Introduce new ingestion pipeline structure, implement internal Likes with it.

lib/pleroma/web/activity_pub/side_effects.ex

@@ -0,0 +1,28 @@
+defmodule Pleroma.Web.ActivityPub.SideEffects do
+  @moduledoc """
+  This module looks at an inserted object and executes the side effects that it
+  implies. For example, a `Like` activity will increase the like count on the
+  liked object, a `Follow` activity will add the user to the follower
+  collection, and so on.
+  """
+  alias Pleroma.Web.ActivityPub.Utils
+  alias Pleroma.Object
+  alias Pleroma.Notification
+
+  def handle(object, meta \\ [])
+
+  # Tasks this handles:
+  # - Add like to object
+  # - Set up notification
+  def handle(%{data: %{"type" => "Like"}} = object, meta) do
+    liked_object = Object.get_by_ap_id(object.data["object"])
+    Utils.add_like_to_object(object, liked_object)
+    Notification.create_notifications(object)
+    {:ok, object, meta}
+  end
+
+  # Nothing to do
+  def handle(object, meta) do
+    {:ok, object, meta}
+  end
+end