class Kramdown::Converter::Html

def convert_codeblock(el, indent)
  attr = el.attr.dup
  lang = extract_code_language!(attr)
  highlighted_code = highlight_code(el.value, lang, :block)
  if highlighted_code
    add_syntax_highlighter_to_class_attr(attr)
    "#{' '*indent}<div#{html_attributes(attr)}>#{highlighted_code}#{' '*indent}</div>\n"
  else
    result = escape_html(el.value)
    result.chomp!
    if el.attr['class'].to_s =~ /\bshow-whitespaces\b/
      result.gsub!(/(?:(^[ \t]+)|([ \t]+$)|([ \t]+))/) do |m|
        suffix = ($1 ? '-l' : ($2 ? '-r' : ''))
        m.scan(/./).map do |c|
          case c
          when "\t" then "<span class=\"ws-tab#{suffix}\">\t</span>"
          when " " then "<span class=\"ws-space#{suffix}\">&#8901;</span>"
          end
        end.join('')
      end
    end
    code_attr = {}
    code_attr['class'] = "language-#{lang}" if lang
    "#{' '*indent}<pre#{html_attributes(attr)}><code#{html_attributes(code_attr)}>#{result}\n</code></pre>\n"
  end
end