search

lochmueller / calendarize

📆 Best TYPO3 Calendar ever 📆
http://typo3.org/extensions/repository/view/calendarize
74 stars 85 forks source link

(Edge case) Wrong time of imported recurring events from different timezones with/without DTS #679

Closed okmiim closed 6 months ago

okmiim commented 2 years ago

Imported recurring events have the wrong time, where the imported date is set in a different timezone (than the server) having no or other Daylight Saving Times (DST). This affects dates, which are in the "other" DST than the first event or where the switch happens at different dates.

Example

Server timezone: Asia/Seoul (no DST) Recurring event from America/New_York (has DTS)

ICS:

DTSTART;TZID=America/New_York:19970904T090000
RRULE:FREQ=MONTHLY;COUNT=10

The following table shows the actual time, the time in the Seoul timezone and the partly wrong generated indices.

New_York New_York -> Seoul Generated (Seoul), wrong
1997-09-04 09:00 1997-09-03 20:00 1997-09-03 20:00
1997-10-04 09:00 1997-10-03 20:00 1997-10-03 20:00
1997-11-04 09:00 1997-11-03 19:00 1997-11-03 20:00
1997-12-04 09:00 1997-12-03 19:00 1997-12-03 20:00
1998-01-04 09:00 1998-01-03 19:00 1998-01-03 20:00
1998-02-04 09:00 1998-02-03 19:00 1998-02-03 20:00
1998-03-04 09:00 1998-03-03 19:00 1998-03-03 20:00
1998-04-04 09:00 1998-04-03 19:00 1998-04-03 20:00
1998-05-04 09:00 1998-05-03 20:00 1998-05-03 20:00
1998-06-04 09:00 1998-06-03 20:00 1998-06-03 20:00

Example 2

Server timezone: Europe/Berlin (no DST) (same ics as above)

Wrong event:

Why:

lochmueller commented 6 months ago

Hey @okmiim I close this issue currently. It is really a edge case and perhaps more or less a problem of the parsing lib. Regards, Tim