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

#define Password_Length 5 //define the length of the password

int buzzer = 11; //define buzzer pin
int rled = 13; //define led pin
int gled = 12;

char InputData[Password_Length]; //array to save user input password
char Master[Password_Length] = "1234"; //array which correct(existing) password is saved

byte data_count = 0; //variable to save the index of the InputData array
byte master_count = 0; //variable to save the index of Master array

//creating a 2D array to save keypad buttons
char key[4][4] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
  };

//initialize rows and colomns
byte pin_row[4] = {8 , 7, 6, 5};
byte pin_column[4] = {4, 3, 2, 1};

//create object kp
Keypad kp = Keypad(makeKeymap(key), pin_row, pin_column, 4, 4);

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  lcd.init();
  lcd.backlight();
  pinMode(buzzer, OUTPUT);
  pinMode(rled, OUTPUT);
  pinMode(gled, OUTPUT);
}

void loop() {
  lcd.setCursor(0,0);
  lcd.print("Enter Password:");
  //get user input and save in the array "InputData"
  char key = kp.getKey();
  if (key){
    InputData[data_count] = key;
    lcd.setCursor(data_count,1);
    lcd.print(InputData[data_count]);
    data_count++;
    }
    //check the user input password is matching to pre-define password
    if(data_count == Password_Length-1){ //when number of characters are equal to variable "data_count"
    lcd.clear();
    if(!strcmp(InputData, Master)){
      lcd.print("Correct");
      digitalWrite(rled, LOW);
      digitalWrite(buzzer, HIGH);
      digitalWrite(gled, HIGH);
      delay(500);
      digitalWrite(buzzer, LOW);
      }
      else{
        lcd.print("Incorrect");
        digitalWrite(gled, LOW);
        digitalWrite(rled, HIGH);
        for(int i=0; i<10; i++){
          digitalWrite(buzzer, HIGH);
          delay(100);
          digitalWrite(buzzer, LOW);
          delay(300);
        }
        }
        lcd.clear();
        //erase the values in the array
        while(data_count !=0){
        InputData[data_count--] = 0;
        }
    }
}