formalize Protocol.target_for() to take any object, not just actors

important because webmention endpoints are per page (object), not per site (actor).

activitypub.py

@@ -102,11 +102,28 @@ class ActivityPub(User, Protocol):
 
     @classmethod
     def target_for(cls, obj, shared=False):
-        """Returns `obj`'s inbox if it has one, otherwise `None`."""
-        assert obj.source_protocol in (cls.LABEL, cls.ABBREV)
+        """Returns `obj`'s or its author's/actor's inbox, if available."""
+        assert obj.source_protocol in (cls.LABEL, cls.ABBREV, 'ui', None), str(obj)
+
+        if not obj.as1:
+            return None
 
         if obj.type not in as1.ACTOR_TYPES:
-            logger.info(f'{obj.key} type {type} is not an actor')
+            for field in 'actor', 'author':
+                inner_obj = as1.get_object(obj.as1, field)
+                inner_id = inner_obj.get('id') or as1.get_url(inner_obj)
+                if not inner_id:
+                    continue
+
+                # TODO: need a "soft" kwarg for load to suppress errors?
+                actor = cls.load(inner_id)
+                if actor and actor.as1:
+                    target = cls.target_for(actor)
+                    if target:
+                        logger.info(f'Target for {obj.key} via {inner_id} is {target}')
+                        return target
+
+            logger.info(f'{obj.key} type {obj.type} is not an actor and has no author or actor with inbox')
 
         actor = obj.as_as2()
 

protocol.py

@@ -236,10 +236,6 @@ class Protocol:
           True if the activity is sent successfully, False if it is ignored due
           to protocol logic. (Failures are raised as exceptions.)
 
-        Returns:
-          True if the activity was sent successfully, False if it was discarded
-          or ignored due to protocol logic, ie not network or other failures
-
         Raises:
           :class:`werkzeug.HTTPException` if the request fails
         """
@@ -282,7 +278,7 @@ class Protocol:
 
     @classmethod
     def target_for(cls, obj, shared=False):
-        """Returns a recipient :class:`Object`'s delivery target (endpoint).
+        """Returns an :class:`Object`'s delivery target (endpoint).
 
         To be implemented by subclasses.
 
@@ -291,7 +287,8 @@ class Protocol:
         * If obj has `source_protocol` `'web'`, returns its URL, as a
           webmention target.
         * If obj is an `'activitypub'` actor, returns its inbox.
-        * If obj is another `'activitypub'` object, returns `None`.
+        * If obj is an `'activitypub'` object, returns it's author's or actor's
+          inbox.
 
         Args:
           obj: :class:`Object`
@@ -300,7 +297,7 @@ class Protocol:
             multiple recipients for efficiency
 
         Returns:
-          str target endpoint or `None`
+          str target endpoint, or `None` if not available.
         """
         raise NotImplementedError()
 

tests/test_activitypub.py

@@ -1784,10 +1784,11 @@ class ActivityPubUtilsTest(TestCase):
         self.assertEqual('@swentel@mas.to', user.readable_id)
         self.assertEqual('@swentel@mas.to', user.readable_or_key_id())
 
-    def test_target_for(self):
+    def test_target_for_not_activitypub(self):
         with self.assertRaises(AssertionError):
             ActivityPub.target_for(Object(source_protocol='web'))
 
+    def test_target_for_actor(self):
         self.assertEqual(ACTOR['inbox'], ActivityPub.target_for(
             Object(source_protocol='ap', as2=ACTOR)))
 
@@ -1810,3 +1811,30 @@ class ActivityPubUtilsTest(TestCase):
             Object(source_protocol='ap', as2=actor)))
         self.assertEqual('so-shared', ActivityPub.target_for(
             Object(source_protocol='ap', as2=actor), shared=True))
+
+    def test_target_for_object(self):
+        obj = Object(as2=NOTE_OBJECT, source_protocol='ap')
+        self.assertIsNone(ActivityPub.target_for(obj))
+
+        Object(id=ACTOR['id'], as2=ACTOR).put()
+        obj.as2 = {
+            **NOTE_OBJECT,
+            'author': ACTOR['id'],
+        }
+        self.assertEqual('http://mas.to/inbox', ActivityPub.target_for(obj))
+
+        del obj.as2['author']
+        obj.as2['actor'] = copy.deepcopy(ACTOR)
+        obj.as2['actor']['url'] = [obj.as2['actor'].pop('id')]
+        self.assertEqual('http://mas.to/inbox', ActivityPub.target_for(obj))
+
+    @patch('requests.get')
+    def test_target_for_object_fetch(self, mock_get):
+        mock_get.return_value = self.as2_resp(ACTOR)
+
+        obj = Object(as2={
+            **NOTE_OBJECT,
+            'author': 'http://the/author',
+        }, source_protocol='ap')
+        self.assertEqual('http://mas.to/inbox', ActivityPub.target_for(obj))
+        mock_get.assert_has_calls([self.as2_req('http://the/author')])

web.py

@@ -253,7 +253,7 @@ class Web(User, Protocol):
     @classmethod
     def target_for(cls, obj, shared=False):
         """Returns `obj`'s id, as a URL webmention target."""
-        assert obj.source_protocol in (cls.LABEL, cls.ABBREV)
+        assert obj.source_protocol in (cls.LABEL, cls.ABBREV, 'ui', None)
 
         if not util.is_web(obj.key.id()):
             logger.warning(f"{obj.key} is source_protocol web but id isn't a URL!")