Introduce instances admin page

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

lib/service/workers/refresh_instances.ex

@@ -0,0 +1,31 @@
+defmodule Mobilizon.Service.Workers.RefreshInstances do
+  @moduledoc """
+  Worker to refresh the instances materialized view and the relay actors
+  """
+
+  use Oban.Worker, unique: [period: :infinity, keys: [:event_uuid, :action]]
+
+  alias Mobilizon.Federation.ActivityPub.Actor, as: ActivityPubActor
+  alias Mobilizon.Instances
+  alias Mobilizon.Instances.Instance
+  alias Oban.Job
+
+  @impl Oban.Worker
+  @spec perform(Oban.Job.t()) :: :ok
+  def perform(%Job{}) do
+    Instances.refresh()
+
+    Instances.all_domains()
+    |> Enum.each(&refresh_instance_actor/1)
+  end
+
+  @spec refresh_instance_actor(Instance.t()) ::
+          {:ok, Mobilizon.Actors.Actor.t()}
+          | {:error,
+             Mobilizon.Federation.ActivityPub.Actor.make_actor_errors()
+             | Mobilizon.Federation.WebFinger.finger_errors()}
+
+  defp refresh_instance_actor(%Instance{domain: domain}) do
+    ActivityPubActor.find_or_make_actor_from_nickname("relay@#{domain}")
+  end
+end