require "metanorma/processor"
require "tempfile"

module Metanorma
  module Ietf
    class Processor < Metanorma::Processor

      def initialize
        @short = :ietf
        @input_format = :asciidoc
        @asciidoctor_backend = :rfc2
      end

      def output_formats
        {
          xmlrfc2: "xml",
          xmlrfc3: "v3.xml",
          html: "html",
          txt: "txt"
        }
      end

      def version
        "Metanorma::Ietf #{::Metanorma::Ietf::VERSION}"
      end

      def input_to_isodoc(file, filename)
        # TODO: storing these two variables for xmlrfc2. Remove when we have IsoDoc
        @file = file
        @filename = filename

        # This is XML RFC v3 output in text
        Metanorma::Input::Asciidoc.new.process(file, filename, @asciidoctor_backend)
      end

      # TODO: we're not yet using IsoDoc here
      def extract_options(isodocxml)
        {}
      end

      # From mislav: https://stackoverflow.com/questions/2108727
      #        /which-in-ruby-checking-if-program-exists-in-path-from-ruby
      def which(cmd)
        exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
        ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
          exts.each { |ext|
            exe = File.join(path, "#{cmd}#{ext}")
            return exe if File.executable?(exe) && !File.directory?(exe)
          }
        end
        nil
      end

      def output(isodoc_node, outname, format, options={})
        case format
        when :xmlrfc2
          # TODO: we're using XML RFC v2 as the central format because our processor
          # is not updated to the new schema

          # xmlrfcdoc = Metanorma::Input::Asciidoc.new.process(@file, @filename, :rfc2)
          # File.open(outname, 'w') { |f| f << xmlrfcdoc }

          # TODO: When we have IsoDoc, we just translate IsoDoc to XML RFC v2
          File.open(outname, 'w') { |f| f << isodoc_node }
        when :xmlrfc3
          # TODO: When we have IsoDoc, we just translate IsoDoc to XML RFC v3
          xmlrfcdoc = Metanorma::Input::Asciidoc.new.process(@file, @filename, :rfc3)
          File.open(outname, 'w') { |f| f << xmlrfcdoc }

        when :txt, :html
          Tempfile.open(outname) do |f|
            f << isodoc_node

            unless which("xml2rfc")
              warn "[metanorma-ietf] Error: unable to generate #{format}, the command `xml2rfc` is not found in path."
              return
            end

            # In xml2rfc, --text and --html are used
            format = :text if format == :txt
            # puts "xml2rfc --#{format} #{f.path} -o #{outname}"
            system("xml2rfc --#{format} #{f.path} -o #{outname}")
          end
        end
      end

    end
  end
end