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

// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define the key map as per your keypad connections
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns

// Define the Keymap
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte rowPins[ROWS] = {9, 8, 7, 6}; 
// Connect keypad COL0, COL1, COL2 and COL3 to these Arduino pins.
byte colPins[COLS] = {5, 4, 3, 2};

// Create the Keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Predefined credentials
String correctUsername = "user";
String correctPassword = "pass";
String inputUser = "";
String inputPass = "";

// Control variables
int attemptCount = 0;
bool isLocked = false;
unsigned long lockStartTime;

void setup() {
  lcd.init();                      // Initialize the lcd 
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Enter Username:");
}

void loop() {
  if (isLocked) {
    if (millis() - lockStartTime > 900000) { // 15 minutes lockout
      isLocked = false;
      attemptCount = 0;
      lcd.clear();
      lcd.print("Enter Username:");
    } else {
      return; // Stay locked
    }
  }

  char key = keypad.getKey();
  
  if (key) {
    lcd.setCursor(0, 1);
    if (inputUser.length() < 4) { // Assuming username is 4 characters
      inputUser += key;
      lcd.print(inputUser);
    } else if (inputPass.length() < 4) { // Assuming password is 4 characters
      inputPass += key;
      lcd.print('*');
    }

    if (inputPass.length() == 4) {
      if (inputUser == correctUsername && inputPass == correctPassword) {
        lcd.clear();
        lcd.print("Access Granted");
        delay(2000); // Display for 2 seconds
        lcd.clear();
        lcd.print("Enter Username:");
        inputUser = "";
        inputPass = "";
      } else {
        attemptCount++;
        if (attemptCount >= 3) {
          lcd.clear();
          lcd.print("Locked 15 min");
          isLocked = true;
          lockStartTime = millis();
        } else {
          lcd.clear();
          lcd.print("Try Again");
          delay(2000); // Display for 2 seconds
          lcd.clear();
          lcd.print("Enter Username:");
        }
        inputUser = "";
        inputPass = "";
      }
    }
  }
}