Add ActivityPub inbox (#4216)

* Add ActivityPub inbox

* Handle ActivityPub deletes

* Handle ActivityPub creates

* Handle ActivityPub announces

* Stubs for handling all activities that need to be handled

* Add ActivityPub actor resolving

* Handle conversation URI passing in ActivityPub

* Handle content language in ActivityPub

* Send accept header when fetching actor, handle JSON parse errors

* Test for ActivityPub::FetchRemoteAccountService

* Handle public key and icon/image when embedded/as array/as resolvable URI

* Implement ActivityPub::FetchRemoteStatusService

* Add stubs for more interactions

* Undo activities implemented

* Handle out of order activities

* Hook up ActivityPub to ResolveRemoteAccountService, handle
Update Account activities

* Add fragment IDs to all transient activity serializers

* Add tests and fixes

* Add stubs for missing tests

* Add more tests

* Add more tests

1 files changed, 25 insertions, 0 deletions

diff --git a/app/lib/activitypub/tag_manager.rb b/app/lib/activitypub/tag_manager.rb
index ec42bcad3..96e610b6d 100644
--- a/app/lib/activitypub/tag_manager.rb
+++ b/app/lib/activitypub/tag_manager.rb
@@ -6,6 +6,8 @@ class ActivityPub::TagManager
   include Singleton
   include RoutingHelper
 
+  CONTEXT = 'https://www.w3.org/ns/activitystreams'
+
   COLLECTIONS = {
     public: 'https://www.w3.org/ns/activitystreams#Public',
   }.freeze
@@ -66,4 +68,27 @@ class ActivityPub::TagManager
 
     cc
   end
+
+  def local_uri?(uri)
+    host = Addressable::URI.parse(uri).normalized_host
+    ::TagManager.instance.local_domain?(host) || ::TagManager.instance.web_domain?(host)
+  end
+
+  def uri_to_local_id(uri, param = :id)
+    path_params = Rails.application.routes.recognize_path(uri)
+    path_params[param]
+  end
+
+  def uri_to_resource(uri, klass)
+    if local_uri?(uri)
+      case klass.name
+      when 'Account'
+        klass.find_local(uri_to_local_id(uri, :username))
+      else
+        klass.find_by(id: uri_to_local_id(uri))
+      end
+    else
+      klass.find_by(uri: uri)
+    end
+  end
 end