Make normalize_markup multilang aware

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

@@ -16,11 +16,27 @@ def filter(%{"type" => type, "object" => child_object} = object)
       when type in ["Create", "Update"] do
     scrub_policy = Pleroma.Config.get([:mrf_normalize_markup, :scrub_policy])
 
-    content =
-      child_object["content"]
-      |> HTML.filter_tags(scrub_policy)
+    object =
+      with %{} = content_map <- child_object["contentMap"] do
+        fixed_content_map =
+          Enum.reduce(content_map, %{}, fn {lang, content}, acc ->
+            Map.put(acc, lang, HTML.filter_tags(content, scrub_policy))
+          end)
 
-    object = put_in(object, ["object", "content"], content)
+        object
+        |> put_in(["object", "contentMap"], fixed_content_map)
+        |> put_in(
+          ["object", "content"],
+          Pleroma.MultiLanguage.map_to_str(fixed_content_map, multiline: true)
+        )
+      else
+        _ ->
+          content =
+            child_object["content"]
+            |> HTML.filter_tags(scrub_policy)
+
+          put_in(object, ["object", "content"], content)
+      end
 
     {:ok, object}
   end

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

@@ -38,6 +38,25 @@ test "it filter html tags" do
     assert res["object"]["content"] == @expected
   end
 
+  test "multilang-aware" do
+    message = %{
+      "type" => "Create",
+      "object" => %{
+        "content" => "some",
+        "contentMap" => %{
+          "a" => @html_sample,
+          "b" => @html_sample
+        }
+      }
+    }
+
+    assert {:ok, res} = NormalizeMarkup.filter(message)
+    assert res["object"]["contentMap"] == %{"a" => @expected, "b" => @expected}
+
+    assert res["object"]["content"] ==
+             Pleroma.MultiLanguage.map_to_str(res["object"]["contentMap"], multiline: true)
+  end
+
   test "history-aware" do
     message = %{
       "type" => "Create",