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/lib/activitypub/activity.rb

@@ -46,6 +46,10 @@ class ActivityPub::Activity
         ActivityPub::Activity::Reject
       when 'Flag'
         ActivityPub::Activity::Flag
+      when 'Add'
+        ActivityPub::Activity::Add
+      when 'Remove'
+        ActivityPub::Activity::Remove
       end
     end
   end

app/lib/activitypub/activity/add.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class ActivityPub::Activity::Add < ActivityPub::Activity
+  def perform
+    return unless @json['target'].present? && value_or_id(@json['target']) == @account.featured_collection_url
+
+    status = status_from_uri(object_uri)
+
+    return unless status.account_id == @account.id && !@account.pinned?(status)
+
+    StatusPin.create!(account: @account, status: status)
+  end
+end

app/lib/activitypub/activity/remove.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class ActivityPub::Activity::Remove < ActivityPub::Activity
+  def perform
+    return unless @json['origin'].present? && value_or_id(@json['origin']) == @account.featured_collection_url
+
+    status = status_from_uri(object_uri)
+
+    return unless status.account_id == @account.id
+
+    pin = StatusPin.find_by(account: @account, status: status)
+    pin&.destroy!
+  end
+end

app/lib/activitypub/adapter.rb

@@ -18,6 +18,7 @@ class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
         'toot'                      => 'http://joinmastodon.org/ns#',
         'Emoji'                     => 'toot:Emoji',
         'focalPoint'                => { '@container' => '@list', '@id' => 'toot:focalPoint' },
+        'featured'                  => 'toot:featured',
       },
     ],
   }.freeze