int ledPins[] = {7, 6, 5, 4, 3, 2, 1, 0};
int buttonPin = 8;
bool loopRunning = false;
int currentLED = 0; // Tracks the current LED
unsigned long previousMillis = 0;
const unsigned long interval = 1000; // 1 second interval (1000 milliseconds)
unsigned long buttonPressStartTime = 0; // To track when the button was pressed
const unsigned long holdDuration = 2000; // 2 seconds hold duration
bool buttonPreviouslyPressed = false; // To track button press state

void setup() {
  for (int i = 0; i < 8; i++) {
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i], 1); // Turn off all LEDs initially
  }
  pinMode(buttonPin, INPUT_PULLUP); // Use internal pull-up resistor
}

void loop() {
  bool currentButtonState = digitalRead(buttonPin);
  
  // Check if the button state has changed
  if (currentButtonState == LOW && !buttonPreviouslyPressed) {
    buttonPressStartTime = millis(); // Record the time when button was first pressed
    buttonPreviouslyPressed = true;
  }

  if (currentButtonState == HIGH && buttonPreviouslyPressed) {
    // Button was released
    unsigned long buttonPressDuration = millis() - buttonPressStartTime;

    if (buttonPressDuration < holdDuration) {
      // Button was pressed but not held for 2 seconds
      loopRunning = !loopRunning; // Toggle the LED sequence
      if (!loopRunning) {
        digitalWrite(ledPins[currentLED], 0); // Keep the current LED on when stopped
      }
    }
    buttonPreviouslyPressed = false;
  }

  if (loopRunning) {
    unsigned long currentMillis = millis();

    // Check if the interval has passed
    if (currentMillis - previousMillis >= interval) {
      previousMillis = currentMillis; // Update the last change time

      // Turn off the previous LED
      digitalWrite(ledPins[currentLED], 1);

      // Move to the next LED
      currentLED++;
      if (currentLED >= 8) {
        currentLED = 0; // Reset to the first LED after the last one
      }

      // Turn on the current LED
      digitalWrite(ledPins[currentLED], 0);
    }
  }
}