Support filtering on recurring events

[jelmer]

Support filtering on recurring events.

Fixes #8

[jelly]

I'm a happy xandikos user and was working on making my eink screen display my weekly calendar but found out that searching with a start/end does not expand my recurring appointments. So I tried to test this PR and with my local data it fails with this backtrace.

This is reproduced with the python caldav module:

client = DAVClient('http://localhost:8080/user/calendars/', auth=None, ssl_verify_cert=False)
calendar = client.principal().calendar('calendar')
events = calendar.search(start=now, end=end, event=True)

127.0.0.1 [17/Jan/2023:21:29:45 +0000] "PROPFIND /user/calendars/calendar/ HTTP/1.1" 207 423 "-" "Mozilla/5.0"
Error handling request
Traceback (most recent call last):
  File "/usr/lib/python3.10/site-packages/aiohttp/web_protocol.py", line 433, in _handle_request
    resp = await request_handler(request)
  File "/usr/lib/python3.10/site-packages/aiohttp/web_app.py", line 504, in _handle
    resp = await handler(request)
  File "/home/jelle/projects/xandikos/./bin/../xandikos/web.py", line 1489, in xandikos_handler
    return await main_app.aiohttp_handler(request, options.route_prefix)
  File "/home/jelle/projects/xandikos/./bin/../xandikos/webdav.py", line 2152, in aiohttp_handler
    response = await self._handle_request(request, environ)
  File "/home/jelle/projects/xandikos/./bin/../xandikos/webdav.py", line 2108, in _handle_request
    return await do.handle(request, environ, self)
  File "/home/jelle/projects/xandikos/./bin/../xandikos/webdav.py", line 1764, in handle
    return await reporter.report(
  File "/home/jelle/projects/xandikos/./bin/../xandikos/webdav.py", line 353, in wrapper
    async for resp in req_fn(self, environ, *args, **kwargs):
  File "/home/jelle/projects/xandikos/./bin/../xandikos/caldav.py", line 566, in report
    async for (href, resource) in webdav.traverse_resource(
  File "/home/jelle/projects/xandikos/./bin/../xandikos/webdav.py", line 1205, in traverse_resource
    for (child_name, child_resource) in members_fn(resource):
  File "/home/jelle/projects/xandikos/./bin/../xandikos/web.py", line 637, in calendar_query
    for (name, file, etag) in self.store.iter_with_filter(filter=filter):
  File "/home/jelle/projects/xandikos/./bin/../xandikos/store/__init__.py", line 314, in _iter_with_filter_naive
    if filter.check(name, file):
  File "/home/jelle/projects/xandikos/./bin/../xandikos/icalendar.py", line 843, in check
    c = file.expanded_calendar
  File "/home/jelle/projects/xandikos/./bin/../xandikos/icalendar.py", line 928, in expanded_calendar
    self._expanded_calendar = expand_calendar_rrule(self.calendar)
  File "/home/jelle/projects/xandikos/./bin/../xandikos/icalendar.py", line 1080, in expand_calendar_rrule
    for outsub in _expand_rrule_component(
  File "/home/jelle/projects/xandikos/./bin/../xandikos/icalendar.py", line 1034, in _expand_rrule_component
    rs = rruleset_from_comp(incomp)
  File "/home/jelle/projects/xandikos/./bin/../xandikos/icalendar.py", line 1011, in rruleset_from_comp
    rrulestr = comp["RRULE"].to_ical().decode("utf-8")
AttributeError: 'list' object has no attribute 'to_ical'
127.0.0.1 [17/Jan/2023:21:29:48 +0000] "REPORT /user/calendars/calendar/ HTTP/1.1" 500 245 "-" "Mozilla/5.0"