const int ledPins[] = {0, 1, 2, 3, 4, 5, 6, 7}; // LED pins
const int analogPin = A0; // Potentiometer pin

// Delay setup
unsigned long delayArea = 100;
unsigned long prevMillis = 0;
const unsigned long delayMs1 = 100;
const unsigned long delayMs2 = 250;
const unsigned long delayMs3 = 500;
const unsigned long delayMs4 = 750;

// Declare bitState variable here
byte bitState = 0b00000001;

void setup() {
  // Set LED pins as outputs
  for (int pin : ledPins) {
    pinMode(pin, OUTPUT);
  }
}

void loop() {
  // Read potentiometer and map to delay range
  int sensorReading = analogRead(analogPin);
  int ledLevel = map(sensorReading, 0, 1023, 0, 4);

  // Update delay based on potentiometer position
  switch (ledLevel) {
    case 0:
      delayArea = delayMs1;
      break;
    case 1:
      delayArea = delayMs2;
      break;
    case 2:
      delayArea = delayMs3;
      break;
    default:
      delayArea = delayMs4;
  }

  unsigned long currMillis = millis();

  // Turn on and shift LED based on delay and bit state
  if (currMillis - prevMillis >= delayArea) {

    PORTD = bitState;
    bitState <<= 1;
    if (bitState == 0) { // Reset bitState when it becomes zero
      bitState = 0b00000001;
    }
    for (int pin : ledPins) {
      digitalWrite(pin, LOW);
    }
    prevMillis = currMillis;
  }
}