Allow restricting public timeline by instance

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -927,16 +927,8 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp restrict_muted_reblogs(query, _), do: query
 
-  defp restrict_instance(query, %{instance: instance}) do
-    users =
-      from(
-        u in User,
-        select: u.ap_id,
-        where: fragment("? LIKE ?", u.nickname, ^"%@#{instance}")
-      )
-      |> Repo.all()
-
-    from(activity in query, where: activity.actor in ^users)
+  defp restrict_instance(query, %{instance: instance}) when is_binary(instance) do
+    from(activity in query, where: ilike(activity.actor, ^"%://#{instance}/%"))
   end
 
   defp restrict_instance(query, _), do: query

lib/pleroma/web/api_spec/operations/timeline_operation.ex

@@ -59,6 +59,7 @@ defmodule Pleroma.Web.ApiSpec.TimelineOperation do
       security: [%{"oAuth" => ["read:statuses"]}],
       parameters: [
         local_param(),
+        instance_param(),
         only_media_param(),
         with_muted_param(),
         exclude_visibilities_param(),
@@ -158,6 +159,15 @@ defmodule Pleroma.Web.ApiSpec.TimelineOperation do
     )
   end
 
+  defp instance_param do
+    Operation.parameter(
+      :instance,
+      :query,
+      %Schema{type: :string},
+      "Show only statuses from the given domain"
+    )
+  end
+
   defp with_muted_param do
     Operation.parameter(:with_muted, :query, BooleanLike, "Includeactivities by muted users")
   end

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

@@ -110,6 +110,7 @@ defmodule Pleroma.Web.MastodonAPI.TimelineController do
         |> Map.put(:blocking_user, user)
         |> Map.put(:muting_user, user)
         |> Map.put(:reply_filtering_user, user)
+        |> Map.put(:instance, params[:instance])
         |> ActivityPub.fetch_public_activities()
 
       conn