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.h

@@ -0,0 +1,93 @@
+/*
+ * This file is a part of Winix
+ * and is not publicly distributed
+ *
+ * Copyright (c) 2012, Tomasz Sowa
+ * All rights reserved.
+ *
+ */
+
+#ifndef headerfile_winix_core_timezone
+#define headerfile_winix_core_timezone
+
+#include <ctime>
+#include "date/date.h"
+#include "space/space.h"
+
+
+
+class TimeZone
+{
+public:
+
+	TimeZone();
+
+
+	/*
+		setting:
+		tz_offset  = 0
+		tz_has_dst = false
+	*/
+	void Clear();
+
+
+	/*
+		reading zime zone values from Space struct
+		the struct should have:
+		  "tz_offset" (long)
+		  "tz_has_dst" (bool)
+		if tz_has_dst is true then also:
+		  "tz_dst_start"  date in the following format: MM:DD HH[:MM[:SS]]
+		  "tz_dst_end"    the same as above
+		  "tz_dst_offset" (long)
+	*/
+	bool SetTz(PT::Space & space);
+
+
+	/*
+		 converting from UTC to local time
+	*/
+	time_t   CalcLocalOffset(const PT::Date & utc_date);
+	time_t   ToLocal(time_t utc_time);
+	PT::Date ToLocal(const PT::Date & utc_date);
+
+
+	/*
+		 converting from local time to UTC
+	*/
+	time_t   CalcUTCOffset(const PT::Date & local_date);
+	time_t   ToUTC(time_t local_time);
+	PT::Date ToUTC(const PT::Date & local_date);
+
+
+
+
+	// time zone offset (in seconds)
+	time_t tz_offset;
+
+	// true if the time zone has daylight saving time
+	bool tz_has_dst;
+
+	// time zone daylight saving time (used if tz_has_dst is true)
+	// the 'year' field is ignored (is always 1970)
+	// these values (hours) are represented in local time (UTC + tz_offset)
+	PT::Date tz_dst_start, tz_dst_end;
+
+	// time zone daylight saving time offset
+	// used when tz_has_dst is true and the current date is whithin tz_dst_start and tz_dst_end
+	time_t tz_dst_offset;
+
+
+};
+
+
+
+
+
+
+
+
+
+
+
+#endif