int closePin = 2;   // force close
int bt = 8;
int LED = 13;


uint32_t previousMillis = 0; // time management
uint32_t actMillis = 0; // time management

constexpr uint16_t intervalDoorOpen = 5000; // wie lange soll die Tür offen bleiben


void setup() {
  Serial.begin(9600);
  pinMode(closePin, INPUT_PULLUP);
  pinMode(LED, OUTPUT);
  pinMode(bt, INPUT_PULLUP);
}

void doorOpen()
{
  Serial.println(F("Tür auf"));
  digitalWrite(LED, HIGH);
 }

void doorClose()
{
  Serial.println(F("Tür zu"));
  digitalWrite(LED, LOW);
  
}

uint16_t showRestInterval(uint32_t const* const prevMillis)
{
  uint16_t seconds;
  static uint32_t previousMillisShow = 0;
  actMillis = millis();
  if (actMillis - previousMillisShow > 1000)
  {
    previousMillisShow = actMillis;
    seconds = (intervalDoorOpen - (actMillis - *prevMillis)) / 1000;
    Serial.print(F("remaining interval in sec:"));
    Serial.println(seconds);
  }
  return seconds;
}

void loop() {
  auswahl();
}
void auswahl () {
  static bool printed = false;
  if (!printed)  {
    Serial.println("bt gedrückt?");
    printed = true;
  }
  if (digitalRead(bt) == LOW) {
    ablauf();
    printed = false;
  }
}
void ablauf() {
  previousMillis = millis();
  doorOpen();
  while (millis() - previousMillis <intervalDoorOpen | digitalRead(closePin) == HIGH) {
    digitalRead(closePin);
    if (!showRestInterval(&previousMillis)) break;
  }
  doorClose();
  auswahl();
}