fun login(): Completable {
        return apiService.login(user, password)
    }

    fun sessionIsValid(): Observable<Boolean> {
        //... return true if session cookie is < 30 min old
    }

    fun getAuth(): Observable<Unit> {
        return sessionIsValid()
                .flatMap { sessionIsValid ->
                    if (!sessionIsValid) {
                        login().subscribe()
                        Observable.just(Unit)
                    } else {
                        Observable.just(Unit)
                    }
                }
    }

    fun getMessages() {
        userRepository
                .getAuth()
                .subscribeOn(Schedulers.io())
                .flatMap { messageRepository.messages() }
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({ messages: List<Message> ->
                    messages.forEach { Timber.d("\n${it.messageTitle}") }
                }, { errors: Throwable -> Timber.e(errors) })
    }