class Importmap::Map

def module_name_from(filename, mapping)
  filename_without_ext_and_version = filename.to_s.remove(filename.extname).split("@").first
  case
  when filename_without_ext_and_version == "index" && mapping.under
    mapping.under
  when mapping.under
    "#{mapping.under}/#{filename_without_ext_and_version}"
  else
    module_name
  end
end