#include <Arduino.h>
#include <ESP32Servo.h>
// Pin definitions
const int trigPin = 5;     
const int echoPin = 18;    
const int servoPin = 4;    

// Constants
const int openPosition = 90;     
const int closedPosition = 0;   
const int detectionDistance = 15; 
const int lockDelay = 5000;      

// Objects
Servo doorServo;

// Function to get distance from ultrasonic sensor
long getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  long distance = duration * 0.034 / 2; // Calculate distance in cm
  return distance;
}

void setup() {
  Serial.begin(115200);

  // Initialize pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Initialize servo
  doorServo.attach(servoPin);
  doorServo.write(closedPosition); // Start with door locked

  Serial.println("Smart Door Lock System Initialized");
}

void loop() {
  long distance = getDistance();
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance > 0 && distance <= detectionDistance) {
    // Object detected within range, unlock the door
    Serial.println("Object detected, unlocking door.");
    doorServo.write(openPosition);
    delay(lockDelay); // Keep door open for specified delay

    // Check distance again after delay
    distance = getDistance();
    if (distance > detectionDistance || distance == 0) {
      Serial.println("No object detected, locking door.");
      doorServo.write(closedPosition); // Lock the door
    }
  } else {
    // No object within range, ensure the door is locked
    doorServo.write(closedPosition);
  }

  delay(500); // Short delay for stability
}