Federate pinned statuses over ActivityPub (#6610)

* Federate pinned statuses over ActivityPub

* Display pinned toots in web UI

Fix #6117

* Fix migration

* Fix tests

* Update outbox_serializer.rb

* Update remove_serializer.rb

* Update add_serializer.rb

* Update fetch_featured_collection_service.rb

app/serializers/activitypub/actor_serializer.rb

@@ -4,7 +4,7 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
   include RoutingHelper
 
   attributes :id, :type, :following, :followers,
-             :inbox, :outbox,
+             :inbox, :outbox, :featured,
              :preferred_username, :name, :summary,
              :url, :manually_approves_followers
 
@@ -53,6 +53,10 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
     account_outbox_url(object)
   end
 
+  def featured
+    account_collection_url(object, :featured)
+  end
+
   def endpoints
     object
   end

app/serializers/activitypub/add_serializer.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+class ActivityPub::AddSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :type, :actor, :target
+  attribute :proper_object, key: :object
+
+  def type
+    'Add'
+  end
+
+  def actor
+    ActivityPub::TagManager.instance.uri_for(object.account)
+  end
+
+  def proper_object
+    ActivityPub::TagManager.instance.uri_for(object)
+  end
+
+  def target
+    account_collection_url(object, :featured)
+  end
+end

app/serializers/activitypub/collection_serializer.rb

@@ -2,7 +2,7 @@
 
 class ActivityPub::CollectionSerializer < ActiveModel::Serializer
   def self.serializer_for(model, options)
-    return ActivityPub::ActivitySerializer if model.class.name == 'Status'
+    return ActivityPub::NoteSerializer if model.class.name == 'Status'
     return ActivityPub::CollectionSerializer if model.class.name == 'ActivityPub::CollectionPresenter'
     super
   end

app/serializers/activitypub/outbox_serializer.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class ActivityPub::OutboxSerializer < ActivityPub::CollectionSerializer
+  def self.serializer_for(model, options)
+    return ActivityPub::ActivitySerializer if model.is_a?(Status)
+    super
+  end
+end

app/serializers/activitypub/remove_serializer.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+class ActivityPub::RemoveSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :type, :actor, :origin
+  attribute :proper_object, key: :object
+
+  def type
+    'Remove'
+  end
+
+  def actor
+    ActivityPub::TagManager.instance.uri_for(object.account)
+  end
+
+  def proper_object
+    ActivityPub::TagManager.instance.uri_for(object)
+  end
+
+  def origin
+    account_collection_url(object, :featured)
+  end
+end