rack_clean_html.rb

require 'rubygems'
require 'tidy'

module Rack
  class CleanHTML
    def initialize(app, options = {})
      options = options.dup

      Tidy.path = options.delete(:tidy_path)

      @app = app
      @tidy_options = options
    end

    def call(env)
      status, headers, response = @app.call(env)

      if headers['Content-Type'] =~ /html/
        response = cleanHtml(response)
        headers['Content-Length'] = response[0].size.to_s
      end

      [status, headers, response]
    end

    private

    def cleanHtml(response)
      body = ''

      response.each do |res|
        body += res
      end

      html = Tidy.open(@tidy_options) do |tidy|
        tidy.clean(body)
      end

      [html]
    end
  end
end