follow UI: specific error message for trying to follow bridged accounts

thanks for the nudge @campegg!

activitypub.py

@@ -63,6 +63,7 @@ class ActivityPub(User, Protocol):
     Key id is AP/AS2 actor id URL. (*Not* fediverse/WebFinger @-@ handle!)
     """
     ABBREV = 'ap'
+    PHRASE = 'the fediverse'
     LOGO_HTML = '<img src="/static/fediverse_logo.svg">'
     CONTENT_TYPE = as2.CONTENT_TYPE
     HAS_FOLLOW_ACCEPTS = True

atproto.py

@@ -57,6 +57,7 @@ class ATProto(User, Protocol):
     https://atproto.com/specs/did
     """
     ABBREV = 'atproto'
+    PHRASE = 'Bluesky'
     LOGO_HTML = '<img src="/static/atproto_logo.png">'
     PDS_URL = f'https://{ABBREV}{common.SUPERDOMAIN}/'
     CONTENT_TYPE = 'application/json'

follow.py

@@ -16,6 +16,7 @@ from activitypub import ActivityPub
 from flask_app import app
 import common
 from models import Follower, Object, PROTOCOLS
+from protocol import Protocol
 from web import Web
 import webfinger
 
@@ -98,17 +99,19 @@ class FollowCallback(indieauth.Callback):
         addr = state
         if util.is_web(addr):
             as2_url = addr
-            if ActivityPub.owns_id(as2_url) is False:
-                flash(f"{as2_url} isn't a native fediverse account")
-                return redirect(user.user_page_path('following'))
         else:  # it's an @-@ handle
-            if ActivityPub.owns_handle(addr) is False:
-                flash(f"{addr} isn't a native fediverse account")
-                return redirect(user.user_page_path('following'))
+            # if ActivityPub.owns_handle(addr) is False:
+            #     flash(f"{addr} isn't a native fediverse account")
+            #     return redirect(user.user_page_path('following'))
             as2_url = webfinger.fetch_actor_url(addr)
-            if ActivityPub.owns_id(as2_url) is False:
-                flash(f"{addr} isn't a native fediverse account")
-                return redirect(user.user_page_path('following'))
+
+        if util.domain_or_parent_in(util.domain_from_link(as2_url), common.DOMAINS):
+            proto = Protocol.for_id(as2_url)
+            flash(f"{addr} is a bridged account. Try following them on {proto.PHRASE}!")
+            return redirect(user.user_page_path('following'))
+        elif ActivityPub.owns_id(as2_url) is False:
+            flash(f"{addr} isn't a native fediverse account")
+            return redirect(user.user_page_path('following'))
 
         # TODO(#512): follower will always be Web here, but we should generalize
         # followee support in UI and here across protocols

protocol.py

@@ -57,6 +57,8 @@ class Protocol:
       LABEL (str): human-readable lower case name
       OTHER_LABELS (list of str): label aliases
       ABBREV (str): lower case abbreviation, used in URL paths
+      PHRASE (str): human-readable name or phrase. Used in phrases like
+        ``Follow this person on {PHRASE}``
       LOGO_HTML (str): logo emoji or ``<img>`` tag
       CONTENT_TYPE (str): MIME type of this protocol's native data format,
         appropriate for the ``Content-Type`` HTTP header.
@@ -64,6 +66,7 @@ class Protocol:
         accept/reject activities in response to follows, eg ActivityPub
     """
     ABBREV = None
+    PHRASE = None
     OTHER_LABELS = ()
     LOGO_HTML = ''
     CONTENT_TYPE = None

tests/test_follow.py

@@ -246,15 +246,28 @@ class FollowTest(TestCase):
 
     def test_callback_bridged_account_error(self, mock_get, mock_post):
         mock_post.return_value = requests_response('me=https://alice.com')
+        mock_get.side_effect = [
+            requests_response(''),  # indieauth https://alice.com fetch for user json
+            requests_response({     # webfinger
+                'subject': 'acct:bob.com@web.brid.gy',
+                'aliases': ['https://bob.com/'],
+                'links': [{
+                    'rel': 'self',
+                    'type': as2.CONTENT_TYPE,
+                    'href': 'https://web.brid.gy/bob.com',
+                }],
+            }),
+        ]
 
-        self.state['state'] = '@example.com@web.brid.gy'
+        self.state['state'] = '@bob.com@web.brid.gy'
         state = util.encode_oauth_state(self.state)
         resp = self.client.get(f'/follow/callback?code=my_code&state={state}')
 
         self.assertEqual(302, resp.status_code)
         self.assertEqual('/web/alice.com/following', resp.headers['Location'])
-        self.assertEqual(["@example.com@web.brid.gy isn't a native fediverse account"],
-                         get_flashed_messages())
+        self.assertEqual(
+            ["@bob.com@web.brid.gy is a bridged account. Try following them on the web!"],
+            get_flashed_messages())
 
     def test_callback_upgraded_bridged_account_error(self, mock_get, mock_post):
         mock_post.return_value = requests_response('me=https://alice.com')
@@ -279,8 +292,9 @@ class FollowTest(TestCase):
 
         self.assertEqual(302, resp.status_code)
         self.assertEqual('/web/alice.com/following', resp.headers['Location'])
-        self.assertEqual(["@bob.com@bob.com isn't a native fediverse account"],
-                         get_flashed_messages())
+        self.assertEqual(
+            ["@bob.com@bob.com is a bridged account. Try following them on the web!"],
+            get_flashed_messages())
 
     def check(self, input, resp, expected_follow, mock_get, mock_post,
               fetched_followee=True):

tests/testutil.py

@@ -66,6 +66,7 @@ COMMENT = {
 
 class Fake(User, protocol.Protocol):
     ABBREV = 'fa'
+    PHRASE = 'fake-phrase'
     CONTENT_TYPE = 'fa/ke'
 
     # maps string ids to dict AS1 objects that can be fetched

web.py

@@ -92,6 +92,7 @@ class Web(User, Protocol):
     The key name is the domain.
     """
     ABBREV = 'web'
+    PHRASE = 'the web'
     OTHER_LABELS = ('webmention',)
     LOGO_HTML = '🌐'  # used to be 🕸️
     CONTENT_TYPE = common.CONTENT_TYPE_HTML