Odate.cpp

//Filename    : ODATE.CPP
//Description : Date Information Object

#include <stdlib.h>
#include <string.h>
#include <windowsx.h>

#include <OSTR.H>
#include <OMISC.H>
#include <ODATE.H>

//--------- Define static member variables -----------//

#define  JULIAN_ADJUSTMENT    1721425L

static char month_str_array[][10] = {
    "January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December"
} ;

static int month_tot[]=
{ 0, 0,  31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }
;

// Jan Feb Mar  Apr  May  Jun   Jul  Aug  Sep  Oct  Nov  Dec
// 31  28  31   30   31   30     31   31   30   31   30   31

//------------ Begin of function DateInfo::julain ----------//
//!
//! Convert from year, month, day integer format to julian date format
//!
//! Julian day is the number of days since the date  Jan 1, 4713 BC
//! Ex.  Jan 1, 1981 is  2444606
//!
//! <int> year, month, day = the components of the date
//!
//! Return : <long> the julian date
//!          -1     illegal given date
//!
long DateInfo::julian( int year, int month, int day ) {
    long  total, dayYear ;

    dayYear    =  day_year( year, month, day) ;

    if (dayYear < 1)
	return( -1) ;                                 /* Illegal Date */

    total =  ytoj(year) ;
    total+=  dayYear ;
    total+=  JULIAN_ADJUSTMENT ;

    return total;
}

//-------------- End of function DateInfo::julian ------------//

//--------- Begin of function DateInfo::julian ---------//
//!
//! Convert a string such as "07/03/93" to long number
//!
//! Returns:
//! <int> >0  -  Julian day
//!              That is the number of days since the date  Jan 1, 4713 BC
//!              Ex.  Jan 1, 1981 is  2444606
//!        0  -  NULL Date (dbf_date is all blank)
//!       -1  -  Illegal Date
//!
long DateInfo::julian( char *dateStr ) {
    return julian( m.atoi( dateStr,4 ), m.atoi( dateStr+4,2 ),
		   m.atoi( dateStr+6,2 ) );
}

//---------- End of function DateInfo::julian ----------//

//------------ Begin of function DateInfo::get_date ---------//
//!
//! Return year, month or day of the given julian date
//!
//! <long> julianDate = the julian date to be converted
//! <char> returnType = 'Y'-year, 'M'-month, 'D'-day
//!
//! Return : the year, month or day of the julian date
//!          -1 if the julian date passed is invalid
//!
int DateInfo::get_date( long julianDate, char returnType ) {
    int   year, month, day, nDays, maxDays ;
    long   totalDays ;

    //JULIAN_ADJUSTMENT = 1721425
    if ( julianDate > 5373484 || julianDate < JULIAN_ADJUSTMENT )
	return -1;

    totalDays  =  (long) (julianDate) - JULIAN_ADJUSTMENT ;
    year       =  (int) ((double)totalDays/365.2425) + 1 ;
    nDays      =  (int) (totalDays -  ytoj(year)) ;

    if ( nDays <= 0 ) {
	year-- ;
	nDays   =  (int) (totalDays - ytoj(year)) ;
    }

    if (year%4 == 0 && year%100 != 0 || year%400 == 0)
	maxDays =  366 ;
    else
	maxDays =  365 ;

    if ( nDays > maxDays ) {
	year++ ;
	nDays -= maxDays ;
    }

    if ( month_day( year, nDays, month, day ) < 0 )
	return -1;

    //............................................//

    switch( returnType ) {
    case 'Y':
	return year;

    case 'M':                                     // return the month
	return month;

    case 'D':
	return day;
    }

    return 0;
}

//------------- End of function DateInfo::get_date --------//

//------------ Begin of function DateInfo::	 ---------//
//!
//! Convert from julian date format to string date format
//! Return a date string in the format of DD MMM YYYY e.g. 15 Jan 1992
//!
//! Julian day is the number of days since the date  Jan 1, 4713 BC
//! Ex.  Jan 1, 1981 is  2444606
//!
//! <long> julianDate    = the julian date to be converted
//! [int]  shortMonthStr = short month string or not (e.g. Jan instead of January)
//!                        (default : 0)
//! [int]  showDate = show date or not
//!                        (default : 1)
//!
//! Return : <char*> the formated date string
//!
char* DateInfo::date_str( long julianDate, int shortMonthStr, int showDate) {
    int    year, month, day, nDays, maxDays ;
    long   totalDays ;
    static char strBuf[10];

    if ( julianDate > 5373484 || julianDate < JULIAN_ADJUSTMENT ) {
	strBuf[0]=NULL;
	return strBuf;
    }

    totalDays  =  (long) (julianDate) - JULIAN_ADJUSTMENT ;
    year       =  (int) ((double)totalDays/365.2425) + 1 ;
    nDays      =  (int) (totalDays -  ytoj(year)) ;

    if ( nDays <= 0 ) {
	year-- ;
	nDays   =  (int) (totalDays - ytoj(year)) ;
    }

    if (year%4 == 0 && year%100 != 0 || year%400 == 0)
	maxDays =  366 ;
    else
	maxDays =  365 ;

    if ( nDays > maxDays ) {
	year++ ;
	nDays -= maxDays ;
    }

    if ( month_day( year, nDays, month, day ) < 0 ) {
	strBuf[0]=NULL;
	return strBuf;
    }

    //--------------------------------------------//

    static String str;

    str = month_str_array[month-1];

    if( shortMonthStr )
	str = str.left(3);

    if( showDate ) {
	str += " ";
	str += itoa(day,strBuf,10);
	str += ",";
    }
    str += " Yr.";
    str += itoa(year,strBuf,10);

    return str;
}

//------------- End of function DateInfo::date_str --------//

//------------ Begin of function DateInfo::month_str ---------//
//!
//! <int> monthNo = the month (1-12)
//!
//! Return : <char*> the month string
//!
char* DateInfo::month_str(int monthNo) {
    return month_str_array[monthNo-1];
}

//------------- End of function DateInfo::month_str --------//

//---------- Begin of function DateInfo::day_year ----------//
//!
//! Returns an (int) day of the year starting from 1.
//! Ex.    Jan 1, returns  1
//!
//! Returns      -1  if it is an illegal date.
//!

int DateInfo::day_year( int year, int month, int day ) {
    int  isLeap, monthDays ;

    isLeap =   ( year%4 == 0 && year%100 != 0 || year%400 == 0 ) ?  1 : 0 ;

    monthDays =  month_tot[ month+1 ] -  month_tot[ month] ;
    if ( month == 2 )  monthDays += isLeap ;

    if ( year  < 0  ||
	 month < 1  ||  month > 12  ||
	 day   < 1  ||  day   > monthDays )
	return( -1 ) ;                                /* Illegal Date */

    if ( month <= 2 )  isLeap = 0 ;

    return(  month_tot[month] + day + isLeap ) ;
}

//------------- End of function DateInfo::day_year -----------//

//----------- Begin of function DateInfo::ytoj ----------//
//!
//! c4ytoj -  Calculates the number of days to the year
//!
//!     This calculation takes into account the fact that
//! 1)  Years divisible by 400 are always leap years.
//! 2)  Years divisible by 100 but not 400 are not leap years.
//! 3)  Otherwise, years divisible by four are leap years.
//!
//!     Since we do not want to consider the current year, we will
//!     subtract the year by 1 before doing the calculation.

long DateInfo::ytoj( int yr ) {
    yr-- ;
    return( yr*365L +  yr/4L - yr/100L + yr/400L ) ;
}

//--------------- End of function DateInfo::ytoj -----------//

//--------- Begin of function DateInfo::month_day ---------//
//!
//!  Given the year and the day of the year, returns the
//!  month and day of month.
//!
int DateInfo::month_day( int year, int days,  int &monthRef,  int &dayRef ) {
    int isLeap, i ;

    isLeap =  ( year%4 == 0 && year%100 != 0 || year%400 == 0 ) ?  1 : 0 ;
    if ( days <= 59 )  isLeap = 0 ;

    for( i = 2; i <= 13; i++) {
	if ( days <=  month_tot[i] + isLeap ) {
	    monthRef =  --i ;
	    if ( i <= 2) isLeap = 0 ;

	    dayRef   =  days - month_tot[ i] - isLeap ;
	    return( 0) ;
	}
    }
    dayRef   =  0 ;
    monthRef =  0 ;

    return( -1 ) ;
}

//----------- End of function DateInfo::month_day -----------//

//--------- Begin of function DateInfo::time_str ---------//
//!
//! Given a integer as time and then return the time string
//!
//! <int> inTime = the time in integer format (e.g. 1600 --> "16:00" )
//!
char* DateInfo::time_str(int inTime) {
    // #### begin Gilbert 18/8 ####//
    static char strBuf[6] = "00:00";
    //itoa( inTime/100, strBuf, 10 );
    //itoa( inTime%100, strBuf+3, 10 );
    strBuf[4] = '0' + inTime % 10;
    strBuf[3] = '0' + (inTime/10) % 10;
    strBuf[1] = '0' + (inTime/100) % 10;
    strBuf[0] = '0' + (inTime/1000) % 10;
    // #### end Gilbert 18/8 ####//

    return strBuf;
}

//---------- End of function DateInfo::time_str ----------//

//-------- Begin of function DateInfo::days_in_month ------//
//!
//! return the no. of days in a given month
//!
//! <int> inMonth = the specified month
//!
//! return : <int> = the no. of days in a given monthh
//!
int DateInfo::days_in_month(int inMonth) {
    return month_tot[inMonth+1] - month_tot[inMonth];
}

//---------- End of function DateInfo::days_in_month ------//

//-------- Begin of function DateInfo::add_months ------//
//!
//! Add months to the given julian date.
//!
//! <int> inDate   = the input julian date
//! <int> addMonth = the no. of months to add
//!
//! return : <int> - the result julian date
//!
int DateInfo::add_months(int inDate, int addMonth) {
    int inYear  = year(inDate);
    int inMonth = month(inDate);
    int inDay   = day(inDate);

    inMonth += addMonth;

    if( inMonth > 12 ) {
	inMonth -= 12;
	inYear++;
    }

    if( inDay > days_in_month(inMonth) )
	inDay = days_in_month(inMonth);

    return julian( inYear, inMonth, inDay );
}

//---------- End of function DateInfo::add_months ------//

//-------- Begin of function DateInfo::file_time_to_julian ------//
//!
int DateInfo::file_time_to_julian(FILETIME& fileTime) {
    /*
      WORD dosTime, dosDate;

      CoFileTimeToDosDateTime( &fileTime, &dosDate, &dosTime );

      //--------------------------------------------//
      // Bits	Contents
      // 0-4	Days of the month (1-31).
      // 5-8	Months (1 = January, 2 = February, and so forth).
      // 9-15	Year offset from 1980 (add 1980 to get actual year).
      //--------------------------------------------//

      return julian( 1980 + (dosDate>>9), (dosDate>>5) & 0x0F, dosDate & 0x0F );
    */
    return 0;
}

//---------- End of function DateInfo::file_time_to_julian ------//