#include <Arduino.h>
#include <LiquidCrystal.h>
#include <Keypad.h>

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

const byte ROWS = 4;
const byte COLS = 3;
char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {13, 10, A0};
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

const String defaultPassword = "1234";
String currentPassword = defaultPassword;
bool isAuthenticated = false;
enum State {
  ENTER_PASSWORD,
  ACCESS_GRANTED,
  ACCESS_DENIED,
  MENU,
  CHANGE_PASSWORD,
  ADD_MODE,
  START_MODE
};
State currentState = ENTER_PASSWORD;

String inputBuffer = "";

void setup() {
  lcd.begin(16, 2);
  Serial.begin(9600);
  lcd.print("Enter password:");
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    if (key == '#') {
      handleInput(inputBuffer);
      inputBuffer = "";
    } else {
      inputBuffer += key;
      lcd.setCursor(inputBuffer.length() - 1, 1);
      lcd.print(key);
    }
  }
}

void handleInput(const String &input) {
  if(input=="reset" || input=="clear") currentState=ENTER_PASSWORD;
  switch (currentState) {
    case ENTER_PASSWORD :
      enterPassword(input);
      break;
    case MENU:
      menu(input);
      break;
    case CHANGE_PASSWORD:
      changePassword(input);
      break;
    case ADD_MODE:
      // Handle ADD_MODE
      break;
    case START_MODE:
      // Handle START_MODE
      break;
    default:
      // Handle other states
      break;
  }
}

void enterPassword(const String &password) {
  if (password == currentPassword) {
    currentState = ACCESS_GRANTED;
    lcd.clear();
    lcd.print("Access granted!");
    delay(500);
    currentState = MENU;
    lcd.clear();
    lcd.print("(1)Change password?");
    delay(1000);
  } else {
    currentState = ENTER_PASSWORD;
    lcd.clear();
    lcd.print("Access denied!");
    delay(500);
    lcd.clear();
    lcd.print("Enter password:");
  }
}

void menu(const String &menuSelection) {
  switch (menuSelection.toInt()) {
    case 1:
      currentState = CHANGE_PASSWORD;
      lcd.clear();
      lcd.print("CHANGE PASSWORD");
      break;
    case 2:
      currentState = ADD_MODE;
      lcd.clear();
      lcd.print("ADD MODE");
      delay(500);
      break;
    case 3:
      currentState = START_MODE;
      lcd.clear();
      lcd.print("START MODE");
      delay(500);
      break;
    default:
      currentState = MENU;
      break;
  }
}

void changePassword(const String &newpassword) {
  lcd.clear();
  lcd.print("New password:");
  if (newpassword.length() >= 4) {
    currentPassword = newpassword;
    currentState = MENU;
  } else {
    lcd.clear();
    lcd.print("Bad Password!");
    delay(500);
    currentState = CHANGE_PASSWORD;
  }
}