if err = json.NewDecoder(resp.Body).Decode(&accessToken); err != nil {
		return err
	}

	k.Lock()
	k.accessToken = accessToken
	k.Unlock()
	return nil
}

// LookupUser lookup user by their userid.
func (k *KeycloakProvider) LookupUser(userid string) (User, error) {
	req, err := http.NewRequest(http.MethodGet, k.adminURL, nil)
	if err != nil {
		return User{}, err
	}

// looking up users, fetching additional attributes etc.
type Provider interface {
	LoginWithUser(username, password string) error
	LoginWithClientID(clientID, clientSecret string) error
	LookupUser(userid string) (User, error)