[#2648] handle legacy case detail URLs with redirect

The case detail URL now contains a reference to the
ZGW api group to be used to fetch the case. It is quite
likely there are various hard-coded URLs in the wild
(especially in notification emails) that point to the
old case detail URLs. This commit adds a redirect
handler for the now-deprecated case detail URL and
tries to handle the request gracefully, depending on
the case.

src/open_inwoner/cms/cases/urls.py

@@ -12,6 +12,7 @@
     CaseDocumentUploadFormView,
     InnerCaseDetailView,
     InnerCaseListView,
+    LegacyCaseDetailHandler,
     OuterCaseDetailView,
     OuterCaseListView,
 )
@@ -61,4 +62,14 @@
     ),
     path("content/", InnerCaseListView.as_view(), name="cases_content"),
     path("", OuterCaseListView.as_view(), name="index"),
+    # Legacy redirects for hard-coded case detail urls lacking a ZGW api group reference
+    # in the url (e.g. from old notification mails). This redirects those URLs
+    # to the new case detail URL with a reference to the only ZGW api group (if 1),
+    # or the case list page with an expiration notice (because we can't be sure which
+    # api group to use).
+    path(
+        "<str:object_id>/status/",
+        LegacyCaseDetailHandler.as_view(),
+        name="legacy_case_detail",
+    ),
 ]

src/open_inwoner/cms/cases/views/__init__.py

@@ -4,6 +4,7 @@
     CaseDocumentDownloadView,
     CaseDocumentUploadFormView,
     InnerCaseDetailView,
+    LegacyCaseDetailHandler,
     OuterCaseDetailView,
 )
 
@@ -14,5 +15,6 @@
     "CaseDocumentDownloadView",
     "CaseDocumentUploadFormView",
     "InnerCaseDetailView",
+    "LegacyCaseDetailHandler",
     "OuterCaseDetailView",
 ]

src/open_inwoner/cms/cases/views/status.py

@@ -7,7 +7,7 @@
 from django.conf import settings
 from django.contrib import messages
 from django.core.exceptions import ObjectDoesNotExist, PermissionDenied
-from django.http import Http404, StreamingHttpResponse
+from django.http import Http404, HttpResponseRedirect, StreamingHttpResponse
 from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
@@ -1029,3 +1029,47 @@ def get_context_data(self, **kwargs):
             "cases:case_detail_contact_form", kwargs=self.kwargs
         )
         return context
+
+
+class LegacyCaseDetailHandler(View):
+    """Redirect the legacy case detail to the current version with ZGW API group ref."""
+
+    def get(
+        self,
+        request,
+        object_id: str,
+    ):
+        redirect_url = None
+        match ZGWApiGroupConfig.objects.count():
+            case 1:
+                target_api_group = ZGWApiGroupConfig.objects.get()
+                redirect_url = reverse(
+                    "cases:case_detail",
+                    kwargs={
+                        "api_group_id": target_api_group.id,
+                        "object_id": object_id,
+                    },
+                )
+            case count if count > 1:
+                messages.add_message(
+                    request,
+                    messages.ERROR,
+                    _(
+                        "The link you clicked on has expired. Please find your case in the"
+                        " list below."
+                    ),
+                )
+                logger.warning(
+                    "Could not automatically handle legacy case detail URL due to multiple"
+                    " ZGWApiGroupConfig objects"
+                )
+                redirect_url = reverse("cases:index")
+            case 0:
+                # This is an invariant violation: there should always be at least
+                # one ZGWApiGroupConfig.
+                logger.error(
+                    "Legacy redirect invoked without any configured API groups"
+                )
+                raise Http404
+
+        return HttpResponseRedirect(redirect_url)

src/open_inwoner/openzaak/tests/test_case_detail_redirects.py

@@ -0,0 +1,74 @@
+from django.contrib.messages import get_messages
+from django.test import TestCase, override_settings
+from django.urls import reverse
+
+from open_inwoner.openzaak.models import ZGWApiGroupConfig
+from open_inwoner.openzaak.tests.factories import ZGWApiGroupConfigFactory
+
+
+@override_settings(
+    ROOT_URLCONF="open_inwoner.cms.tests.urls",
+)
+class LegacyCaseDetailUrlRedirectTest(TestCase):
+    def setUp(self):
+        self.url_patterns = [
+            "case_detail",
+        ]
+
+    def test_legacy_url_redirects_to_only_api_group_prefix(self):
+        first = ZGWApiGroupConfigFactory()
+
+        object_id = "test_object_id"
+        legacy_handler_url = reverse(
+            "cases:legacy_case_detail",
+            kwargs={"object_id": object_id},
+        )
+        target_url = reverse(
+            "cases:case_detail",
+            kwargs={"api_group_id": first.id, "object_id": object_id},
+        )
+
+        response = self.client.get(legacy_handler_url)
+        self.assertEqual(ZGWApiGroupConfig.objects.count(), 1)
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response["Location"], target_url)
+
+    def test_legacy_url_redirects_to_case_list_if_multiple_api_groups(self):
+        ZGWApiGroupConfigFactory(), ZGWApiGroupConfigFactory()
+
+        object_id = "test_object_id"
+        legacy_handler_url = reverse(
+            "cases:legacy_case_detail",
+            kwargs={"object_id": object_id},
+        )
+        target_url = reverse("cases:index")
+
+        response = self.client.get(legacy_handler_url)
+        messages = [str(m) for m in get_messages(response.wsgi_request)]
+
+        self.assertEqual(ZGWApiGroupConfig.objects.count(), 2)
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response["Location"], reverse("cases:index"))
+        self.assertEqual(
+            messages,
+            [
+                "The link you clicked on has expired. Please find your case in the"
+                " list below."
+            ],
+        )
+
+    def test_legacy_url_redirect_returns_404_on_missing_api_groups(self):
+        object_id = "test_object_id"
+        legacy_handler_url = reverse(
+            "cases:legacy_case_detail",
+            kwargs={"object_id": object_id},
+        )
+
+        legacy_handler_url = reverse(
+            "cases:legacy_case_detail",
+            kwargs={"object_id": object_id},
+        )
+
+        response = self.client.get(legacy_handler_url)
+        self.assertEqual(ZGWApiGroupConfig.objects.count(), 0)
+        self.assertEqual(response.status_code, 404)