Add customizable ordering and new request type for timeslot queryset

Hello!

In this MR I added a way to customize the ordering of the TimeSlot queryset with a new order GET parameter. It defaults to sorting by reverse start date. (aka -start).

I also added a new query parameter surrounding which returns the 10 timeslots closest to the current date.

Since it's been a while since I've written Python, I'm not sure if this is the most safe/optimal way to do it, but I hope I did alright :D

If I should change anything, please let me know!

program/views.py

@@ -19,6 +19,7 @@
 #
 
 import json
+import logging
 from datetime import date, datetime, time, timedelta
 
 from django.contrib.auth.models import User
@@ -37,6 +38,7 @@ from program.serializers import TypeSerializer, LanguageSerializer, MusicFocusSe
     UserSerializer
 from program.utils import get_cached_shows
 
+logger = logging.getLogger(__name__)
 
 def json_day_schedule(request, year=None, month=None, day=None):
     if year is None and month is None and day is None:
@@ -507,6 +509,7 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
     /timeslots/{pk} eturns the given timeslot (GET)
     /timeslots/?start={start_date}&end={end_date} returns timeslots within the time range (GET)
     /shows/{show_pk}/timeslots returns timeslots of the show (GET, POST)
+    /shows/{show_pk}/timeslots?surrounding returns the 10 nearest timeslots for the current date (GET)
     /shows/{show_pk}/timeslots/{pk} returns a timeslots by its ID (GET, PUT, DELETE)
     /shows/{show_pk}/timeslots/?start={start_date}&end={end_date} returns timeslots of the show within the time range
     /shows/{show_pk}/schedules/{schedule_pk}/timeslots returns all timeslots of the schedule (GET, POST)
@@ -522,7 +525,6 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
     def get_queryset(self):
         show_pk = int_or_none('show_pk', self.kwargs)
         schedule_pk = int_or_none('schedule_pk', self.kwargs)
-
         # Filters
 
         # Return next 60 days by default
@@ -533,6 +535,25 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
             start = datetime.combine(datetime.strptime(self.request.query_params.get('start'), '%Y-%m-%d').date(), time(0, 0))
             end = datetime.combine(datetime.strptime(self.request.query_params.get('end'), '%Y-%m-%d').date(), time(23, 59))
 
+        default_order = '-start'
+        order = self.request.query_params.get('order', default_order)
+
+        # If someone tries to sort by a field that isn't available on the model
+        # we silently ignore that and use the default sort order.
+        model_fields = [field.name for field in TimeSlot._meta.get_fields()]
+        if order.lstrip('-') not in model_fields:
+            order = default_order
+
+
+        if 'surrounding' in self.request.query_params:
+            today = datetime.today()
+
+            nearest_timeslots_in_future = TimeSlot.objects.filter(start__gte=today).order_by('start').values_list('id', flat=True)[:5]
+            nearest_timeslots_in_past = TimeSlot.objects.filter(start__lt=today).order_by('-start').values_list('id', flat=True)[:5]
+            relevant_timeslot_ids = list(nearest_timeslots_in_future) + list(nearest_timeslots_in_past)
+
+            return TimeSlot.objects.filter(id__in=relevant_timeslot_ids).order_by(order)
+
         # Endpoints
 
         #
@@ -541,7 +562,7 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
         #     Returns timeslots of the given show and schedule
         #
         if show_pk and schedule_pk:
-            return TimeSlot.objects.filter(show=show_pk, schedule=schedule_pk, start__gte=start, end__lte=end).order_by('start')
+            return TimeSlot.objects.filter(show=show_pk, schedule=schedule_pk, start__gte=start, end__lte=end).order_by(order)
 
         #
         #     /shows/1/timeslots/
@@ -549,7 +570,7 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
         #     Returns timeslots of the show
         #
         elif show_pk and schedule_pk is None:
-            return TimeSlot.objects.filter(show=show_pk, start__gte=start, end__lte=end).order_by('start')
+            return TimeSlot.objects.filter(show=show_pk, start__gte=start, end__lte=end).order_by(order)
 
         #
         #     /timeslots/
@@ -557,12 +578,13 @@ class APITimeSlotViewSet(viewsets.ModelViewSet):
         #     Returns all timeslots
         #
         else:
-            return TimeSlot.objects.filter(start__gte=start, end__lte=end).order_by('start')
+            return TimeSlot.objects.filter(start__gte=start, end__lte=end).order_by(order)
 
     def retrieve(self, request, *args, **kwargs):
         pk = int_or_none('pk', self.kwargs)
         show_pk = int_or_none('show_pk', self.kwargs)
 
+
         if show_pk:
             timeslot = get_object_or_404(TimeSlot, pk=pk, show=show_pk)
         else: