Put ActivityPub alternate link into Atom, prefer it when processing Atom (#4623)

app/lib/ostatus/activity/base.rb

@@ -29,16 +29,28 @@ class OStatus::Activity::Base
   end
 
   def url
-    link = @xml.at_xpath('./xmlns:link[@rel="alternate"]', xmlns: TagManager::XMLNS)
+    link = @xml.xpath('./xmlns:link[@rel="alternate"]', xmlns: TagManager::XMLNS).find { |link_candidate| link_candidate['type'] == 'text/html' }
     link.nil? ? nil : link['href']
   end
 
+  def activitypub_uri
+    link = @xml.xpath('./xmlns:link[@rel="alternate"]', xmlns: TagManager::XMLNS).find { |link_candidate| ['application/activity+json', 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'].include?(link_candidate['type']) }
+    link.nil? ? nil : link['href']
+  end
+
+  def activitypub_uri?
+    activitypub_uri.present?
+  end
+
   private
 
   def find_status(uri)
     if TagManager.instance.local_id?(uri)
       local_id = TagManager.instance.unique_tag_to_local_id(uri, 'Status')
       return Status.find_by(id: local_id)
+    elsif ActivityPub::TagManager.instance.local_uri?(uri)
+      local_id = ActivityPub::TagManager.instance.uri_to_local_id(uri)
+      return Status.find_by(id: local_id)
     end
 
     Status.find_by(uri: uri)

app/lib/ostatus/activity/creation.rb

@@ -8,6 +8,7 @@ class OStatus::Activity::Creation < OStatus::Activity::Base
     end
 
     return [nil, false] if @account.suspended?
+    return perform_via_activitypub if activitypub_uri?
 
     Rails.logger.debug "Creating remote status #{id}"
 
@@ -52,6 +53,10 @@ class OStatus::Activity::Creation < OStatus::Activity::Base
     [status, true]
   end
 
+  def perform_via_activitypub
+    [find_status(activitypub_uri) || ActivityPub::FetchRemoteStatusService.new.call(activitypub_uri), false]
+  end
+
   def content
     @xml.at_xpath('./xmlns:content', xmlns: TagManager::XMLNS).content
   end

app/lib/ostatus/activity/remote.rb

@@ -2,6 +2,10 @@
 
 class OStatus::Activity::Remote < OStatus::Activity::Base
   def perform
-    find_status(id) || FetchRemoteStatusService.new.call(url)
+    if activitypub_uri?
+      find_status(activitypub_uri) || FetchRemoteStatusService.new.call(url)
+    else
+      find_status(id) || FetchRemoteStatusService.new.call(url)
+    end
   end
 end