#include <Servo.h>

// Define pins for the ultrasonic sensor and servo
const int trigPin = 9;
const int echoPin = 10;
const int servoPin = 7;

// Define distance threshold and timeout duration
const int distanceThreshold = 100; // Distance threshold in cm
const unsigned long delayDuration = 5000; // Delay time in milliseconds (5 seconds)

// Variables for distance measurement and timing
long duration;
int distance;
unsigned long objectLeftTime = 0;
bool objectDetected = false;

// Create a Servo object
Servo myServo;

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);

  // Initialize sensor and servo pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Attach the servo to the specified pin
  myServo.attach(servoPin);

  // Set initial servo position to 90 degrees (neutral)
  myServo.write(90);
}

void loop() {
  // Measure the distance
  distance = measureDistance();

  // Check if the object is within the distance threshold
  if (distance <= distanceThreshold) {
    // Object is detected within range, move servo to -180 degrees
    myServo.write(0); // -180 degrees in servo terms
    objectDetected = true;
    Serial.println("Door is open"); // print on serial door is open
    objectLeftTime = 0; // Reset the timer since the object is still within range
  } else {
    // Object is out of range
    if (objectDetected) {
      // Start or continue timing the object's absence
      if (objectLeftTime == 0) {
        objectLeftTime = millis(); // Record the time when the object left
      } else if (millis() - objectLeftTime >= delayDuration) {
        // If the object has been out of range for more than the delay duration
        myServo.write(90); // Move servo back to 90 degrees
        Serial.println("Door is closed");
        objectDetected = false;
      }
    }
  }
/*
  // Optional: Print the distance for debugging
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Small delay to stabilize readings
  delay(100);*/
}

// Function to measure distance using the ultrasonic sensor
int measureDistance() {
  // Clear the trigger pin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigger pin high for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echo pin and calculate the distance
  duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2; // Convert duration to cm
  return distance;
}