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

const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns

char keys[ROWS][COLS] =
{
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {9, 8, 7, 6}; // Connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3, 2}; // Connect to the column pinouts of the keypad

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

const int relayPin = 13; // Connect the relay to pin 13

// Define passcode
const char passcode[] = "0704"; // Change this to your desired passcode

char enteredCode[5]; // Buffer to store entered code

// Initialize the LCD
LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD I2C address to 0x27, 16 characters and 2 lines

void setup()
{
  pinMode(relayPin, OUTPUT); // Set the relay pin as output
  Serial.begin(9600); // Initialize serial communication for debugging
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  Serial.println("Enter Passcode:");
  lcd.print("Enter Passcode:");
  lcd.setCursor(0, 1); // Set cursor to the first column of the second row
}

void loop()
{
  char key = keypad.getKey();
  
  if (key)
  {
    if (key == '#') // If # key is pressed, check the passcode
    {
      if (strlen(enteredCode) == 4) // Check if passcode length is 4
      {
        enteredCode[4] = '\0'; // Null terminate the string
        if (strcmp(enteredCode, passcode) == 0) // If the entered passcode matches the stored passcode, activate the relay
        {
          digitalWrite(relayPin, HIGH);
          lcd.clear();
          Serial.println("\nAccess Granted");
          lcd.print("Access Granted");
          delay(20000); // Delay to keep the relay activated for a short duration
          digitalWrite(relayPin, LOW); // Deactivate the relay after delay
          lcd.clear();
        }
        else
        {
          lcd.clear();
          Serial.println("\nAccess Denied");
          lcd.print("Access Denied");
        }
        memset(enteredCode, 0, sizeof(enteredCode)); // Clear the entered code buffer
      }
      else
      {
        lcd.clear();
        Serial.println("\nInvalid Passcode");
        lcd.print("Invalid Passcode");
        memset(enteredCode, 0, sizeof(enteredCode)); // Clear the entered code buffer
      }
      delay(1000);
      lcd.clear();
      Serial.println("\nEnter Passcode:");
      lcd.print("Enter Passcode:"); // Display prompt for next passcode entry
      lcd.setCursor(0, 1); // Set cursor to the first column of the second row
    }
    else if (strlen(enteredCode) < 4) // If less than 4 digits have been entered
    {
      enteredCode[strlen(enteredCode)] = key; // Store the pressed key
      Serial.print(key);
      lcd.print(key); // Print the pressed key on LCD
    }
  }
}