Rxy-livedatay-example

UsernameSarchViewModel.kt

class UsernameSearchViewModel(
  api: CostarApi,
  schedulersContainer: SchedulersContainer,
  analytics: Analytics
) : ViewModel() {

  enum class VisibleSearchComponent { Loading, List, EmptyMessage }

  private val minCharacterCount = 3
  private val disposables = CompositeDisposable()
  private val usernameInputSubject = PublishSubject.create<String>()
  private val addFriendSubject = PublishSubject.create<UserSearch>()

  val listItemsLiveData = MutableLiveData<List<UserSearch>>()
  val visibleSearchComponentLiveData = MutableLiveData<VisibleSearchComponent>()

  init {
    val searchObservable = usernameInputSubject
      .filter { it.length >= minCharacterCount }
      .throttleLatest(300, TimeUnit.MILLISECONDS, schedulersContainer.computation)
      .doOnNext { visibleSearchComponentLiveData.postValue(Loading) }
      .flatMapMaybe { api.searchUser(it).asNetworkCall(null, schedulersContainer.io) }
      .doOnNext { visibleSearchComponentLiveData.postValue(VisibleSearchComponent.List) }
      .filter { it.isSuccessful && it.body() != null }
      .map { it.body()!! }
      .share()

    // Search for users
    searchObservable
      .subscribe(listItemsLiveData::postValue)
      .addTo(disposables)

    // Show an empty message if we get no search matches
    searchObservable
      .map { if (it.isEmpty()) EmptyMessage else VisibleSearchComponent.List }
      .subscribe(visibleSearchComponentLiveData::postValue)
      .addTo(disposables)

    val hasAlreadySearched = usernameInputSubject.filter { it.length >= 3 }
      .switchMap { Observable.just(true) }

    // If the user has already made a valid search, show the empty message if their search
    // text is too short.
    hasAlreadySearched
      .flatMap { usernameInputSubject }
      .filter { it.length < minCharacterCount }
      .subscribe { visibleSearchComponentLiveData.postValue(EmptyMessage) }
      .addTo(disposables)

    // Send a friend request to a user
    addFriendSubject
      .flatMapMaybe { api.addFriend(it.id).asNetworkCall(null, schedulersContainer.io) }
      .subscribe()
      .addTo(disposables)

    // Log that we executed a search
    searchObservable
      .subscribe { analytics.logEvent(SearchPerformSearch) }
      .addTo(disposables)

    // Log that we executed a search and got back results
    searchObservable
      .filter { it.isNotEmpty() }
      .subscribe { analytics.logEvent(SearchResults) }
      .addTo(disposables)

    // Log that we executed a search and got back no results
    searchObservable
      .filter { it.isEmpty() }
      .subscribe { analytics.logEvent(SearchNoResults) }
      .addTo(disposables)

    // Log that a friend was added from search
    addFriendSubject
      .subscribe { analytics.logEvent(SearchAddFriend) }
      .addTo(disposables)
  }

  fun usernameInput(text: CharSequence) = usernameInputSubject.onNext(text.toString())
  fun addFriendClicked(user: UserSearch) = addFriendSubject.onNext(user)

  override fun onCleared() {
    super.onCleared()
    disposables.clear()
  }