module BrDanfe
  module DanfeLib
    class Cst
      def self.to_danfe(xml)
        value = origin(xml)

        if csosn?(xml)
          value += xml.css("ICMS/*/CSOSN").text
        elsif cst?(xml)
          value += xml.css("ICMS/*/CST").text
        end

        value
      end

      private
      def self.origin(xml)
        xml.css("ICMS/*/orig").text
      end

      def self.cst?(xml)
        xml.css("ICMS/*/CST").text != ""
      end

      def self.csosn?(xml)
        xml.css("ICMS/*/CSOSN").text != ""
      end
    end
  end
end