const int HEARTBEAT_PIN = LED_BUILTIN;  // GP25 – onboard LED (sign of life)
const int LED_PIN       = 15;           // GP15 – external LED
const int BUTTON_PIN    = 2;            // GP2  – push-button (active-LOW)
const int POT_PIN       = 26;           // GP26 – potentiometer (ADC0)

// --- Heartbeat ---
unsigned long lastHeartbeat = 0;

// --- Blink ---
bool blinkEnabled      = false;
unsigned long lastBlinkTime  = 0;
unsigned long blinkInterval  = 500;

// --- Button ---
bool lastButtonState       = HIGH;
unsigned long lastPressTime = 0;        // prevents multiple triggers per click

void setup() {
  pinMode(HEARTBEAT_PIN, OUTPUT);
  pinMode(LED_PIN,       OUTPUT);
  pinMode(BUTTON_PIN,    INPUT_PULLUP);

  Serial1.begin(115200);
  Serial1.println("=== Task 1 gestartet ===");
  Serial1.println("Blink ist jetzt: AUS");
}

void loop() {
  unsigned long now = millis();

  // --- Heartbeat ---
  // Toggles onboard LED every 300 ms – always running, sign of life
  if (now - lastHeartbeat >= 300) {
    lastHeartbeat = now;
    digitalWrite(HEARTBEAT_PIN, !digitalRead(HEARTBEAT_PIN));
  }

  // --- Button ---
  // Edge detection + 300 ms time guard to prevent multiple triggers per press
  bool current = digitalRead(BUTTON_PIN);
  if (lastButtonState == HIGH && current == LOW && (now - lastPressTime) > 300) {
    lastPressTime = now;
    blinkEnabled  = !blinkEnabled;

    if (blinkEnabled) {
      Serial1.println("ON");
    } else {
      Serial1.println("OFF");
      digitalWrite(LED_PIN, LOW);
    }
  }
  lastButtonState = current;

  // --- Potentiometer -> blink interval ---
  // Maps ADC 0-4095 to 50-1000 ms, prints to Serial when value changes
  blinkInterval = map(analogRead(POT_PIN), 0, 4095, 50, 1000);

  static unsigned long lastPrintedInterval = 0;
  if (abs((long)blinkInterval - (long)lastPrintedInterval) > 5) {
    lastPrintedInterval = blinkInterval;
    Serial1.print("Intervall: ");
    Serial1.print(blinkInterval);
    Serial1.println(" ms");
  }

  // --- Non-blocking blink ---
  // Toggles external LED only when enabled and interval has elapsed
  if (blinkEnabled && (now - lastBlinkTime >= blinkInterval)) {
    lastBlinkTime = now;
    digitalWrite(LED_PIN, !digitalRead(LED_PIN));
  }
}