Fix sending group events to followers on Mastodon

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/federation/activity_pub/utils.ex

@@ -458,10 +458,8 @@ defmodule Mobilizon.Federation.ActivityPub.Utils do
           Logger.debug("Making announce data for a group private object")
 
           to =
-            (object["to"] || [])
-            |> MapSet.new()
-            |> MapSet.intersection(MapSet.new([actor.followers_url, actor.members_url]))
-            |> MapSet.to_list()
+            Map.get(object, "to", []) ++
+              Map.get(object, "cc", []) ++ [actor.followers_url, actor.members_url]
 
           {to, []}
         else
@@ -478,6 +476,11 @@ defmodule Mobilizon.Federation.ActivityPub.Utils do
       "cc" => cc
     }
 
+    data =
+      if object["attributedTo"],
+        do: Map.put(data, "attributedTo", object["attributedTo"]),
+        else: data
+
     if activity_id, do: Map.put(data, "id", activity_id), else: data
   end
 

lib/federation/activity_stream/converter/event.ex

@@ -107,7 +107,7 @@ defmodule Mobilizon.Federation.ActivityStream.Converter.Event do
   def model_to_as(%EventModel{} = event) do
     {to, cc} =
       if event.visibility == :public,
-        do: {[@ap_public], []},
+        do: {[@ap_public], [event.organizer_actor.followers_url]},
         else: {[attributed_to_or_default(event).followers_url], [@ap_public]}
 
     %{