feat: add DEPRECATED_AUTHENTICATION_PROVIDERS setting (#2461)

![image](https://github.com/user-attachments/assets/00a55dfa-2e41-40bf-a6aa-bf70903645e4)

docs/config/settings.md

@@ -28,6 +28,14 @@ Can be set through env var too: `ALLOWED_HOSTS=umap.mydomain.org,u.mydomain.org`
 
 Set it to `True` for easier debugging in case of error.
 
+#### DEPRECATED_AUTHENTICATION_PROVIDERS
+
+List of auth providers to deprecate. Defining this will display a message to
+all users using this provider, to encourage them to configure another provider to
+their account.
+
+    DEPRECATED_AUTHENTICATION_PROVIDERS = ["social_core.backends.twitter_oauth2.TwitterOAuth2"]
+
 #### EMAIL_BACKEND
 
 Must be configured if you want uMap to send emails to anonymous users.

umap/settings/base.py

@@ -306,6 +306,7 @@ LOGIN_URL = "login"
 SOCIAL_AUTH_LOGIN_REDIRECT_URL = "/login/popup/end/"
 
 AUTHENTICATION_BACKENDS = ()
+DEPRECATED_AUTHENTICATION_BACKENDS = []
 
 SOCIAL_AUTH_OPENSTREETMAP_OAUTH2_KEY = env(
     "SOCIAL_AUTH_OPENSTREETMAP_OAUTH2_KEY", default=""

umap/views.py

@@ -15,7 +15,7 @@ from urllib.request import Request, build_opener
 
 from django.conf import settings
 from django.contrib import messages
-from django.contrib.auth import get_user_model
+from django.contrib.auth import BACKEND_SESSION_KEY, get_user_model
 from django.contrib.auth import logout as do_logout
 from django.contrib.gis.measure import D
 from django.contrib.postgres.search import SearchQuery, SearchVector
@@ -1419,3 +1419,18 @@ class LoginPopupEnd(TemplateView):
     """
 
     template_name = "umap/login_popup_end.html"
+
+    def get(self, *args, **kwargs):
+        backend = self.request.session[BACKEND_SESSION_KEY]
+        if backend in settings.DEPRECATED_AUTHENTICATION_BACKENDS:
+            name = backend.split(".")[-1]
+            messages.error(
+                self.request,
+                _(
+                    "Using “%(name)s” to authenticate is deprecated. "
+                    "Please configure another provider in your profile page."
+                )
+                % {"name": name},
+            )
+            return HttpResponseRedirect(reverse("user_profile"))
+        return super().get(*args, **kwargs)