Android reactive programming sample

ProfileActivity.kt

import com.jakewharton.rxbinding2.view.clicks
…
viewModel.bind(follow_button.clicks().map{ ProfileUiEvent.Follow })
…
viewModel.uiState.observe(this, ::showState)
viewModel.uiContent.observe(this, ::showContent)
…

ProfileUiEvent.kt

sealed class ProfileUiEvent {
   data class Show(val userId: String) : ProfileUiEvent()
   data class OpenTweet(val tweetId: String) : ProfileUiEvent()
   object Follow : ProfileUiEvent()
   ...
}

ProfileViewModel.kt

internal class ProfileViewModel @Inject constructor(
   ...
   getUserInteractor: GetUserInteractor,
   followUserInteractor: FollowUserInteractor,
) : ReactiveViewModel<ProfileUiEvent>() {

   val uiState: LiveData<UiState>
   val uiContent: LiveData<ProfileUiModel>

   init {
       val userDetailsStream = eventStream
           .ofType<ProfileUiEvent.Show>()
           .map { GetUserRequest(it.userId) }
           .compose(getUserInteractor)

       val uiContentStream = userDetailsStream
           .ofType<GetUserRequest.Success>
           .mapToUserUiModel()

       val followUserStream = eventsStream
           .ofType<ProfileUiEvent.Follow>()
           .withLatestFrom(uiContentStream)
           .map { (_, uiContent) -> FollowRequest(uiContent.userId) }
           .compose(followUserInteractor)

       val uiStateStream = Flowable
           .merge(
               userDetailsStream.mapUserState(),
               followUserStream.mapFollowState()
           )

       uiState = fromPublisher(uiStateStream)
       uiContent = fromPublisher(uiContentStream)
   }

   private fun Flowable<FollowResponse>.mapFollowState(): Flowable<UiState> {
       return this.map { response ->
           when (response) {
               is FollowResponse.InFlight -> UiState.Loading
               is FollowResponse.Error -> UiState.Error(mapError(response))
               is FollowResponse.Success -> UiState.Success
           }
       }
   }
}