module Qeweney

def self.rack_env_value_from_request(request, key)
  case key
  when 'REQUEST_METHOD' then request.method.upcase
  when 'PATH_INFO'      then request.path
  when 'QUERY_STRING'   then request.query_string || ''
  when 'SERVER_NAME'    then request.headers['host']
  when 'rack.input'     then InputStream.new(request)
  when HTTP_HEADER_RE   then request.headers[$1.gsub('_', '-').downcase]
  else                       RACK_ENV[key]
  end
end