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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.ActivityPub.MRF.ActivityExpirationPolicy do
   6   @moduledoc "Adds expiration to all local Create activities"
   7   @behaviour Pleroma.Web.ActivityPub.MRF
   8
   9   @impl true
  10   def filter(activity) do
  11     activity =
  12       if note?(activity) and local?(activity) do
  13         maybe_add_expiration(activity)
  14       else
  15         activity
  16       end
  17
  18     {:ok, activity}
  19   end
  20
  21   @impl true
  22   def describe, do: {:ok, %{}}
  23
  24   defp local?(%{"actor" => actor}) do
  25     String.starts_with?(actor, Pleroma.Web.Endpoint.url())
  26   end
  27
  28   defp note?(activity) do
  29     match?(%{"type" => "Create", "object" => %{"type" => "Note"}}, activity)
  30   end
  31
  32   defp maybe_add_expiration(activity) do
  33     days = Pleroma.Config.get([:mrf_activity_expiration, :days], 365)
  34     expires_at = DateTime.utc_now() |> Timex.shift(days: days)
  35
  36     with %{"expires_at" => existing_expires_at} <- activity,
  37          :lt <- DateTime.compare(existing_expires_at, expires_at) do
  38       activity
  39     else
  40       _ -> Map.put(activity, "expires_at", expires_at)
  41     end
  42   end
  43
  44   @impl true
  45   def config_description do
  46     %{
  47       key: :mrf_activity_expiration,
  48       related_policy: "Pleroma.Web.ActivityPub.MRF.ActivityExpirationPolicy",
  49       label: "MRF Activity Expiration Policy",
  50       description: "Adds automatic expiration to all local activities",
  51       children: [
  52         %{
  53           key: :days,
  54           type: :integer,
  55           description: "Default global expiration time for all local activities (in days)",
  56           suggestions: [90, 365]
  57         }
  58       ]
  59     }
  60   end
  61 end