/****************************************************************************

** 

**

** Implementation of date and time classes

**

** Created : 940124

**

** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.

**

** This file is part of the tools module of the Qt GUI Toolkit.

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** This file may be distributed under the terms of the Q Public License

** as defined by Trolltech AS of Norway and appearing in the file

** LICENSE.QPL included in the packaging of this file.

**

** This file may be distributed and/or modified under the terms of the

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** Foundation and appearing in the file LICENSE.GPL included in the

** packaging of this file.

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** licenses may use this file in accordance with the Qt Commercial License

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**********************************************************************/

#define gettimeofday	__hide_gettimeofday

#include "qdatetime.h"

#include "qdatastream.h"

#include <stdio.h>

#include <time.h>

#if defined(_OS_WIN32_)

#if defined(_CC_BOOL_DEF_)

#undef	bool

#include <windows.h>

#define bool int

#else

#include <windows.h>

#endif

#elif defined(_OS_MSDOS_)

#include <dos.h>

#elif defined(_OS_OS2_)

#include <os2.h>

#elif defined(_OS_UNIX_)

#include <sys/time.h>

#include <unistd.h>

#undef	gettimeofday

extern "C" int gettimeofday( struct timeval *, struct timezone * );

#endif

static const uint FIRST_DAY	= 2361222;	// Julian day for 1752/09/14

static const int  FIRST_YEAR	= 1752;		// ### wrong for many countries

static const uint SECS_PER_DAY	= 86400;

static const uint MSECS_PER_DAY = 86400000;

static const uint SECS_PER_HOUR = 3600;

static const uint MSECS_PER_HOUR= 3600000;

static const uint SECS_PER_MIN	= 60;

static const uint MSECS_PER_MIN = 60000;

static const short monthDays[] ={0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

// ##### Localize.

const char * const QDate::monthNames[] = {

    "Jan", "Feb", "Mar", "Apr", "May", "Jun",

    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };

const char * const QDate::weekdayNames[] ={

    "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };

/*****************************************************************************

  QDate member functions

 *****************************************************************************/

// REVISED: aavit

/*!

  \class QDate qdatetime.h

  \brief The QDate class provides date functions.

  \ingroup time

  A QDate object contains a calendar date, i.e. year, month, and day

  numbers in the modern western (Gregorian) calendar. It can read the

  current date from the system clock. It provides functions for

  comparing dates and for manipulating a date by adding a number of

  days.

  A QDate object is typically created either by giving the year, month

  and day numbers explicitly, or by using the static function

  currentDate(), which makes a QDate object which contains the

  system's clock date. An explicit date can also be set using

  setYMD().

  The year(), month(), and day() functions provide access to the year,

  month, and day numbers. Also, dayOfWeek() and dayOfYear() functions

  are provided. The same information is provided in textual format by

  the toString(), dayName(), and monthName() functions.

  QDate provides a full set of operators to compare two QDate

  objects. A date is considered smaller than another if it is earlier

  than the other.

  The date a given number of days later than a given date can be found

  using the addDays() function. Correspondingly, the number of days

  between two dates can be found using the daysTo() function.

  The daysInMonth() and daysInYear() functions tell how many days

  there are in this date's month and year, respectively. The

  isLeapYear() function tells whether this date is in a leap year.

  Note that QDate may not be used for date calculations for dates in

  the remote past, i.e. prior to the introduction of the Gregorian

  calendar. This calendar was adopted by England Sep. 14. 1752 (hence

  this is the earliest valid QDate), and subsequently by most other

  western countries, until 1923.

  The end of time is reached around 8000AD, by which time we expect Qt

  to be obsolete.

  \sa QTime, QDateTime

*/

/*!

  \fn QDate::QDate()

  Constructs a null date. Null dates are invalid.

  \sa isNull(), isValid()

*/

/*!

  Constructs a date with the year \a y, month \a m and day \a d.

  \a y must be in the range 1752-ca. 8000, \a m must be in the range

  1-12, and \a d must be in the range 1-31. Exception: if \a y is in

  the range 0-99, it is interpreted as 1900-1999.

  \sa isValid()

*/

QDate::QDate( int y, int m, int d )

{

    jd = 0;

    setYMD( y, m, d );

}

/*!

  \fn bool QDate::isNull() const

  Returns TRUE if the date is null.  A null date is invalid.

  \sa isValid()

*/

/*!

  Returns TRUE if this date is valid.

  \sa isNull()

*/

bool QDate::isValid() const

{

    return jd >= FIRST_DAY;

}

/*!

  Returns the year (>= 1752) of this date.

  \sa month(), day()

*/

int QDate::year() const

{

    int y, m, d;

    jul2greg( jd, y, m, d );

    return y;

}

/*!

  Returns the month (January=1 .. December=12) of this date.

  \sa year(), day()

*/

int QDate::month() const

{

    int y, m, d;

    jul2greg( jd, y, m, d );

    return m;

}

/*!

  Returns the day of the month (1..31) of this date.

  \sa year(), month(), dayOfWeek()

*/

int QDate::day() const

{

    int y, m, d;

    jul2greg( jd, y, m, d );

    return d;

}

/*!

  Returns the weekday (Monday=1 .. Sunday=7) for this date.

  \sa day(), dayOfYear()

*/

int QDate::dayOfWeek() const

{

    return (((jd+1) % 7) + 6)%7 + 1;

}

/*!

  Returns the day of the year (1..365) for this date.

  \sa day(), dayOfWeek()

*/

int QDate::dayOfYear() const

{

    return jd - greg2jul(year(), 1, 1) + 1;

}

/*!

  Returns the number of days in the month (28..31) for this date.

  \sa day(), daysInYear()

*/

int QDate::daysInMonth() const

{

    int y, m, d;

    jul2greg( jd, y, m, d );

    if ( m == 2 && leapYear(y) )

	return 29;

    else

	return monthDays[m];

}

/*!

  Returns the number of days in the year (365 or 366) for this date.

  \sa day(), daysInMonth()

*/

int QDate::daysInYear() const

{

    int y, m, d;

    jul2greg( jd, y, m, d );

    return leapYear(y) ? 366 : 365;

}

/*!

  Returns the name of the \a month.

  Month 1 == "Jan", month 2 == "Feb" etc.

  \sa toString(), dayName()

*/

QString QDate::monthName( int month ) const

{

#if defined(CHECK_RANGE)

    if ( month < 1 || month > 12 ) {

	qWarning( "QDate::monthName: Parameter out ouf range." );

	month = 1;

    }

#endif

    // ### Remove the fromLatin1 during localization

    return QString::fromLatin1(monthNames[month-1]);

}

/*!

  Returns the name of the \a weekday.

  Weekday 1 == "Mon", day 2 == "Tue" etc.

  \sa toString(), monthName()

*/

QString QDate::dayName( int weekday ) const

{

#if defined(CHECK_RANGE)

    if ( weekday < 1 || weekday > 7 ) {

	qWarning( "QDate::dayName: Parameter out of range." );

	weekday = 1;

    }

#endif

    // ### Remove the fromLatin1 during localization

    return QString::fromLatin1(weekdayNames[weekday-1]);

}

/*!

  Returns the date as a string.

  The string format is "Sat May 20 1995". This function uses the

  dayName() and monthName() functions to generate the string.

  \sa dayName(), monthName()

*/

QString QDate::toString() const

{

    int y, m, d;

    jul2greg( jd, y, m, d );

    QString buf = dayName(dayOfWeek());

    buf += ' ';

    buf += monthName(m);

    QString t;

    t.sprintf( " %d %d", d, y);

    buf += t;

    return buf;

}

/*!

  Sets the year \a y, month \a m and day \a d.

  \a y must be in the range 1752-ca. 8000, \a m must be in the range

  1-12, and \a d must be in the range 1-31. Exception: if \a y is in

  the range 0-99, it is interpreted as 1900-1999.

  Returns TRUE if the date is valid, otherwise FALSE.

*/

bool QDate::setYMD( int y, int m, int d )

{

    if ( !isValid(y,m,d) ) {

#if defined(CHECK_RANGE)

	 qWarning( "QDate::setYMD: Invalid date %04d/%02d/%02d", y, m, d );

#endif

	 return FALSE;

    }

    jd = greg2jul( y, m, d );

#if defined(DEBUG)

    ASSERT( year() == (y > 99 ? y : 1900+y) && month() == m && day() == d );

#endif

    return TRUE;

}

/*!

  Returns a QDate object containing a date \a ndays later than the

  date of this object (or earlier if \a ndays is negative).

  \sa daysTo()

*/

QDate QDate::addDays( int ndays ) const

{

    QDate d;

    d.jd = jd + ndays;

    return d;

}

/*!

  Returns the number of days from this date to \a d (which is negative

  if \a d is earlier than this date).

  Example:

  \code

    QDate d1( 1995, 5, 17 );		// May 17th 1995

    QDate d2( 1995, 5, 20 );		// May 20th 1995

    d1.daysTo( d2 );			// returns 3

    d2.daysTo( d1 );			// returns -3

  \endcode

  \sa addDays()

*/

int QDate::daysTo( const QDate &d ) const

{

    return d.jd - jd;

}

/*!

  \fn bool QDate::operator==( const QDate &d ) const

  Returns TRUE if this date is equal to \a d, or FALSE if

  they are different.

*/

/*!

  \fn bool QDate::operator!=( const QDate &d ) const

  Returns TRUE if this date is different from \a d, or FALSE if

  they are equal.

*/

/*!

  \fn bool QDate::operator<( const QDate &d ) const

  Returns TRUE if this date is earlier than \a d, otherwise FALSE.

*/

/*!

  \fn bool QDate::operator<=( const QDate &d ) const

  Returns TRUE if this date is earlier than or equal to \a d, otherwise FALSE.

*/

/*!

  \fn bool QDate::operator>( const QDate &d ) const

  Returns TRUE if this date is later than \a d, otherwise FALSE.

*/

/*!

  \fn bool QDate::operator>=( const QDate &d ) const

  Returns TRUE if this date is later than or equal to \a d, otherwise FALSE.

*/

/*!

  Returns the current date, as reported by the system clock.

  \sa QTime::currentTime(), QDateTime::currentDateTime()

*/

QDate QDate::currentDate()

{

#if defined(_OS_WIN32_)

    SYSTEMTIME t;

    GetLocalTime( &t );

    QDate d;

    d.jd = greg2jul( t.wYear, t.wMonth, t.wDay );

    return d;

#else

    time_t ltime;

    time( &ltime );

    tm *t = localtime( &ltime );

    QDate d;

    d.jd = greg2jul( t->tm_year + 1900, t->tm_mon + 1, t->tm_mday );

    return d;

#endif

}

/*!

  Returns TRUE if the specified date (year \a y, month \a m and day \a

  d) is valid.

  Example:

  \code

    QDate::isValid( 2002, 5, 17 );	// TRUE;  May 17th 2002 is OK.

    QDate::isValid( 2002, 2, 30 );	// FALSE; Feb 30th does not exist

    QDate::isValid( 2004, 2, 29 );	// TRUE; 2004 is a leap year

    QDate::isValid( 1202, 6, 6 );	// FALSE; 1202 is pre-Gregorian

  \endcode

  Note that a \a y value in the range 00-99 is interpreted as

  1900-1999.

  \sa isNull(), setYMD()

*/

bool QDate::isValid( int y, int m, int d )

{

    if ( y >= 0 && y <= 99 )

	y += 1900;

    else if ( y < FIRST_YEAR || (y == FIRST_YEAR && (m < 9 ||

						    (m == 9 && d < 14))) )

	return FALSE;

    return (d > 0 && m > 0 && m <= 12) &&

	   (d <= monthDays[m] || (d == 29 && m == 2 && leapYear(y)));

}

/*!

  Returns TRUE if the specified year \a y is a leap year.

*/

bool QDate::leapYear( int y )

{

    return y % 4 == 0 && y % 100 != 0 || y % 400 == 0;

}

/*!

  \internal

  Converts a Gregorian date to a Julian day.

  This algorithm is taken from Communications of the ACM, Vol 6, No 8.

  \sa jul2greg()

*/

uint QDate::greg2jul( int y, int m, int d )

{

    uint c, ya;

    if ( y <= 99 )

	y += 1900;

    if ( m > 2 ) {

	m -= 3;

    } else {

	m += 9;

	y--;

    }

    c = y;					// NOTE: Sym C++ 6.0 bug

    c /= 100;

    ya = y - 100*c;

    return 1721119 + d + (146097*c)/4 + (1461*ya)/4 + (153*m+2)/5;

}

/*!

  \internal

  Converts a Julian day to a Gregorian date.

  This algorithm is taken from Communications of the ACM, Vol 6, No 8.

  \sa greg2jul()

*/

void QDate::jul2greg( uint jd, int &y, int &m, int &d )