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

#define RELAY_PIN1  25

const int ROW_NUM    = 4; // four rows
const int COLUMN_NUM = 4; // four columns

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] = {2, 0, 4, 16};      // connect to the row pinouts of the keypad
byte pin_column[COLUMN_NUM] = {12, 14, 27, 26}; // connect to the column pinouts of the keypad

Keypad keypad = Keypad(makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows

const String password_1 = "555";
const String password_2 = "0";
String input_password;

int cursorColumn = 0;

void setup(){
  
  Serial.begin(9600);
  input_password.reserve(32); // maximum password size is 32, change if needed
  pinMode(RELAY_PIN1, OUTPUT);
   // initialize pin as an output.
  digitalWrite(RELAY_PIN1, LOW);
  
  lcd.init(); // initialize the lcd
  lcd.backlight();
 
}

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

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

    if (key) {
    lcd.setCursor(cursorColumn, 0); // move cursor to   (cursorColumn, 0)
    lcd.print(key);
                     // print key at (cursorColumn, 0)

    cursorColumn++;                 // move cursor to next position
    if(cursorColumn == 16) {        // if reaching limit, clear LCD
      lcd.clear();
      cursorColumn = 0;
     }
    }

    if (key == '*') {
      input_password = ""; // reset the input password
    } else if (key == '#') {
      if (input_password == password_1 , input_password == password_2 ) {
        Serial.println("The password is correct, turning ON relay");
        digitalWrite(RELAY_PIN1, HIGH);
        
      } else {
        Serial.println("The password is incorrect, try again");
      }

      input_password = ""; // reset the input password
    } else {
      input_password += key; // append new character to input password string
    }
    
  }
  
}