Controller.swift

class Controller {
    enum Action {
        case confirm
    }

    let disposeBag = DisposeBag()
    let viewController: ViewController
    let rewardsManager: RewardsManager

    lazy var action: Observable<Action> = {
        return self.viewController.confirm.map { .confirm }
    }()

    init(status: Observable<CardStatus>,
         rewardsManager: RewardsManager = .init(),
         viewController: ViewController = .init()) {
        self.viewController = viewController
        self.rewardsManager = rewardsManager

        subscribe(toStatus: status)
        subscribe(toAction: action)
    }

    func subscribe(toStatus accountStatus: Observable<CardStatus>) {
        accountStatus
            .subscribe(onNext: { [viewController] in
                let viewModel = ViewModel(cardStatus: $0)
                viewController.bind(viewModel)
            }).disposed(by: disposeBag)
    }

    func subscribe(toAction action: Observable<Action>) {
        action
            .flatMap { [rewardsManager] action -> Completable in
                switch action {
                case .confirm:
                    return rewardsManager.signup()
                }
            }.subscribe()
            .disposed(by: disposeBag)
    }
}