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

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

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// create RTC_DS1307 instance
RTC_DS1307 rtc;
boolean check = false;

// create array of a week days
char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

void setup() {
  // put your setup code here, to run once:

  // initialize serial communication
  Serial.begin(9600);

  // start I2C communication
  while(!check)
    if (rtc.begin())
      check = true;
    else Serial.println("begin....");

  // set initial Date-Time
  check = false;
  while(!check){
    if (rtc.isrunning()) {
      rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
      check = true;
    }
    else Serial.println("isrunning....");
    delay(500);
  }

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  // Clear the buffer
  display.clearDisplay();

}

void loop() {
  // put your main code here, to run repeatedly:

    // read value from RTC module
    DateTime dateTime = rtc.now();

    display.clearDisplay();

    display.setTextSize(1);      // Normal 1:1 pixel scale
    display.setTextColor(SSD1306_WHITE); // Draw white text
    display.setCursor(0, 0);     // Start at top-left corner
    display.cp437(true);         // Use full 256 char 'Code Page 437' font

    display.print(dateTime.year(), DEC);
    display.print('/');
    display.print(dateTime.month(), DEC);
    display.print('/');
    display.print(dateTime.day(), DEC);
    display.print(" (");
    display.print(daysOfTheWeek[dateTime.dayOfTheWeek()]);
    display.print(") ");
    display.print(dateTime.hour(), DEC);
    display.print(':');
    display.print(dateTime.minute(), DEC);
    display.print(':');
    display.print(dateTime.second(), DEC);
    display.println(' ');
    
    display.display();
    delay(1000);

}