Need to support Windows timezones

[derekantrican]

Example ICAL from a user (generated from Microsoft Outlook):

BEGIN:VEVENT
DESCRIPTION:Test sync
UID:040000008200E00074C5B7101A82E00800000000C0F85EF4991CD401000000000000000
010000000D8D1B7BF8927144E9F2E19D9CBAEF85C
SUMMARY:Test
DTSTART;TZID=Mountain Standard Time:20180716T080000
DTEND;TZID=Mountain Standard Time:20180716T090000
CLASS:PUBLIC
PRIORITY:5
DTSTAMP:20180716T034238Z
TRANSP:OPAQUE
STATUS:CONFIRMED
SEQUENCE:0
X-MICROSOFT-CDO-APPT-SEQUENCE:0
X-MICROSOFT-CDO-BUSYSTATUS:BUSY
X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
X-MICROSOFT-CDO-ALLDAYEVENT:FALSE
X-MICROSOFT-CDO-IMPORTANCE:1
X-MICROSOFT-CDO-INSTTYPE:0
X-MICROSOFT-DONOTFORWARDMEETING:FALSE
X-MICROSOFT-DISALLOW-COUNTER:FALSE
END:VEVENT

Note how the timezones are "Mountain Standard Time". This is a Windows way of representing the timezone and is not supported by Moment.js (which uses IANA timezone formats)

It's also somewhat important to note that when Moment can't match a timezone, it assumes the datetime is in UTC

[derekantrican]

This will probably be useful: https://github.com/chrisdavies/js-windows-timezones/blob/master/win-timezones.js

And this may be even more useful (see the second table, a direct mapping of Windows timezone to TZID): http://unicode.org/cldr/charts/32/supplemental/zone_tzid.html

[arjanvdberg]

I think this is the same issue as #3 . There should be a VTIMEZONE section in the ICAL that defines the timezone. The "Mountain Standard Time" is just a reference to this VTIMEZONE block.

[derekantrican]

@arjanvdberg Looks like you were right - this is the same as #3

Here is this user's VTIMEZONE section

BEGIN:VTIMEZONE
TZID:Mountain Standard Time
BEGIN:STANDARD
DTSTART:16010101T020000
TZOFFSETFROM:-0600
TZOFFSETTO:-0700
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=1SU;BYMONTH=11
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T020000
TZOFFSETFROM:-0700
TZOFFSETTO:-0600
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=2SU;BYMONTH=3
END:DAYLIGHT
END:VTIMEZONE

[derekantrican]

Closing as a duplicate of #3