// --- English Translation & Fixes by AI --- 

// All the pins for the LEDs (total of 6 LEDs)
const uint8_t ledPins[] = { 9, 11, 10, 6, 3, 5 };
const int ledCount = sizeof(ledPins) / sizeof(ledPins[0]);

// The pin for the potentiometer
byte potentiometerPin = A3;
// The pin for the mode switch
byte switchPin = 12;

// The value read from the potentiometer
int potentiometerValue;
// The value read from the switch (HIGH/1 = not pressed, LOW/0 = pressed)
int switchValue;

// Indicates the direction for the chaser effect (-1 for left, 1 for right)
int direction;

// Keeps track of the index of the currently active LED or LED pair
int currentLed = 0; // Start at 0 for cleaner logic

// --- Variables for the "Chaser" effect (Mode 1) only ---
byte trail1 = 0;
byte trail2 = 0;
byte trail3 = 0;
byte trail4 = 0;

// --- Timing variables ---
unsigned long previousMillis = 0;
long interval = 200; // Default interval

void setup() {
  // Turn on the serial monitor for debugging
  Serial.begin(115200);

  // Initialize all LED pins as outputs
  for (int i = 0; i < ledCount; i++) {
    pinMode(ledPins[i], OUTPUT);
  }

  // Initialize the switch pin with an internal pull-up resistor.
  // This means the pin will be HIGH when the switch is not pressed,
  // and LOW when the switch is pressed (connected to ground).
  pinMode(switchPin, INPUT_PULLUP);
}

void CollectInput() {
  // Read the potentiometer value (0-1023)
  potentiometerValue = analogRead(potentiometerPin);
  // Read the switch state (HIGH or LOW)
  switchValue = digitalRead(switchPin);
}

void Process() {
  // --- Mode 1: Chaser with fading tail (Switch is NOT pressed) ---
  if (switchValue == 1) {
    // Determine direction and speed from potentiometer
    direction = 0;
    interval = 5000; // Default interval if in the middle "dead zone"

    if (potentiometerValue < 482) { // Turning left
      direction = -1;
      interval = map(potentiometerValue, 482, 0, 500, 75);
    }
    if (potentiometerValue > 542) { // Turning right
      direction = 1;
      interval = map(potentiometerValue, 1023, 542, 75, 500);
    }

    // Update the trail LEDs
    trail4 = trail3;
    trail3 = trail2;
    trail2 = trail1;
    trail1 = currentLed;

    // Move the leading LED
    currentLed += direction;

    // Wrap the LED index around if it goes out of bounds
    if (currentLed < 0) {
      currentLed = ledCount - 1;
    }
    if (currentLed >= ledCount) {
      currentLed = 0;
    }
  }
  // --- Mode 2: "2x2 Burning" Pairs (Switch IS pressed) ---
  else { // switchValue == 0
    // The potentiometer only controls the speed
    interval = map(potentiometerValue, 0, 1023, 500, 75);

    // Advance to the next pair of LEDs
    currentLed += 2;

    // If we've gone past the last pair, wrap around to the first pair (index 0)
    if (currentLed >= ledCount) {
      currentLed = 0;
    }
  }
}


void Display() {
  // **IMPORTANT**: Turn all LEDs off before lighting the new ones.
  // This prevents LEDs from previous frames from staying on.
  for (int i = 0; i < ledCount; i++) {
    analogWrite(ledPins[i], 0);
  }

  // --- Display Logic for Mode 1: Chaser ---
  if (switchValue == 1) {
    // Light the leading LED at full brightness
    analogWrite(ledPins[currentLed], 255);

    // Light the trailing LEDs with fading brightness
    analogWrite(ledPins[trail1], 117);
    analogWrite(ledPins[trail2], 54);
    analogWrite(ledPins[trail3], 25);
    // trail4 is now off because it was pushed out
  }
  // --- Display Logic for Mode 2: Pairs ---
  else { // switchValue == 0
    // The desired effect: light up LEDs in pairs.
    // Example: 1&2 ON, then 3&4 ON, then 5&6 ON.
    // Our 'ledPins' array is 0-indexed, so pairs are (0,1), (2,3), (4,5).
    
    // Light the current pair at full brightness
    analogWrite(ledPins[currentLed], 255);
    analogWrite(ledPins[currentLed + 1], 255);
  }
}

// Timer function remains the same
bool timer() {
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;
    return true;
  }
  return false;
}

void loop() {
  // Always check for input
  CollectInput();

  // Only process and display a new frame when the timer is ready
  if (timer()) {
    Process();
    Display();

    // Debugging output to see what's happening
    Serial.print("Mode: ");
    Serial.print(switchValue == 1 ? "Chaser" : "Pairs");
    Serial.print(" | currentLed: ");
    Serial.print(currentLed);
    Serial.print(" | Interval: ");
    Serial.println(interval);
  }
}