/*
   ESP32-Based Smart Door Lock System
   
   Purpose:
   This project implements a smart door lock system using an ESP32 microcontroller. The system consists of:
   - A 16x2 I2C LCD for displaying instructions and feedback.
   - A 4x4 matrix keypad for entering the password.
   - A servo motor to physically lock and unlock the door.
   - A predefined password that must be entered correctly to unlock the door.
   - A feature to hide the entered password using '*' characters on the LCD.
   
   How it works:
   - The user enters a 6-digit password using the keypad.
   - The LCD displays '*' for each key press to hide the actual password.
   - If the correct password is entered, the servo rotates to unlock the door.
   - After a few seconds, the door locks automatically.
   - If an incorrect password is entered, an error message is displayed, and the system resets.
*/

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>  // Library for the LCD
#include <Keypad.h>  // Library for handling keypad input
#include <ESP32Servo.h>  // Library for controlling the servo on ESP32

// LCD Configuration
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Servo Configuration
Servo myServo;
int servoPin = 13;  // ESP32 GPIO pin for the servo (Ensure this is a PWM-capable pin)
int closedPos = 0;  // Position when the door is locked
int openPos = 90;   // Position when the door is unlocked

// Keypad Configuration
const uint8_t ROWS = 4;  // Number of rows in the keypad
const uint8_t COLS = 4;  // Number of columns in the keypad
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
uint8_t rowPins[ROWS] = {19, 18, 5, 17};  // GPIO pins connected to the rows
uint8_t colPins[COLS] = {16, 4, 0, 2};    // GPIO pins connected to the columns
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Password Configuration
String password = "123456";  // This is the password
String inputP = "";  // This will store user input

void setup() {
  myServo.attach(servoPin);  
  myServo.write(closedPos);  

  lcd.init();  
  lcd.backlight();  
  lcd.setCursor(0, 0);
  lcd.print("Enter Password:");
}

void loop() {
  char key = keypad.getKey();  

  if (key) {  
    inputP += key;  
    lcd.setCursor(0, 1);
    
    // Display '*' for each character entered (hiding the actual password)
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Enter Password:");
    lcd.setCursor(0, 1);
    for (int i = 0; i < inputP.length(); i++) {
      lcd.print("*");
    }
    

    if (inputP.length() == 6) {
      if (inputP == password) {  // If the entered password is correct
        lcd.clear();
        lcd.print("Unlocked");  // Display unlocked message
        myServo.write(openPos);  // Move servo to unlock the door
        delay(3000);  // Keep the door open for 3 seconds
        lcd.clear();
        lcd.print("Enter Password:");  // Reset display
        myServo.write(closedPos);  // Lock the door again
      } else {
        lcd.clear();
        lcd.print("Wrong Password");  // Display incorrect password message
        delay(2000);  // Wait for 2 seconds
        lcd.clear();
        lcd.print("Enter Password:");  // Reset display
      }
      inputP = "";  // Reset input for next attempt
    }
  }
}