// Define the LED pins
const int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9};
const int numLeds = sizeof(ledPins) / sizeof(ledPins[0]);

// Define the potentiometer pin
const int potPin = A0;

// Variables to store LED index and direction
int ledIndex = 0;
int direction = 1;

void setup() {
  // Initialize the LED pins as outputs
  for (int i = 0; i < numLeds; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
  // Initialize the serial communication
  Serial.begin(9600);
}

void loop() {
  // Read the potentiometer value (0 to 1023)
  int potValue = analogRead(potPin);
  
  // Map the potentiometer value to a suitable delay time (10 to 100 milliseconds)
  int delayTime = map(potValue, 0, 1023, 10, 100);

  // Fade in the current LED and fade out the previous LED
  int previousLedIndex = ledIndex - direction;
  if (previousLedIndex < 0) {
    previousLedIndex = numLeds - 1;
  } else if (previousLedIndex >= numLeds) {
    previousLedIndex = 0;
  }

  for (int brightness = 0; brightness <= 255; brightness++) {
    analogWrite(ledPins[ledIndex], brightness);
    analogWrite(ledPins[previousLedIndex], 255 - brightness);
    delay(delayTime);
  }

  // Update the LED index and direction
  ledIndex += direction;
  if (ledIndex == numLeds - 1 || ledIndex == 0) {
    direction = -direction; // Reverse direction at the ends
  }
}