#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>

#define widthScreen 128
#define heightScreen 64

Adafruit_SSD1306 display(widthScreen, heightScreen, &Wire, -1);

int buttonSatu = 6;
int buttonDua = 5;
int enter = 4;
int back = 3;

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

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED gagal terkoneksi");
    for (;;);
  }

  pinMode(buttonSatu, INPUT_PULLUP);
  pinMode(buttonDua, INPUT_PULLUP);
  pinMode(enter, INPUT_PULLUP);
  pinMode(back, INPUT_PULLUP);
}

void loop() {
  mainMenu();
}

void mainMenu() {
  display.clearDisplay();
  int menu = 0;
  int submenu = 0;

  while (1) {
    byte readbuttonSatu = digitalRead(buttonSatu);
    byte readbuttonDua = digitalRead(buttonDua);
    byte readEnter = digitalRead(enter);
    byte readBack = digitalRead(back);

    if (submenu == 0) {
      if (readbuttonSatu == 0) {
        menu++;
        delay(200);
      }

      if (readbuttonDua == 0) {
        menu--;
        delay(200);
      }

      if (menu > 3) {
        menu = 0;
      }

      if (menu < 0) {
        menu = 2;
      }
    }

    if (readEnter == 0 && menu == 0) {
      submenu = 1;
      menu = 4;
    }
    if (readEnter == 0 && menu == 1) {
      submenu = 2;
      menu = 4;
    }
    if (readEnter == 0 && menu == 2) {
      submenu = 3;
      menu = 4;
    }

     if (readBack == 0) {
      if (submenu == 1) {
        menu = 0;
      }
      if (submenu == 2) {
        menu = 1;
      }
      if (submenu == 3) {
        menu = 2;
      }
      submenu = 0;
    }

    switch (menu) {
      case 0:
        display.clearDisplay();
        display.setTextSize(1);
        display.setCursor(0, 0);
        display.setTextColor(WHITE);
        display.println("> Calculator");
        display.println("  Setting");
        display.println("  Contact");
        display.display();
        break;
      case 1:
        display.clearDisplay();
        display.setTextSize(1);
        display.setCursor(0, 0);
        display.setTextColor(WHITE);
        display.println("  Calculator");
        display.println("> Setting");
        display.println("  Contact");
        display.display();
        break;
      case 2:
        display.clearDisplay();
        display.setTextSize(1);
        display.setCursor(0, 0);
        display.setTextColor(WHITE);
        display.println("  Calculator");
        display.println("  Setting");
        display.println("> Contact");
        display.display();
        break;
    }

    switch (submenu) {
      case 1:
        display.clearDisplay();
        display.setTextSize(1);
        display.setTextColor(WHITE);
        display.setCursor(0, 0);
        display.println("Ini Calculator");
        display.display();
        break;
      case 2:
        display.clearDisplay();
        display.setTextSize(1);
        display.setTextColor(WHITE);
        display.setCursor(0, 0);
        display.println("Ini Settings");
        display.display();
        break;
      case 3:
        display.clearDisplay();
        display.setTextSize(1);
        display.setTextColor(WHITE);
        display.setCursor(0, 0);
        display.println("Ini Contact");
        display.display();
        break;
    }
  }
}