#include <Adafruit_NeoPixel.h>

#define NEOPIXEL_PIN  13  // Pin connected to the NeoPixel strip
#define NUM_LEDS      16  // Number of LEDs in the strip
#define BUTTON_PIN    2   // Push button connected to pin 2
#define BUZZER_PIN    12  // Buzzer connected to pin 12

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

enum TimerState {STOPPED, RUNNING, PAUSED};
TimerState timerState = STOPPED;

unsigned long lastButtonPressTime = 0;
unsigned long lastUpdateTime = 0; // Track last update time for non-blocking delay
const long debounceTime = 50; // Debounce time for button presses
const int updateInterval = 1000; // Time between updates in milliseconds
int ledIndex = -1; // Initialize outside valid range to indicate not started

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
  strip.begin();
  strip.show(); // Turn off all pixels initially
  fillStripWithColor(strip.Color(255, 0, 255)); // Start with all LEDs as magenta
}

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

  // Button press detection with debounce
  if (buttonState == LOW && millis() - lastButtonPressTime > debounceTime) {
    lastButtonPressTime = millis();

    if (timerState == STOPPED || timerState == PAUSED) {
      timerState = RUNNING; // Start or resume the timer
      if (ledIndex == -1) {
        ledIndex = 0; // Start from the first LED if we were stopped
      }
    } else if (timerState == RUNNING) {
      timerState = PAUSED; // Pause the timer
    }
  }

  // Non-blocking LED update logic
  if (timerState == RUNNING && millis() - lastUpdateTime > updateInterval) {
    lastUpdateTime = millis();
    
    if (ledIndex < NUM_LEDS) {
      updateLEDs();
      ledIndex++;
    } else {
      pulseLastLED(); // When all LEDs have been updated, pulse the last LED
      timerState = STOPPED; // Stop the timer cycle after completion
      ledIndex = -1; // Reset to indicate we've completed the cycle
    }
  }
}

void updateLEDs() {
  // Calculate which third of the cycle we're in
  int third = NUM_LEDS / 3;
  if (ledIndex < third) {
    fillStripWithColor(strip.Color(0, 255, 0)); // Green
  } else if (ledIndex < 2 * third) {
    fillStripWithColor(strip.Color(255, 165, 0)); // Orange
  } else {
    fillStripWithColor(strip.Color(255, 0, 0)); // Red
  }
}

void fillStripWithColor(uint32_t color) {
  for (int i = 0; i < NUM_LEDS; i++) {
    strip.setPixelColor(i, color);
  }
  strip.show();
}

void pulseLastLED() {
  for (int i = 0; i < 10; i++) {
    strip.setPixelColor(NUM_LEDS - 1, strip.Color(255, 0, 0)); // Red
    strip.show();
    delay(100);
    strip.setPixelColor(NUM_LEDS - 1, 0); // Turn off the LED
    strip.show();
    delay(100);
  }
  // Activate buzzer
  digitalWrite(BUZZER_PIN, HIGH);
  delay(500);
  digitalWrite(BUZZER_PIN, LOW);
}