private static TimeZoneInfo ParseTZBuffer(string id, byte [] buffer, int length)
{
//Reading the header. 4 bytes for magic, 16 are reserved
int ttisgmtcnt = ReadBigEndianInt32(buffer, 20);
int ttisstdcnt = ReadBigEndianInt32(buffer, 24);
int leapcnt = ReadBigEndianInt32(buffer, 28);
int timecnt = ReadBigEndianInt32(buffer, 32);
int typecnt = ReadBigEndianInt32(buffer, 36);
int charcnt = ReadBigEndianInt32(buffer, 40);
if (length < 44 + timecnt * 5 + typecnt * 6 + charcnt + leapcnt * 8 + ttisstdcnt + ttisgmtcnt)
{
throw new InvalidTimeZoneException();
}
Dictionary <int, string> abbreviations = ParseAbbreviations(buffer, 44 + 4 * timecnt + timecnt + 6 * typecnt, charcnt);
Dictionary <int, TimeType> time_types = ParseTimesTypes(buffer, 44 + 4 * timecnt + timecnt, typecnt, abbreviations);
List <KeyValuePair <DateTime, TimeType> > transitions = ParseTransitions(buffer, 44, timecnt, time_types);
if (time_types.Count == 0)
{
throw new InvalidTimeZoneException();
}
if (time_types.Count == 1 && ((TimeType)time_types[0]).IsDst)
{
throw new InvalidTimeZoneException();
}
TimeSpan baseUtcOffset = new TimeSpan(0);
TimeSpan dstDelta = new TimeSpan(0);
string standardDisplayName = null;
string daylightDisplayName = null;
bool dst_observed = false;
DateTime dst_start = DateTime.MinValue;
List <AdjustmentRule> adjustmentRules = new List <AdjustmentRule> ();
for (int i = 0; i < transitions.Count; i++)
{
var pair = transitions [i];
DateTime ttime = pair.Key;
TimeType ttype = pair.Value;
if (!ttype.IsDst)
{
if (standardDisplayName != ttype.Name || baseUtcOffset.TotalSeconds != ttype.Offset)
{
standardDisplayName = ttype.Name;
daylightDisplayName = null;
baseUtcOffset = new TimeSpan(0, 0, ttype.Offset);
adjustmentRules = new List <AdjustmentRule> ();
dst_observed = false;
}
if (dst_observed)
{
//FIXME: check additional fields for this:
//most of the transitions are expressed in GMT
dst_start += baseUtcOffset;
DateTime dst_end = ttime + baseUtcOffset + dstDelta;
//some weird timezone (America/Phoenix) have end dates on Jan 1st
if (dst_end.Date == new DateTime(dst_end.Year, 1, 1) && dst_end.Year > dst_start.Year)
{
dst_end -= new TimeSpan(24, 0, 0);
}
DateTime dateStart, dateEnd;
if (dst_start.Month < 7)
{
dateStart = new DateTime(dst_start.Year, 1, 1);
}
else
{
dateStart = new DateTime(dst_start.Year, 7, 1);
}
if (dst_end.Month >= 7)
{
dateEnd = new DateTime(dst_end.Year, 12, 31);
}
else
{
dateEnd = new DateTime(dst_end.Year, 6, 30);
}
TransitionTime transition_start = TransitionTime.CreateFixedDateRule(new DateTime(1, 1, 1) + dst_start.TimeOfDay, dst_start.Month, dst_start.Day);
TransitionTime transition_end = TransitionTime.CreateFixedDateRule(new DateTime(1, 1, 1) + dst_end.TimeOfDay, dst_end.Month, dst_end.Day);
if (transition_start != transition_end) //y, that happened in Argentina in 1943-1946
{
adjustmentRules.Add(AdjustmentRule.CreateAdjustmentRule(dateStart, dateEnd, dstDelta, transition_start, transition_end));
}
}
dst_observed = false;
}
else
{
if (daylightDisplayName != ttype.Name || dstDelta.TotalSeconds != ttype.Offset - baseUtcOffset.TotalSeconds)
{
daylightDisplayName = ttype.Name;
dstDelta = new TimeSpan(0, 0, ttype.Offset) - baseUtcOffset;
}
dst_start = ttime;
dst_observed = true;
}
}
if (adjustmentRules.Count == 0)
{
TimeType t = (TimeType)time_types [0];
if (standardDisplayName == null)
{
standardDisplayName = t.Name;
baseUtcOffset = new TimeSpan(0, 0, t.Offset);
}
return(CreateCustomTimeZone(id, baseUtcOffset, id, standardDisplayName));
}
else
{
return(CreateCustomTimeZone(id, baseUtcOffset, id, standardDisplayName, daylightDisplayName, ValidateRules(adjustmentRules).ToArray()));
}
}