/*****************************************************************************
 * VLCMediaLibraryManager.swift
 * VLC for iOS
 *****************************************************************************
 * Copyright © 2018 VideoLAN. All rights reserved.
 * Copyright © 2018 Videolabs
 *
 * Authors: Soomin Lee <bubu # mikan.io>
 *
 * Refer to the COPYING file of the official project for license.
 *****************************************************************************/

extension Notification.Name {
    static let VLCNewFileAddedNotification = Notification.Name("NewFileAddedNotification")
}

// For objc
extension NSNotification {
    @objc static let VLCNewFileAddedNotification = Notification.Name.VLCNewFileAddedNotification
}

@objc protocol MediaLibraryObserver: class {
    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                      didUpdateVideo video: [VLCMLMedia])

    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                      didAddVideo video: [VLCMLMedia])

    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                                     didAddShowEpisode showEpisode: [VLCMLMedia])

    // Audio
    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                                     didAddAudio audio: [VLCMLMedia])

    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                                     didAddAlbumTrack audio: [VLCMLMedia])

    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                                     didAddArtist artist: [VLCMLArtist])

    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                                     didAddAlbum album: [VLCMLAlbum])

    @objc optional func medialibrary(_ medialibrary: VLCMediaLibraryManager,
                                     didAddGenre genre: [VLCMLGenre])
}

class VLCMediaLibraryManager: NSObject {

    private static let databaseName: String = "medialibrary.db"
    private var databasePath: String!
    private var thumbnailPath: String!

    // Using ObjectIdentifier to avoid duplication and facilitate
    // identification of observing object
    private var observers = [ObjectIdentifier: Observer]()

    private lazy var medialib: VLCMediaLibrary = {
        let medialibrary = VLCMediaLibrary()
        medialibrary.delegate = self
        return medialibrary
    }()

    override init() {
        super.init()
        setupMediaLibrary()
        NotificationCenter.default.addObserver(self, selector: #selector(reload),
                                               name: .VLCNewFileAddedNotification, object: nil)
    }

    // MARK: Private
    private func setupMediaLibrary() {
        guard let documentPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first,
            let dbPath = NSSearchPathForDirectoriesInDomains(.libraryDirectory, .userDomainMask, true).first else {
                preconditionFailure("VLCMediaLibraryManager: Unable to init medialibrary.")
        }

        databasePath = dbPath + "/" + VLCMediaLibraryManager.databaseName
        thumbnailPath = documentPath

        let medialibraryStatus = medialib.setupMediaLibrary(databasePath: databasePath,
                                                            thumbnailPath: thumbnailPath)

        switch medialibraryStatus {
        case .success:
            guard medialib.start() else {
                assertionFailure("VLCMediaLibraryManager: Medialibrary failed to start.")
                return
            }
            medialib.reload()
            medialib.discover(onEntryPoint: "file://" + documentPath)
            break
        case .alreadyInitialized:
            assertionFailure("VLCMediaLibraryManager: Medialibrary already initialized.")
            break
        case .failed:
            preconditionFailure("VLCMediaLibraryManager: Failed to setup medialibrary.")
            break
        case .dbReset:
            // should still start and discover but warn the user that the db has been wipped
            assertionFailure("VLCMediaLibraryManager: The database was resetted, please re-configure.")
            break
        }
    }

    // MARK: Internal

    @objc private func reload() {
        medialib.reload()
    }

    /// Returns number of *ALL* files(audio and video) present in the medialibrary database
    func numberOfFiles() -> Int {
        var media = medialib.audioFiles(with: .filename, desc: false)

        media += medialib.videoFiles(with: .filename, desc: false)
        return media.count
    }


    /// Returns *ALL* file found for a specified VLCMLMediaType
    ///
    /// - Parameter type: Type of the media
    /// - Returns: Array of VLCMLMedia
    func media(ofType type: VLCMLMediaType, sortingCriteria sort: VLCMLSortingCriteria = .filename, desc: Bool = false) -> [VLCMLMedia] {
        return type == .video ? medialib.videoFiles(with: sort, desc: desc) : medialib.audioFiles(with: sort, desc: desc)
    }

    func genre(sortingCriteria sort: VLCMLSortingCriteria = .default, desc: Bool = false) -> [VLCMLGenre] {
        return medialib.genres(with: sort, desc: desc)
    }
}

// MARK: - Observer

private extension VLCMediaLibraryManager {
    struct Observer {
        weak var observer: MediaLibraryObserver?

        init(_ observer: MediaLibraryObserver) {
            self.observer = observer
        }
    }
}

extension VLCMediaLibraryManager {
    func addObserver(_ observer: MediaLibraryObserver) {
        let identifier = ObjectIdentifier(observer)
        observers[identifier] = Observer(observer)
    }

    func removeObserver(_ observer: MediaLibraryObserver) {
        let identifier = ObjectIdentifier(observer)
        observers.removeValue(forKey: identifier)
    }
}

// MARK: MediaDataSource - Audio methods

extension VLCMediaLibraryManager {
    private func getAllAudio() {
//        foundAudio = medialibrary.media(ofType: .audio)
//        artistsFromAudio()
//        albumsFromAudio()
//        audioPlaylistsFromAudio()
//        genresFromAudio()
    }

    func getArtists() -> [VLCMLArtist] {
        return medialib.artists(with: .artist, desc: false, all: true)
    }

    func getAlbums() -> [VLCMLAlbum] {
        return medialib.albums(with: .album, desc: false)
    }

    private func getAudioPlaylists() {
//        let labels = MLLabel.allLabels() as! [MLLabel]
//        audioPlaylist = labels.filter {
//            let audioFiles = $0.files.filter {
//                if let file = $0 as? MLFile {
//                    return file.isSupportedAudioFile()
//                }
//                return false
//            }
//            return !audioFiles.isEmpty
//        }
    }

    private func genresFromAudio() {
//        let albumtracks = MLAlbumTrack.allTracks() as! [MLAlbumTrack]
//        let tracksWithArtist = albumtracks.filter { $0.genre != nil && $0.genre != "" }
//        genres = tracksWithArtist.map { $0.genre }
    }
}

// MARK: MediaDataSource - Video methods

extension VLCMediaLibraryManager {
    private func getAllVideos() {
//        moviesFromVideos()
//        episodesFromVideos()
        //        videoPlaylistsFromVideos()
    }

    private func getMovies() {
//        movies = foundVideos.filter { $0.subtype() == .movie }
    }

    private func getShowEpisodes() {
//        episodes = foundVideos.filter { $0.subtype() == .showEpisode }
    }

    private func getVideoPlaylists() {
//        let labels = MLLabel.allLabels() as! [MLLabel]
//        audioPlaylist = labels.filter {
//            let audioFiles = $0.files.filter {
//                if let file = $0 as? MLFile {
//                    return file.isShowEpisode() || file.isMovie() || file.isClip()
//                }
//                return false
//            }
//            return !audioFiles.isEmpty
//        }
    }
}

// MARK: VLCMediaLibraryDelegate
extension VLCMediaLibraryManager: VLCMediaLibraryDelegate {
    func medialibrary(_ medialibrary: VLCMediaLibrary, didAddMedia media: [VLCMLMedia]) {
        let video = media.filter {( $0.type() == .video )}
        let audio = media.filter {( $0.type() == .audio )}
        let showEpisode = media.filter {( $0.subtype() == .showEpisode )}
        let albumTrack = media.filter {( $0.subtype() == .albumTrack )}

        for observer in observers {
            observer.value.observer?.medialibrary?(self, didAddVideo: video)
            observer.value.observer?.medialibrary?(self, didAddAudio: audio)
            observer.value.observer?.medialibrary?(self, didAddShowEpisode: showEpisode)
            observer.value.observer?.medialibrary?(self, didAddAlbumTrack: albumTrack)
        }
    }

    func medialibrary(_ medialibrary: VLCMediaLibrary, didAdd artists: [VLCMLArtist]) {
        print("VLCMediaLibraryDelegate: Did add artists: \(artists), with count: \(artists.count)")
        for observer in observers {
            observer.value.observer?.medialibrary?(self, didAddArtist: artists)
        }
    }

    func medialibrary(_ medialibrary: VLCMediaLibrary, didAdd albums: [VLCMLAlbum]) {
        print("VLCMediaLibraryDelegate: Did add albums: \(albums), with count: \(albums.count)")
        for observer in observers {
            observer.value.observer?.medialibrary?(self, didAddAlbum: albums)
        }
    }

    func medialibrary(_ medialibrary: VLCMediaLibrary, didStartDiscovery entryPoint: String) {
    }

    func medialibrary(_ medialibrary: VLCMediaLibrary, didCompleteDiscovery entryPoint: String) {
    }

    func medialibrary(_ medialibrary: VLCMediaLibrary, didProgressDiscovery entryPoint: String) {
    }

    func medialibrary(_ medialibrary: VLCMediaLibrary, didUpdateParsingStatsWithPercent percent: UInt32) {
    }
}

// MARK: Future MediaDataSource extension

// Todo: implement the remove
//    - (void)removeMediaObjectFromFolder:(NSManagedObject *)managedObject
// {
//    NSAssert(([managedObject isKindOfClass:[MLFile class]] && ((MLFile *)managedObject).labels.count > 0), @"All media in a folder should be of type MLFile and it should be in a folder");
//
//    if (![managedObject isKindOfClass:[MLFile class]]) return;
//
//    MLFile *mediaFile = (MLFile *)managedObject;
//    [self rearrangeFolderTrackNumbersForRemovedItem:mediaFile];
//    mediaFile.labels = nil;
//    mediaFile.folderTrackNumber = nil;
//    }
//
//    - (void)removeMediaObject:(NSManagedObject *)managedObject
// {
//    if ([managedObject isKindOfClass:[MLAlbum class]]) {
//        MLAlbum *album = (MLAlbum *)managedObject;
//        NSSet *iterAlbumTrack = [NSSet setWithSet:album.tracks];
//
//        for (MLAlbumTrack *track in iterAlbumTrack) {
//            NSSet *iterFiles = [NSSet setWithSet:track.files];
//
//            for (MLFile *file in iterFiles)
//                [self _deleteMediaObject:file];
//        }
//        [[MLMediaLibrary sharedMediaLibrary] removeObject: album];
//        // delete all episodes from a show
//    } else if ([managedObject isKindOfClass:[MLShow class]]) {
//        MLShow *show = (MLShow *)managedObject;
//        NSSet *iterShowEpisodes = [NSSet setWithSet:show.episodes];
//
//        for (MLShowEpisode *episode in iterShowEpisodes) {
//            NSSet *iterFiles = [NSSet setWithSet:episode.files];
//
//            for (MLFile *file in iterFiles)
//                [self _deleteMediaObject:file];
//        }
//        [[MLMediaLibrary sharedMediaLibrary] removeObject: show];
//        // delete all files from an episode
//    } else if ([managedObject isKindOfClass:[MLShowEpisode class]]) {
//        MLShowEpisode *episode = (MLShowEpisode *)managedObject;
//        NSSet *iterFiles = [NSSet setWithSet:episode.files];
//
//        for (MLFile *file in iterFiles)
//            [self _deleteMediaObject:file];
//        // delete all files from a track
//        [[MLMediaLibrary sharedMediaLibrary] removeObject: episode];
//    } else if ([managedObject isKindOfClass:[MLAlbumTrack class]]) {
//        MLAlbumTrack *track = (MLAlbumTrack *)managedObject;
//        NSSet *iterFiles = [NSSet setWithSet:track.files];
//
//        for (MLFile *file in iterFiles)
//            [self _deleteMediaObject:file];
//    } else if ([managedObject isKindOfClass:[MLLabel class]]) {
//        MLLabel *folder = (MLLabel *)managedObject;
//        NSSet *iterFiles = [NSSet setWithSet:folder.files];
//        [folder removeFiles:folder.files];
//        for (MLFile *file in iterFiles)
//            [self _deleteMediaObject:file];
//        [[MLMediaLibrary sharedMediaLibrary] removeObject:folder];
//    }
//    else
//    [self _deleteMediaObject:(MLFile *)managedObject];
//    }
//
//    - (void)_deleteMediaObject:(MLFile *)mediaObject
// {
//    [self rearrangeFolderTrackNumbersForRemovedItem:mediaObject];
//
//    /* stop playback if needed */
//    VLCPlaybackController *vpc = [VLCPlaybackController sharedInstance];
//    VLCMedia *media = [vpc currentlyPlayingMedia];
//    MLFile *currentlyPlayingFile = [MLFile fileForURL:media.url].firstObject;
//    if (currentlyPlayingFile && currentlyPlayingFile == mediaObject) {
//        [vpc stopPlayback];
//    }
//
//    NSFileManager *fileManager = [NSFileManager defaultManager];
//    NSString *folderLocation = [[mediaObject.url path] stringByDeletingLastPathComponent];
//    NSArray *allfiles = [fileManager contentsOfDirectoryAtPath:folderLocation error:nil];
//    NSString *fileName = [mediaObject.path.lastPathComponent stringByDeletingPathExtension];
//    if (!fileName)
//    return;
//    NSIndexSet *indexSet = [allfiles indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
//        return ([obj rangeOfString:fileName].location != NSNotFound);
//        }];
//    NSUInteger count = indexSet.count;
//    NSString *additionalFilePath;
//    NSUInteger currentIndex = [indexSet firstIndex];
//    for (unsigned int x = 0; x < count; x++) {
//        additionalFilePath = allfiles[currentIndex];
//        if ([additionalFilePath isSupportedSubtitleFormat])
//        [fileManager removeItemAtPath:[folderLocation stringByAppendingPathComponent:additionalFilePath] error:nil];
//        currentIndex = [indexSet indexGreaterThanIndex:currentIndex];
//    }
//    [fileManager removeItemAtURL:mediaObject.url error:nil];
//    }
//
//    - (void)rearrangeFolderTrackNumbersForRemovedItem:(MLFile *) mediaObject
// {
//    MLLabel *label = [mediaObject.labels anyObject];
//    NSSet *allFiles = label.files;
//    for (MLFile *file in allFiles) {
//        if (file.folderTrackNumber > mediaObject.folderTrackNumber) {
//            int value = [file.folderTrackNumber intValue];
//            file.folderTrackNumber = [NSNumber numberWithInt:value - 1];
//        }
//    }
// }
// @end