VideosViewModelStep1.kt

@HiltViewModel
class VideosViewModel @Inject constructor() : ViewModel() {
    
    val videos = MutableStateFlow<List<VideoItem>>(listOf())
    val currentlyPlayingIndex = MutableStateFlow<Int?>(null)

    init {
        populateVideosWithTestData()
    }
    
    fun onPlayVideoClick(playbackPosition: Long, videoIndex: Int) {
        when (currentlyPlayingIndex.value) {
            null -> currentlyPlayingIndex.value = videoIndex
            videoIndex -> {
                currentlyPlayingIndex.value = null
                videos.value = videos.value!!.toMutableList().also { list ->
                    list[videoIndex] = list[videoIndex].copy(lastPlayedPosition = playbackPosition)
                }
            }
            else -> {
                videos.value = videos.value!!.toMutableList().also { list ->
                    list[currentlyPlayingIndex.value!!] = list[currentlyPlayingIndex.value!!].copy(lastPlayedPosition = playbackPosition)
                }
                currentlyPlayingIndex.value = videoIndex
            }
        }
    }
}