// Include the library to control Servo motors with ESP32
#include <ESP32Servo.h>

// Include the library to use a keypad
#include <Keypad.h>

// Include the library to control an I2C LCD display
#include <LiquidCrystal_I2C.h>

// Define Blynk credentials for the project
#define BLYNK_TEMPLATE_ID "*********************"
#define BLYNK_TEMPLATE_NAME "IoT Project -Password protect door lock using ESP32 "
#define BLYNK_AUTH_TOKEN "*************************"

// Include libraries required for Blynk and Wi-Fi connectivity
#include <BlynkSimpleEsp32.h>
#include <WiFi.h>
#include <WiFiClient.h>


// WiFi credentials
char ssid[] = "XXXXXXXXXXXXXXXXXXXXXXX";   // SSID of the Wi-Fi network
char pass[] = "XXXXXXXXXXXXXXXX";              // Wi-Fi password (empty for Wokwi guest)

// Define ultrasonic sensor pins
#define PIN_TRIG 34            // Trigger pin of ultrasonic sensor
#define PIN_ECHO 35            // Echo pin of ultrasonic sensor
#define timeDelay 5000         // Delay in milliseconds after successful unlock

// Define keypad configuration
const uint8_t ROWS = 4;        // Number of rows in keypad
const uint8_t COLS = 3;        // Number of columns in keypad

// Key mapping on the keypad
char keys[ROWS][COLS] = {
  { '1', '2', '3',},
  { '4', '5', '6',},
  { '7', '8', '9',},
  { '*', '0', '#',}
};

// Pin numbers for keypad rows and columns
uint8_t rowPins[ROWS] = { 23, 19, 18, 15 }; // Connect to R1, R2, R3, R4
uint8_t colPins[COLS] = { 5, 4, 2 };        // Connect to C1, C2, C3

// Create Servo, LCD, and Keypad objects
Servo myservo;
LiquidCrystal_I2C lcd(0x27, 20, 4);  // I2C address 0x27, 20 columns x 4 rows LCD
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Define default password
String password = "********";     
String enterPass = "";        // To store user-entered password
bool passEntered;             // Flag to check if password prompt was shown

void setup() {
  Serial.begin(9600);                          // Start serial communication

  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);   // Connect to Blynk server using credentials
  
  myservo.attach(11);                          // Attach servo to GPIO 11
  lcd.init();                                  // Initialize the LCD

  pinMode(PIN_TRIG, OUTPUT);                   // Set TRIG pin as output
  pinMode(PIN_ECHO, INPUT);                    // Set ECHO pin as input
}

void loop() {
  // Send a 10 microsecond pulse to trigger the ultrasonic sensor
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

  Blynk.run();  // Keep the Blynk connection alive

  // Read distance from ultrasonic sensor
  int duration = pulseIn(PIN_ECHO, HIGH); // Time of echo pulse
  int distance = duration / 58;           // Convert to centimeters

  if(distance < 150) {  // If an object (e.g., person) is within 150cm
    char key = keypad.getKey(); // Read key press from keypad
    lcd.backlight();            // Turn on LCD backlight

    if (passEntered == false) {  // If password prompt not shown yet
      lcd.setCursor(1, 1);
      lcd.print("ENTER PASSWORD :");
      passEntered = true;        // Mark prompt as shown
    }

    if (key != NO_KEY) {         // If a key was pressed
      if (key == '#') {          // If user presses '#' to submit password
        if (password == enterPass) {  // If password is correct
          beep();                    // Sound buzzer
          myservo.write(0);         // Open the door (servo moves to 0°)

          lcd.clear();              
          lcd.setCursor(1, 0);
          lcd.print("PASSWORD CORRECT");

          lcd.setCursor(1, 1);
          lcd.print("DOOR OPENED");

          delay(timeDelay);         // Wait before closing again
          lcd.clear();
          reset();                  // Reset input and flags
        }
        else {  // If password is incorrect
          myservo.write(90);        // Keep door closed (servo at 90°)

          lcd.clear();
          lcd.setCursor(1, 0);
          lcd.print("PASSWORD INCORRECT");

          reset();                  // Reset input and flags
        }
      }
      else {  // If key is a digit (not '#')
        enterPass += key;            // Append digit to entered password
        lcd.setCursor(1, 3);
        lcd.print(enterPass);        // Show entered password on LCD
      }
    }

  } else { // No one is near the sensor
    myservo.write(90);        // Keep door closed (servo at 90°)

    lcd.clear();              
    lcd.noBacklight();        // Turn off LCD backlight to save power

    reset();                  // Reset input and flags
  }
}

// Function to sound a buzzer
void beep() {
  tone(8, 1000, 50);   // Play tone on pin 8 at 1kHz for 50ms
}

// Function to reset password input
void reset() {
  passEntered = false;  // Reset flag
  enterPass = "";       // Clear entered password
}