Refactor collection_case_details: simplify case retrieval logic and improve parameter naming for clarity

atlas/views.py

@@ -3094,20 +3094,14 @@ def collection_case_questions(request, exam_id, case_id):
     )
 
 @user_is_collection_author_or_atlas_editor
-def collection_case_details(request, exam_id, case_id):
+def collection_case_details(request, exam_id, case_number):
     # Accept either case_number (index into collection) or case_id (case PK).
-    casedetail = None
-    collection = None
+    collection = get_object_or_404(CaseCollection, pk=exam_id)
     try:
-        casedetail = CaseDetail.objects.get(case=case_id, collection=exam_id)
-        collection = casedetail.collection
+        case_obj = collection.get_case_by_index(int(case_number))
+        casedetail = CaseDetail.objects.get(case=case_obj, collection=collection)
     except Exception:
-        collection = get_object_or_404(CaseCollection, pk=exam_id)
-        try:
-            case_obj = collection.get_case_by_index(int(case_id))
-            casedetail = CaseDetail.objects.get(case=case_obj, collection=collection)
-        except Exception:
-            raise Http404("Case not found in collection")
+        raise Http404("Case not found in collection")
 
     if request.method == "POST":
         form = CaseDetailForm(request.POST, instance=casedetail)