#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <windows.h>
short Year, Month, Day, Weekday;
short Hour, Minute, Second;
short DaysThisMonth;

char Months[13][4] = { " ", "JAN", "FEB", "MAR", "APR", "MAY", "JUN",
                        "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"};

char Days[8][12] = {" ", "SUNDAY ", "MONDAY ", "TUESDAY ",
                     "WEDNESDAY ", "THURSDAY", "FRIDAY ", "SATURDAY "};

short DaysInMonth[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

void ShowTime(void)
{
    printf("%d %d %d %d:%d:%d\n",Year,Month,Day,Hour,Minute,Second);

}
bool IsLeapYear(short thisyear)
// is thisyear a leap year?
{
  bool result;
  result = false;
  if ( (thisyear % 1000) == 0 )
  { // millenium
    result = ((thisyear / 1000) % 2) == 0;
  } // millenium
  else
  { // not millenium
    if ( (thisyear % 400) == 0)
    { // every 400 years
      result = true;
    } // every 400 years
    else
    { // not 400 years
      if ( (thisyear % 100) == 0)
      { // every 100 years
        result = false;
      } // every 100 years
      else
      { // not 100 years
        if ( (thisyear % 4) == 0)
        { // every 4 years
          result = false;
        } // every 4 years
      } // not 100 years
    } // not 400 years
  } // not millenium
  return result;
}

short DaysInThisMonth(short year, short month)
// how many days in year, month
{
  short days;
  days = 28;
  if (month == 2)
  { // February
    if ( IsLeapYear(year) ) days = 29;
  } // February
  else
  { // Not February
    days = DaysInMonth[month];
  } // Not February
  return days;
}
void init_Date_Time(void)
{
  Year = 2000;
  Month = 2;
  Day = 28;
  Weekday = 3; // Sunday = 1

  Hour = 23;
  Minute = 59;
  Second = 55;

  DaysThisMonth = DaysInThisMonth(Year, Month);
}

int main()
{
    init_Date_Time();
    while(1)
    {
        Sleep(1000);
        if (++Second >= 60)
  { // next mimute
    Second = 0;
    if (++Minute >= 60)
    { // next hour
      Minute = 0;
      if (++Hour >=24)
      { // next day
        Hour = 0;
        if (++Weekday > 7) Weekday = 1;
        if (++Day > DaysThisMonth)
        { // next month
          Day = 1;
          ++Month;
          DaysThisMonth = DaysInThisMonth(Year, Month);
          if (Month > 12)
           { // new year
             ++Year;
             Month = 1;
             DaysThisMonth = 31;  // January
           } // new year
        } // next month
      } // next day
    } // next hour
  } // next minute
  ShowTime();
    }
}