class AuthenticatonRestore {
  private clearAuthData() {
	sessionStorage.removeItem(sessionTokenKey);
	sessionStorage.removeItem(userKey);
	sessionStorage.removeItem(lastTokenUpdateKey);
  }

  private get sessionToken() {
    return sessionStorage.getItem('pdsui-session-token');
  }

  private get user() {
    sessionStorage.getItem('user');
  }

  private get sessionToken() {
    sessionStorage.getItem(sessionTokenKey);
  }

  private getDiff() {
 	const lastTokenUpdateDateString = sessionStorage.getItem(lastTokenUpdateKey);
 	const lastTokenUpdate = lastTokenUpdateDateString && moment(lastTokenUpdateDateString, moment.ISO_8601) || null;
 	return now.diff(lastTokenUpdate);
  }

  private shouldUpdateImmediately(diff) {
    return diff < SESSION_REFRESH_INTERVAL;
  }

  private shouldClearAuth() {
    const diff = getDiff();

    return (
      this.lastTokenUpdateDate == null ||
      !this.lastTokenUpdateDate.isValid() ||
      diff < 0 ||
      diff > TOKEN_EXPIRATION_TIME ||
      !this.sessionToken ||
      !this.user
    );
  }

  public restore() {
  	if (this.shouldClearAuth) {
  	  this.clearAuthData();
  	} else {
	  axios.defaults.headers.common.Authorization = sessionToken;
	  store.dispatch(loginSuccess(JSON.parse(user)));
	  this.sessionUpdater.start(this.shouldUpdateImmediately);
	  this.idleMonitor.start();
  	}
  }
}