#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
#include <Servo.h>

#define BUZZER 8
#define trigPin 13
#define echoPin 12
#define MAX_DISTANCE 20000

LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo servo;

bool doorClosed = true; // Initialize door state
const int predefinedOTP = 1234; // Predefined numeric OTP
long distance;

const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {7, 6, 5, 4};
byte colPins[COLS] = {3, 2, 1, 0};
Keypad customKeypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.print("SMART DOOR LOCK SYSTEM");
  lcd.setCursor(0, 1);
  delay(1000);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(BUZZER, OUTPUT);
  digitalWrite(BUZZER, LOW);
  servo.attach(10);
  servo.write(90);
  delay(500);
}

void loop() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("OTP BASED DOOR");
  lcd.setCursor(0, 1);
  lcd.print("LOCK USING IOT");

  measureDistance(); // Check distance using ultrasonic sensor

  if (distance <= 200) {
    activateAlarm();
    doorClosed = true;
  } else {
    deactivateAlarm();
  }

  char key = customKeypad.getKey();
  if (key) {
    if (isDigit(key)) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Enter OTP:");
      int enteredOTP = key - '0'; // Convert char to int
      if (enteredOTP == predefinedOTP) {
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Access Granted");
        lcd.setCursor(0, 1);
        lcd.print("Door Opening");
        delay(2000);
        toggleDoor();
        delay(10000);
        toggleDoor(); // Close the door after 10 seconds
        lcd.clear();
        lcd.print("* WELCOME *");
        delay(3000);
      } else {
        lcd.clear();
        lcd.print("Access Failed");
        lcd.setCursor(0, 1);
        lcd.print("Try Again !!!");
        digitalWrite(BUZZER, HIGH);
        delay(2000);
        digitalWrite(BUZZER, LOW);
        delay(3000);
      }
    }
  }
}

void activateAlarm() {
  tone(BUZZER, 200);
}

void deactivateAlarm() {
  noTone(BUZZER);
}

void measureDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  distance = pulseIn(echoPin, HIGH) * 0.034 / 2;
}

void toggleDoor() {
  if (doorClosed) {
    servo.write(180);
    doorClosed = false;
  } else {
    servo.write(90);
    doorClosed = true;
  }
}