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

LiquidCrystal_I2C lcd(0x27, 20, 4); // Change the I2C address if needed

const int BUTTON_UP = 15;     // Pin for the "Up" button
const int BUTTON_DOWN = 18;   // Pin for the "Down" button
const int BUTTON_SELECT = 19; // Pin for the "Select" button

enum Screen {
  START,
  MAIN_MENU,
  SUB_MENU,
};

Screen currentScreen = START;
int selectedOption = 0;
bool submenuActive = false;

void setup() {
  lcd.init();
  lcd.backlight();
  pinMode(BUTTON_UP, INPUT_PULLUP);
  pinMode(BUTTON_DOWN, INPUT_PULLUP);
  pinMode(BUTTON_SELECT, INPUT_PULLUP);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("START");
  delay(2000);
  lcd.clear();
}

void loop() {
  handleButtons();

  switch (currentScreen) {
    case START:
      displayStartScreen();
      break;
    case MAIN_MENU:
      displayMainMenu();
      break;
    case SUB_MENU:
      displaySubMenu();
      break;
  }
}

void handleButtons() {
  static unsigned long lastDebounceTime = 0;
  static unsigned long debounceDelay = 50;

  int readingUp = digitalRead(BUTTON_UP);
  int readingDown = digitalRead(BUTTON_DOWN);
  int readingSelect = digitalRead(BUTTON_SELECT);

  if (millis() - lastDebounceTime > debounceDelay) {
    if (readingUp == LOW) {
      if (currentScreen == MAIN_MENU || (currentScreen == SUB_MENU && submenuActive)) {
        selectedOption = (selectedOption + 1) % (submenuActive ? 6 : 5);
      }
      lastDebounceTime = millis();
    } else if (readingDown == LOW) {
      if (currentScreen == MAIN_MENU || (currentScreen == SUB_MENU && submenuActive)) {
        selectedOption = (selectedOption + (submenuActive ? 5 : 4)) % (submenuActive ? 6 : 5);
      }
      lastDebounceTime = millis();
    } else if (readingSelect == LOW) {
      if (currentScreen == START) {
        currentScreen = MAIN_MENU;
      } else if (currentScreen == MAIN_MENU) {
        if (selectedOption == 4) {
          currentScreen = START;
        } else {
          if (selectedOption == 3) {
            submenuActive = true;
            selectedOption = 0;
            currentScreen = SUB_MENU;
          } else {
            // Handle actions for other options in the main menu
          }
        }
      } else if (currentScreen == SUB_MENU) {
        // Handle actions for options in the sub-menu
      }
      lastDebounceTime = millis();
    }
  }
}

void displayStartScreen() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("START");
}

void displayMainMenu() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Option 1");
  lcd.setCursor(0, 1);
  lcd.print("Option 2");
  lcd.setCursor(0, 2);
  lcd.print("Option 3");
  lcd.setCursor(0, 3);
  lcd.print("Option 4");
  lcd.setCursor(0, 4);
  lcd.print("Return");
}

void displaySubMenu() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Sub-option 1");
  lcd.setCursor(0, 1);
  lcd.print("Sub-option 2");
  lcd.setCursor(0, 2);
  lcd.print("Sub-option 3");
  lcd.setCursor(0, 3);
  lcd.print("Sub-option 4");
  lcd.setCursor(0, 4);
  lcd.print("Sub-option 5");
  lcd.setCursor(0, 5);
  lcd.print("Sub-option 6");
}