lib/pleroma/object/updater.ex

@@ -198,7 +198,7 @@ def make_new_object_data_from_update_object(original_data, new_data) do
     }
   end
 
-  defp for_each_history_item(%{"orderedItems" => items} = history, _object, fun) do
+  def for_each_history_item(%{"orderedItems" => items} = history, _object, fun) do
     new_items =
       Enum.map(items, fun)
       |> Enum.reduce_while(
@@ -215,7 +215,7 @@ defp for_each_history_item(%{"orderedItems" => items} = history, _object, fun) d
     end
   end
 
-  defp for_each_history_item(history, _, _) do
+  def for_each_history_item(history, _, _) do
     {:ok, history}
   end
 

lib/pleroma/web/activity_pub/mrf.ex

@@ -53,10 +53,53 @@ defmodule Pleroma.Web.ActivityPub.MRF do
 
   @required_description_keys [:key, :related_policy]
 
+  def filter_one(policy, message) do
+    should_plug_history? =
+      if function_exported?(policy, :history_awareness, 0) do
+        policy.history_awareness()
+      else
+        :manual
+      end
+      |> Kernel.==(:auto)
+
+    if not should_plug_history? do
+      policy.filter(message)
+    else
+      main_result = policy.filter(message)
+
+      with {_, {:ok, main_message}} <- {:main, main_result},
+           {_,
+            %{
+              "formerRepresentations" => %{
+                "orderedItems" => [_ | _]
+              }
+            }} = {_, object} <- {:object, message["object"]},
+           {_, {:ok, new_history}} <-
+             {:history,
+              Pleroma.Object.Updater.for_each_history_item(
+                object["formerRepresentations"],
+                object,
+                fn item ->
+                  with {:ok, filtered} <- policy.filter(Map.put(message, "object", item)) do
+                    {:ok, filtered["object"]}
+                  else
+                    e -> e
+                  end
+                end
+              )} do
+        {:ok, put_in(main_message, ["object", "formerRepresentations"], new_history)}
+      else
+        {:main, _} -> main_result
+        {:object, _} -> main_result
+        {:history, e} -> e
+      end
+    end
+  end
+
   def filter(policies, %{} = message) do
     policies
     |> Enum.reduce({:ok, message}, fn
-      policy, {:ok, message} -> policy.filter(message)
+      policy, {:ok, message} -> filter_one(policy, message)
       _, error -> error
     end)
   end

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

@@ -10,6 +10,8 @@ defmodule Pleroma.Web.ActivityPub.MRF.EnsureRePrepended do
 
   @reply_prefix Regex.compile!("^re:[[:space:]]*", [:caseless])
 
+  def history_awareness, do: :auto
+
   def filter_by_summary(
         %{data: %{"summary" => parent_summary}} = _in_reply_to,
         %{"summary" => child_summary} = child
@@ -27,8 +29,8 @@ def filter_by_summary(
 
   def filter_by_summary(_in_reply_to, child), do: child
 
-  def filter(%{"type" => "Create", "object" => child_object} = object)
-      when is_map(child_object) do
+  def filter(%{"type" => type, "object" => child_object} = object)
+      when type in ["Create", "Update"] and is_map(child_object) do
     child =
       child_object["inReplyTo"]
       |> Object.normalize(fetch: false)

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

@@ -12,5 +12,6 @@ defmodule Pleroma.Web.ActivityPub.MRF.Policy do
               label: String.t(),
               description: String.t()
             }
-  @optional_callbacks config_description: 0
+  @callback history_awareness() :: :auto | :manual
+  @optional_callbacks config_description: 0, history_awareness: 0
 end

test/pleroma/web/activity_pub/mrf/ensure_re_prepended_test.exs

@@ -7,6 +7,7 @@ defmodule Pleroma.Web.ActivityPub.MRF.EnsureRePrependedTest do
 
   alias Pleroma.Activity
   alias Pleroma.Object
+  alias Pleroma.Web.ActivityPub.MRF
   alias Pleroma.Web.ActivityPub.MRF.EnsureRePrepended
 
   describe "rewrites summary" do
@@ -35,10 +36,58 @@ test "it adds `re:` to summary object when child summary containts re-subject of
       assert {:ok, res} = EnsureRePrepended.filter(message)
       assert res["object"]["summary"] == "re: object-summary"
     end
+
+    test "it adds `re:` to history" do
+      message = %{
+        "type" => "Create",
+        "object" => %{
+          "summary" => "object-summary",
+          "inReplyTo" => %Activity{object: %Object{data: %{"summary" => "object-summary"}}},
+          "formerRepresentations" => %{
+            "orderedItems" => [
+              %{
+                "summary" => "object-summary",
+                "inReplyTo" => %Activity{object: %Object{data: %{"summary" => "object-summary"}}}
+              }
+            ]
+          }
+        }
+      }
+
+      assert {:ok, res} = MRF.filter_one(EnsureRePrepended, message)
+      assert res["object"]["summary"] == "re: object-summary"
+
+      assert Enum.at(res["object"]["formerRepresentations"]["orderedItems"], 0)["summary"] ==
+               "re: object-summary"
+    end
+
+    test "it accepts Updates" do
+      message = %{
+        "type" => "Update",
+        "object" => %{
+          "summary" => "object-summary",
+          "inReplyTo" => %Activity{object: %Object{data: %{"summary" => "object-summary"}}},
+          "formerRepresentations" => %{
+            "orderedItems" => [
+              %{
+                "summary" => "object-summary",
+                "inReplyTo" => %Activity{object: %Object{data: %{"summary" => "object-summary"}}}
+              }
+            ]
+          }
+        }
+      }
+
+      assert {:ok, res} = MRF.filter_one(EnsureRePrepended, message)
+      assert res["object"]["summary"] == "re: object-summary"
+
+      assert Enum.at(res["object"]["formerRepresentations"]["orderedItems"], 0)["summary"] ==
+               "re: object-summary"
+    end
   end
 
   describe "skip filter" do
-    test "it skip if type isn't 'Create'" do
+    test "it skip if type isn't 'Create' or 'Update'" do
       message = %{
         "type" => "Annotation",
         "object" => %{"summary" => "object-summary"}