Add a MRF Policy for appending re: to identical subjects in replies.

1 files changed, 37 insertions, 0 deletions

diff --git a/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex b/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex
new file mode 100644
index 000000000..3f216010e
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex
@@ -0,0 +1,37 @@
+defmodule Pleroma.Web.ActivityPub.MRF.EnsureRePrepended do
+  alias Pleroma.Activity
+
+  @behaviour Pleroma.Web.ActivityPub.MRF
+
+  def filter_by_summary(
+        %{"summary" => parent_summary} = parent,
+        %{"summary" => child_summary} = child
+      )
+      when not is_nil(child_summary) and child_summary == parent_summary and
+             byte_size(child_summary) > 1 do
+    if not String.starts_with?(child_summary, "re:") do
+      Map.put(child, "summary", "re: " <> child_summary)
+    else
+      child
+    end
+  end
+
+  def filter_by_summary(parent, child), do: child
+
+  def filter(%{"type" => activity_type} = object) when activity_type == "Create" do
+    child = object["object"]
+    in_reply_to = Activity.get_create_activity_by_object_ap_id(child["inReplyTo"])
+
+    child =
+      if(in_reply_to,
+        do: filter_by_summary(in_reply_to.data["object"], child),
+        else: child
+      )
+
+    object = Map.put(object, "object", child)
+
+    {:ok, object}
+  end
+
+  def filter(object), do: {:ok, object}
+end