public login(user: string, password: string): Observable<any> {
    const body = new HttpParams()
      .set(`grant_type`, `password`)
      .set(`username`, user)
      .set(`password`, password);
    const headers = new HttpHeaders({
      'Content-Type': `application/x-www-form-urlencoded`,
      'Authorization': `Basic Y2xpZW50OnNlY3JldA==`})

    return this.http.post(api+`oauth/token`, body.toString(), { headers: headers, withCredentials: true })
      .pipe(
        map((res: any) => res)
      , catchError((err: any) => {throw(err)})
      )
  }