// Pin configuration
const int statePin = 2;      // Input pin from green/red wire
const int relayA = 8;        // Output pin to drive lock
const int relayB = 9;        // Output pin to drive unlock

// Debounce and edge detection
bool lastState = HIGH;       // Initially assume locked
unsigned long lastActionTime = 0;
bool actionInProgress = false;

void setup() {
  pinMode(statePin, INPUT_PULLUP);  // Internal pull-up to detect ground
  pinMode(relayA, OUTPUT);
  pinMode(relayB, OUTPUT);

  digitalWrite(relayA, LOW);
  digitalWrite(relayB, LOW);
}

void loop() {
  bool currentState = digitalRead(statePin); // LOW = unlocked, HIGH = locked

  // Detect state change
  if (currentState != lastState && !actionInProgress) {
    actionInProgress = true;
    lastActionTime = millis();

    if (currentState == LOW) {
      // Central locking says "unlock"
      digitalWrite(relayB, HIGH);  // Reverse polarity
      digitalWrite(relayA, LOW);
    } else {
      // Central locking says "lock"
      digitalWrite(relayA, HIGH);  // Forward polarity
      digitalWrite(relayB, LOW);
    }

    lastState = currentState;
  }

  // Timeout after 2 seconds
  if (actionInProgress && (millis() - lastActionTime > 2000)) {
    digitalWrite(relayA, LOW);
    digitalWrite(relayB, LOW);
    actionInProgress = false;
  }
}