#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "RTClib.h"
RTC_DS3231 rtc;
char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 32 // OLED display height, in pixels
#define OLED_RESET 4
int Uhr_h;                    // Variablen für Uhrzeit
int Sommer; 
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
void setup() {
  Serial.begin(9600);
  delay(3000); // wait for console opening
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }
  if (rtc.lostPower()) {
    Serial.println("RTC lost power, lets set the time!");
    // following line sets the RTC to the date & time this sketch was compiled
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
     //rtc.adjust(DateTime(2022, 10, 9, 2, 59, 0));
  }
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3C (for the 128x32)// Check your I2C address and enter it here, in Our case address is 0x3C
  display.clearDisplay();
  display.display(); // this command will display all the data which is in buffer
  display.setTextColor(WHITE, BLACK);
  display.drawRect(118, 25, 3, 3, WHITE);     // Put degree symbol ( ° )
  draw_text(0, 25, "Temperatur =", 1);
  draw_text(122, 25, "C", 1);
}
void loop() {
  Sommer = Sommerzeit();  


  DateTime now = rtc.now();
  /*============Display Date=================*/
display.setTextSize(1);
display.setCursor(0,0);
display.print(daysOfTheWeek[now.dayOfTheWeek()]);
char currentDate [16];
uint8_t thisDay, thisMonth ;
thisDay = now.day();
thisMonth = now.month();
sprintf (currentDate, "%02d/%02d/", thisDay, thisMonth); //add leading zeros to the day and month
display.setTextSize(1);
display.setCursor(62,0);
display.print(currentDate);
display.setTextSize(1);
display.setCursor(102,0);
display.print(now.year(), DEC);
/*================Display Time================*/ 
char buffer [16];
uint8_t thisSec, thisMin, thisHour;
thisSec = now.second();
thisMin = now.minute();
thisHour = (Uhr_h);
sprintf (buffer, "%02d:%02d:%02d", thisHour, thisMin, thisSec);
display.setTextSize(2);
display.setCursor(15,9);
display.print(buffer);
/*=============Display Temperature=====================*/
display.setTextSize(1);
display.setCursor(82,25);
display.print(rtc.getTemperature());
display.display(); 
}
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();
Serial.println(Uhr_h);
Serial.println(Sommer);

}

// Subroutine Uhrzeit ---------------------------------------------------------------
   void Uhrzeit() {
   DateTime now = rtc.now();                   // Datum und Zeit ermitteln
   Uhr_h = int(now.hour());                    // Stunden ermitteln
   if (Sommer = true)              {          // bei Sommerzeit
       Uhr_h = int(now.hour()+1);   }          // 1 Stunde addieren
                  // Uhrzeit
   } // Ende Uhrzeit ----------------------------------------------------------------

   // Subroutine Sommerzeit ermitteln --------------------------------------------------
   boolean Sommerzeit()   {
   DateTime now = rtc.now();
   if (now.month()<3 || now.month()>10) return false;  // keine Sommerzeit Jan - Dez
   if (now.month()>3 && now.month()<10) return true;   // Sommerzeit Apr bis Sep
   if (now.month()==3 && now.day()<25) return false;   // keine Sommerzeit bis 25.März
   if (now.month()==10 && now.day()<25) return true;   // Sommerzeit bis 25.Okt.
   if (now.month()==3 && (now.hour() + 24 * now.day())
       >=(1 + 24*(31 - (5 * now.year() /4 + 4) % 7))
      || now.month()==10 && (now.hour() + 24 * now.day())
      <(1 + 24*(31 - (5 * now.year() /4 + 1) % 7)))
     return true;
   else
     return false;
   } // Ende Sommerzeit -------------------------------------------------------------