const int BUTTON_PIN = 2;

// ---- Job A: keep-alive ----
const unsigned long ALIVE_INTERVAL_MS = 2000;
unsigned long lastAlive = 0;

// ---- Job B: debounced press detection ----
const unsigned long DEBOUNCE_MS = 50;
int lastReading = HIGH;
int stableState = HIGH;
unsigned long lastChangeTime = 0;

void setup() {
  Serial.begin(115200);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
}

void loop() {
  // ---- Job A: print "System Alive" every 2 seconds ----
  if (millis() - lastAlive >= ALIVE_INTERVAL_MS) {
    lastAlive = millis();
    Serial.println("System Alive");
  }

  // ---- Job B: print "Button pressed" once per debounced press ----
  int reading = digitalRead(BUTTON_PIN);
  if (reading != lastReading) {
    lastChangeTime = millis();
  }
  if (millis() - lastChangeTime >= DEBOUNCE_MS) {
    if (reading != stableState) {
      stableState = reading;
      if (stableState == LOW) {           // the press edge (active-low)
        Serial.println("Button pressed");
      }
    }
  }
  lastReading = reading;
}