private static OracleTimeZone tzCacheObj;

[SecurityPermission(SecurityAction.Assert, SerializationFormatter = true)]
internal static OracleTimeZone GetInstance()
{
	try
	{
		if (tzCacheObj == null)
			tzCacheObj = new TimeZoneFileReader().ReadObj();
	}
	catch (Exception ex)
	{
		throw ex;
	}
	return tzCacheObj;
}

internal OracleTimeZone ReadObj()
{
	int latestTZVersion = 0;
	string name = "";
	Assembly executingAssembly = Assembly.GetExecutingAssembly();
	string[] manifestResourceNames = executingAssembly.GetManifestResourceNames();
	foreach (string text in manifestResourceNames)
	{
		if (text.StartsWith("OracleInternal.I18N.TimeZone", StringComparison.InvariantCultureIgnoreCase)
				&& text.EndsWith(".dst", StringComparison.InvariantCultureIgnoreCase))
		{
			latestTZVersion = Convert.ToInt32(text.Split('_', '.')[3]);
			name = text;
			break;
		}
	}
	using (GZipStream gZipStream = new GZipStream(executingAssembly.GetManifestResourceStream(name), CompressionMode.Decompress))
		using (MemoryStream memoryStream = new MemoryStream())
		{
			gZipStream.CopyTo(memoryStream);
			memoryStream.Position = 0L;
			BinaryReader binaryReader = new BinaryReader(memoryStream);
			LTZHead lTZHead = new LTZHead();
			int errcode = -1;
			lTZHead = PopulateHead(binaryReader, out errcode);
			if (errcode != 0)
				throw new Exception("Errorcode not present, Error in populating the head");
			LdiDateTime[] dttab = ReadTransitionsOfAllZones(lTZHead, binaryReader);
			LTZtag[] tagtab = PopulateTagArray(lTZHead, binaryReader);
			short[] tagmap = PopulateTagMapArray(lTZHead, binaryReader);
			byte[] dstflag = PopulateDSTFlagArray(lTZHead, binaryReader);
			Dictionary<int, string> zoneIdMap = PopulateZoneIdMapHashtable(lTZHead, binaryReader);
			Hashtable zoneIdtoOffsetMap = PopulateZoneOffsetMapHashtable(lTZHead, dttab, tagmap, tagtab, dstflag);
			OracleTimeZone oracleTimeZone = new OracleTimeZone();
			oracleTimeZone.SetZoneIdMap(zoneIdMap);
			oracleTimeZone.SetZoneIdtoOffsetMap(zoneIdtoOffsetMap);
			oracleTimeZone.SetLatestTZVersion(latestTZVersion);
			binaryReader.Close();
			return oracleTimeZone;
		}
}

internal Hashtable PopulateZoneOffsetMapHashtable(LTZHead head, LdiDateTime[] dttab, short[] tagmap, LTZtag[] tagtab, byte[] dstflag)
{
	Hashtable hashtable = new Hashtable();
	for (int i = 0; i < 8192; i++)
	{
		ZoneValue zoneValue = default(ZoneValue);
		LTZMeta lTZMeta = head.meta_ltzhead[i];
		uint ntrans_ltzmeta;
		if ((ntrans_ltzmeta = (uint)lTZMeta.ntrans_ltzmeta) == 0)
			continue;
		zoneValue.m_transitions = new Transitions[ntrans_ltzmeta];
		int num = 0;
		for (int j = 0; j < ntrans_ltzmeta; j++)
		{
			int num2 = lTZMeta.trans_ltzmeta + j;
			LdiDateTime ldiDateTime = dttab[num2];
			short num3 = tagmap[num2];
			LTZtag lTZtag = tagtab[num3];
			zoneValue.m_transitions[j] = default(Transitions);
			zoneValue.m_transitions[j].m_dateTimeInUtc = new DateTime(
				ldiDateTime.year_LdiDateTime,
				ldiDateTime.month_LdiDateTime,
				ldiDateTime.day_LdiDateTime,
				ldiDateTime.hour_LdiDateTime,
				ldiDateTime.minute_LdiDateTime,
				ldiDateTime.second_LdiDateTime
			);
			zoneValue.m_transitions[j].m_hourOffset = GetTimeSpan(lTZtag.gmtoff_ltztag);
			zoneValue.m_transitions[j].m_dst = dstflag[num2];
			zoneValue.m_transitions[j].m_dateTimeInLocal = zoneValue.m_transitions[j].m_dateTimeInUtc.Add(zoneValue.m_transitions[j].m_hourOffset);
			int num4 = lTZtag.gmtoff_ltztag - num;
			if (num4 < 0)
				num4 = -num4;
			zoneValue.m_transitions[j].m_dstDuration = GetTimeSpan(num4);
			if (zoneValue.m_transitions[j].m_dst != 0)
				zoneValue.m_transitions[j].m_dateTimeInLocal = zoneValue.m_transitions[j].m_dateTimeInLocal.Add(GetTimeSpan(-num4));
			num = lTZtag.gmtoff_ltztag;
		}
		hashtable.Add(i, zoneValue);
	}
	return hashtable;
}