Add unlist_undescribed_media.ex to mrf policies folder

lib/pleroma/web/activity_pub/mrf/unlist_undescribed_media.ex

@@ -0,0 +1,58 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.UnlistUndescribedMedia do
+  alias Pleroma.User
+  @moduledoc "Unlists posts with media that does not have a description, written by foxes@myfriendsare.gay"
+  @behaviour Pleroma.Web.ActivityPub.MRF.Policy
+
+  require Pleroma.Constants
+
+  defp check_media(%{"attachment" => attachments}),
+  do: not Enum.all?(attachments, fn x -> x["name"] != nil && x["name"] |> String.trim() != "" end)
+  defp check_media(_),
+  do: false
+
+  def filter(
+        %{
+          "type" => "Create",
+          "to" => to,
+          "cc" => cc,
+          "actor" => actor,
+          "object" => object
+        } = message
+      ) do
+    user = User.get_cached_by_ap_id(actor)
+    undescribed = check_media(object)
+
+    # unlist
+    if undescribed and Enum.member?(to, Pleroma.Constants.as_public()) do
+      to = List.delete(to, Pleroma.Constants.as_public()) ++ [user.follower_address]
+      cc = List.delete(cc, user.follower_address) ++ [Pleroma.Constants.as_public()]
+
+      object =
+        object
+        |> Map.put("to", to)
+        |> Map.put("cc", cc)
+
+      message =
+        message
+        |> Map.put("to", to)
+        |> Map.put("cc", cc)
+        |> Map.put("object", object)
+
+      {:ok, message}
+    else
+      {:ok, message}
+    end
+  end
+
+
+
+  @impl true
+  def filter(message), do: {:ok, message}
+
+  @impl true
+  def describe, do: {:ok, %{}}
+end