added: TimeZone struct (core)

this class has information about a time zone (utf offset, daylight saving time)
       and methods for converting between UTC and local time
       structs User and Config has a TimeZone object
       System::ToLocal() and System::ToUTC() uses it for converting
       (depending whether a user is logged or not)


git-svn-id: svn://ttmath.org/publicrep/winix/trunk@842 e52654a7-88a9-db11-a3e9-0013d4bc506e

core/timezone.cpp

@@ -0,0 +1,163 @@
+/*
+ * This file is a part of Winix
+ * and is not publicly distributed
+ *
+ * Copyright (c) 2012, Tomasz Sowa
+ * All rights reserved.
+ *
+ */
+
+#include "timezone.h"
+
+
+
+
+TimeZone::TimeZone()
+{
+	Clear();
+}
+
+
+
+
+void TimeZone::Clear()
+{
+	tz_offset     = 0;
+	tz_has_dst    = false;
+	tz_dst_offset = 0;
+	tz_dst_start.Clear();
+	tz_dst_end.Clear();
+}
+
+
+
+time_t TimeZone::CalcLocalOffset(const PT::Date & utc_date)
+{
+time_t offset;
+
+	offset = tz_offset;
+
+	// !! CHECK ME need to be tested
+
+	if( tz_has_dst )
+	{
+		PT::Date local(utc_date);
+
+		local += tz_offset;
+		local.year      = tz_dst_start.year;
+		tz_dst_end.year = tz_dst_start.year;
+
+		if( tz_dst_start <= local && local < tz_dst_end )
+			offset += tz_dst_offset;
+	}
+
+return offset;
+}
+
+
+
+time_t TimeZone::ToLocal(time_t utc_time)
+{
+	time_t offset = CalcLocalOffset(PT::Date(utc_time));
+
+return utc_time + offset;
+}
+
+
+PT::Date TimeZone::ToLocal(const PT::Date & utc_date)
+{
+	PT::Date local(utc_date);
+	local += CalcLocalOffset(utc_date);
+
+return local;
+}
+
+
+time_t TimeZone::CalcUTCOffset(const PT::Date & local_date)
+{
+time_t offset;
+
+	offset = tz_offset;
+
+	if( tz_has_dst )
+	{
+		// !! CHECK ME need to be tested
+
+		PT::Date local(local_date);
+		local -= tz_dst_offset;
+		local.year      = tz_dst_start.year;
+		tz_dst_end.year = tz_dst_start.year;
+
+		if( tz_dst_start <= local && local < tz_dst_end )
+			offset += tz_dst_offset;
+	}
+
+return offset;
+}
+
+
+time_t TimeZone::ToUTC(time_t local_time)
+{
+	time_t offset = CalcUTCOffset(PT::Date(local_time));
+
+return local_time - offset;
+}
+
+
+
+PT::Date TimeZone::ToUTC(const PT::Date & local_date)
+{
+time_t offset;
+PT::Date utc(local_date);
+
+	offset = CalcUTCOffset(local_date);
+	utc   -= offset;
+
+return utc;
+}
+
+
+
+bool TimeZone::SetTz(PT::Space & space)
+{
+bool result = true;
+
+	tz_offset  = space.Long(L"tz_offset",  0);
+	tz_has_dst = space.Bool(L"tz_has_dst", false);
+
+	time_t h13 = 60 * 60 * 13; // 13 hours
+	time_t h15 = 60 * 60 * 15; // 15 hours
+	time_t h24 = 60 * 60 * 24; // 24 hours
+
+	if( tz_offset < -h13 || tz_offset > h15 )
+		result = false;
+
+	if( tz_has_dst )
+	{
+		tz_dst_start.year = 1970;
+		tz_dst_end.year   = 1970;
+
+		if( !tz_dst_start.ParseMonthDayTime(space.Text(L"tz_dst_start")) )
+			result = false;
+
+		if( !tz_dst_end.ParseMonthDayTime(space.Text(L"tz_dst_end")) )
+			result = false;
+
+		tz_dst_offset = space.Long(L"tz_dst_offset");
+
+		if( tz_dst_offset < -h24 || tz_dst_offset > h24 )
+			result = false;
+	}
+	else
+	{
+		tz_dst_start.Clear();
+		tz_dst_end.Clear();
+		tz_dst_offset = 0;
+	}
+
+	if( !result )
+		Clear();
+
+return result;
+}
+