Generate VTIMEZONE components

[niccokunzmann]

The icalendar can be enhanced by allowing the generation of the VTIMEZONE component automatically. The problem we are facing is recorded here, too:

• Generate VTIMEZONEs when not available mergecal/python-mergecal#7
• Insert VTIMEZONE information pycalendar/x-wr-timezone#4

When someone creates an .ics file, they want to have it easy to create a valid file #596 and that includes VTIMEZONE information. The timezone information is given by zoneinfo/tzdata and can be translated into a VTIMEZONE component. However, this is not implemented in this package. May people would benefit from that.

Maybe, in this ecosystem, there is someone who has already implemented this. This could be evaluated:

• https://pypi.org/project/ics-vtimezones/
• https://www.djangosnippets.org/snippets/10569/
• https://github.com/libical/vzic - looks promising
  • https://www.npmjs.com/package/timezones-ical-library - does what we want just in node - https://tz.add-to-calendar-technology.com/ easy enough.

See also:

• Mandatory properties are neither enforced nor set to a default #596
• Generate VTIMEZONEs when not available mergecal/python-mergecal#7
• Insert VTIMEZONE information pycalendar/x-wr-timezone#4
• https://www.iana.org/time-zones

[niccokunzmann]

I created a fundraiser to make this happen: https://gofund.me/b30287a9 Please fund!

[niccokunzmann]

https://icalendar.readthedocs.io/en/latest/api.html#icalendar.cal.Calendar.add_missing_timezones

>>> from icalendar import Calendar, Event
>>> from datetime import datetime
>>> from zoneinfo import ZoneInfo
>>> calendar = Calendar()
>>> event = Event()
>>> calendar.add_component(event)
>>> event.start = datetime(1990, 10, 11, 12, tzinfo=ZoneInfo("Europe/Berlin"))
>>> calendar.timezones
[]
>>> calendar.add_missing_timezones()
>>> calendar.timezones[0].tz_name
'Europe/Berlin'
>>> calendar.get_missing_tzids()  # check that all are added
set()