#include <Keypad.h>

const int RELAY_PIN  = A5; 
const int ROW_NUM    = 4; 
const int COLUMN_NUM = 4; 

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

byte pin_rows[ROW_NUM] = {9, 8, 7, 6}; 
byte pin_column[COLUMN_NUM] = {5, 4, 3, 2}; 

Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );

const String password_1 = "1234ABC"; 
const String password_2 = "5642CD";  
const String password_3 = "4545B";   
String input_password;


int buttonState = 0;
void setup() {
  Serial.begin(9600);
  input_password.reserve(32);
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW); 
  pinMode(10, OUTPUT);
   
}

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

  if (key){
    Serial.println(key);

    if(key == '*') {
      input_password = ""; 
    } else if(key == '#') {
      if(input_password == password_1 || input_password == password_2 || input_password == password_3) {
        Serial.println("The password is correct, unlocking the door in 20 seconds");
        digitalWrite(RELAY_PIN, HIGH);
        digitalWrite(11, HIGH);
        delay(2000);
        digitalWrite(RELAY_PIN, LOW); 
        digitalWrite(11, LOW);
      } else {
       digitalWrite(10, HIGH);
      }
   


      input_password = ""; 
    } else {
      input_password += key; 
    }
  }
}