module Kitabu
  module Footnotes
    class PDF < Base
      def process
        remove_duplicated_attributes
        html.css(".chapter").each(&method(:process_chapter))
      end

      def remove_duplicated_attributes
        # https://github.com/sparklemotion/nokogiri/issues/339
        html.css('html').first.tap do |element|
          next unless element
          element.delete('xmlns')
          element.delete('xml:lang')
        end
      end

      def process_chapter(chapter)
        chapter.css('.footnotes li').each do |footnote|
          process_footnote(chapter, footnote)
          increment_footnote_index!
        end

        chapter.css('.footnotes').each(&:remove)
      end

      def process_footnote(chapter, footnote)
        # Remove rev links
        footnote.css('[rev=footnote]').map(&:remove)

        # Create an element for storing the footnote description
        description = Nokogiri::XML::Node.new('span', Nokogiri::HTML::DocumentFragment.parse(''))
        description.set_attribute 'class', 'footnote'
        description.inner_html = footnote.css('p').map(&:inner_html).join("\n")

        # Find ref based on footnote's id
        fn_id = footnote.get_attribute('id')

        refs = chapter.css("a[href='##{fn_id}']").each do |ref|
          sup = ref.parent
          sup.after(description)
          sup.remove
        end
      end
    end
  end
end