class Middleman::CoreExtensions::Internationalization

def build_resource(path, source_path, page_id, lang)
  old_locale = ::I18n.locale
  ::I18n.locale = lang
  localized_page_id = ::I18n.t("paths.#{page_id}", default: page_id, fallback: [])
  prefix = if (options[:mount_at_root] == lang) || (options[:mount_at_root].nil? && langs[0] == lang)
    '/'
  else
    replacement = options[:lang_map].fetch(lang, lang)
    options[:path].sub(':locale', replacement.to_s)
  end
  # path needs to be changed if file has a localizable extension. (options[mount_at_root] == lang)
  path = ::Middleman::Util.normalize_path(
    File.join(prefix, path.sub(page_id, localized_page_id))
  )
  path = path.sub(options[:templates_dir] + '/', '')
  p = ::Middleman::Sitemap::ProxyResource.new(app.sitemap, path, source_path)
  p.add_metadata locals: { lang: lang, page_id: path }, options: { lang: lang }
  ::I18n.locale = old_locale
  p
end