module TextMagic

  class API

    module Charset

      GSM_CHARSET =
        "@£$¥èéùìòÇ\nØø\rÅåΔ_ΦΓΛΩΠΨΣΘΞ\e\f^{}\\[~]|€ÆæßÉ !\"#¤%&'()*+,-./0123456789:;<=>?¡"\
        "ABCDEFGHIJKLMNOPQRSTUVWXYZÄÖÑܧ¿abcdefghijklmnopqrstuvwxyzäöñüà".scan(/./u).freeze
      ESCAPED_CHARS = "{}\\~[]|€".freeze

      # Returns +true+ if the supplied text contains only characters from
      # GSM 03.38 charset, otherwise it returns +false+.
      def gsm?(text)
        text.scan(/./u).each { |c| return false unless GSM_CHARSET.include?(c) }
        true
      end
      alias is_gsm gsm?

      # Returns +true+ if the supplied text contains characters outside of
      # GSM 03.38 charset, otherwise it returns +false+.
      def unicode?(text)
        !is_gsm(text)
      end
      alias is_unicode unicode?

      def real_length(text, unicode)
        text.size + (unicode ? 0 : text.scan(/[\{\}\\~\[\]\|€]/).size)
      end

    end

  end

end