Refactor current meeting logic

[hancush]

This PR:

• Refactors LAMetroEvent.current_meeting
• Removes methods superseded by the refactor from lametro.utils
• Refactors tests for current_meeting functionality

[fgregg]

Looking pretty good. There's one troubling thing with the GUID and we need a bit more explanation of intent in some of the docstrings.

[fgregg]

seeing guid.upper() suggests something is pretty wrong upstream?

[hancush]

guids are all-uppercase in the api, but are all-lowercase in the running events endpoint. i'd prefer not to alter the source data in the scrape, so it seems appropriate to do a transformation for this instance-specific comparison. happy to hear an alternate perspective!

[fgregg]

yikes, okay. add a comment that explains why this thing is happening.

[fgregg]

This is a pretty good explanation of what the code is doing, but it would be even better if it explained why.

In particular, if there is not streaming_meeting, then why do want to show the meetings that started within the last 20 minutes.

Is the idea that streaming_meetings is not completely reliable to indicate that a a meeting is happening right now?

[hancush]

no, per metro, events "regularly" start (e.g., show up as streaming) later than their scheduled start time. if we are only looking for meetings five minutes in the future, a meeting that does not start on time will not appear as current.

so, if there is not a streaming meeting, we also look for meetings scheduled to start up to 20 minutes ago (i consulted with omar on this buffer), so meetings that start late are still returned as current in the interim.

[hancush]

@fgregg i expounded on this in the docstring

[fgregg]

Okay, that's the kind of thing that would be good to have in your comment. This code would be clearer to me if you used if elif else constructs instead of returns.

     if scheduled_meetings:
            streaming_meeting = cls._streaming_meeting()

            if streaming_meeting:
                current_meetings = streaming_meeting
            else:
                # explanation that sometimes a meeting stream shows up late
                twenty_minutes_ago = cls._time_ago(minutes=20)

                # '.annotate' adds a boolean field, 'is_board_meeting'. We want to
                # show board meetings first, so order in reverse, since False (0)
                # comes before True (1).
                current_meetings = scheduled_meetings.filter(start_time__gte=twenty_minutes_ago)\
                                     .annotate(is_board_meeting=RawSQL("name like %s", ('%Board Meeting%',)))\
                                     .order_by('-is_board_meeting')
      else:
           current_meetings = cls.objects.none()

      return current_meetings