// ============================================
// Knight Rider LED Chaser with Speed Control
// ============================================

// Variable Declaration
int led[] = {22, 24, 26, 28, 30, 32, 34, 36};  // Array of LED pin numbers
int number_of_leds = sizeof(led)/sizeof(int);   // Calculate total number of LEDs (8)
int position = 0;                               // Current LED position in array
int direction = 1;                              // Movement direction: 1 = forward, -1 = backward
int potentiometer = A0;                         // Potentiometer connected to analog pin A0
int potentiometer_value = 0;                    // Variable to store potentiometer reading
int speed = 0;                                  // Variable to control animation speed

void setup() {
  // Initialize all LED pins and test them
  for(int i = 0; i < number_of_leds; i++) {
    pinMode(led[i], OUTPUT);      // Set each LED pin as OUTPUT
    digitalWrite(led[i], HIGH);   // Turn ON all LEDs for functionality test
  }
  delay(500);                     // Keep all LEDs ON for 500ms to verify connections
  
  // Turn OFF all LEDs after test
  for(int i = 0; i < number_of_leds; i++) {
    digitalWrite(led[i], LOW);
  }
}

// Main Program Loop
void loop() {
  
  // Turn ON the LED at current position
  digitalWrite(led[position], HIGH);
  
  // Update position based on current direction
  position += direction;  // Move forward (+1) or backward (-1)
  
  // Check if we've reached the boundaries and reverse direction
  if(position == number_of_leds - 1 || position == 0) {
    direction *= -1;  // Reverse direction (1 becomes -1, or -1 becomes 1)
  }
  
  // Turn OFF the LED at the new position (creates chaser effect)
  digitalWrite(led[position], LOW);
  
  // Read potentiometer value (0 to 1023)
  potentiometer_value = analogRead(potentiometer);
  
  // Use potentiometer value as delay time to control speed
  delay(potentiometer_value);  // Higher value = slower animation
}