]> git.saurik.com Git - wxWidgets.git/blobdiff - src/common/datetime.cpp
fix harmless warnings about uninitialized (not really) variables in MSVC release...
[wxWidgets.git] / src / common / datetime.cpp
index 901156a569d02ab5d00b29a6c97e70ae9f702545..e13ac2e8083756c9e0e719dabd4884fcec2d3742 100644 (file)
@@ -1,13 +1,49 @@
-/////////////////////////////////////////////////////////////////////////////
-// Name:        wx/datetime.h
+///////////////////////////////////////////////////////////////////////////////
+// Name:        src/common/datetime.cpp
 // Purpose:     implementation of time/date related classes
+//              (for formatting&parsing see datetimefmt.cpp)
 // Author:      Vadim Zeitlin
 // Modified by:
 // Created:     11.05.99
 // RCS-ID:      $Id$
-// Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
-// Licence:     wxWindows license
-/////////////////////////////////////////////////////////////////////////////
+// Copyright:   (c) 1999 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
+//              parts of code taken from sndcal library by Scott E. Lee:
+//
+//               Copyright 1993-1995, Scott E. Lee, all rights reserved.
+//               Permission granted to use, copy, modify, distribute and sell
+//               so long as the above copyright and this permission statement
+//               are retained in all copies.
+//
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+/*
+ * Implementation notes:
+ *
+ * 1. the time is stored as a 64bit integer containing the signed number of
+ *    milliseconds since Jan 1. 1970 (the Unix Epoch) - so it is always
+ *    expressed in GMT.
+ *
+ * 2. the range is thus something about 580 million years, but due to current
+ *    algorithms limitations, only dates from Nov 24, 4714BC are handled
+ *
+ * 3. standard ANSI C functions are used to do time calculations whenever
+ *    possible, i.e. when the date is in the range Jan 1, 1970 to 2038
+ *
+ * 4. otherwise, the calculations are done by converting the date to/from JDN
+ *    first (the range limitation mentioned above comes from here: the
+ *    algorithm used by Scott E. Lee's code only works for positive JDNs, more
+ *    or less)
+ *
+ * 5. the object constructed for the given DD-MM-YYYY HH:MM:SS corresponds to
+ *    this moment in local time and may be converted to the object
+ *    corresponding to the same date/time in another time zone by using
+ *    ToTimezone()
+ *
+ * 6. the conversions to the current (or any other) timezone are done when the
+ *    internal time representation is converted to the broken-down one in
+ *    wxDateTime::Tm.
+ */
 
 // ============================================================================
 // declarations
 // headers
 // ----------------------------------------------------------------------------
 
-#ifdef __GNUG__
-    #pragma implementation "datetime.h"
-#endif
-
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
     #pragma hdrstop
 #endif
 
+#if !defined(wxUSE_DATETIME) || wxUSE_DATETIME
+
 #ifndef WX_PRECOMP
+    #ifdef __WXMSW__
+        #include "wx/msw/wrapwin.h"
+    #endif
     #include "wx/string.h"
-    #include "wx/intl.h"
     #include "wx/log.h"
+    #include "wx/intl.h"
+    #include "wx/stopwatch.h"           // for wxGetLocalTimeMillis()
+    #include "wx/module.h"
+    #include "wx/crt.h"
 #endif // WX_PRECOMP
 
 #include "wx/thread.h"
+#include "wx/tokenzr.h"
+
+#include <ctype.h>
 
-#define wxDEFINE_TIME_CONSTANTS
+#ifdef __WINDOWS__
+    #include <winnls.h>
+    #ifndef __WXWINCE__
+        #include <locale.h>
+    #endif
+#endif
 
 #include "wx/datetime.h"
 
+// ----------------------------------------------------------------------------
+// wxXTI
+// ----------------------------------------------------------------------------
+
+#if wxUSE_EXTENDED_RTTI
+
+template<> void wxStringReadValue(const wxString &s , wxDateTime &data )
+{
+    data.ParseFormat(s,"%Y-%m-%d %H:%M:%S", NULL);
+}
+
+template<> void wxStringWriteValue(wxString &s , const wxDateTime &data )
+{
+    s = data.Format("%Y-%m-%d %H:%M:%S");
+}
+
+wxCUSTOM_TYPE_INFO(wxDateTime, wxToStringConverter<wxDateTime> , wxFromStringConverter<wxDateTime>)
+
+#endif // wxUSE_EXTENDED_RTTI
+
+
+// ----------------------------------------------------------------------------
+// conditional compilation
+// ----------------------------------------------------------------------------
+
+#if defined(__MWERKS__) && wxUSE_UNICODE
+    #include <wtime.h>
+#endif
+
+#if !defined(WX_TIMEZONE) && !defined(WX_GMTOFF_IN_TM)
+    #if defined(__WXPALMOS__)
+        #define WX_GMTOFF_IN_TM
+    #elif defined(__BORLANDC__) || defined(__MINGW32__) || defined(__VISAGECPP__)
+        #define WX_TIMEZONE _timezone
+    #elif defined(__MWERKS__)
+        long wxmw_timezone = 28800;
+        #define WX_TIMEZONE wxmw_timezone
+    #elif defined(__DJGPP__) || defined(__WINE__)
+        #include <sys/timeb.h>
+        #include <values.h>
+        static long wxGetTimeZone()
+        {
+            static long timezone = MAXLONG; // invalid timezone
+            if (timezone == MAXLONG)
+            {
+                struct timeb tb;
+                ftime(&tb);
+                timezone = tb.timezone;
+            }
+            return timezone;
+        }
+        #define WX_TIMEZONE wxGetTimeZone()
+    #elif defined(__DARWIN__)
+        #define WX_GMTOFF_IN_TM
+    #elif defined(__WXWINCE__) && defined(__VISUALC8__)
+        // _timezone is not present in dynamic run-time library
+        #if 0
+        // Solution (1): use the function equivalent of _timezone
+        static long wxGetTimeZone()
+        {
+            static long s_Timezone = MAXLONG; // invalid timezone
+            if (s_Timezone == MAXLONG)
+            {
+                int t;
+                _get_timezone(& t);
+                s_Timezone = (long) t;
+            }
+            return s_Timezone;
+        }
+        #define WX_TIMEZONE wxGetTimeZone()
+        #elif 1
+        // Solution (2): using GetTimeZoneInformation
+        static long wxGetTimeZone()
+        {
+            static long timezone = MAXLONG; // invalid timezone
+            if (timezone == MAXLONG)
+            {
+                TIME_ZONE_INFORMATION tzi;
+                ::GetTimeZoneInformation(&tzi);
+                timezone = tzi.Bias;
+            }
+            return timezone;
+        }
+        #define WX_TIMEZONE wxGetTimeZone()
+        #else
+        // Old method using _timezone: this symbol doesn't exist in the dynamic run-time library (i.e. using /MD)
+        #define WX_TIMEZONE _timezone
+        #endif
+    #else // unknown platform - try timezone
+        #define WX_TIMEZONE timezone
+    #endif
+#endif // !WX_TIMEZONE && !WX_GMTOFF_IN_TM
+
+// NB: VC8 safe time functions could/should be used for wxMSW as well probably
+#if defined(__WXWINCE__) && defined(__VISUALC8__)
+
+struct tm *wxLocaltime_r(const time_t *t, struct tm* tm)
+{
+    __time64_t t64 = *t;
+    return _localtime64_s(tm, &t64) == 0 ? tm : NULL;
+}
+
+struct tm *wxGmtime_r(const time_t* t, struct tm* tm)
+{
+    __time64_t t64 = *t;
+    return _gmtime64_s(tm, &t64) == 0 ? tm : NULL;
+}
+
+#else // !wxWinCE with VC8
+
+#if (!defined(HAVE_LOCALTIME_R) || !defined(HAVE_GMTIME_R)) && wxUSE_THREADS && !defined(__WINDOWS__)
+static wxMutex timeLock;
+#endif
+
+#ifndef HAVE_LOCALTIME_R
+struct tm *wxLocaltime_r(const time_t* ticks, struct tm* temp)
+{
+#if wxUSE_THREADS && !defined(__WINDOWS__)
+  // No need to waste time with a mutex on windows since it's using
+  // thread local storage for localtime anyway.
+  wxMutexLocker locker(timeLock);
+#endif
+
+  // Borland CRT crashes when passed 0 ticks for some reason, see SF bug 1704438
+#ifdef __BORLANDC__
+  if ( !*ticks )
+      return NULL;
+#endif
+
+  const tm * const t = localtime(ticks);
+  if ( !t )
+      return NULL;
+
+  memcpy(temp, t, sizeof(struct tm));
+  return temp;
+}
+#endif // !HAVE_LOCALTIME_R
+
+#ifndef HAVE_GMTIME_R
+struct tm *wxGmtime_r(const time_t* ticks, struct tm* temp)
+{
+#if wxUSE_THREADS && !defined(__WINDOWS__)
+  // No need to waste time with a mutex on windows since it's
+  // using thread local storage for gmtime anyway.
+  wxMutexLocker locker(timeLock);
+#endif
+
+#ifdef __BORLANDC__
+  if ( !*ticks )
+      return NULL;
+#endif
+
+  const tm * const t = gmtime(ticks);
+  if ( !t )
+      return NULL;
+
+  memcpy(temp, gmtime(ticks), sizeof(struct tm));
+  return temp;
+}
+#endif // !HAVE_GMTIME_R
+
+#endif // wxWinCE with VC8/other platforms
+
+// ----------------------------------------------------------------------------
+// macros
+// ----------------------------------------------------------------------------
+
+// debugging helper: just a convenient replacement of wxCHECK()
+#define wxDATETIME_CHECK(expr, msg) \
+    wxCHECK2_MSG(expr, *this = wxInvalidDateTime; return *this, msg)
+
+// ----------------------------------------------------------------------------
+// private classes
+// ----------------------------------------------------------------------------
+
+class wxDateTimeHolidaysModule : public wxModule
+{
+public:
+    virtual bool OnInit()
+    {
+        wxDateTimeHolidayAuthority::AddAuthority(new wxDateTimeWorkDays);
+
+        return true;
+    }
+
+    virtual void OnExit()
+    {
+        wxDateTimeHolidayAuthority::ClearAllAuthorities();
+        wxDateTimeHolidayAuthority::ms_authorities.clear();
+    }
+
+private:
+    DECLARE_DYNAMIC_CLASS(wxDateTimeHolidaysModule)
+};
+
+IMPLEMENT_DYNAMIC_CLASS(wxDateTimeHolidaysModule, wxModule)
+
 // ----------------------------------------------------------------------------
 // constants
 // ----------------------------------------------------------------------------
 
-// note that all these constants should be signed or we'd get some big
-// surprizes with C integer arithmetics
+// some trivial ones
 static const int MONTHS_IN_YEAR = 12;
 
-static const int SECONDS_IN_MINUTE = 60;
+static const int SEC_PER_MIN = 60;
+
+static const int MIN_PER_HOUR = 60;
+
+static const int HOURS_PER_DAY = 24;
+
+static const long SECONDS_PER_DAY = 86400l;
 
-// the number of days in month in Julian/Gregorian calendar: the first line is
-// for normal years, the second one is for the leap ones
-static wxDateTime::wxDateTime_t gs_daysInMonth[2][MONTHS_IN_YEAR] =
+static const int DAYS_PER_WEEK = 7;
+
+static const long MILLISECONDS_PER_DAY = 86400000l;
+
+// this is the integral part of JDN of the midnight of Jan 1, 1970
+// (i.e. JDN(Jan 1, 1970) = 2440587.5)
+static const long EPOCH_JDN = 2440587l;
+
+// these values are only used in asserts so don't define them if asserts are
+// disabled to avoid warnings about unused static variables
+#if wxDEBUG_LEVEL
+// the date of JDN -0.5 (as we don't work with fractional parts, this is the
+// reference date for us) is Nov 24, 4714BC
+static const int JDN_0_YEAR = -4713;
+static const int JDN_0_MONTH = wxDateTime::Nov;
+static const int JDN_0_DAY = 24;
+#endif // wxDEBUG_LEVEL
+
+// the constants used for JDN calculations
+static const long JDN_OFFSET         = 32046l;
+static const long DAYS_PER_5_MONTHS  = 153l;
+static const long DAYS_PER_4_YEARS   = 1461l;
+static const long DAYS_PER_400_YEARS = 146097l;
+
+// this array contains the cumulated number of days in all previous months for
+// normal and leap years
+static const wxDateTime::wxDateTime_t gs_cumulatedDays[2][MONTHS_IN_YEAR] =
 {
-    { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
-    { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 },
+    { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335 }
 };
 
+const long wxDateTime::TIME_T_FACTOR = 1000l;
+
 // ----------------------------------------------------------------------------
-// globals
+// global data
 // ----------------------------------------------------------------------------
 
-// a critical section is needed to protect GetTimeZone() static
-// variable in MT case
-#ifdef wxUSE_THREADS
-    wxCriticalSection gs_critsectTimezone;
-#endif // wxUSE_THREADS
+const char *wxDefaultDateTimeFormat = "%c";
+const char *wxDefaultTimeSpanFormat = "%H:%M:%S";
+
+// in the fine tradition of ANSI C we use our equivalent of (time_t)-1 to
+// indicate an invalid wxDateTime object
+const wxDateTime wxDefaultDateTime;
+
+wxDateTime::Country wxDateTime::ms_country = wxDateTime::Country_Unknown;
 
 // ----------------------------------------------------------------------------
 // private functions
 // ----------------------------------------------------------------------------
 
+// debugger helper: this function can be called from a debugger to show what
+// the date really is
+extern const char *wxDumpDate(const wxDateTime* dt)
+{
+    static char buf[128];
+
+    wxString fmt(dt->Format("%Y-%m-%d (%a) %H:%M:%S"));
+    wxStrlcpy(buf,
+              (fmt + " (" + dt->GetValue().ToString() + " ticks)").ToAscii(),
+              WXSIZEOF(buf));
+
+    return buf;
+}
+
 // get the number of days in the given month of the given year
 static inline
 wxDateTime::wxDateTime_t GetNumOfDaysInMonth(int year, wxDateTime::Month month)
 {
-    return gs_daysInMonth[wxDateTime::IsLeapYear(year)][month];
+    // the number of days in month in Julian/Gregorian calendar: the first line
+    // is for normal years, the second one is for the leap ones
+    static wxDateTime::wxDateTime_t daysInMonth[2][MONTHS_IN_YEAR] =
+    {
+        { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+        { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+    };
+
+    return daysInMonth[wxDateTime::IsLeapYear(year)][month];
 }
 
-// ensure that the timezone variable is set by calling localtime
-static int GetTimeZone()
+// returns the time zone in the C sense, i.e. the difference UTC - local
+// (in seconds)
+// NOTE: not static because used by datetimefmt.cpp
+int GetTimeZone()
 {
-    // set to TRUE when the timezone is set
-    static bool s_timezoneSet = FALSE;
-
-    wxCRIT_SECT_LOCKER(lock, gs_critsectTimezone);
+    // set to true when the timezone is set
+    static bool s_timezoneSet = false;
+    static long gmtoffset = LONG_MAX; // invalid timezone
 
+    // ensure that the timezone variable is set by calling wxLocaltime_r
     if ( !s_timezoneSet )
     {
-        (void)localtime(0);
+        // just call wxLocaltime_r() instead of figuring out whether this
+        // system supports tzset(), _tzset() or something else
+        time_t t = 0;
+        struct tm tm;
+
+        wxLocaltime_r(&t, &tm);
+        s_timezoneSet = true;
+
+#ifdef WX_GMTOFF_IN_TM
+        // note that GMT offset is the opposite of time zone and so to return
+        // consistent results in both WX_GMTOFF_IN_TM and !WX_GMTOFF_IN_TM
+        // cases we have to negate it
+        gmtoffset = -tm.tm_gmtoff;
+#else // !WX_GMTOFF_IN_TM
+        gmtoffset = WX_TIMEZONE;
+#endif // WX_GMTOFF_IN_TM/!WX_GMTOFF_IN_TM
+    }
 
-        s_timezoneSet = TRUE;
+    return (int)gmtoffset;
+}
+
+// return the integral part of the JDN for the midnight of the given date (to
+// get the real JDN you need to add 0.5, this is, in fact, JDN of the
+// noon of the previous day)
+static long GetTruncatedJDN(wxDateTime::wxDateTime_t day,
+                            wxDateTime::Month mon,
+                            int year)
+{
+    // CREDIT: code below is by Scott E. Lee (but bugs are mine)
+
+    // check the date validity
+    wxASSERT_MSG(
+      (year > JDN_0_YEAR) ||
+      ((year == JDN_0_YEAR) && (mon > JDN_0_MONTH)) ||
+      ((year == JDN_0_YEAR) && (mon == JDN_0_MONTH) && (day >= JDN_0_DAY)),
+      _T("date out of range - can't convert to JDN")
+                );
+
+    // make the year positive to avoid problems with negative numbers division
+    year += 4800;
+
+    // months are counted from March here
+    int month;
+    if ( mon >= wxDateTime::Mar )
+    {
+        month = mon - 2;
+    }
+    else
+    {
+        month = mon + 10;
+        year--;
     }
 
-    return (int)timezone;
+    // now we can simply add all the contributions together
+    return ((year / 100) * DAYS_PER_400_YEARS) / 4
+            + ((year % 100) * DAYS_PER_4_YEARS) / 4
+            + (month * DAYS_PER_5_MONTHS + 2) / 5
+            + day
+            - JDN_OFFSET;
 }
 
-// this function is a wrapper around strftime(3)
-static wxString CallStrftime(const wxChar *format, const tm* tm)
+#ifdef wxHAS_STRFTIME
+
+// this function is a wrapper around strftime(3) adding error checking
+// NOTE: not static because used by datetimefmt.cpp
+wxString CallStrftime(const wxString& format, const tm* tm)
 {
-    wxChar buf[1024];
+    wxChar buf[4096];
+    // Create temp wxString here to work around mingw/cygwin bug 1046059
+    // http://sourceforge.net/tracker/?func=detail&atid=102435&aid=1046059&group_id=2435
+    wxString s;
+
     if ( !wxStrftime(buf, WXSIZEOF(buf), format, tm) )
     {
-        // is ti really possible that 1024 is too short?
+        // if the format is valid, buffer must be too small?
         wxFAIL_MSG(_T("strftime() failed"));
+
+        buf[0] = '\0';
     }
 
-    return wxString(buf);
+    s = buf;
+    return s;
 }
 
+#endif // wxHAS_STRFTIME
+
 // if year and/or month have invalid values, replace them with the current ones
 static void ReplaceDefaultYearMonthWithCurrent(int *year,
                                                wxDateTime::Month *month)
 {
     struct tm *tmNow = NULL;
+    struct tm tmstruct;
 
     if ( *year == wxDateTime::Inv_Year )
     {
-        tmNow = wxDateTime::GetTmNow();
+        tmNow = wxDateTime::GetTmNow(&tmstruct);
 
         *year = 1900 + tmNow->tm_year;
     }
@@ -126,23 +495,29 @@ static void ReplaceDefaultYearMonthWithCurrent(int *year,
     if ( *month == wxDateTime::Inv_Month )
     {
         if ( !tmNow )
-            tmNow = wxDateTime::GetTmNow();
+            tmNow = wxDateTime::GetTmNow(&tmstruct);
 
         *month = (wxDateTime::Month)tmNow->tm_mon;
     }
 }
 
+// fill the struct tm with default values
+// NOTE: not static because used by datetimefmt.cpp
+void InitTm(struct tm& tm)
+{
+    // struct tm may have etxra fields (undocumented and with unportable
+    // names) which, nevertheless, must be set to 0
+    memset(&tm, 0, sizeof(struct tm));
+
+    tm.tm_mday = 1;   // mday 0 is invalid
+    tm.tm_year = 76;  // any valid year
+    tm.tm_isdst = -1; // auto determine
+}
+
 // ============================================================================
 // implementation of wxDateTime
 // ============================================================================
 
-// ----------------------------------------------------------------------------
-// static data
-// ----------------------------------------------------------------------------
-
-wxDateTime::Country wxDateTime::ms_country = wxDateTime::Country_Unknown;
-wxDateTime wxDateTime::ms_InvDateTime;
-
 // ----------------------------------------------------------------------------
 // struct Tm
 // ----------------------------------------------------------------------------
@@ -152,36 +527,41 @@ wxDateTime::Tm::Tm()
     year = (wxDateTime_t)wxDateTime::Inv_Year;
     mon = wxDateTime::Inv_Month;
     mday = 0;
-    hour = min = sec = 0;
+    hour = min = sec = msec = 0;
     wday = wxDateTime::Inv_WeekDay;
 }
 
-wxDateTime::Tm::Tm(const struct tm& tm)
+wxDateTime::Tm::Tm(const struct tm& tm, const TimeZone& tz)
+              : m_tz(tz)
 {
-    sec = tm.tm_sec;
-    min = tm.tm_min;
-    hour = tm.tm_hour;
-    mday = tm.tm_mday;
+    msec = 0;
+    sec = (wxDateTime::wxDateTime_t)tm.tm_sec;
+    min = (wxDateTime::wxDateTime_t)tm.tm_min;
+    hour = (wxDateTime::wxDateTime_t)tm.tm_hour;
+    mday = (wxDateTime::wxDateTime_t)tm.tm_mday;
     mon = (wxDateTime::Month)tm.tm_mon;
     year = 1900 + tm.tm_year;
-    wday = tm.tm_wday;
-    yday = tm.tm_yday;
+    wday = (wxDateTime::wxDateTime_t)tm.tm_wday;
+    yday = (wxDateTime::wxDateTime_t)tm.tm_yday;
 }
 
 bool wxDateTime::Tm::IsValid() const
 {
     // we allow for the leap seconds, although we don't use them (yet)
     return (year != wxDateTime::Inv_Year) && (mon != wxDateTime::Inv_Month) &&
-           (mday < GetNumOfDaysInMonth(year, mon)) &&
-           (hour < 24) && (min < 60) && (sec < 62);
+           (mday <= GetNumOfDaysInMonth(year, mon)) &&
+           (hour < 24) && (min < 60) && (sec < 62) && (msec < 1000);
 }
 
 void wxDateTime::Tm::ComputeWeekDay()
 {
-    wxFAIL_MSG(_T("TODO"));
+    // compute the week day from day/month/year: we use the dumbest algorithm
+    // possible: just compute our JDN and then use the (simple to derive)
+    // formula: weekday = (JDN + 1.5) % 7
+    wday = (wxDateTime::wxDateTime_t)((GetTruncatedJDN(mday, mon, year) + 2) % 7);
 }
 
-void wxDateTime::Tm::AddMonths(wxDateTime::wxDateTime_t monDiff)
+void wxDateTime::Tm::AddMonths(int monDiff)
 {
     // normalize the months field
     while ( monDiff < -mon )
@@ -191,27 +571,32 @@ void wxDateTime::Tm::AddMonths(wxDateTime::wxDateTime_t monDiff)
         monDiff += MONTHS_IN_YEAR;
     }
 
-    while ( monDiff + mon > MONTHS_IN_YEAR )
+    while ( monDiff + mon >= MONTHS_IN_YEAR )
     {
         year++;
+
+        monDiff -= MONTHS_IN_YEAR;
     }
 
     mon = (wxDateTime::Month)(mon + monDiff);
 
-    wxASSERT_MSG( mon >= 0 && mon < 12, _T("logic error") );
+    wxASSERT_MSG( mon >= 0 && mon < MONTHS_IN_YEAR, _T("logic error") );
+
+    // NB: we don't check here that the resulting date is valid, this function
+    //     is private and the caller must check it if needed
 }
 
-void wxDateTime::Tm::AddDays(wxDateTime::wxDateTime_t dayDiff)
+void wxDateTime::Tm::AddDays(int dayDiff)
 {
     // normalize the days field
-    mday += dayDiff;
-    while ( mday < 1 )
+    while ( dayDiff + mday < 1 )
     {
         AddMonths(-1);
 
-        mday += GetNumOfDaysInMonth(year, mon);
+        dayDiff += GetNumOfDaysInMonth(year, mon);
     }
 
+    mday = (wxDateTime::wxDateTime_t)( mday + dayDiff );
     while ( mday > GetNumOfDaysInMonth(year, mon) )
     {
         mday -= GetNumOfDaysInMonth(year, mon);
@@ -232,7 +617,9 @@ wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
     switch ( tz )
     {
         case wxDateTime::Local:
-            // leave offset to be 0
+            // get the offset from C RTL: it returns the difference GMT-local
+            // while we want to have the offset _from_ GMT, hence the '-'
+            m_offset = -GetTimeZone();
             break;
 
         case wxDateTime::GMT_12:
@@ -247,7 +634,7 @@ wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
         case wxDateTime::GMT_3:
         case wxDateTime::GMT_2:
         case wxDateTime::GMT_1:
-            m_offset = -60*(wxDateTime::GMT0 - tz);
+            m_offset = -3600*(wxDateTime::GMT0 - tz);
             break;
 
         case wxDateTime::GMT0:
@@ -263,12 +650,13 @@ wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
         case wxDateTime::GMT10:
         case wxDateTime::GMT11:
         case wxDateTime::GMT12:
-            m_offset = 60*(tz - wxDateTime::GMT0);
+        case wxDateTime::GMT13:
+            m_offset = 3600*(tz - wxDateTime::GMT0);
             break;
 
         case wxDateTime::A_CST:
             // Central Standard Time in use in Australia = UTC + 9.5
-            m_offset = 9*60 + 30;
+            m_offset = 60l*(9*MIN_PER_HOUR + MIN_PER_HOUR/2);
             break;
 
         default:
@@ -280,6 +668,13 @@ wxDateTime::TimeZone::TimeZone(wxDateTime::TZ tz)
 // static functions
 // ----------------------------------------------------------------------------
 
+/* static */
+struct tm *wxDateTime::GetTmNow(struct tm *tmstruct)
+{
+    time_t t = GetTimeNow();
+    return wxLocaltime_r(&t, tmstruct);
+}
+
 /* static */
 bool wxDateTime::IsLeapYear(int year, wxDateTime::Calendar cal)
 {
@@ -303,7 +698,7 @@ bool wxDateTime::IsLeapYear(int year, wxDateTime::Calendar cal)
     {
         wxFAIL_MSG(_T("unknown calendar"));
 
-        return FALSE;
+        return false;
     }
 }
 
@@ -313,12 +708,6 @@ int wxDateTime::GetCentury(int year)
     return year > 0 ? year / 100 : year / 100 - 1;
 }
 
-/* static */
-void wxDateTime::SetCountry(wxDateTime::Country country)
-{
-    ms_country = country;
-}
-
 /* static */
 int wxDateTime::ConvertYearToBC(int year)
 {
@@ -353,7 +742,6 @@ wxDateTime::Month wxDateTime::GetCurrentMonth(wxDateTime::Calendar cal)
     {
         case Gregorian:
             return Now().GetMonth();
-            break;
 
         case Julian:
             wxFAIL_MSG(_T("TODO"));
@@ -381,7 +769,6 @@ wxDateTime::wxDateTime_t wxDateTime::GetNumberOfDays(int year, Calendar cal)
         case Gregorian:
         case Julian:
             return IsLeapYear(year) ? 366 : 365;
-            break;
 
         default:
             wxFAIL_MSG(_T("unsupported calendar"));
@@ -416,160 +803,852 @@ wxDateTime::wxDateTime_t wxDateTime::GetNumberOfDays(wxDateTime::Month month,
     }
 }
 
-/* static */
-wxString wxDateTime::GetMonthName(wxDateTime::Month month, bool abbr)
+namespace
 {
-    wxCHECK_MSG( month != Inv_Month, _T(""), _T("invalid month") );
 
-    tm tm = { 0, 0, 0, 1, month, 76 };  // any year will do
+// helper function used by GetEnglish/WeekDayName(): returns 0 if flags is
+// Name_Full and 1 if it is Name_Abbr or -1 if the flags is incorrect (and
+// asserts in this case)
+//
+// the return value of this function is used as an index into 2D array
+// containing full names in its first row and abbreviated ones in the 2nd one
+int NameArrayIndexFromFlag(wxDateTime::NameFlags flags)
+{
+    switch ( flags )
+    {
+        case wxDateTime::Name_Full:
+            return 0;
+
+        case wxDateTime::Name_Abbr:
+            return 1;
+
+        default:
+            wxFAIL_MSG( "unknown wxDateTime::NameFlags value" );
+    }
 
-    return CallStrftime(abbr ? _T("%b") : _T("%B"), &tm);
+    return -1;
 }
 
+} // anonymous namespace
+
 /* static */
-wxString wxDateTime::GetWeekDayName(wxDateTime::WeekDay wday, bool abbr)
+wxString wxDateTime::GetEnglishMonthName(Month month, NameFlags flags)
 {
-    wxCHECK_MSG( wday != Inv_WeekDay, _T(""), _T("invalid weekday") );
+    wxCHECK_MSG( month != Inv_Month, wxEmptyString, "invalid month" );
 
-    // take some arbitrary Sunday
-    tm tm = { 0, 0, 0, 28, Nov, 99 };
+    static const char *monthNames[2][MONTHS_IN_YEAR] =
+    {
+        { "January", "February", "March", "April", "May", "June",
+          "July", "August", "September", "October", "November", "December" },
+        { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+          "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }
+    };
 
-    // and offset it by the number of days needed to get 
-    tm.tm_mday += wday;
+    const int idx = NameArrayIndexFromFlag(flags);
+    if ( idx == -1 )
+        return wxString();
 
-    return CallStrftime(abbr ? _T("%a") : _T("%A"), &tm);
+    return monthNames[idx][month];
 }
 
-// ----------------------------------------------------------------------------
-// constructors and assignment operators
-// ----------------------------------------------------------------------------
+/* static */
+wxString wxDateTime::GetMonthName(wxDateTime::Month month,
+                                  wxDateTime::NameFlags flags)
+{
+#ifdef wxHAS_STRFTIME
+    wxCHECK_MSG( month != Inv_Month, wxEmptyString, _T("invalid month") );
+
+    // notice that we must set all the fields to avoid confusing libc (GNU one
+    // gets confused to a crash if we don't do this)
+    tm tm;
+    InitTm(tm);
+    tm.tm_mon = month;
+
+    return CallStrftime(flags == Name_Abbr ? _T("%b") : _T("%B"), &tm);
+#else // !wxHAS_STRFTIME
+    return GetEnglishMonthName(month, flags);
+#endif // wxHAS_STRFTIME/!wxHAS_STRFTIME
+}
 
-wxDateTime& wxDateTime::Set(const struct tm& tm1)
+/* static */
+wxString wxDateTime::GetEnglishWeekDayName(WeekDay wday, NameFlags flags)
 {
-    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+    wxCHECK_MSG( wday != Inv_WeekDay, wxEmptyString, _T("invalid weekday") );
 
-    tm tm2(tm1);
-    time_t timet = mktime(&tm2);
-    if ( timet == (time_t)(-1) )
+    static const char *weekdayNames[2][DAYS_PER_400_YEARS] =
     {
-        wxFAIL_MSG(_T("Invalid time"));
+        { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
+          "Saturday" },
+        { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" },
+    };
 
-        return ms_InvDateTime;
-    }
-    else
-    {
-        return Set(timet);
-    }
+    const int idx = NameArrayIndexFromFlag(flags);
+    if ( idx == -1 )
+        return wxString();
+
+    return weekdayNames[idx][wday];
 }
 
-wxDateTime& wxDateTime::Set(wxDateTime_t hour,
-                            wxDateTime_t minute,
-                            wxDateTime_t second,
-                            wxDateTime_t millisec)
+/* static */
+wxString wxDateTime::GetWeekDayName(wxDateTime::WeekDay wday,
+                                    wxDateTime::NameFlags flags)
 {
-    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
-
-    // we allow seconds to be 61 to account for the leap seconds, even if we
-    // don't use them really
-    wxCHECK_MSG( hour < 24 && second < 62 && minute < 60 && millisec < 1000,
-                 ms_InvDateTime,
-                 _T("Invalid time in wxDateTime::Set()") );
-
-    // get the current date from system
-    time_t timet = GetTimeNow();
-    struct tm *tm = localtime(&timet);
-
-    // adjust the time
-    tm->tm_hour = hour;
-    tm->tm_min = minute;
-    tm->tm_sec = second;
+#ifdef wxHAS_STRFTIME
+    wxCHECK_MSG( wday != Inv_WeekDay, wxEmptyString, _T("invalid weekday") );
+
+    // take some arbitrary Sunday (but notice that the day should be such that
+    // after adding wday to it below we still have a valid date, e.g. don't
+    // take 28 here!)
+    tm tm;
+    InitTm(tm);
+    tm.tm_mday = 21;
+    tm.tm_mon = Nov;
+    tm.tm_year = 99;
+
+    // and offset it by the number of days needed to get the correct wday
+    tm.tm_mday += wday;
 
-    (void)Set(*tm);
+    // call mktime() to normalize it...
+    (void)mktime(&tm);
 
-    // and finally adjust milliseconds
-    return SetMillisecond(millisec);
+    // ... and call strftime()
+    return CallStrftime(flags == Name_Abbr ? _T("%a") : _T("%A"), &tm);
+#else // !wxHAS_STRFTIME
+    return GetEnglishWeekDayName(wday, flags);
+#endif // wxHAS_STRFTIME/!wxHAS_STRFTIME
 }
 
-wxDateTime& wxDateTime::Set(wxDateTime_t day,
-                            Month        month,
-                            int          year,
-                            wxDateTime_t hour,
-                            wxDateTime_t minute,
-                            wxDateTime_t second,
-                            wxDateTime_t millisec)
+/* static */
+void wxDateTime::GetAmPmStrings(wxString *am, wxString *pm)
 {
-    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+    tm tm;
+    InitTm(tm);
+    wxChar buffer[64];
+    // @Note: Do not call 'CallStrftime' here! CallStrftime checks the return code
+    // and causes an assertion failed if the buffer is to small (which is good) - OR -
+    // if strftime does not return anything because the format string is invalid - OR -
+    // if there are no 'am' / 'pm' tokens defined for the current locale (which is not good).
+    // wxDateTime::ParseTime will try several different formats to parse the time.
+    // As a result, GetAmPmStrings might get called, even if the current locale
+    // does not define any 'am' / 'pm' tokens. In this case, wxStrftime would
+    // assert, even though it is a perfectly legal use.
+    if ( am )
+    {
+        if (wxStrftime(buffer, WXSIZEOF(buffer), _T("%p"), &tm) > 0)
+            *am = wxString(buffer);
+        else
+            *am = wxString();
+    }
+    if ( pm )
+    {
+        tm.tm_hour = 13;
+        if (wxStrftime(buffer, WXSIZEOF(buffer), _T("%p"), &tm) > 0)
+            *pm = wxString(buffer);
+        else
+            *pm = wxString();
+    }
+}
 
-    wxCHECK_MSG( hour < 24 && second < 62 && minute < 60 && millisec < 1000,
-                 ms_InvDateTime,
-                 _T("Invalid time in wxDateTime::Set()") );
 
-    ReplaceDefaultYearMonthWithCurrent(&year, &month);
+// ----------------------------------------------------------------------------
+// Country stuff: date calculations depend on the country (DST, work days,
+// ...), so we need to know which rules to follow.
+// ----------------------------------------------------------------------------
 
-    wxCHECK_MSG( day <= GetNumberOfDays(month, year), ms_InvDateTime,
-                 _T("Invalid date in wxDateTime::Set()") );
+/* static */
+wxDateTime::Country wxDateTime::GetCountry()
+{
+    // TODO use LOCALE_ICOUNTRY setting under Win32
+#ifndef __WXWINCE__
+    if ( ms_country == Country_Unknown )
+    {
+        // try to guess from the time zone name
+        time_t t = time(NULL);
+        struct tm tmstruct;
+        struct tm *tm = wxLocaltime_r(&t, &tmstruct);
 
-    // the range of time_t type (inclusive)
-    static const int yearMinInRange = 1970;
-    static const int yearMaxInRange = 2037;
+        wxString tz = CallStrftime(_T("%Z"), tm);
+        if ( tz == _T("WET") || tz == _T("WEST") )
+        {
+            ms_country = UK;
+        }
+        else if ( tz == _T("CET") || tz == _T("CEST") )
+        {
+            ms_country = Country_EEC;
+        }
+        else if ( tz == _T("MSK") || tz == _T("MSD") )
+        {
+            ms_country = Russia;
+        }
+        else if ( tz == _T("AST") || tz == _T("ADT") ||
+                  tz == _T("EST") || tz == _T("EDT") ||
+                  tz == _T("CST") || tz == _T("CDT") ||
+                  tz == _T("MST") || tz == _T("MDT") ||
+                  tz == _T("PST") || tz == _T("PDT") )
+        {
+            ms_country = USA;
+        }
+        else
+        {
+            // well, choose a default one
+            ms_country = USA;
+        }
+    }
+#else // __WXWINCE__
+     ms_country = USA;
+#endif // !__WXWINCE__/__WXWINCE__
 
-    // test only the year instead of testing for the exact end of the Unix
-    // time_t range - it doesn't bring anything to do more precise checks
-    if ( year >= yearMinInRange && year <= yearMaxInRange )
-    {
-        // use the standard library version if the date is in range - this is
-        // probably more efficient than our code
-        struct tm tm;
-        tm.tm_year = year - 1900;
-        tm.tm_mon = month;
-        tm.tm_mday = day;
-        tm.tm_hour = hour;
-        tm.tm_min = minute;
-        tm.tm_sec = second;
+    return ms_country;
+}
 
-        (void)Set(tm);
+/* static */
+void wxDateTime::SetCountry(wxDateTime::Country country)
+{
+    ms_country = country;
+}
 
-        // and finally adjust milliseconds
-        return SetMillisecond(millisec);
-    }
-    else
+/* static */
+bool wxDateTime::IsWestEuropeanCountry(Country country)
+{
+    if ( country == Country_Default )
     {
-        // do time calculations ourselves: we want to calculate the number of
-        // milliseconds between the given date and the epoch
-        wxFAIL_MSG(_T("TODO"));
+        country = GetCountry();
     }
 
-    return *this;
+    return (Country_WesternEurope_Start <= country) &&
+           (country <= Country_WesternEurope_End);
 }
 
 // ----------------------------------------------------------------------------
-// time_t <-> broken down time conversions
+// DST calculations: we use 3 different rules for the West European countries,
+// USA and for the rest of the world. This is undoubtedly false for many
+// countries, but I lack the necessary info (and the time to gather it),
+// please add the other rules here!
 // ----------------------------------------------------------------------------
 
-wxDateTime::Tm wxDateTime::GetTm() const
+/* static */
+bool wxDateTime::IsDSTApplicable(int year, Country country)
 {
-    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
-
-    time_t time = GetTicks();
-    if ( time != (time_t)-1 )
+    if ( year == Inv_Year )
     {
-        // use C RTL functions
-        tm *tm = localtime(&time);
-
-        // should never happen
-        wxCHECK_MSG( tm, Tm(), _T("localtime() failed") );
+        // take the current year if none given
+        year = GetCurrentYear();
+    }
 
-        return Tm(*tm);
+    if ( country == Country_Default )
+    {
+        country = GetCountry();
     }
-    else
+
+    switch ( country )
     {
-        wxFAIL_MSG(_T("TODO"));
+        case USA:
+        case UK:
+            // DST was first observed in the US and UK during WWI, reused
+            // during WWII and used again since 1966
+            return year >= 1966 ||
+                   (year >= 1942 && year <= 1945) ||
+                   (year == 1918 || year == 1919);
 
-        return Tm();
+        default:
+            // assume that it started after WWII
+            return year > 1950;
     }
 }
 
-wxDateTime& wxDateTime::SetYear(int year)
+/* static */
+wxDateTime wxDateTime::GetBeginDST(int year, Country country)
+{
+    if ( year == Inv_Year )
+    {
+        // take the current year if none given
+        year = GetCurrentYear();
+    }
+
+    if ( country == Country_Default )
+    {
+        country = GetCountry();
+    }
+
+    if ( !IsDSTApplicable(year, country) )
+    {
+        return wxInvalidDateTime;
+    }
+
+    wxDateTime dt;
+
+    if ( IsWestEuropeanCountry(country) || (country == Russia) )
+    {
+        // DST begins at 1 a.m. GMT on the last Sunday of March
+        if ( !dt.SetToLastWeekDay(Sun, Mar, year) )
+        {
+            // weird...
+            wxFAIL_MSG( _T("no last Sunday in March?") );
+        }
+
+        dt += wxTimeSpan::Hours(1);
+    }
+    else switch ( country )
+    {
+        case USA:
+            switch ( year )
+            {
+                case 1918:
+                case 1919:
+                    // don't know for sure - assume it was in effect all year
+
+                case 1943:
+                case 1944:
+                case 1945:
+                    dt.Set(1, Jan, year);
+                    break;
+
+                case 1942:
+                    // DST was installed Feb 2, 1942 by the Congress
+                    dt.Set(2, Feb, year);
+                    break;
+
+                    // Oil embargo changed the DST period in the US
+                case 1974:
+                    dt.Set(6, Jan, 1974);
+                    break;
+
+                case 1975:
+                    dt.Set(23, Feb, 1975);
+                    break;
+
+                default:
+                    // before 1986, DST begun on the last Sunday of April, but
+                    // in 1986 Reagan changed it to begin at 2 a.m. of the
+                    // first Sunday in April
+                    if ( year < 1986 )
+                    {
+                        if ( !dt.SetToLastWeekDay(Sun, Apr, year) )
+                        {
+                            // weird...
+                            wxFAIL_MSG( _T("no first Sunday in April?") );
+                        }
+                    }
+                    else if ( year > 2006 )
+                    // Energy Policy Act of 2005, Pub. L. no. 109-58, 119 Stat 594 (2005).
+                    // Starting in 2007, daylight time begins in the United States on the
+                    // second Sunday in March and ends on the first Sunday in November
+                    {
+                        if ( !dt.SetToWeekDay(Sun, 2, Mar, year) )
+                        {
+                            // weird...
+                            wxFAIL_MSG( _T("no second Sunday in March?") );
+                        }
+                    }
+                    else
+                    {
+                        if ( !dt.SetToWeekDay(Sun, 1, Apr, year) )
+                        {
+                            // weird...
+                            wxFAIL_MSG( _T("no first Sunday in April?") );
+                        }
+                    }
+
+                    dt += wxTimeSpan::Hours(2);
+
+                    // TODO what about timezone??
+            }
+
+            break;
+
+        default:
+            // assume Mar 30 as the start of the DST for the rest of the world
+            // - totally bogus, of course
+            dt.Set(30, Mar, year);
+    }
+
+    return dt;
+}
+
+/* static */
+wxDateTime wxDateTime::GetEndDST(int year, Country country)
+{
+    if ( year == Inv_Year )
+    {
+        // take the current year if none given
+        year = GetCurrentYear();
+    }
+
+    if ( country == Country_Default )
+    {
+        country = GetCountry();
+    }
+
+    if ( !IsDSTApplicable(year, country) )
+    {
+        return wxInvalidDateTime;
+    }
+
+    wxDateTime dt;
+
+    if ( IsWestEuropeanCountry(country) || (country == Russia) )
+    {
+        // DST ends at 1 a.m. GMT on the last Sunday of October
+        if ( !dt.SetToLastWeekDay(Sun, Oct, year) )
+        {
+            // weirder and weirder...
+            wxFAIL_MSG( _T("no last Sunday in October?") );
+        }
+
+        dt += wxTimeSpan::Hours(1);
+    }
+    else switch ( country )
+    {
+        case USA:
+            switch ( year )
+            {
+                case 1918:
+                case 1919:
+                    // don't know for sure - assume it was in effect all year
+
+                case 1943:
+                case 1944:
+                    dt.Set(31, Dec, year);
+                    break;
+
+                case 1945:
+                    // the time was reset after the end of the WWII
+                    dt.Set(30, Sep, year);
+                    break;
+
+                default: // default for switch (year)
+                    if ( year > 2006 )
+                      // Energy Policy Act of 2005, Pub. L. no. 109-58, 119 Stat 594 (2005).
+                      // Starting in 2007, daylight time begins in the United States on the
+                      // second Sunday in March and ends on the first Sunday in November
+                    {
+                        if ( !dt.SetToWeekDay(Sun, 1, Nov, year) )
+                        {
+                            // weird...
+                            wxFAIL_MSG( _T("no first Sunday in November?") );
+                        }
+                    }
+                    else
+                     // pre-2007
+                     // DST ends at 2 a.m. on the last Sunday of October
+                    {
+                        if ( !dt.SetToLastWeekDay(Sun, Oct, year) )
+                        {
+                            // weirder and weirder...
+                            wxFAIL_MSG( _T("no last Sunday in October?") );
+                        }
+                    }
+
+                    dt += wxTimeSpan::Hours(2);
+
+            // TODO: what about timezone??
+            }
+            break;
+
+        default: // default for switch (country)
+            // assume October 26th as the end of the DST - totally bogus too
+            dt.Set(26, Oct, year);
+    }
+
+    return dt;
+}
+
+// ----------------------------------------------------------------------------
+// constructors and assignment operators
+// ----------------------------------------------------------------------------
+
+// return the current time with ms precision
+/* static */ wxDateTime wxDateTime::UNow()
+{
+    return wxDateTime(wxGetLocalTimeMillis());
+}
+
+// the values in the tm structure contain the local time
+wxDateTime& wxDateTime::Set(const struct tm& tm)
+{
+    struct tm tm2(tm);
+    time_t timet = mktime(&tm2);
+
+    if ( timet == (time_t)-1 )
+    {
+        // mktime() rather unintuitively fails for Jan 1, 1970 if the hour is
+        // less than timezone - try to make it work for this case
+        if ( tm2.tm_year == 70 && tm2.tm_mon == 0 && tm2.tm_mday == 1 )
+        {
+            return Set((time_t)(
+                       GetTimeZone() +
+                       tm2.tm_hour * MIN_PER_HOUR * SEC_PER_MIN +
+                       tm2.tm_min * SEC_PER_MIN +
+                       tm2.tm_sec));
+        }
+
+        wxFAIL_MSG( _T("mktime() failed") );
+
+        *this = wxInvalidDateTime;
+
+        return *this;
+    }
+    else
+    {
+        return Set(timet);
+    }
+}
+
+wxDateTime& wxDateTime::Set(wxDateTime_t hour,
+                            wxDateTime_t minute,
+                            wxDateTime_t second,
+                            wxDateTime_t millisec)
+{
+    // we allow seconds to be 61 to account for the leap seconds, even if we
+    // don't use them really
+    wxDATETIME_CHECK( hour < 24 &&
+                      second < 62 &&
+                      minute < 60 &&
+                      millisec < 1000,
+                      _T("Invalid time in wxDateTime::Set()") );
+
+    // get the current date from system
+    struct tm tmstruct;
+    struct tm *tm = GetTmNow(&tmstruct);
+
+    wxDATETIME_CHECK( tm, _T("wxLocaltime_r() failed") );
+
+    // make a copy so it isn't clobbered by the call to mktime() below
+    struct tm tm1(*tm);
+
+    // adjust the time
+    tm1.tm_hour = hour;
+    tm1.tm_min = minute;
+    tm1.tm_sec = second;
+
+    // and the DST in case it changes on this date
+    struct tm tm2(tm1);
+    mktime(&tm2);
+    if ( tm2.tm_isdst != tm1.tm_isdst )
+        tm1.tm_isdst = tm2.tm_isdst;
+
+    (void)Set(tm1);
+
+    // and finally adjust milliseconds
+    return SetMillisecond(millisec);
+}
+
+wxDateTime& wxDateTime::Set(wxDateTime_t day,
+                            Month        month,
+                            int          year,
+                            wxDateTime_t hour,
+                            wxDateTime_t minute,
+                            wxDateTime_t second,
+                            wxDateTime_t millisec)
+{
+    wxDATETIME_CHECK( hour < 24 &&
+                      second < 62 &&
+                      minute < 60 &&
+                      millisec < 1000,
+                      _T("Invalid time in wxDateTime::Set()") );
+
+    ReplaceDefaultYearMonthWithCurrent(&year, &month);
+
+    wxDATETIME_CHECK( (0 < day) && (day <= GetNumberOfDays(month, year)),
+                      _T("Invalid date in wxDateTime::Set()") );
+
+    // the range of time_t type (inclusive)
+    static const int yearMinInRange = 1970;
+    static const int yearMaxInRange = 2037;
+
+    // test only the year instead of testing for the exact end of the Unix
+    // time_t range - it doesn't bring anything to do more precise checks
+    if ( year >= yearMinInRange && year <= yearMaxInRange )
+    {
+        // use the standard library version if the date is in range - this is
+        // probably more efficient than our code
+        struct tm tm;
+        tm.tm_year = year - 1900;
+        tm.tm_mon = month;
+        tm.tm_mday = day;
+        tm.tm_hour = hour;
+        tm.tm_min = minute;
+        tm.tm_sec = second;
+        tm.tm_isdst = -1;       // mktime() will guess it
+
+        (void)Set(tm);
+
+        // and finally adjust milliseconds
+        if (IsValid())
+            SetMillisecond(millisec);
+
+        return *this;
+    }
+    else
+    {
+        // do time calculations ourselves: we want to calculate the number of
+        // milliseconds between the given date and the epoch
+
+        // get the JDN for the midnight of this day
+        m_time = GetTruncatedJDN(day, month, year);
+        m_time -= EPOCH_JDN;
+        m_time *= SECONDS_PER_DAY * TIME_T_FACTOR;
+
+        // JDN corresponds to GMT, we take localtime
+        Add(wxTimeSpan(hour, minute, second + GetTimeZone(), millisec));
+    }
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::Set(double jdn)
+{
+    // so that m_time will be 0 for the midnight of Jan 1, 1970 which is jdn
+    // EPOCH_JDN + 0.5
+    jdn -= EPOCH_JDN + 0.5;
+
+    m_time.Assign(jdn*MILLISECONDS_PER_DAY);
+
+    // JDNs always are in UTC, so we don't need any adjustments for time zone
+
+    return *this;
+}
+
+wxDateTime& wxDateTime::ResetTime()
+{
+    Tm tm = GetTm();
+
+    if ( tm.hour || tm.min || tm.sec || tm.msec )
+    {
+        tm.msec =
+        tm.sec =
+        tm.min =
+        tm.hour = 0;
+
+        Set(tm);
+    }
+
+    return *this;
+}
+
+wxDateTime wxDateTime::GetDateOnly() const
+{
+    Tm tm = GetTm();
+    tm.msec =
+    tm.sec =
+    tm.min =
+    tm.hour = 0;
+    return wxDateTime(tm);
+}
+
+// ----------------------------------------------------------------------------
+// DOS Date and Time Format functions
+// ----------------------------------------------------------------------------
+// the dos date and time value is an unsigned 32 bit value in the format:
+// YYYYYYYMMMMDDDDDhhhhhmmmmmmsssss
+//
+// Y = year offset from 1980 (0-127)
+// M = month (1-12)
+// D = day of month (1-31)
+// h = hour (0-23)
+// m = minute (0-59)
+// s = bisecond (0-29) each bisecond indicates two seconds
+// ----------------------------------------------------------------------------
+
+wxDateTime& wxDateTime::SetFromDOS(unsigned long ddt)
+{
+    struct tm tm;
+    InitTm(tm);
+
+    long year = ddt & 0xFE000000;
+    year >>= 25;
+    year += 80;
+    tm.tm_year = year;
+
+    long month = ddt & 0x1E00000;
+    month >>= 21;
+    month -= 1;
+    tm.tm_mon = month;
+
+    long day = ddt & 0x1F0000;
+    day >>= 16;
+    tm.tm_mday = day;
+
+    long hour = ddt & 0xF800;
+    hour >>= 11;
+    tm.tm_hour = hour;
+
+    long minute = ddt & 0x7E0;
+    minute >>= 5;
+    tm.tm_min = minute;
+
+    long second = ddt & 0x1F;
+    tm.tm_sec = second * 2;
+
+    return Set(mktime(&tm));
+}
+
+unsigned long wxDateTime::GetAsDOS() const
+{
+    unsigned long ddt;
+    time_t ticks = GetTicks();
+    struct tm tmstruct;
+    struct tm *tm = wxLocaltime_r(&ticks, &tmstruct);
+    wxCHECK_MSG( tm, ULONG_MAX, _T("time can't be represented in DOS format") );
+
+    long year = tm->tm_year;
+    year -= 80;
+    year <<= 25;
+
+    long month = tm->tm_mon;
+    month += 1;
+    month <<= 21;
+
+    long day = tm->tm_mday;
+    day <<= 16;
+
+    long hour = tm->tm_hour;
+    hour <<= 11;
+
+    long minute = tm->tm_min;
+    minute <<= 5;
+
+    long second = tm->tm_sec;
+    second /= 2;
+
+    ddt = year | month | day | hour | minute | second;
+    return ddt;
+}
+
+// ----------------------------------------------------------------------------
+// time_t <-> broken down time conversions
+// ----------------------------------------------------------------------------
+
+wxDateTime::Tm wxDateTime::GetTm(const TimeZone& tz) const
+{
+    wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
+
+    time_t time = GetTicks();
+    if ( time != (time_t)-1 )
+    {
+        // use C RTL functions
+        struct tm tmstruct;
+        tm *tm;
+        if ( tz.GetOffset() == -GetTimeZone() )
+        {
+            // we are working with local time
+            tm = wxLocaltime_r(&time, &tmstruct);
+
+            // should never happen
+            wxCHECK_MSG( tm, Tm(), _T("wxLocaltime_r() failed") );
+        }
+        else
+        {
+            time += (time_t)tz.GetOffset();
+#if defined(__VMS__) || defined(__WATCOMC__) // time is unsigned so avoid warning
+            int time2 = (int) time;
+            if ( time2 >= 0 )
+#else
+            if ( time >= 0 )
+#endif
+            {
+                tm = wxGmtime_r(&time, &tmstruct);
+
+                // should never happen
+                wxCHECK_MSG( tm, Tm(), _T("wxGmtime_r() failed") );
+            }
+            else
+            {
+                tm = (struct tm *)NULL;
+            }
+        }
+
+        if ( tm )
+        {
+            // adjust the milliseconds
+            Tm tm2(*tm, tz);
+            long timeOnly = (m_time % MILLISECONDS_PER_DAY).ToLong();
+            tm2.msec = (wxDateTime_t)(timeOnly % 1000);
+            return tm2;
+        }
+        //else: use generic code below
+    }
+
+    // remember the time and do the calculations with the date only - this
+    // eliminates rounding errors of the floating point arithmetics
+
+    wxLongLong timeMidnight = m_time + tz.GetOffset() * 1000;
+
+    long timeOnly = (timeMidnight % MILLISECONDS_PER_DAY).ToLong();
+
+    // we want to always have positive time and timeMidnight to be really
+    // the midnight before it
+    if ( timeOnly < 0 )
+    {
+        timeOnly = MILLISECONDS_PER_DAY + timeOnly;
+    }
+
+    timeMidnight -= timeOnly;
+
+    // calculate the Gregorian date from JDN for the midnight of our date:
+    // this will yield day, month (in 1..12 range) and year
+
+    // actually, this is the JDN for the noon of the previous day
+    long jdn = (timeMidnight / MILLISECONDS_PER_DAY).ToLong() + EPOCH_JDN;
+
+    // CREDIT: code below is by Scott E. Lee (but bugs are mine)
+
+    wxASSERT_MSG( jdn > -2, _T("JDN out of range") );
+
+    // calculate the century
+    long temp = (jdn + JDN_OFFSET) * 4 - 1;
+    long century = temp / DAYS_PER_400_YEARS;
+
+    // then the year and day of year (1 <= dayOfYear <= 366)
+    temp = ((temp % DAYS_PER_400_YEARS) / 4) * 4 + 3;
+    long year = (century * 100) + (temp / DAYS_PER_4_YEARS);
+    long dayOfYear = (temp % DAYS_PER_4_YEARS) / 4 + 1;
+
+    // and finally the month and day of the month
+    temp = dayOfYear * 5 - 3;
+    long month = temp / DAYS_PER_5_MONTHS;
+    long day = (temp % DAYS_PER_5_MONTHS) / 5 + 1;
+
+    // month is counted from March - convert to normal
+    if ( month < 10 )
+    {
+        month += 3;
+    }
+    else
+    {
+        year += 1;
+        month -= 9;
+    }
+
+    // year is offset by 4800
+    year -= 4800;
+
+    // check that the algorithm gave us something reasonable
+    wxASSERT_MSG( (0 < month) && (month <= 12), _T("invalid month") );
+    wxASSERT_MSG( (1 <= day) && (day < 32), _T("invalid day") );
+
+    // construct Tm from these values
+    Tm tm;
+    tm.year = (int)year;
+    tm.mon = (Month)(month - 1); // algorithm yields 1 for January, not 0
+    tm.mday = (wxDateTime_t)day;
+    tm.msec = (wxDateTime_t)(timeOnly % 1000);
+    timeOnly -= tm.msec;
+    timeOnly /= 1000;               // now we have time in seconds
+
+    tm.sec = (wxDateTime_t)(timeOnly % SEC_PER_MIN);
+    timeOnly -= tm.sec;
+    timeOnly /= SEC_PER_MIN;        // now we have time in minutes
+
+    tm.min = (wxDateTime_t)(timeOnly % MIN_PER_HOUR);
+    timeOnly -= tm.min;
+
+    tm.hour = (wxDateTime_t)(timeOnly / MIN_PER_HOUR);
+
+    return tm;
+}
+
+wxDateTime& wxDateTime::SetYear(int year)
 {
     wxASSERT_MSG( IsValid(), _T("invalid wxDateTime") );
 
@@ -656,10 +1735,27 @@ wxDateTime& wxDateTime::Add(const wxDateSpan& diff)
 
     tm.year += diff.GetYears();
     tm.AddMonths(diff.GetMonths());
+
+    // check that the resulting date is valid
+    if ( tm.mday > GetNumOfDaysInMonth(tm.year, tm.mon) )
+    {
+        // We suppose that when adding one month to Jan 31 we want to get Feb
+        // 28 (or 29), i.e. adding a month to the last day of the month should
+        // give the last day of the next month which is quite logical.
+        //
+        // Unfortunately, there is no logic way to understand what should
+        // Jan 30 + 1 month be - Feb 28 too or Feb 27 (assuming non leap year)?
+        // We make it Feb 28 (last day too), but it is highly questionable.
+        tm.mday = GetNumOfDaysInMonth(tm.year, tm.mon);
+    }
+
     tm.AddDays(diff.GetTotalDays());
 
     Set(tm);
 
+    wxASSERT_MSG( IsSameTime(tm),
+                  _T("Add(wxDateSpan) shouldn't modify time") );
+
     return *this;
 }
 
@@ -667,23 +1763,175 @@ wxDateTime& wxDateTime::Add(const wxDateSpan& diff)
 // Weekday and monthday stuff
 // ----------------------------------------------------------------------------
 
+// convert Sun, Mon, ..., Sat into 6, 0, ..., 5
+static inline int ConvertWeekDayToMondayBase(int wd)
+{
+    return wd == wxDateTime::Sun ? 6 : wd - 1;
+}
+
+/* static */
+wxDateTime
+wxDateTime::SetToWeekOfYear(int year, wxDateTime_t numWeek, WeekDay wd)
+{
+    wxASSERT_MSG( numWeek > 0,
+                  _T("invalid week number: weeks are counted from 1") );
+
+    // Jan 4 always lies in the 1st week of the year
+    wxDateTime dt(4, Jan, year);
+    dt.SetToWeekDayInSameWeek(wd);
+    dt += wxDateSpan::Weeks(numWeek - 1);
+
+    return dt;
+}
+
+#if WXWIN_COMPATIBILITY_2_6
+// use a separate function to avoid warnings about using deprecated
+// SetToTheWeek in GetWeek below
+static wxDateTime
+SetToTheWeek(int year,
+             wxDateTime::wxDateTime_t numWeek,
+             wxDateTime::WeekDay weekday,
+             wxDateTime::WeekFlags flags)
+{
+    // Jan 4 always lies in the 1st week of the year
+    wxDateTime dt(4, wxDateTime::Jan, year);
+    dt.SetToWeekDayInSameWeek(weekday, flags);
+    dt += wxDateSpan::Weeks(numWeek - 1);
+
+    return dt;
+}
+
+bool wxDateTime::SetToTheWeek(wxDateTime_t numWeek,
+                              WeekDay weekday,
+                              WeekFlags flags)
+{
+    int year = GetYear();
+    *this = ::SetToTheWeek(year, numWeek, weekday, flags);
+    if ( GetYear() != year )
+    {
+        // oops... numWeek was too big
+        return false;
+    }
+
+    return true;
+}
+
+wxDateTime wxDateTime::GetWeek(wxDateTime_t numWeek,
+                               WeekDay weekday,
+                               WeekFlags flags) const
+{
+    return ::SetToTheWeek(GetYear(), numWeek, weekday, flags);
+}
+#endif // WXWIN_COMPATIBILITY_2_6
+
 wxDateTime& wxDateTime::SetToLastMonthDay(Month month,
                                           int year)
 {
     // take the current month/year if none specified
-    ReplaceDefaultYearMonthWithCurrent(&year, &month);
+    if ( year == Inv_Year )
+        year = GetYear();
+    if ( month == Inv_Month )
+        month = GetMonth();
 
     return Set(GetNumOfDaysInMonth(year, month), month, year);
 }
 
+wxDateTime& wxDateTime::SetToWeekDayInSameWeek(WeekDay weekday, WeekFlags flags)
+{
+    wxDATETIME_CHECK( weekday != Inv_WeekDay, _T("invalid weekday") );
+
+    int wdayDst = weekday,
+        wdayThis = GetWeekDay();
+    if ( wdayDst == wdayThis )
+    {
+        // nothing to do
+        return *this;
+    }
+
+    if ( flags == Default_First )
+    {
+        flags = GetCountry() == USA ? Sunday_First : Monday_First;
+    }
+
+    // the logic below based on comparing weekday and wdayThis works if Sun (0)
+    // is the first day in the week, but breaks down for Monday_First case so
+    // we adjust the week days in this case
+    if ( flags == Monday_First )
+    {
+        if ( wdayThis == Sun )
+            wdayThis += 7;
+        if ( wdayDst == Sun )
+            wdayDst += 7;
+    }
+    //else: Sunday_First, nothing to do
+
+    // go forward or back in time to the day we want
+    if ( wdayDst < wdayThis )
+    {
+        return Subtract(wxDateSpan::Days(wdayThis - wdayDst));
+    }
+    else // weekday > wdayThis
+    {
+        return Add(wxDateSpan::Days(wdayDst - wdayThis));
+    }
+}
+
+wxDateTime& wxDateTime::SetToNextWeekDay(WeekDay weekday)
+{
+    wxDATETIME_CHECK( weekday != Inv_WeekDay, _T("invalid weekday") );
+
+    int diff;
+    WeekDay wdayThis = GetWeekDay();
+    if ( weekday == wdayThis )
+    {
+        // nothing to do
+        return *this;
+    }
+    else if ( weekday < wdayThis )
+    {
+        // need to advance a week
+        diff = 7 - (wdayThis - weekday);
+    }
+    else // weekday > wdayThis
+    {
+        diff = weekday - wdayThis;
+    }
+
+    return Add(wxDateSpan::Days(diff));
+}
+
+wxDateTime& wxDateTime::SetToPrevWeekDay(WeekDay weekday)
+{
+    wxDATETIME_CHECK( weekday != Inv_WeekDay, _T("invalid weekday") );
+
+    int diff;
+    WeekDay wdayThis = GetWeekDay();
+    if ( weekday == wdayThis )
+    {
+        // nothing to do
+        return *this;
+    }
+    else if ( weekday > wdayThis )
+    {
+        // need to go to previous week
+        diff = 7 - (weekday - wdayThis);
+    }
+    else // weekday < wdayThis
+    {
+        diff = wdayThis - weekday;
+    }
+
+    return Subtract(wxDateSpan::Days(diff));
+}
+
 bool wxDateTime::SetToWeekDay(WeekDay weekday,
                               int n,
                               Month month,
                               int year)
 {
-    wxCHECK_MSG( weekday != Inv_WeekDay, FALSE, _T("invalid weekday") );
+    wxCHECK_MSG( weekday != Inv_WeekDay, false, _T("invalid weekday") );
 
-    // we don't check explicitly that -5 <= n <= 5 because we will return FALSE
+    // we don't check explicitly that -5 <= n <= 5 because we will return false
     // anyhow in such case - but may be should still give an assert for it?
 
     // take the current month/year if none specified
@@ -709,9 +1957,9 @@ bool wxDateTime::SetToWeekDay(WeekDay weekday,
         // add advance n-1 weeks more
         diff += 7*(n - 1);
 
-        dt -= wxDateSpan::Days(diff);
+        dt += wxDateSpan::Days(diff);
     }
-    else
+    else // count from the end of the month
     {
         // get the last day of the month
         dt.SetToLastMonthDay(month, year);
@@ -725,7 +1973,7 @@ bool wxDateTime::SetToWeekDay(WeekDay weekday,
             diff += 7;
 
         // and rewind n-1 weeks from there
-        diff += 7*(n - 1);
+        diff += 7*(-n - 1);
 
         dt -= wxDateSpan::Days(diff);
     }
@@ -735,70 +1983,396 @@ bool wxDateTime::SetToWeekDay(WeekDay weekday,
     {
         *this = dt;
 
-        return TRUE;
+        return true;
     }
     else
     {
         // no such day in this month
-        return FALSE;
+        return false;
+    }
+}
+
+static inline
+wxDateTime::wxDateTime_t GetDayOfYearFromTm(const wxDateTime::Tm& tm)
+{
+    return (wxDateTime::wxDateTime_t)(gs_cumulatedDays[wxDateTime::IsLeapYear(tm.year)][tm.mon] + tm.mday);
+}
+
+wxDateTime::wxDateTime_t wxDateTime::GetDayOfYear(const TimeZone& tz) const
+{
+    return GetDayOfYearFromTm(GetTm(tz));
+}
+
+wxDateTime::wxDateTime_t
+wxDateTime::GetWeekOfYear(wxDateTime::WeekFlags flags, const TimeZone& tz) const
+{
+    if ( flags == Default_First )
+    {
+        flags = GetCountry() == USA ? Sunday_First : Monday_First;
     }
+
+    Tm tm(GetTm(tz));
+    wxDateTime_t nDayInYear = GetDayOfYearFromTm(tm);
+
+    int wdTarget = GetWeekDay(tz);
+    int wdYearStart = wxDateTime(1, Jan, GetYear()).GetWeekDay();
+    int week;
+    if ( flags == Sunday_First )
+    {
+        // FIXME: First week is not calculated correctly.
+        week = (nDayInYear - wdTarget + 7) / 7;
+        if ( wdYearStart == Wed || wdYearStart == Thu )
+            week++;
+    }
+    else // week starts with monday
+    {
+        // adjust the weekdays to non-US style.
+        wdYearStart = ConvertWeekDayToMondayBase(wdYearStart);
+        wdTarget = ConvertWeekDayToMondayBase(wdTarget);
+
+        // quoting from http://www.cl.cam.ac.uk/~mgk25/iso-time.html:
+        //
+        //      Week 01 of a year is per definition the first week that has the
+        //      Thursday in this year, which is equivalent to the week that
+        //      contains the fourth day of January. In other words, the first
+        //      week of a new year is the week that has the majority of its
+        //      days in the new year. Week 01 might also contain days from the
+        //      previous year and the week before week 01 of a year is the last
+        //      week (52 or 53) of the previous year even if it contains days
+        //      from the new year. A week starts with Monday (day 1) and ends
+        //      with Sunday (day 7).
+        //
+
+        // if Jan 1 is Thursday or less, it is in the first week of this year
+        if ( wdYearStart < 4 )
+        {
+            // count the number of entire weeks between Jan 1 and this date
+            week = (nDayInYear + wdYearStart + 6 - wdTarget)/7;
+
+            // be careful to check for overflow in the next year
+            if ( week == 53 && tm.mday - wdTarget > 28 )
+                    week = 1;
+        }
+        else // Jan 1 is in the last week of the previous year
+        {
+            // check if we happen to be at the last week of previous year:
+            if ( tm.mon == Jan && tm.mday < 8 - wdYearStart )
+                week = wxDateTime(31, Dec, GetYear()-1).GetWeekOfYear();
+            else
+                week = (nDayInYear + wdYearStart - 1 - wdTarget)/7;
+        }
+    }
+
+    return (wxDateTime::wxDateTime_t)week;
+}
+
+wxDateTime::wxDateTime_t wxDateTime::GetWeekOfMonth(wxDateTime::WeekFlags flags,
+                                                    const TimeZone& tz) const
+{
+    Tm tm = GetTm(tz);
+    wxDateTime dtMonthStart = wxDateTime(1, tm.mon, tm.year);
+    int nWeek = GetWeekOfYear(flags) - dtMonthStart.GetWeekOfYear(flags) + 1;
+    if ( nWeek < 0 )
+    {
+        // this may happen for January when Jan, 1 is the last week of the
+        // previous year
+        nWeek += IsLeapYear(tm.year - 1) ? 53 : 52;
+    }
+
+    return (wxDateTime::wxDateTime_t)nWeek;
+}
+
+wxDateTime& wxDateTime::SetToYearDay(wxDateTime::wxDateTime_t yday)
+{
+    int year = GetYear();
+    wxDATETIME_CHECK( (0 < yday) && (yday <= GetNumberOfDays(year)),
+                      _T("invalid year day") );
+
+    bool isLeap = IsLeapYear(year);
+    for ( Month mon = Jan; mon < Inv_Month; wxNextMonth(mon) )
+    {
+        // for Dec, we can't compare with gs_cumulatedDays[mon + 1], but we
+        // don't need it neither - because of the CHECK above we know that
+        // yday lies in December then
+        if ( (mon == Dec) || (yday <= gs_cumulatedDays[isLeap][mon + 1]) )
+        {
+            Set((wxDateTime::wxDateTime_t)(yday - gs_cumulatedDays[isLeap][mon]), mon, year);
+
+            break;
+        }
+    }
+
+    return *this;
+}
+
+// ----------------------------------------------------------------------------
+// Julian day number conversion and related stuff
+// ----------------------------------------------------------------------------
+
+double wxDateTime::GetJulianDayNumber() const
+{
+    return m_time.ToDouble() / MILLISECONDS_PER_DAY + EPOCH_JDN + 0.5;
+}
+
+double wxDateTime::GetRataDie() const
+{
+    // March 1 of the year 0 is Rata Die day -306 and JDN 1721119.5
+    return GetJulianDayNumber() - 1721119.5 - 306;
 }
 
 // ----------------------------------------------------------------------------
-// timezone stuff
+// timezone and DST stuff
 // ----------------------------------------------------------------------------
 
-wxDateTime& wxDateTime::MakeUTC()
+int wxDateTime::IsDST(wxDateTime::Country country) const
+{
+    wxCHECK_MSG( country == Country_Default, -1,
+                 _T("country support not implemented") );
+
+    // use the C RTL for the dates in the standard range
+    time_t timet = GetTicks();
+    if ( timet != (time_t)-1 )
+    {
+        struct tm tmstruct;
+        tm *tm = wxLocaltime_r(&timet, &tmstruct);
+
+        wxCHECK_MSG( tm, -1, _T("wxLocaltime_r() failed") );
+
+        return tm->tm_isdst;
+    }
+    else
+    {
+        int year = GetYear();
+
+        if ( !IsDSTApplicable(year, country) )
+        {
+            // no DST time in this year in this country
+            return -1;
+        }
+
+        return IsBetween(GetBeginDST(year, country), GetEndDST(year, country));
+    }
+}
+
+wxDateTime& wxDateTime::MakeTimezone(const TimeZone& tz, bool noDST)
 {
-    return Add(wxTimeSpan::Seconds(GetTimeZone()));
+    long secDiff = GetTimeZone() + tz.GetOffset();
+
+    // we need to know whether DST is or not in effect for this date unless
+    // the test disabled by the caller
+    if ( !noDST && (IsDST() == 1) )
+    {
+        // FIXME we assume that the DST is always shifted by 1 hour
+        secDiff -= 3600;
+    }
+
+    return Add(wxTimeSpan::Seconds(secDiff));
 }
 
-wxDateTime& wxDateTime::MakeTimezone(const TimeZone& tz)
+wxDateTime& wxDateTime::MakeFromTimezone(const TimeZone& tz, bool noDST)
 {
-    int minDiff = GetTimeZone() / SECONDS_IN_MINUTE + tz.GetOffset();
-    return Add(wxTimeSpan::Minutes(minDiff));
+    long secDiff = GetTimeZone() + tz.GetOffset();
+
+    // we need to know whether DST is or not in effect for this date unless
+    // the test disabled by the caller
+    if ( !noDST && (IsDST() == 1) )
+    {
+        // FIXME we assume that the DST is always shifted by 1 hour
+        secDiff -= 3600;
+    }
+
+    return Subtract(wxTimeSpan::Seconds(secDiff));
 }
 
-wxDateTime& wxDateTime::MakeLocalTime(const TimeZone& tz)
+// ============================================================================
+// wxDateTimeHolidayAuthority and related classes
+// ============================================================================
+
+#include "wx/arrimpl.cpp"
+
+WX_DEFINE_OBJARRAY(wxDateTimeArray)
+
+static int wxCMPFUNC_CONV
+wxDateTimeCompareFunc(wxDateTime **first, wxDateTime **second)
 {
-    int minDiff = GetTimeZone() / SECONDS_IN_MINUTE + tz.GetOffset();
-    return Substract(wxTimeSpan::Minutes(minDiff));
+    wxDateTime dt1 = **first,
+               dt2 = **second;
+
+    return dt1 == dt2 ? 0 : dt1 < dt2 ? -1 : +1;
 }
 
 // ----------------------------------------------------------------------------
-// wxDateTime to/from text representations
+// wxDateTimeHolidayAuthority
 // ----------------------------------------------------------------------------
 
-wxString wxDateTime::Format(const wxChar *format) const
+wxHolidayAuthoritiesArray wxDateTimeHolidayAuthority::ms_authorities;
+
+/* static */
+bool wxDateTimeHolidayAuthority::IsHoliday(const wxDateTime& dt)
 {
-    time_t time = GetTicks();
-    if ( time != (time_t)-1 )
+    size_t count = ms_authorities.size();
+    for ( size_t n = 0; n < count; n++ )
     {
-        // use strftime()
-        tm *tm = localtime(&time);
+        if ( ms_authorities[n]->DoIsHoliday(dt) )
+        {
+            return true;
+        }
+    }
 
-        // should never happen
-        wxCHECK_MSG( tm, _T(""), _T("localtime() failed") );
+    return false;
+}
+
+/* static */
+size_t
+wxDateTimeHolidayAuthority::GetHolidaysInRange(const wxDateTime& dtStart,
+                                               const wxDateTime& dtEnd,
+                                               wxDateTimeArray& holidays)
+{
+    wxDateTimeArray hol;
+
+    holidays.Clear();
+
+    const size_t countAuth = ms_authorities.size();
+    for ( size_t nAuth = 0; nAuth < countAuth; nAuth++ )
+    {
+        ms_authorities[nAuth]->DoGetHolidaysInRange(dtStart, dtEnd, hol);
 
-        return CallStrftime(format, tm);
+        WX_APPEND_ARRAY(holidays, hol);
     }
-    else
+
+    holidays.Sort(wxDateTimeCompareFunc);
+
+    return holidays.size();
+}
+
+/* static */
+void wxDateTimeHolidayAuthority::ClearAllAuthorities()
+{
+    WX_CLEAR_ARRAY(ms_authorities);
+}
+
+/* static */
+void wxDateTimeHolidayAuthority::AddAuthority(wxDateTimeHolidayAuthority *auth)
+{
+    ms_authorities.push_back(auth);
+}
+
+wxDateTimeHolidayAuthority::~wxDateTimeHolidayAuthority()
+{
+    // required here for Darwin
+}
+
+// ----------------------------------------------------------------------------
+// wxDateTimeWorkDays
+// ----------------------------------------------------------------------------
+
+bool wxDateTimeWorkDays::DoIsHoliday(const wxDateTime& dt) const
+{
+    wxDateTime::WeekDay wd = dt.GetWeekDay();
+
+    return (wd == wxDateTime::Sun) || (wd == wxDateTime::Sat);
+}
+
+size_t wxDateTimeWorkDays::DoGetHolidaysInRange(const wxDateTime& dtStart,
+                                                const wxDateTime& dtEnd,
+                                                wxDateTimeArray& holidays) const
+{
+    if ( dtStart > dtEnd )
     {
-        wxFAIL_MSG(_T("TODO"));
+        wxFAIL_MSG( _T("invalid date range in GetHolidaysInRange") );
+
+        return 0u;
+    }
 
-        return _T("");
+    holidays.Empty();
+
+    // instead of checking all days, start with the first Sat after dtStart and
+    // end with the last Sun before dtEnd
+    wxDateTime dtSatFirst = dtStart.GetNextWeekDay(wxDateTime::Sat),
+               dtSatLast = dtEnd.GetPrevWeekDay(wxDateTime::Sat),
+               dtSunFirst = dtStart.GetNextWeekDay(wxDateTime::Sun),
+               dtSunLast = dtEnd.GetPrevWeekDay(wxDateTime::Sun),
+               dt;
+
+    for ( dt = dtSatFirst; dt <= dtSatLast; dt += wxDateSpan::Week() )
+    {
+        holidays.Add(dt);
     }
+
+    for ( dt = dtSunFirst; dt <= dtSunLast; dt += wxDateSpan::Week() )
+    {
+        holidays.Add(dt);
+    }
+
+    return holidays.GetCount();
 }
 
 // ============================================================================
-// wxTimeSpan
+// other helper functions
 // ============================================================================
 
-wxString wxTimeSpan::Format(const wxChar *format) const
+// ----------------------------------------------------------------------------
+// iteration helpers: can be used to write a for loop over enum variable like
+// this:
+//  for ( m = wxDateTime::Jan; m < wxDateTime::Inv_Month; wxNextMonth(m) )
+// ----------------------------------------------------------------------------
+
+WXDLLIMPEXP_BASE void wxNextMonth(wxDateTime::Month& m)
+{
+    wxASSERT_MSG( m < wxDateTime::Inv_Month, _T("invalid month") );
+
+    // no wrapping or the for loop above would never end!
+    m = (wxDateTime::Month)(m + 1);
+}
+
+WXDLLIMPEXP_BASE void wxPrevMonth(wxDateTime::Month& m)
+{
+    wxASSERT_MSG( m < wxDateTime::Inv_Month, _T("invalid month") );
+
+    m = m == wxDateTime::Jan ? wxDateTime::Inv_Month
+                             : (wxDateTime::Month)(m - 1);
+}
+
+WXDLLIMPEXP_BASE void wxNextWDay(wxDateTime::WeekDay& wd)
+{
+    wxASSERT_MSG( wd < wxDateTime::Inv_WeekDay, _T("invalid week day") );
+
+    // no wrapping or the for loop above would never end!
+    wd = (wxDateTime::WeekDay)(wd + 1);
+}
+
+WXDLLIMPEXP_BASE void wxPrevWDay(wxDateTime::WeekDay& wd)
+{
+    wxASSERT_MSG( wd < wxDateTime::Inv_WeekDay, _T("invalid week day") );
+
+    wd = wd == wxDateTime::Sun ? wxDateTime::Inv_WeekDay
+                               : (wxDateTime::WeekDay)(wd - 1);
+}
+
+#ifdef __WXMSW__
+
+wxDateTime& wxDateTime::SetFromMSWSysTime(const SYSTEMTIME& st)
 {
-    wxFAIL_MSG( _T("TODO") );
+    return Set(st.wDay,
+            static_cast<wxDateTime::Month>(wxDateTime::Jan + st.wMonth - 1),
+            st.wYear,
+            0, 0, 0);
+}
 
-    wxString str;
+void wxDateTime::GetAsMSWSysTime(SYSTEMTIME* st) const
+{
+    const wxDateTime::Tm tm(GetTm());
+
+    st->wYear = (WXWORD)tm.year;
+    st->wMonth = (WXWORD)(tm.mon - wxDateTime::Jan + 1);
+    st->wDay = tm.mday;
 
-    return str;
+    st->wDayOfWeek =
+    st->wHour =
+    st->wMinute =
+    st->wSecond =
+    st->wMilliseconds = 0;
 }
+#endif // __WXMSW__
+
+#endif // wxUSE_DATETIME