DefaultAuthInteractor.kt

class DefaultAuthInteractor @Inject constructor(
    private val checkUserRegisteredUseCase: CheckUserRegisteredUseCase,
    private val trustedLoginUserUseCase: TrustedLoginUserUseCase
) : AuthInteractor {

    /**
     * See how AuthInteractor coordinates the work between use-cases.
     */
    override fun login(): Completable =
        checkUserRegisteredUseCase.source()
            .flatMap { isRegistered ->
                if (isRegistered) {
                    trustedLoginUserUseCase.source {
                        PARAM_KEY_REG_PIN_CODE of "12345" 
                    }
                } else {
                    // perform registration step via UseCase
                }
            }
        
}