int ledPin = 26;
int pirPin = 27;

int mode = 0; // 0=NORMAL, 1=NIGHT, 2=AWAY

unsigned long lastMotionTime = 0;
const int delayTime = 5000;

bool ledState = false;
bool lastPIRState = LOW; // PIR starts LOW (no motion)

String command = "";

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(pirPin, INPUT); // PIR drives its own signal, no pullup needed
  Serial.begin(9600);
  Serial.println("Mode: NORMAL"); // print initial mode
}

void loop() {

  // ---- SERIAL COMMAND HANDLING ----
  if (Serial.available()) {
    command = Serial.readStringUntil('\n');
    command.trim();

    if (command == "ON") {
      if (mode == 0) {
        ledState = true;
        Serial.println("App: Light ON");
      } else {
        Serial.println("ON command ignored (not in NORMAL mode)");
      }
    }
    else if (command == "OFF") {
      if (mode == 0) {
        ledState = false;
        Serial.println("App: Light OFF");
      } else {
        Serial.println("OFF command ignored (not in NORMAL mode)");
      }
    }
    else if (command == "NORMAL") {
      mode = 0;
      ledState = false;
      Serial.println("Mode: NORMAL");
    }
    else if (command == "NIGHT") {
      mode = 1;
      ledState = false;
      lastMotionTime = 0;
      Serial.println("Mode: NIGHT");
    }
    else if (command == "AWAY") {
      mode = 2;
      ledState = false;
      Serial.println("Mode: AWAY");
    }

    command = "";
  }

  // ---- MODE LOGIC ----

  if (mode == 0) {
    // NORMAL: LED controlled only by serial ON/OFF
  }

  else if (mode == 1) {
    // NIGHT: PIR triggers LED for 5 seconds
    int currentPIRState = digitalRead(pirPin);

    // Detect rising edge (PIR goes HIGH when motion detected)
    if (lastPIRState == LOW && currentPIRState == HIGH) {
      ledState = true;
      lastMotionTime = millis();
      Serial.println("Motion detected -> ON");
    }
    lastPIRState = currentPIRState;

    // Auto OFF after 5 seconds
    if (ledState == true && millis() - lastMotionTime >= delayTime) {
      ledState = false;
      Serial.println("No motion -> OFF");
    }
  }

  else if (mode == 2) {
    // AWAY: always OFF, no exceptions
    ledState = false;
  }

  digitalWrite(ledPin, ledState);
}