#define SENSOR_PIN 2
#define RELAY_PIN 3

unsigned long lastMotionTime = 0;
bool relayState = false;

void setup() {
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(SENSOR_PIN, INPUT);

  digitalWrite(RELAY_PIN, HIGH); // OFF (relay is LOW-level triggered)
  Serial.begin(9600);
  Serial.println("System Ready. Waiting for motion...");
}

void loop() {
  int sensorValue = digitalRead(SENSOR_PIN);

  if (sensorValue == HIGH) {
    digitalWrite(RELAY_PIN, LOW); // Turn ON the relay
    if (!relayState) {
      Serial.println("Motion Detected! Light ON");
    }
    relayState = true;
    lastMotionTime = millis();
  }

  // Check if 5 seconds passed after last motion
  if (relayState && (millis() - lastMotionTime >= 5000)) {
    digitalWrite(RELAY_PIN, HIGH); // Turn OFF the relay
    relayState = false;
    Serial.println("No Motion. 5 seconds passed. Light OFF");
  }

  delay(100); // Small delay for stable reading
}