From 488c4b8b983f99d036e3f3bf67dec782f9959319 Mon Sep 17 00:00:00 2001
From: Mark Felder <feld@feld.me>
Date: Fri, 15 Mar 2024 15:10:45 -0400
Subject: MRF.FODirectReply

Force replies to followers-only posts to always be direct
---
 .../web/activity_pub/mrf/fo_direct_reply.ex        | 65 ++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 lib/pleroma/web/activity_pub/mrf/fo_direct_reply.ex

(limited to 'lib')

diff --git a/lib/pleroma/web/activity_pub/mrf/fo_direct_reply.ex b/lib/pleroma/web/activity_pub/mrf/fo_direct_reply.ex
new file mode 100644
index 000000000..4eb97afa8
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/fo_direct_reply.ex
@@ -0,0 +1,65 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2024 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.FODirectReply do
+  @moduledoc """
+  FODirectReply alters the scope of replies to activities which are Followers Only to be Direct. The purpose of this policy is to prevent broken threads for followers of the reply author because their response was to a user that they are not also following.
+  """
+
+  alias Pleroma.User
+
+  @behaviour Pleroma.Web.ActivityPub.MRF.Policy
+
+  @impl true
+  def filter(
+        %{
+          "type" => "Create",
+          "to" => to,
+          "object" => %{
+            "actor" => actor,
+            "type" => "Note",
+            "inReplyTo" => in_reply_to
+          }
+        } = activity
+      ) do
+    with true <- is_binary(in_reply_to),
+         %User{follower_address: followers_collection, local: true} <- User.get_by_ap_id(actor),
+         true <- followers_only?(in_reply_to) do
+      direct_to = to -- [followers_collection]
+
+      updated_activity =
+        activity
+        |> Map.put("cc", [])
+        |> Map.put("to", direct_to)
+        |> Map.put("directMessage", true)
+        |> put_in(["object", "cc"], [])
+        |> put_in(["object", "to"], direct_to)
+
+      {:ok, updated_activity}
+    else
+      _ -> {:ok, activity}
+    end
+  end
+
+  @impl true
+  def filter(activity), do: {:ok, activity}
+
+  @impl true
+  def describe, do: {:ok, %{}}
+
+  defp followers_only?(parent_ap_id) do
+    with %Pleroma.Object{} = object <- Pleroma.Object.get_by_ap_id(parent_ap_id),
+         object_data <- Map.get(object, :data),
+         %Pleroma.User{} = user <- User.get_cached_by_ap_id(object_data["actor"]) do
+      if user.follower_address in object_data["to"] do
+        true
+      else
+        false
+      end
+    else
+      _ ->
+        false
+    end
+  end
+end
-- 
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