MusicDetailViewModel.kt

@HiltViewModel
class MusicDetailViewModel @Inject constructor(
    private val savedStateHandle: SavedStateHandle, private val repository: MusicRepository
) : ViewModel() {

    val state: StateFlow<MusicDetailScreenState>

    init {
        val musicDetails = savedStateHandle.getStateFlow<Long>(MUSIC_ID, -1).filter { it != -1L }
            .flatMapLatest { getMusicDetails(it) }

        state = musicDetails.map { music ->
            MusicDetailScreenState(
                uiMModel = music
            )
        }.stateIn(
            scope = viewModelScope,
            started = SharingStarted.WhileSubscribed(stopTimeoutMillis = 5000),
            initialValue = MusicDetailScreenState()
        )
    }

    private suspend fun getMusicDetails(musicId: Long): Flow<MusicUiModel> {
        return repository.getMusic(musicId).map {
            MusicUiModel(
                trackId = it.trackId,
                musicTitle = it.musicTitle,
                albumName = it.albumName,
                artisName = it.artisName,
                imageUrl = it.imageUrl.replace("100", "460"),
                previewUrl = it.previewUrl
            )
        }.flowOn(Dispatchers.IO)
    }

    override fun onCleared() {
        savedStateHandle[MUSIC_ID] = state.value.uiMModel.trackId
        viewModelScope.cancel()
        super.onCleared()
    }
}

const val MUSIC_ID = "music_id"