Add richer filters for Event content listing plugin

- filter events shown in listing by primary/secondary `EventType`
- filter events shown in listing to those with occurrences within
  given start/end datetimes
- filter events shown in listing to those with occurrences that end
  after N days ago, and/or start before N days hence.

icekit_events/plugins/event_content_listing/abstract_models.py

@@ -1,6 +1,13 @@
+from datetime import timedelta
+
+from django.db import models
+from django.db.models import Q
 from django.utils.encoding import python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
 
+from timezone import timezone as djtz  # django-timezone
+
+from icekit_events.models import EventType
 from icekit.plugins.content_listing.abstract_models import \
     AbstractContentListingItem
 
@@ -10,6 +17,34 @@ class AbstractEventContentListingItem(AbstractContentListingItem):
     """
     An embedded listing of event content items.
     """
+    limit_to_types = models.ManyToManyField(
+        EventType,
+        help_text="Leave empty to show all events.",
+        blank=True,
+        db_table="ik_event_listing_types",
+    )
+    from_date = models.DateTimeField(
+        blank=True, null=True,
+        help_text="Only show events with occurrences that end after this"
+                  " date and time.",
+    )
+    to_date = models.DateTimeField(
+        blank=True, null=True,
+        help_text="Only show events with occurrences that start before this"
+                  " date and time.",
+    )
+    from_days_ago = models.IntegerField(
+        blank=True, null=True,
+        help_text="Only show events with occurrences after this number of"
+                  " days into the past. Set this to zero to show only events"
+                  " with future occurrences.",
+    )
+    to_days_ahead = models.IntegerField(
+        blank=True, null=True,
+        help_text="Only show events with occurrences before this number of"
+                  " days into the future. Set this to zero to show only events"
+                  " with past occurrences.",
+    )
 
     class Meta:
         abstract = True
@@ -19,4 +54,26 @@ def __str__(self):
         return 'Event Content Listing of %s' % self.content_type
 
     def get_items(self):
-        return super(AbstractEventContentListingItem, self).get_items()
+        qs = super(AbstractEventContentListingItem, self).get_items(
+            apply_limit=False)
+        if self.limit_to_types.count():
+            types = self.limit_to_types.all()
+            qs = qs.filter(
+                Q(primary_type__in=types) |
+                Q(secondary_types__in=types)
+            )
+        # Apply `from_date` and `to_date` limits
+        qs = qs.overlapping(self.from_date, self.to_date)
+        # Apply `from_days_ago` and `to_days_ahead` limits
+        today = djtz.now().date()
+        from_date = to_date = None
+        if self.from_days_ago is not None:
+            from_date = today - timedelta(days=self.from_days_ago)
+        if self.to_days_ahead is not None:
+            to_date = today + timedelta(days=self.to_days_ahead)
+        qs = qs.overlapping(from_date, to_date)
+        # Apply a sensible default ordering
+        qs = qs.order_by_first_occurrence()
+        if self.limit:
+            qs = qs[:self.limit]
+        return qs

icekit_events/plugins/event_content_listing/migrations/0002_auto_20170222_1136.py

@@ -0,0 +1,40 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('icekit_events', '0016_auto_20161208_0030'),
+        ('ik_event_listing', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='eventcontentlistingitem',
+            name='from_date',
+            field=models.DateTimeField(help_text=b'Only show events with occurrences that end after this date and time.', null=True, blank=True),
+        ),
+        migrations.AddField(
+            model_name='eventcontentlistingitem',
+            name='from_days_ago',
+            field=models.IntegerField(help_text=b'Only show events with occurrences after this number of days into the past. Set this to zero to show only events with future occurrences.', null=True, blank=True),
+        ),
+        migrations.AddField(
+            model_name='eventcontentlistingitem',
+            name='limit_to_types',
+            field=models.ManyToManyField(help_text=b'Leave empty to show all events.', to='icekit_events.EventType', db_table=b'ik_event_listing_types', blank=True),
+        ),
+        migrations.AddField(
+            model_name='eventcontentlistingitem',
+            name='to_date',
+            field=models.DateTimeField(help_text=b'Only show events with occurrences that start before this date and time.', null=True, blank=True),
+        ),
+        migrations.AddField(
+            model_name='eventcontentlistingitem',
+            name='to_days_ahead',
+            field=models.IntegerField(help_text=b'Only show events with occurrences before this number of days into the future. Set this to zero to show only events with past occurrences.', null=True, blank=True),
+        ),
+    ]