) {
    direction = 1;           // rotate right
  }

  // -------- LED UPDATE --------
  for (int i = 0; i < NUM_PER_RING; i++) {
    uint32_t color = 0;

    if (i == offset || i == (offset + 8) % NUM_PER_RING) {
      color = colors[colorIndex];
    }

    pixels.setPixelColor(i, color);
    pixels.setPixelColor(i + NUM_PER_RING, color);
  }
  pixels.show();

  // track previous offset to detect full rotation
  int previousOffset = offset;

  offset += direction;
  if (offset >= NUM_PER_RING) offset = 0;
  if (offset < 0) offset = NUM_PER_RING - 1;

  // -------- CHANGE COLOR AFTER FULL ROTATION --------
  bool fullRotation =
      (direction == 1 && offset == 0 && previousOffset == NUM_PER_RING - 1) ||
      (direction == -1 && offset == NUM_PER_RING - 1 && previousOffset == 0);

  if (fullRotation) {
    colorIndex++;
    if (colorIndex >= totalColors) colorIndex = 0;
  }

  // -------- SPEED ANIMATION --------
  speed += speedStep;

  if (speed >= maxSpeed || speed <= minSpeed) {
    speedStep = -speedStep;
    // DO NOT CHANGE direction here (button controls direction)
  }

  delay(speed);
}