require 'd-mark'

module DMarkBook
  module Translators
    class HTML < DMark::Translator
      def handle_string(node)
        [html_escape(node)]
      end

      def handle_element(node, path)
        case node.name
        when 'p', 'dl', 'dt', 'dd', 'ol', 'ul', 'li', 'code', 'kbd', 'blockquote'
          wrap(node.name) { handle_children(node, path) }
        when 'h'
          depth = path.count { |node| node.name == 'section' } + 1
          wrap("h#{depth}") { handle_children(node, path) }
        when 'section'
          wrap('section', id: id_for_section(node)) { handle_children(node, path) }
        when 'em'
          wrap('em') { handle_children(node, path) }
        when 'link'
          wrap('a', href: node.attributes['target']) { handle_children(node, path) }
        when 'listing'
          wrap('pre') { wrap('code') { handle_children(node, path) } }
        else
          raise DMark::Translator::UnhandledNode.new(node)
        end
      end

      def wrap(name, params = {})
        params_string = params.map { |k, v| " #{k}=\"#{html_escape(v)}\"" }.join('')
        ["<#{name}#{params_string}>", yield, "</#{name}>"]
      end

      def html_escape(s)
        s.gsub('&', '&amp;').gsub('<', '&lt;')
      end

      def id_for_section(node)
        header = node.children.find { |c| c.name == 'h' }
        text = header.children.join('')
        text.downcase.gsub(/[^a-zA-Z-]/, '-')
      end
    end
  end
end

class SpecialHTML < DMarkBook::Translators::HTML
  def handle_element(node, depths)
    case node.name
    when 'firstterm', 'prompt', 'filename'
      wrap('span', class: node.name) { handle_children(node, depths) }
    when 'note', 'todo'
      wrap('div', class: node.name) { handle_children(node, depths) }
    else
      super
    end
  end
end

content = File.readlines('site/content/index.dmark').drop(4).join
parser = DMark::Parser.new(content)
tree = parser.parse

puts SpecialHTML.new.translate(tree)