data class Album(
    val id: Int,
    val name: String
)

sealed class TaskState<out T> {
    object Initial : TaskState<Nothing>()
    object Progress : TaskState<Nothing>()
    class Failure(val error: Exception) : TaskState<Exception>()
    class Success<out T>(val result: T) : TaskState<T>()
}

class TaskViewModel : ViewModel() {

    sealed class AvailableTask<T>() {
        class Move : AvailableTask<Boolean>()
        class NewAlbum : AvailableTask<Album>()
    }

    private val moveStateFlow = MutableStateFlow<TaskState<Boolean>>(TaskState.Initial)
    private val newAlbumStateFlow = MutableStateFlow<TaskState<Album>>(TaskState.Initial)


    fun <T> observeTaskState(
        task: AvailableTask<T>,
        observer: Observer<TaskState<T>>
    ) {
        viewModelScope.launch(viewModelScope.coroutineContext + Job()) {
            val stateFlow = when (task) {
                is AvailableTask.Move -> moveStateFlow
                is AvailableTask.NewAlbum -> newAlbumStateFlow
            }

            stateFlow.collect {
                observer.onChanged(it)
            }
        }
    }
}