#include <U8g2lib.h>
#include <Wire.h>

U8G2_SSD1306_128X64_NONAME_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 4, /* data=*/ 0, /* reset=*/ U8X8_PIN_NONE);

const unsigned char bitmap_item_sel_outline [] PROGMEM = {
  0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 
  0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 
  0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 
  0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0
};

const int NUM_ITEMS = 3;
const int MAX_ITEM_LENGTH = 20;

char menu_items [NUM_ITEMS] [MAX_ITEM_LENGTH] = {
  { "Temperature" }, 
  { "Humidity" }, 
  { "Pressure" }
 };

void screenOpenTemp() {
  u8g2.setFont(u8g2_font_unifont_t_symbols);
  u8g2.setColorIndex(1);
  u8g2.drawStr(0, 20, "Hello 3D Cube!");
}

void screenOpenHum() {
  u8g2.setFont(u8g2_font_unifont_t_symbols);
  u8g2.setColorIndex(1);
  u8g2.drawStr(0, 20, "Hello Battery!");
}

void screenOpenPres() {
  u8g2.setFont(u8g2_font_unifont_t_symbols);
  u8g2.setColorIndex(1);
  u8g2.drawStr(0, 20, "Hello Dash!");
}

void (*screenOpen[NUM_ITEMS])() = {
  screenOpenTemp, 
  screenOpenHum, 
  screenOpenPres
};

#define BUTTON_UP_PIN 12
#define BUTTON_SELECT_PIN 5
#define BUTTON_DOWN_PIN 18

int button_up_clicked = 0;
int button_select_clicked = 0;
int button_down_clicked = 0;
int item_selected = 0;
int item_sel_previous;
int item_sel_next;
int current_screen = 0;

void setup() {
  u8g2.begin();
  pinMode(BUTTON_UP_PIN, INPUT_PULLUP);
  pinMode(BUTTON_SELECT_PIN, INPUT_PULLUP);
  pinMode(BUTTON_DOWN_PIN, INPUT_PULLUP);
}

void loop() {
  if (current_screen == 0) {
      if ((digitalRead(BUTTON_UP_PIN) == LOW) && (button_up_clicked == 0)) {
        item_selected = item_selected - 1;
        button_up_clicked = 1;
        if (item_selected < 0) {
          item_selected = NUM_ITEMS-1;
        }
      }
      else if ((digitalRead(BUTTON_DOWN_PIN) == LOW) && (button_down_clicked == 0)) {
        item_selected = item_selected + 1;
        button_down_clicked = 1;
        if (item_selected >= NUM_ITEMS) {
          item_selected = 0;
          }
      } 

      if ((digitalRead(BUTTON_UP_PIN) == HIGH) && (button_up_clicked == 1)) { 
        button_up_clicked = 0;
      }
      if ((digitalRead(BUTTON_DOWN_PIN) == HIGH) && (button_down_clicked == 1)) {
        button_down_clicked = 0;
      }
  }

  if ((digitalRead(BUTTON_SELECT_PIN) == LOW) && (button_select_clicked == 0)) {
     button_select_clicked = 1;
     if (current_screen == 0) {current_screen = 1;}
     else {current_screen = 0;}
  }
  if ((digitalRead(BUTTON_SELECT_PIN) == HIGH) && (button_select_clicked == 1)) {
    button_select_clicked = 0;
  }

  item_sel_previous = item_selected - 1;
  if (item_sel_previous < 0) {item_sel_previous = NUM_ITEMS - 1;}
  item_sel_next = item_selected + 1;  
  if (item_sel_next >= NUM_ITEMS) {item_sel_next = 0;}

  u8g2.firstPage();
  do {

    if (current_screen == 0) { // MENU SCREEN
      u8g2.drawBitmap(0, 22, 128/8, 21, bitmap_item_sel_outline);
      u8g2.setFont(u8g2_font_7x14_tf);
      u8g2.drawStr(25, 15, menu_items[item_sel_previous]);         
      u8g2.setFont(u8g2_font_7x14B_tf);   
      u8g2.drawStr(25, 15+20+2, menu_items[item_selected]);       
      u8g2.setFont(u8g2_font_7x14_tf);     
      u8g2.drawStr(25, 15+20+20+2+2, menu_items[item_sel_next]);     
      //u8g2.drawBitmapP(128-8, 0, 8/8, 64, bitmap_scrollbar_background);
      u8g2.drawBox(125, 64/NUM_ITEMS * item_selected, 3, 64/NUM_ITEMS);              
    } 
    else if (current_screen == 1) {
        screenOpen[item_selected]();
    }  
  } while ( u8g2.nextPage() );
  }