/* Date.c -- implementation of Gregorian calendar dates

	THIS SOFTWARE FITS THE DESCRIPTION IN THE U.S. COPYRIGHT ACT OF A
	"UNITED STATES GOVERNMENT WORK".  IT WAS WRITTEN AS A PART OF THE
	AUTHOR'S OFFICIAL DUTIES AS A GOVERNMENT EMPLOYEE.  THIS MEANS IT
	CANNOT BE COPYRIGHTED.  THIS SOFTWARE IS FREELY AVAILABLE TO THE
	PUBLIC FOR USE WITHOUT A COPYRIGHT NOTICE, AND THERE ARE NO
	RESTRICTIONS ON ITS USE, NOW OR SUBSEQUENTLY.

Author:
	Edward M. Persky
	Bg. 12A, Rm. 2031
	Computer Systems Laboratory
	Division of Computer Research and Technology
	National Institutes of Health
	Bethesda, Maryland 20892
	Phone: (301) 402-1818
	uucp: uunet!nih-csl!tpersky
	Internet: tpersky@alw.nih.gov

Function:
	Provides an object that contains a date, stored as a Julian Day Number.
	Note: Julian Day Number for Jan. 29, 1988 is not 88029; it is different.
	
Log: Date.c,v
 *
 * Revision 3.15  92/12/19  15:52:57  sandy
 * removed extraneous semi-colon
 * 
 * Revision 3.14  92/07/26  14:32:04  sandy
 * include directive in form '#include <nihcl/foo.h>'
 * 
 * Revision 3.13  92/04/30  15:48:02  sandy
 * one initor in DEFINE_CLASS macros
 * 
 * Revision 3.12  92/01/23  15:18:41  sandy
 * changed usage of ::time() in Date::Date() to use time_t
 * 
 * Revision 3.11  91/08/15  09:27:04  tpersky
 * Changed Ted's phone no.
 * 
 * Revision 3.10  91/02/18  21:06:08  kgorlen
 * Release for 3rd printing of 1st edition.
 * 
 * Revision 3.3  91/02/18  13:31:07  kgorlen
 * Fix overflow in mdy() on 16-bit machines.
 * 
 * Revision 3.2  91/02/05  13:08:17  kgorlen
 * Correct test for invalid monthNumber and weekDayNumber.
 * 
 * Revision 3.1  90/12/22  08:45:09  kgorlen
 * ARM-compliant nested types.
 * 
 * Revision 3.0  90/05/20  00:19:23  kgorlen
 * Release for 1st edition.
 * 
*/

/*
  Modified by Vectaport, Inc.
*/

#include <Time/Date.h>
#include <Time/Time.h>
#include <OS/string.h>

#include <iomanip.h>
#include <ctype.h>
#include <string.h>
#include <stdio.h>

#define	THIS	Date
#define	BASE	Object
#define BASE_CLASSES BASE::desc()
#define MEMBER_CLASSES
#define VIRTUAL_BASE_CLASSES Object::desc()
#define PARTIAL 0
#define FULL    1


#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
static const dayTy first_day_of_month[12] = {1,32,60,91,121,152,182,213,244,274,305,335 };
#else
static const Date::dayTy first_day_of_month[12] = {1,32,60,91,121,152,182,213,244,274,305,335 };
#endif
static const unsigned char days_in_month[12] = {31,28,31,30,31,30,31,31,30,31,30,31 };
static const char* month_names[12] = {"January","February","March","April","May","June",
	"July","August","September","October","November","December" };
static const char* uc_month_names[12] = {"JANUARY","FEBRUARY","MARCH","APRIL","MAY","JUNE",
	"JULY","AUGUST","SEPTEMBER","OCTOBER","NOVEMBER","DECEMBER" };
static const char* week_day_names[7] = {"Monday","Tuesday","Wednesday",
	"Thursday","Friday","Saturday","Sunday" };
static const char* uc_week_day_names[7] = {"MONDAY","TUESDAY","WEDNESDAY",
	"THURSDAY","FRIDAY","SATURDAY","SUNDAY" };
static const unsigned int seconds_in_day = 24*60*60;

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
julTy Date::jday(monthTy m, dayTy d, yearTy y)
#else
Date::julTy Date::jday(monthTy m, dayTy d, yearTy y)
#endif
/*
Convert Gregorian calendar date to the corresponding Julian day number
j.  Algorithm 199 from Communications of the ACM, Volume 6, No. 8,
(Aug. 1963), p. 444.  Gregorian calendar started on Sep. 14, 1752.
This function not valid before that.
*/
{
	unsigned long c, ya;
	if (m > 2)
		m -= 3;
	else {
		m += 9;
		y--;
	} /* else */
	c = y / 100;
	ya = y - 100*c;
	return ((146097*c)>>2) + ((1461*ya)>>2) + (153*m + 2)/5 + d + 1721119;
} /* jday */

void Date::mdy(monthTy& mm, dayTy& dd, yearTy& yy) const
/*
Convert a Julian day number to its corresponding Gregorian calendar
date.  Algorithm 199 from Communications of the ACM, Volume 6, No. 8,
(Aug. 1963), p. 444.  Gregorian calendar started on Sep. 14, 1752.
This function not valid before that.
*/
{
	julTy j = julnum - 1721119;
	unsigned long y = ((j<<2) - 1) / 146097;
	j = (j<<2) - 1 - 146097*y;
	unsigned long d = j>>2;
	j = ((d<<2) + 3) / 1461;
	d = (d<<2) + 3 - 1461*j;
	d = (d + 4)>>2;
	unsigned long m = (5*d - 3)/153;
	d = 5*d - 3 - 153*m;
	d = (d + 5)/5;
	y = 100*y + j;
	if (m < 10)
		m += 3;
	else {
		m -= 9;
		y++;
	} /* else */
	mm = (monthTy)m;
	dd = (dayTy)d;
	yy = (yearTy)y;
} /* mdy */

Date::Date()
/*
	Construct a Date for today's date.
*/
{
// Thu Jan 23 15:17:56 EST 1992 changed for portability. S.M.Orlow
//	long clk = time(0); 
	time_t clk = time(0);
	const struct tm* now = localtime(&clk);
	julnum = jday(now->tm_mon+1, now->tm_mday, now->tm_year+1900);
}

Date::Date(long dayCount, yearTy referenceYear)
/*
        The base date for this computation is Dec. 31 of the previous year.  That
	is "day zero" in relation to the addition which is to take place.  Therefore,
	we call jday() with the base date and then perform the addition.  Note
	that dayCount may be positive or negative and that this function will
	work the same in either case.
*/
{
	julnum = jday(12, 31, referenceYear-1) + dayCount;  
}


Date::Date(long dayCount)
/*
	Constructs a date with Jan. 1, 1901 as the "day zero".  Date(-1) = Dec. 31, 1900
	and Date(1) = Jan. 2, 1901.
*/
{
	julnum = jday(1, 1, 1901) + dayCount;
}

boolean Date::dayWithinMonth(monthTy month, dayTy day, yearTy year)
{
	if (day <= 0) return 0;
	unsigned daysInMonth  = days_in_month[month-1];
	if (leapYear(year) && month == 2) daysInMonth++;
	if (day > daysInMonth) return 0;
	return 1;
}

Date::Date(dayTy day, const char* monthName, yearTy year)
/*
      Construct a Date for the given day, monthName, and year.
*/
{
	monthTy m = numberOfMonth(monthName);
	if (year <= 99) year += 1900;
	if (!dayWithinMonth(m, day, year))
	    fprintf(stderr, "Bad month day error %d %s %d\n", day,monthName,year);
	julnum = jday(m, day, year);			
}

static void skipDelim(istream& strm)
{
	char c;
	if (!strm.good()) return;
	strm >> c;
	while (strm.good() && !isalnum(c)) strm >> c;
	if (strm.good()) strm.putback(c);
}

static const char* parseMonth(istream& strm)
/*
	Parse the name of a month from input stream.
*/
{
	static char month[10];
	register char* p = month;
	char c;
	skipDelim(strm);
	strm.get(c);
	while (strm.good() && isalpha(c) && (p != &month[10])) {
		*p++ = c;
		strm.get(c);
	}
	if (strm.good()) strm.putback(c);
	*p = '\0';
	return month;
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
julTy Date::parseDate(istream& strm)
#else
Date::julTy Date::parseDate(istream& strm)
#endif
/*
	Parse a date from the specified input stream.  The date must be in one
	of the following forms: dd-mmm-yy, mm/dd/yy, or mmm dd,yy; e.g.: 10-MAR-86,
	3/10/86, or March 10, 1986.  Any non-alphanumeric character may be used as
	a delimiter.
*/
{
	unsigned d,m,y;
	const char* mon;		// name of month 
	if (strm.good()) {
		skipDelim(strm);
		strm >> m;		// try to parse day or month number 
		skipDelim(strm);
		if (strm.eof()) return 0;
		if (strm.fail()) {	// parse <monthName><day><year> 
			strm.clear();
			mon = parseMonth(strm);	// parse month name 
			skipDelim(strm);
			strm >> d;		// parse day 
		}
		else {			// try to parse day number 
			strm >> d;
			if (strm.eof()) return 0;
			if (strm.fail()) {	// parse <day><monthName><year> 
				d = m;
				strm.clear();
				mon = parseMonth(strm);		// parse month name 
			}
			else {			// parsed <monthNumber><day><year> 
				mon = nameOfMonth(m);
			}
		}
		skipDelim(strm);
		strm >> y;
	}
	if (!strm.good()) return 0;
	return Date(d,mon,y).julnum;
}

Date::Date(istream& strm)	{ julnum = parseDate(strm); }

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
dayTy Date::dayOfWeek(const char* nameOfDay)
#else
Date::dayTy Date::dayOfWeek(const char* nameOfDay)
#endif
/*
	Returns the number, 1-7, of the day of the week named nameOfDay.
*/
{
	{
		String s(nameOfDay);
		register unsigned len = s.length();
		if (len > 2) {
			for (register unsigned i =0; i<7; i++)
			if (s.case_insensitive_equal(uc_week_day_names[i])) return i+1;
		}
	}
	fprintf(stderr, "Bad day name error %s", nameOfDay);
	return 0;	// never executed 
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
dayTy Date::daysInYear(yearTy year)
#else
Date::dayTy Date::daysInYear(yearTy year)
#endif
/*
	How many days are in the given yearTy year?
*/
{
	if (leapYear(year))
		return 366;
	else
		return 365;
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
monthTy Date::numberOfMonth(const char* nameOfMonth)
#else
Date::monthTy Date::numberOfMonth(const char* nameOfMonth)
#endif
/*
	Returns the number, 1-12, of the month named nameOfMonth.
*/
{
	{
		register unsigned len = strlen(nameOfMonth);
		if (len > 2) {
			char p[len+1];
			for (int j = 0; j < len+1; j++)
			    p[j] = toupper(nameOfMonth[j]);
			for (register unsigned i =0; i<12; i++)
				if (strncmp(p,uc_month_names[i],len)==0) return i+1;
		}
	}
	fprintf(stderr,"Bad month name error %s\n", nameOfMonth);
	return 0;	// never executed 
}

boolean Date::leapYear(yearTy year)
{
/*
	Algorithm from K & R, "The C Programming Language", 1st ed.
*/
	if ((year&3) == 0 && year%100 != 0 || year % 400 == 0)
		return 1;
	else
		return 0;
}

boolean Date::leap() const
{
	return leapYear(year());
}

const char* Date::nameOfMonth(monthTy monthNumber)
/*
	Returns a string name for the month number.
*/
{
	if (monthNumber < 1 || monthNumber > 12)
	    fprintf(stderr,"Bad month error %d\n",monthNumber);
	return month_names[monthNumber-1];
}

const char* Date::nameOfDay(dayTy weekDayNumber)
/*
	Returns a string name for the weekday number.
	Monday == 1, ... , Sunday == 7
*/
{
	if (weekDayNumber < 1 || weekDayNumber > 7)
	    fprintf(stderr, "Bad day error %d\n", weekDayNumber);
	return week_day_names[weekDayNumber-1];
}

const char* Date::nameOfMonth() const	{ return nameOfMonth(month()); }

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
monthTy Date::month() const
#else
Date::monthTy Date::month() const
#endif
{
	monthTy m; dayTy d; yearTy y;
	mdy(m, d, y);
	return m;
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
dayTy Date::firstDayOfMonth(monthTy month) const
#else
Date::dayTy Date::firstDayOfMonth(monthTy month) const
#endif
{
	if (month > 12)
	    fprintf(stderr, "Bad month error %d\n", month);
	unsigned firstDay = first_day_of_month[month-1];
	if (month > 2 && leap()) firstDay++;
	return firstDay;
}

Date Date::previous(const char* nameOfDay) const
{
	dayTy this_day_Of_Week, desired_day_Of_Week;
	julTy j;

//	Set the desired and current day of week to start at 0 (Monday)
//	and end at 6 (Sunday).

	desired_day_Of_Week = dayOfWeek(nameOfDay) - 1; // These functions return a value
	this_day_Of_Week    = weekDay() - 1;		// from 1-7.  Subtract 1 for 0-6.
	j = julnum;

//	Have to determine how many days difference from current day back to
//	desired, if any.  Special calculation under the 'if' statement to
//	effect the wraparound counting from Monday (0) back to Sunday (6).

	if (desired_day_Of_Week > this_day_Of_Week)
		this_day_Of_Week += 7 - desired_day_Of_Week;
	else
		this_day_Of_Week -= desired_day_Of_Week;
	j -= this_day_Of_Week; // Adjust j to set it at the desired day of week.
	return Date(j);
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
dayTy Date::weekDay() const
#else
Date::dayTy Date::weekDay() const
#endif
/*
	Although this seems a little strange, it works.  (julnum + 1) % 7 gives the
	value 0 for Sunday ... 6 for Saturday.  Since we want the list to start at
	Monday, add 6 (mod 7) to this.  Now we have Monday at 0 ... Sunday at
	6.  Simply add 1 to the result to obtain Monday (1) ... Sunday (7).
*/
{
	return ((((julnum + 1) % 7) + 6) % 7) + 1;
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
yearTy Date::year() const
#else
Date::yearTy Date::year() const
#endif
/*
	Returns the year of this Date.
*/
{
	monthTy m; dayTy d; yearTy y;
	mdy(m, d, y);
	return y;
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
dayTy Date::day() const
#else
Date::dayTy Date::day() const
#endif
/*
	Returns the day of the year of this Date.  First we need to find what year we
	are talking about, and then subtract this julnum from the julnum for December 31
	of the preceeding year.
*/
{
	return julnum - jday(12, 31, year()-1);
}

#if defined(NO_NESTED_TYPES) || defined(ATT_R21)
dayTy Date::dayOfMonth() const
#else
Date::dayTy Date::dayOfMonth() const
#endif
{
	monthTy m; dayTy d; yearTy y;
	mdy(m, d, y);
	return d;
}

void Date::printOn(ostream& strm) const
{
 	strm << setfill(' ') << setw(2) << dayOfMonth() << '-';
 	strm.write(nameOfMonth(), 3);
 	strm << '-' << setfill('0') << setw(2) << (year() /* % 100 */);
}

void Date::scanFrom(istream& strm)	{ julnum = parseDate(strm); }