GalleryViewModel.kt

class GalleryViewModel : ViewModel(), KoinComponent {
    var setting: AlbumSetting? = null
    val multipleSelectMedia = BehaviorSubject.createDefault<MutableList<Media>>(mutableListOf())
    val singleSelectMedia = PublishSubject.create<Media>()
    val currentAlbumItem = BehaviorSubject.create<AlbumItem>()

    private val albumRepo: AlbumRepo by inject()

    fun loadAlbums(): Completable {
        return albumRepo.fetchAlbums(setting)
            .doOnComplete { selectAlbum(albumRepo.getAlbumItemSync(ALL_MEDIA_ALBUM_NAME, setting)!!) }
    }

    fun getAlbums(): Observable<List<AlbumItem>> = albumRepo.getAlbums(setting)

    fun selectAlbum(album: AlbumItem) {
        currentAlbumItem.onNext(album)
    }

    fun selectMedia(media: Media) {
        if (true == setting?.multipleSelection) {
            multipleSelectMedia.value?.run {
                if (this.contains(media))
                    this.remove(media)
                else {
                    setting?.maxSelection?.let {
                        if (this.size < it)
                            this.add(media)
                    } ?: kotlin.run {
                        this.add(media)
                    }
                }
                multipleSelectMedia.onNext(this)
            }
        } else {
            singleSelectMedia.onNext(media)
        }
    }

    fun isSelect(media: Media): Boolean = multipleSelectMedia.value!!.contains(media)
}