class Rack::Static

def call(env)
  path = env[PATH_INFO]
  if can_serve(path)
    if overwrite_file_path(path)
      env[PATH_INFO] = (add_index_root?(path) ? path + @index : @urls[path])
    elsif @gzip && env['HTTP_ACCEPT_ENCODING'] && /\bgzip\b/.match?(env['HTTP_ACCEPT_ENCODING'])
      path = env[PATH_INFO]
      env[PATH_INFO] += '.gz'
      response = @file_server.call(env)
      env[PATH_INFO] = path
      if response[0] == 404
        response = nil
      elsif response[0] == 304
        # Do nothing, leave headers as is
      else
        response[1][CONTENT_TYPE] = Mime.mime_type(::File.extname(path), 'text/plain')
        response[1]['content-encoding'] = 'gzip'
      end
    end
    path = env[PATH_INFO]
    response ||= @file_server.call(env)
    if @cascade && response[0] == 404
      return @app.call(env)
    end
    headers = response[1]
    applicable_rules(path).each do |rule, new_headers|
      new_headers.each { |field, content| headers[field] = content }
    end
    response
  else
    @app.call(env)
  end
end