public static TimeZoneInfo ToSystemTimeZone(this PosixTz posixTz, int year, bool isDaylightSavingTime = true)
{
if ((object)posixTz == null)
{
return(null);
}
var id = posixTz.name;
if (id.Length > 32)
{
id = id.Substring(0, 32);
}
var baseOffset = TimeSpan.FromSeconds(-posixTz.offset);
if ((object)posixTz.dst == null || !isDaylightSavingTime)
{
return(TimeZoneInfo.CreateCustomTimeZone(
id, baseOffset, posixTz.Format(), posixTz.name
));
}
var daylightDelta = TimeSpan.FromSeconds(
posixTz.offset - posixTz.dst.offset
);
var start = posixTz.dst.start.ToSystemTransitionTime(year);
var end = posixTz.dst.end.ToSystemTransitionTime(year);
var adjustmentRule = TimeZoneInfo.AdjustmentRule.CreateAdjustmentRule(
new DateTime(year, 1, 1), new DateTime(year, 12, 31), daylightDelta, start, end
);
return(TimeZoneInfo.CreateCustomTimeZone(
id, baseOffset, posixTz.Format(), posixTz.name, posixTz.dst.name, new[] { adjustmentRule }
));
}
public static DateTime ConvertUtcTimeToLocal(this PosixTz posixTz, DateTime time, bool isDaylightSavingTime = true)
{
if ((object)posixTz == null)
{
throw new ArgumentNullException("posixTz");
}
var tz = posixTz.ToSystemTimeZone(time.Year, isDaylightSavingTime);
return(TimeZoneInfo.ConvertTimeFromUtc(time, tz));
}
public void WriteTimeZone(PosixTz tz)
{
WriteName(tz.name);
WriteTimeOffset(tz.offset);
var dst = tz.dst;
if (dst != null)
{
WriteName(dst.name);
if (dst.offset != PosixTz.GetDefaultDstOffset(tz.offset))
{
WriteTimeOffset(dst.offset);
}
sb.Append(",");
WriteRule(dst.start);
sb.Append(",");
WriteRule(dst.end);
}
}
//std offset [dst[offset],start[/time],end[/time]]
public PosixTz ReadExpandedTimeZone()
{
SkipWhiteSpaces();
string std_name = null;
if (!ReadName(ref std_name) || std_name.Length < 3)
{
//std is required and should be no less than three characters
RaiseParseError();
}
SkipWhiteSpaces();
int std_ofs = 0;
if (!ReadTimeOffset(ref std_ofs))
{
//The offset following std shall be required.
RaiseParseError();
}
SkipWhiteSpaces();
if (AtEnd())
{
//if dst is missing, then the alternative time does not apply in this locale.
return(new PosixTz(std_name, std_ofs, null));
}
//parse dst clause
string dst_name = null;
if (!ReadName(ref dst_name))
{
//dst clause should begin with dst name which should be no less than three characters
RaiseParseError();
}
SkipWhiteSpaces();
int dst_offset = 0;
if (!ReadTimeOffset(ref dst_offset))
{
//if no offset follows dst, the alternative time is assumed to be one hour ahead
//of standard time.
dst_offset = PosixTz.GetDefaultDstOffset(std_ofs);
}
SkipWhiteSpaces();
if (!ReadSpecChar(',', ';'))
{
//no rules is specified
RaiseParseError();
}
SkipWhiteSpaces();
PosixTz.DstRule start = null;
if (!ReadRule(ref start))
{
//start rule is not specified
RaiseParseError();
}
SkipWhiteSpaces();
if (!ReadSpecChar(',', ';'))
{
//end rule is not specified
RaiseParseError();
}
SkipWhiteSpaces();
PosixTz.DstRule end = null;
if (!ReadRule(ref end))
{
//end rule is not specified
RaiseParseError();
}
var dst = new PosixTz.Dst(dst_name, dst_offset, start, end);
SkipWhiteSpaces();
if (!AtEnd())
{
//unexpected
RaiseParseError();
}
return(new PosixTz(std_name, std_ofs, dst));
}
