class EBuilder
  
  # Some Rack handlers (Thin, Rainbows!) implement an extended body object protocol, however,
  # some middleware (namely Rack::Lint) will break it by not mirroring the methods in question.
  # This middleware will detect an extended body object and will make sure it reaches the
  # handler directly. We do this here, so our middleware and middleware set up by the app will
  # still be able to run.
  unless defined?(EBuilder::ExtendedRack)
    class ExtendedRack < Struct.new(:app) # kindly borrowed from Sinatra
      def call(env)
        result, callback = app.call(env), env['async.callback']
        return result unless callback and async?(*result)
        after_response { callback.call result }
        setup_close(env, *result)
        throw :async
      end

      private
      def setup_close(env, status, header, body)
        return unless body.respond_to? :close and env.include? 'async.close'
        env['async.close'].callback { body.close }
        env['async.close'].errback { body.close }
      end

      def after_response(&block)
        raise NotImplementedError, "only supports EventMachine at the moment" unless defined? EventMachine
        EventMachine.next_tick(&block)
      end

      def async?(status, headers, body)
        return true if status == -1
        body.respond_to? :callback and body.respond_to? :errback
      end
    end
  end
end