// Include the library code:
#include<Bounce2.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

Bounce2::Button buttonUP = Bounce2::Button();
Bounce2::Button buttonDOWN = Bounce2::Button();

#define UPDATE_INTERVAL 1 // Time is seconds

#define BUTTONUP_PIN 4
#define BUTTONDOWN_PIN 3

int menuIndex = 0;
unsigned long prevMillis = 0;

void setup()
{
  Serial.begin(9600);

  buttonUP.attach(BUTTONUP_PIN, INPUT_PULLUP);
  buttonDOWN.attach(BUTTONDOWN_PIN, INPUT_PULLUP);

  buttonUP.interval(5);
  buttonUP.setPressedState(LOW);

  buttonDOWN.interval(5);
  buttonDOWN.setPressedState(LOW);

  lcd.init();
  lcd.backlight();

  prevMillis = (millis() - (UPDATE_INTERVAL * 1000UL));
  
  Serial.print("prevMillis: ");
  Serial.println(prevMillis);
}

uint8_t i = 0;

void loop()
{
  buttonUP.update();
  buttonDOWN.update();

  if (buttonUP.pressed())
  {
    menuIndex++;
    prevMillis = millis() - (UPDATE_INTERVAL * 1000UL);
    if (menuIndex > 3)
    {
      menuIndex = 3;
    }
  }

  if (buttonDOWN.pressed())
  {
    menuIndex--;
    prevMillis = millis() - (UPDATE_INTERVAL * 1000UL);
    if (menuIndex < 0)
    {
      menuIndex = 0;
    }
  }

  switch (menuIndex)
  {
    case 0:
      {
        if ((millis() - prevMillis) > (UPDATE_INTERVAL * 1000UL))
        {
          lcd.setCursor(0, 0);
          lcd.print("Menu 0");
          lcd.setCursor(0, 1);
          lcd.print(millis() / 1000);
          prevMillis = millis();
        }
        break;
      }
    case 1:
      {
        if ((millis() - prevMillis) > (UPDATE_INTERVAL * 1000UL))
        {
          lcd.setCursor(0, 0);
          lcd.print("Menu 1");
          lcd.setCursor(0, 1);
          lcd.print(millis() / 1000);
          prevMillis = millis();
        }
        break;
      }
    case 2:
      {
        if ((millis() - prevMillis) > (UPDATE_INTERVAL * 1000UL))
        {
          lcd.setCursor(0, 0);
          lcd.print("Menu 2");
          lcd.setCursor(0, 1);
          lcd.print(millis() / 1000);
          prevMillis = millis();
        }
        break;
      }
    case 3:
      {
        if ((millis() - prevMillis) > (UPDATE_INTERVAL * 1000UL))
        {
          lcd.setCursor(0, 0);
          lcd.print("Menu 3");
          lcd.setCursor(0, 1);
          lcd.print(millis() / 1000);
          prevMillis = millis();
        }
        break;
      }
    default:
      {
        break;
      }
  }
}