annoucment logic implemented, fixing looks

nonpacks/announcements/notifications.py

@@ -0,0 +1,32 @@
+from django.db import transaction
+
+from .models import Notification
+
+PERSONAL_NOTIFICATION_LIMIT = 200
+
+
+def notify_project_change(project, actor, kind, text):
+    """Notify the project's owner + contributors about a change, excluding the actor.
+
+    Retention: keeps only the newest ~200 notifications per recipient."""
+    if actor is None or not actor.is_authenticated:
+        return
+    recipient_ids = {project.owner_id}
+    recipient_ids.update(project.contributors.values_list('user_id', flat=True))
+    recipient_ids.discard(actor.pk)
+    if not recipient_ids:
+        return
+    with transaction.atomic():
+        for uid in recipient_ids:
+            Notification.objects.create(
+                user_id=uid, actor=actor, project=project, kind=kind, text=text,
+            )
+        # Prune each recipient down to the newest limit.
+        for uid in recipient_ids:
+            stale = list(
+                Notification.objects.filter(user_id=uid)
+                .order_by('-created_at', '-pk')
+                .values_list('pk', flat=True)[PERSONAL_NOTIFICATION_LIMIT:]
+            )
+            if stale:
+                Notification.objects.filter(pk__in=stale).delete()