Add sync functionality for prerequisite users in collection detail

atlas/views.py

@@ -2189,9 +2189,7 @@ def collection_take_start(request, pk, cid=None, passcode=None):
     Returns:
         _type_: _description_
     """
-    print(f"Collection take start: {pk}, cid: {cid}, passcode: {passcode}")
     collection = get_object_or_404(CaseCollection, pk=pk)
-    print(f"Collection: {collection}")
 
     try:
         collection.check_user_can_take(cid, passcode, request.user)
@@ -2204,7 +2202,7 @@ def collection_take_start(request, pk, cid=None, passcode=None):
         return render(
             request,
             'atlas/prerequisite_required.html',
-            {'message': str(e), 'prereq': prereq},
+            {'message': str(e), 'prereq': prereq, 'cid': cid, 'passcode': passcode},
         )
 
 
@@ -2626,7 +2624,7 @@ def collection_take_overview(
         collection.check_user_can_take(cid, passcode, request.user)
     except PrerequisiteRequired as e:
         prereq = getattr(e, 'prereq', None)
-        return render(request, 'atlas/prerequisite_required.html', {'message': str(e), 'prereq': prereq})
+        return render(request, 'atlas/prerequisite_required.html', {'message': str(e), 'prereq': prereq, 'cid': cid, 'passcode': passcode})
 
     cid_user_exam = collection.get_or_create_cid_user_exam(
         cid=cid, user_user=request.user
@@ -2703,7 +2701,7 @@ def collection_case_view_take_answers(
         collection.check_user_can_take(cid, passcode, request.user)
     except PrerequisiteRequired as e:
         prereq = getattr(e, 'prereq', None)
-        return render(request, 'atlas/prerequisite_required.html', {'message': str(e), 'prereq': prereq})
+        return render(request, 'atlas/prerequisite_required.html', {'message': str(e), 'prereq': prereq, 'cid': cid, 'passcode': passcode})
 
     case, case_count = collection.get_case_by_index(case_number, case_count=True)
 
@@ -2756,7 +2754,7 @@ def collection_case_view_take(
         collection.check_user_can_take(cid, passcode, request.user)
     except PrerequisiteRequired as e:
         prereq = getattr(e, 'prereq', None)
-        return render(request, 'atlas/prerequisite_required.html', {'message': str(e), 'prereq': prereq})
+        return render(request, 'atlas/prerequisite_required.html', {'message': str(e), 'prereq': prereq, 'cid': cid, 'passcode': passcode})
 
     case, case_count = collection.get_case_by_index(case_number, case_count=True)
 
@@ -3563,6 +3561,64 @@ def collection_question_schemas(request, exam_id: int):
     )
 
 
+@user_is_collection_author_or_atlas_editor
+def collection_sync_prerequisite_users(request, pk: int):
+    """Copy valid cid_users and user_users from all prerequisite collections into this collection.
+
+    This endpoint is intended to be called via HTMX from the collection detail page.
+    """
+    if not request.htmx:
+        raise Http404("Invalid request")
+
+    collection = get_object_or_404(CaseCollection, pk=pk)
+
+    # Collect the closure of collections: the target collection and all prerequisites (recursively)
+    to_visit = [collection]
+    visited = {}
+    while to_visit:
+        col = to_visit.pop()
+        if col.pk in visited:
+            continue
+        visited[col.pk] = col
+        for p in col.prerequisites.all():
+            if p.pk not in visited:
+                to_visit.append(p)
+
+    collections = list(visited.values())
+
+    # Compute the union of all cid users and user users across the set
+    union_cid_users = set()
+    union_user_users = set()
+    for col in collections:
+        union_cid_users.update(list(col.valid_cid_users.all()))
+        union_user_users.update(list(col.valid_user_users.all()))
+
+    # Apply the union to each collection and count additions
+    total_added_cid = 0
+    total_added_user = 0
+    per_collection_added = []
+    for col in collections:
+        added_cid = 0
+        added_user = 0
+        for cid_user in union_cid_users:
+            if not col.valid_cid_users.filter(pk=cid_user.pk).exists():
+                col.valid_cid_users.add(cid_user)
+                added_cid += 1
+        for user in union_user_users:
+            if not col.valid_user_users.filter(pk=user.pk).exists():
+                col.valid_user_users.add(user)
+                added_user += 1
+        if added_cid or added_user:
+            col.save()
+        total_added_cid += added_cid
+        total_added_user += added_user
+        per_collection_added.append((col.pk, added_cid, added_user))
+
+    return HttpResponse(
+        f"Two-way sync complete — total added: {total_added_cid} cid(s), {total_added_user} user(s)."
+    )
+
+
 def collection_reset_answers_user_list(request, exam_id: int):
     if request.htmx:
         collection = get_object_or_404(CaseCollection, pk=exam_id)