module Rpub
  class Epub
    class Toc < XmlFile
      def render
        xml.instruct!
        xml.declare! :DOCTYPE, :ncx, :PUBLIC, "-//W3C//DTD XHTML 1.1//EN", 'http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd'
        xml.ncx :xmlns => 'http://www.daisy.org/z3986/2005/ncx/', :version => '2005-1' do
          xml.head do
            xml.meta :name => 'dtb:uid',            :content => book.uid
            xml.meta :name => 'dtb:depth',          :content => max_level
            xml.meta :name => 'dtb:totalPageCount', :content => '0'
            xml.meta :name => 'dtb:maxPageNumber',  :content => '0'
          end
          xml.docTitle { xml.text book.config.title }
          xml.navMap do
            book.chapters.each do |chapter|
              nav_points_nested_by_level chapter.toc, chapter.filename
            end
          end
        end
      end

      private

      def max_level
        book.config.max_level || 2
      end

      def play_order
        @play_order ||= 0
      end

      def play_order=(v)
        @play_order = v
      end

      def next_play_order
        self.play_order = play_order + 1
      end

      def nav_points_nested_by_level(heading, filename, level = 1)
        heading.children.each do |heading|
          html_id = heading.attr[:id]
          source = filename+'#'+html_id
          if heading.value.options[:level] <= max_level
            nav_point html_id, next_play_order, heading.value.options[:raw_text], source do
                nav_points_nested_by_level heading, filename, level + 1
            end
          end
        end
      end

      def nav_point(id, play_order, text, filename)
        xml.navPoint :id => id, :playOrder => play_order do
          xml.navLabel { xml.text text }
          xml.content :src => filename
          yield if block_given?
        end
      end
    end
  end
end