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

#define widthScreen 128
#define heightScreen 64
#define resetPin -1

Adafruit_SSD1306 oled(widthScreen, heightScreen, &Wire, resetPin);

const int button1 = 5;
const int button2 = 6;
const int buttonOk = 3;
const int buttonBack = 9;

void setup() {
  Serial.begin(9600);
  if (!oled.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("oled Tidak JALAN");
    for (;;);
  };

  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(buttonOk, INPUT_PULLUP);
  pinMode(buttonBack, INPUT_PULLUP);
}

void loop() {
  mainMenu();
}

void mainMenu() {
  oled.clearDisplay();
  int menu = 0;
  int page = 0;

  while (1) {
    byte readButton1 = digitalRead(button1);
    byte readButton2 = digitalRead(button2);
    byte readButtonOk = digitalRead(buttonOk);
    byte readButtonBack = digitalRead(buttonBack);

    if (page == 0) {
      if (readButton1 == 0) {
        menu++;
        delay(200);
      }
      if (readButton2 == 0) {
        menu--;
        delay(200);
      }
      if (menu >= 3) {
        menu = 0;
      }
      if (menu < 0) {
        menu = 2;
      }
    }

    if (readButtonOk == 0 && menu == 0) {
      page = 1;
      menu = 4;
    }
    if (readButtonOk == 0 && menu == 1) {
      page = 2;
      menu = 4;
    }
    if (readButtonOk == 0 && menu == 2) {
      page = 3;
      menu = 4;
    }
    if (readButtonBack == 0) {
      if (page == 1) {
        menu = 0;
      }
      if (page == 2) {
        menu = 1;
      }
      if (page == 3) {
        menu = 2;
      }
      page = 0;
    }
    switch (menu) {
      case 0:
        oled.clearDisplay();
        oled.setTextSize(1);
        oled.setTextColor(WHITE);
        oled.setCursor(0, 0);
        oled.println("> CALCULATOR");
        oled.println();
        oled.println("  SETTINGS");
        oled.println();
        oled.println("  CONTACTS");
        oled.display();
        break;
      case 1:
        oled.clearDisplay();
        oled.setTextSize(1);
        oled.setTextColor(WHITE);
        oled.setCursor(0, 0);
        oled.println("  CALCULATOR");
        oled.println();
        oled.println("> SETTINGS");
        oled.println();
        oled.println("  CONTACTS");
        oled.display();
        break;
      case 2:
        oled.clearDisplay();
        oled.setTextSize(1);
        oled.setTextColor(WHITE);
        oled.setCursor(0, 0);
        oled.println("  CALCULATOR");
        oled.println();
        oled.println("  SETTINGS");
        oled.println();
        oled.println("> CONTACTS");
        oled.display();
        break;
    }
    switch (page) {
      case 1:
        oled.clearDisplay();
        oled.setTextSize(1);
        oled.setTextColor(WHITE);
        oled.setCursor(0, 0);
        oled.println("Ini Calculator");
        oled.println();
        oled.println("=");
        oled.println();
        oled.println("");
        oled.display();
        break;
      case 2:
        oled.clearDisplay();
        oled.setTextSize(1);
        oled.setTextColor(WHITE);
        oled.setCursor(0, 0);
        oled.println("welcome");
        oled.println();
        oled.println("Ada yang bisa dibantu?");
        oled.println();
        oled.println("---^---");
        oled.display();
        break;
      case 3:
        oled.clearDisplay();
        oled.setTextSize(1);
        oled.setTextColor(WHITE);
        oled.setCursor(0, 0);
        oled.println("Hai! ^_^");
        oled.println();
        oled.println("Selamat, Siang!");
        oled.println();
        oled.println("---^---");
        oled.display();
        break;
    }
  }

}