#include <Keypad.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 10

// Define your passcode
const char passcode[] = "1234"; // Change this to your desired passcode

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

void setup() {
  pinMode(relayPin, OUTPUT); // Set the relay pin as output
  Serial.begin(9600); // Initialize serial communication for debugging
  Serial.println("Enter Passcode:"); // Display initial prompt
}

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);
          Serial.println("\n\n*****Access Granted*****\n");
          delay(2000); // Delay to keep the relay activated for a short duration
          digitalWrite(relayPin, LOW); // Deactivate the relay after delay
        } else {
          Serial.println("\n\n*****Access Denied*****\n");
        }
        memset(enteredCode, 0, sizeof(enteredCode)); // Clear the entered code buffer
      } else {
        Serial.println("\n\n*****Invalid Passcode*****\n");
        memset(enteredCode, 0, sizeof(enteredCode)); // Clear the entered code buffer
      }
      Serial.println("Enter Passcode:"); // Display prompt for next passcode entry
    } else if (strlen(enteredCode) < 4) { // If less than 4 digits have been entered
      Serial.print(key); // Print the pressed key
      enteredCode[strlen(enteredCode)] = key; // Store the pressed key
    }
  }
}