Improve ActivityPub/OStatus compatibility (#4632)

*Note: OStatus URIs are invalid for ActivityPub. But we have them for
as long as we want to keep old OStatus-sourced content and as long as
we remain OStatus-compatible.*

- In Announce handling, if object URI is not a URL, fallback to object URL
- Do not use specialized ThreadResolveWorker, rely on generalized handling
- When serializing notes, if parent's URI is not a URL, use parent's URL

app/lib/activitypub/activity/announce.rb

@@ -2,8 +2,8 @@
 
 class ActivityPub::Activity::Announce < ActivityPub::Activity
   def perform
-    original_status = status_from_uri(object_uri)
-    original_status = ActivityPub::FetchRemoteStatusService.new.call(object_uri) if original_status.nil?
+    original_status   = status_from_uri(object_uri)
+    original_status ||= fetch_remote_original_status
 
     return if original_status.nil? || delete_arrived_first?(@json['id'])
 
@@ -11,4 +11,14 @@ class ActivityPub::Activity::Announce < ActivityPub::Activity
     distribute(status)
     status
   end
+
+  private
+
+  def fetch_remote_original_status
+    if object_uri.start_with?('http')
+      ActivityPub::FetchRemoteStatusService.new.call(object_uri)
+    elsif @object['url'].present?
+      ::FetchRemoteStatusService.new.call(@object['url'])
+    end
+  end
 end

app/lib/activitypub/activity/create.rb

@@ -91,7 +91,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
 
   def resolve_thread(status)
     return unless status.reply? && status.thread.nil?
-    ActivityPub::ThreadResolveWorker.perform_async(status.id, @object['inReplyTo'])
+    ThreadResolveWorker.perform_async(status.id, @object['inReplyTo'])
   end
 
   def conversation_from_uri(uri)