class Google::Auth::WebUserAuthorizer

def self.extract_callback_state request
  state = MultiJson.load(request.params[STATE_PARAM] || "{}")
  redirect_uri = state[CURRENT_URI_KEY]
  callback_state = {
    AUTH_CODE_KEY  => request.params[AUTH_CODE_KEY],
    ERROR_CODE_KEY => request.params[ERROR_CODE_KEY],
    SESSION_ID_KEY => state[SESSION_ID_KEY],
    SCOPE_KEY      => request.params[SCOPE_KEY]
  }
  [callback_state, redirect_uri]
end