Store private announcements in object.data["announcements"], filter them on display

lib/pleroma/web/mastodon_api/controllers/status_controller.ex

@@ -242,7 +242,19 @@ defmodule Pleroma.Web.MastodonAPI.StatusController do
   def reblogged_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
     with %Activity{} = activity <- Activity.get_by_id_with_object(id),
          {:visible, true} <- {:visible, Visibility.visible_for_user?(activity, user)},
-         %Object{data: %{"announcements" => announces}} <- Object.normalize(activity) do
+         %Object{data: %{"announcements" => announces, "id" => ap_id}} <-
+           Object.normalize(activity) do
+      announces =
+        "Announce"
+        |> Activity.Queries.by_type()
+        |> Ecto.Query.where([a], a.actor in ^announces)
+        # this is to use the index
+        |> Activity.Queries.by_object_id(ap_id)
+        |> Repo.all()
+        |> Enum.filter(&Visibility.visible_for_user?(&1, user))
+        |> Enum.map(& &1.actor)
+        |> Enum.uniq()
+
       users =
         User
         |> Ecto.Query.where([u], u.ap_id in ^announces)