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