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


#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET     4 
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


void setup(void) {
  delay(1000);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3D);

  display.clearDisplay();
  display.display();

//Display write
  display.setTextColor(WHITE, BLACK);
}

char Time[] = "  :  :  ";
char Calendar[] = "  /  /20  ";
byte i, second, minute, hour, day, date, month, year;

//Display day
void display_day() {
  switch (day) {
    case 1:
      draw_text(38, 54, " SUNDAY  ", 1);
      break;
    case 2:
      draw_text(38, 54, " MONDAY  ", 1);
      break;
    case 3:
      draw_text(38, 54, " TUESDAY ", 1);
      break;
    case 4:
      draw_text(38, 54, "WEDNESDAY", 1);
      break;
    case 5:
      draw_text(38, 54, "THURSDAY ", 1);
      break;
    case 6:
      draw_text(38, 54, " FRIDAY  ", 1);
      break;
    default:
      draw_text(38, 54, "SATURDAY ", 1);
  }
}

//Display date and time
void DS1307_display() {
  second = (second >> 4) * 10 + (second & 0x0F);
  minute = (minute >> 4) * 10 + (minute & 0x0F);
  hour = (hour >> 4) * 10 + (hour & 0x0F);
  date = (date >> 4) * 10 + (date & 0x0F);
  month = (month >> 4) * 10 + (month & 0x0F);
  year = (year >> 4) * 10 + (year & 0x0F);

  Time[7] = second % 10 + 48;
  Time[6] = second / 10 + 48;
  Time[4] = minute % 10 + 48;
  Time[3] = minute / 10 + 48;
  Time[1] = hour % 10 + 48;
  Time[0] = hour / 10 + 48;
  Calendar[9] = year % 10 + 48;
  Calendar[8] = year / 10 + 48;
  Calendar[4] = date % 10 + 48;
  Calendar[3] = date / 10 + 48;
  Calendar[1] = month % 10 + 48;
  Calendar[0] = month / 10 + 48;


  draw_text(32, 5, Calendar, 1);
  draw_text(14, 25, Time, 2);
}

//Display  texts
void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
  display.setCursor(x_pos, y_pos);
  display.setTextSize(text_size);
  display.print(text);
  display.display();
}

void loop() {
  Wire.beginTransmission(0x68);
  Wire.write(0);
  Wire.endTransmission(false);
  Wire.requestFrom(0x68, 7);
  second = Wire.read();
  minute = Wire.read();
  hour = Wire.read();
  day = Wire.read();
  date = Wire.read();
  month = Wire.read();
  year = Wire.read();
  Wire.beginTransmission(0x68);
  Wire.write(0x11);
  Wire.endTransmission(false);
  Wire.requestFrom(0x68, 2);

  display_day();
  DS1307_display();

  delay(50);
}