module Rocx
  module Properties
    class Language < ComplexProperty
      include AttributeBuilder

      tag :lang
      attribute :bidi, expects: :valid_language
      attribute :east_asia, expects: :valid_language
      attribute :latin, expects: :valid_language, displays_as: :val

    private

      def valid_language(value)
        message = "Invalid #{name}: must be a language code (RFC 4646)"
        raise ArgumentError, message unless value =~ /[a-z]{2}-[A-Z]{2}/
      end

    end
  end
end