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

lib/pleroma/web/activity_pub/builder.ex

@@ -0,0 +1,43 @@
+defmodule Pleroma.Web.ActivityPub.Builder do
+  @moduledoc """
+  This module builds the objects. Meant to be used for creating local objects.
+
+  This module encodes our addressing policies and general shape of our objects.
+  """
+
+  alias Pleroma.Web.ActivityPub.Utils
+  alias Pleroma.Web.ActivityPub.Visibility
+  alias Pleroma.User
+  alias Pleroma.Object
+
+  @spec like(User.t(), Object.t()) :: {:ok, map(), keyword()}
+  def like(actor, object) do
+    object_actor = User.get_cached_by_ap_id(object.data["actor"])
+
+    # Address the actor of the object, and our actor's follower collection if the post is public.
+    to =
+      if Visibility.is_public?(object) do
+        [actor.follower_address, object.data["actor"]]
+      else
+        [object.data["actor"]]
+      end
+
+    # CC everyone who's been addressed in the object, except ourself and the object actor's
+    # follower collection
+    cc =
+      (object.data["to"] ++ (object.data["cc"] || []))
+      |> List.delete(actor.ap_id)
+      |> List.delete(object_actor.follower_address)
+
+    {:ok,
+     %{
+       "id" => Utils.generate_activity_id(),
+       "actor" => actor.ap_id,
+       "type" => "Like",
+       "object" => object.data["id"],
+       "to" => to,
+       "cc" => cc,
+       "context" => object.data["context"]
+     }, []}
+  end
+end