require 'ndr_support/safe_file'
require 'ndr_import/helpers/file/xml'
require 'ndr_import/helpers/file/xml_streaming'
require_relative 'registry'

module NdrImport
  # This is one of a collection of file handlers that deal with individual formats of data.
  # They can be instantiated directly or via the factory method Registry.tables
  module File
    # This class is a xml file handler that returns a single table.
    class Xml < Base
      include NdrImport::Helpers::File::Xml
      include NdrImport::Helpers::File::XmlStreaming

      def initialize(*)
        super

        @pattern_match_xpath = @options['pattern_match_record_xpath']
      end

      private

      # Iterate through the file, yielding each 'xml_record_xpath' element in turn.
      def rows(&block)
        return enum_for(:rows) unless block

        if @options['slurp']
          record_elements(read_xml_file(@filename)).each(&block)
        else
          each_node(@filename, xml_record_xpath, @pattern_match_xpath, &block)
        end
      end

      def xml_record_xpath
        @pattern_match_xpath ? @options['xml_record_xpath'] : "*/#{@options['xml_record_xpath']}"
      end

      def record_elements(doc)
        if @pattern_match_xpath
          doc.root.children.find_all do |element|
            element.name =~ Regexp.new(@options['xml_record_xpath'])
          end
        else
          doc.root.xpath(@options['xml_record_xpath'])
        end
      end
    end
    # Not all xml files may want to be registered, so 'xml' is not registered by design.
    Registry.register(Xml, 'xml_table')
  end
end