DenisBronx

// A wrapper for handling failing requests
sealed class Result<T> {

    data class Success<T>(val value: T) : Result<T>()

    data class Failure<T>(val throwable: Throwable) : Result<T>()

}

// A DataSource for the SharedPreferences

DenisBronx

class ProductRepositoryImpl(
    private val productApiService: ProductApiService,
    private val productDataMapper: Mapper<DataProduct, Product>,
    private val productPreferences: ProductPreferences
) : ProductRepository {
  
    override fun getWishlist(): Single<Result<List<Product>>> {
        return productApiService.getWishlist(productPreferences.getFavourites()).map {
            when (it) {
                is Result.Success -> Result.Success(mapWishlist(it.value))

DenisBronx

interface Mapper<I, O> {
    fun map(input: I): O
}

DenisBronx

class TransactionsViewModelImpl(
    private val userRepository: UserRepository,
    private val transactionRepository: TransactionRepository
) : TransactionsViewModel, ViewModel() {

    private val compositeDisposable = CompositeDisposable()

    override val transactions = MutableLiveData<List<Transaction>>()
    override val showProgress = MutableLiveData<Boolean>()
    override val showError = MutableLiveData<Boolean>()

DenisBronx

// A wrapper for handling failing requests
sealed class Result<T> {

    data class Success<T>(val value: T) : Result<T>()

    data class Failure<T>(val throwable: Throwable) : Result<T>()

}

// The models (simplified)

DenisBronx

// User
interface GetCurrentUserUseCase {
    operator fun invoke(): Result<User>
}

class GetCurrentUserUseCaseImpl(
    private val userRepository: UserRepository
) : GetCurrentUserUseCase {
    override fun invoke(): Result<User> = userRepository.getUser()
}

DenisBronx

class TransactionsViewModelImpl(
    private val getUserTransactionsUseCase: GetUserTransactionsUseCase
) : TransactionsViewModel, ViewModel() {

    private val compositeDisposable = CompositeDisposable()

    override val transactions = MutableLiveData<List<Transaction>>()
    override val showProgress = MutableLiveData<Boolean>()
    override val showError = MutableLiveData<Boolean>()
    override val showContent = MutableLiveData<Boolean>()

DenisBronx

// Non-nullable to Non-nullable
inline fun <I, O> mapList(input: List<I>, mapSingle: (I) -> O): List<O> {
    return input.map { mapSingle(it) }
}

// Nullable to Non-nullable
inline fun <I, O> mapNullInputList(input: List<I>?, mapSingle: (I) -> O): List<O> {
    return input?.map { mapSingle(it) } ?: emptyList()
}

DenisBronx

// Aggregate
data class Album(
    val id: String,
    val title: String,
    val songs: List<Song>
)

// Entity
data class Song(
    val id: String,

DenisBronx

data class NetworkAlbum(
    @SerializedName("id")
    val id: String?,
    @SerializedName("title")
    val title: String?,
    @SerializedName("songs")
    val songs: List<NetworkSong>?
)

data class NetworkSong(