#include <Keypad.h>
#include <LiquidCrystal.h>
#include <string.h>
#define RLedPin 10
#define GLedPin 13

// Create an LCD object
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
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] = {9, 8, 7, 6}; // connect to the row pinouts of the keypad
byte pin_column[COLUMN_NUM] = {A1, A2, A3, A4}; // connect to the column pinouts of the keypad

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

int count = 0;
char code[4] = "";

void setup(){
  Serial.begin(9600);
  // Set up the number of columns and rows on the LCD
  lcd.begin(16, 2);
  pinMode(RLedPin, OUTPUT);
  pinMode(GLedPin, OUTPUT);
  welcome();
}

void loop(){
  char key = keypad.getKey();
  
  if (key){
    lcd.print(key);
    strncat(code, &key, 1);
    
    if(count == 4){
      // remove the null character from the end of the code array
      code[4] = '\0';
      if(strcmp(code,"1234") == 0){
        lcd.clear();
        lcd.print("access Granted");
        digitalWrite(GLedPin, HIGH);
        digitalWrite(RLedPin, LOW); // turn off the red LED
      }
      else{
        lcd.clear();
        lcd.print("access Denied");
        digitalWrite(RLedPin, HIGH); // turn on the red LED
        digitalWrite(GLedPin, LOW); // turn off the green LED
      }
      delay(2000);
      // clear the code array by setting all of its elements to \0
      for (int i = 0; i < 4; i++) {
        code[i] = '\0';
      }
      count = 0; // reset the count variable
      welcome();
    }
    else{
      count += 1;
    }
  }
}

void welcome(){
  lcd.clear();
  lcd.print("Welcome");
  delay(2000);
  lcd.clear();
  lcd.print(" enter code:");
}