//Include the graphics library.
#include "U8glib.h" 
//Initialize display.
U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE | U8G_I2C_OPT_DEV_0);

 #define outputA 2
 #define outputB 3

 int counter = 0; 
 int aState;
 int aLastState; 

 #define MENU_ITEMS 3
const char *menu_strings[MENU_ITEMS] = { " ","DASHBOARD", "SETTINGS", "CALIBRATE"};
void setup(void)
{
   pinMode (outputA,INPUT);
   pinMode (outputB,INPUT);

   Serial.begin(115200);
    //Set font.
    u8g.setFont(u8g_font_unifont);
}
void loop(void)
{
  rotary();
    u8g.firstPage();
    do {
        draw();
        drawSubMenu();
    } while (u8g.nextPage());
    //Delay before repeating the loop.
    delay(50);
}
void draw(void)
{
    //Write text. (x, y, text)
    u8g.setFont(u8g_font_unifont);
    u8g.drawStr(25, 10, "MAIN MENU");
    u8g.drawHLine(0,12,128);  
    
}

void drawSubMenu(){
    u8g.setFont(u8g_font_5x7);
    for(int i=0;i<=MENU_ITEMS;i++){
    u8g.drawStr(5, 20*i, menu_strings[i]);
    }
}

void rotary(){
  aState = digitalRead(outputA); // Reads the "current" state of the outputA
   // If the previous and the current state of the outputA are different, that means a Pulse has occured
   if (aState != aLastState){     
     // If the outputB state is different to the outputA state, that means the encoder is rotating clockwise
     if (digitalRead(outputB) != aState) { 
       counter ++;
     } else {
       counter --;
     }
     Serial.print("Position: ");
     Serial.println(counter);
   } 
   aLastState = aState; // Updates the previous state of the outputA with the current state
}