Pass history items through ObjectValidator for updatable object types

lib/pleroma/web/activity_pub/object_validator.ex

@@ -128,15 +128,20 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
       end
 
     with {:ok, object} <-
-           object
-           |> validator.cast_and_validate()
-           |> Ecto.Changeset.apply_action(:insert) do
-      object = stringify_keys(object)
+           do_separate_with_history(object, fn object ->
+             with {:ok, object} <-
+                    object
+                    |> validator.cast_and_validate()
+                    |> Ecto.Changeset.apply_action(:insert) do
+               object = stringify_keys(object)
 
-      # Insert copy of hashtags as strings for the non-hashtag table indexing
-      tag = (object["tag"] || []) ++ Object.hashtags(%Object{data: object})
-      object = Map.put(object, "tag", tag)
+               # Insert copy of hashtags as strings for the non-hashtag table indexing
+               tag = (object["tag"] || []) ++ Object.hashtags(%Object{data: object})
+               object = Map.put(object, "tag", tag)
 
+               {:ok, object}
+             end
+           end) do
       {:ok, object, meta}
     end
   end
@@ -262,4 +267,54 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
     Object.normalize(object["object"], fetch: true)
     :ok
   end
+
+  defp for_each_history_item(
+         %{"type" => "OrderedCollection", "orderedItems" => items} = history,
+         object,
+         fun
+       ) do
+    processed_items =
+      Enum.map(items, fn item ->
+        with item <- Map.put(item, "id", object["id"]),
+             {:ok, item} <- fun.(item) do
+          item
+        else
+          _ -> nil
+        end
+      end)
+
+    if Enum.all?(processed_items, &(not is_nil(&1))) do
+      {:ok, Map.put(history, "orderedItems", processed_items)}
+    else
+      {:error, :invalid_history}
+    end
+  end
+
+  defp for_each_history_item(nil, _object, _fun) do
+    {:ok, nil}
+  end
+
+  defp for_each_history_item(_, _object, _fun) do
+    {:error, :invalid_history}
+  end
+
+  # fun is (object -> {:ok, validated_object_with_string_keys})
+  defp do_separate_with_history(object, fun) do
+    with history <- object["formerRepresentations"],
+         object <- Map.drop(object, ["formerRepresentations"]),
+         {_, {:ok, object}} <- {:main_body, fun.(object)},
+         {_, {:ok, history}} <- {:history_items, for_each_history_item(history, object, fun)} do
+      object =
+        if history do
+          Map.put(object, "formerRepresentations", history)
+        else
+          object
+        end
+
+      {:ok, object}
+    else
+      {:main_body, e} -> e
+      {:history_items, e} -> e
+    end
+  end
 end