const metadata = require('../libs/metadata.js');
const { extname } = require('path');

const Artist = require('../models/Artist.js');
const Album = require('../models/Album.js');
const Track = require('../models/Track.js');
const AlbumToArtist = require('../models/AlbumToArtist.js');

class Queue {

    constructor() {
        this.queue = [];
        this.filter = this.getFilter();
        this.handleQueue();
    }

    add(event, file, stats) {
        if (file === undefined || !this.filter.includes(extname(file))) {
            return;
        }
        const element = { file: file };
        switch (event) {
            case constants.FS_EVENT_ADD:
                element.event = constants.FS_EVENT_ADD;
                break;
            case constants.FS_EVENT_UNLINK:
                element.event = constants.FS_EVENT_UNLINK;
                break;
            case constants.FS_EVENT_CHANGE:
                element.event = constants.FS_EVENT_CHANGE;
                break;
            default:
                return;
        }
        this.queue.push(element);
    }

    async handleQueue() {
        if (this.queue.length === 0) {
            if (this.timeout === undefined) {
                this.timeout = 10;
            } else {
                if (this.timeout > 60000) {
                    this.timeout = 60000;
                } else {
                    this.timeout += 10;
                }
            }
            logger.debug('queue is currently empty - sleeping for ' + this.timeout + 'ms...');
            setTimeout(() => {
                this.handleQueue()
            }, this.timeout);
            return;
        }
        if (this.timeout !== undefined) {
            this.timeout = undefined;
        }
        const element = this.queue[0];
        this.queue.shift();
        const timestamp = new Date().getTime();
        logger.debug('handling event \'' + element.event + '\' for queued file \'' + element.file + '\'...');
        switch (element.event) {
            case constants.FS_EVENT_ADD:
                await this.eventAdd(element.file);
                break;
            case constants.FS_EVENT_UNLINK:
                await this.eventUnlink(element.file);
                break;
            case constants.FS_EVENT_CHANGE:
                await this.eventChange(element.file);
                break;
        }
        logger.debug('event \'' + element.event + '\' for file \'' + element.file + '\' handled after ' + (new Date().getTime() - timestamp) + 'ms');
        this.handleQueue();
    }

    async eventAdd(file) {
        if (file === undefined) {
            return;
        }
        const tags = await metadata.parseFile(file);
        const artists = await this.addArtist(tags);
        const album = await this.addAlbum(tags);
        const track = await this.addTrack(tags, file);
        // this.linkTrackToArtist(track, artist);
        // this.linkTrackToAlbum(track, album);
        this.linkAlbumToArtists(album, artists);
    }

    async eventUnlink(file) {
        if (file === undefined) {
            return;
        }
        try {
            await database.models.Track.destroy({
                where: { file: file }
            });
        } catch (err) {
            logger.error(err);
        }
    }

    async eventChange(file) {
        if (file === undefined) {
            return;
        }
        let artist = tags.common.artist;
        const artists = tags.common.artists || [];
        if (artist !== undefined && !artists.includes(artist)) {
            artists.push(artist);
        }
        for (let index = 0; index < artists.length; index++) {
            artist = new Artist(artists[index]);
            await artist.save();
            artists[index] = artist;
        }
        return artists;
    }

    async addArtist(tags) {
        if (tags?.common?.artist === undefined && tags?.common?.artists === undefined) {
            return;
        }
        let artist = tags.common.artist;
        const artists = tags.common.artists || [];
        if (artist !== undefined && !artists.includes(artist)) {
            artists.push(artist);
        }
        for (let index = 0; index < artists.length; index++) {
            artist = new Artist(artists[index]);
            await artist.save();
            artists[index] = artist;
        }
        return artists;
    }

    async addAlbum(tags) {
        if (tags?.common?.album === undefined) {
            return;
        }
        let album = new Album(tags.common.album);
        await album.save();
        return album;
    }

    async addTrack(tags, file) {
        if (tags?.common?.title === undefined || file === undefined) {
            return;
        }
        let track = new Track(tags, file);
        await track.save();
        return track;
    }

    async linkTrackToArtist(track, artist) {
        if (track === undefined || artist === undefined) {
            return;
        }
        try {
            const [element, created] = await database.models.TrackToArtist.findOrCreate({
                where: {
                    track: track.id,
                    artist: artist.id
                }
            });
            if (created) {
                logger.debug('linked track \'' + track.id + '\' to artist \'' + artist.id + '\': ' + JSON.stringify(element));
            }
            return element;
        } catch (err) {
            logger.error('error finding or creating tracktoartist entry for track \'' + track.id + '\' and album \'' + artist.id + '\' > ' + err);
        }
    }

    async linkTrackToAlbum(track, album) {
        if (track === undefined || album === undefined) {
            return;
        }
        try {
            const [element, created] = await database.models.TrackToAlbum.findOrCreate({
                where: {
                    track: track.id,
                    album: album.id
                }
            });
            if (created) {
                logger.debug('linked track \'' + track.id + '\' to album \'' + album.id + '\': ' + JSON.stringify(element));
            }
            return element;
        } catch (err) {
            logger.error('error finding or creating tracktoalbum entry for track \'' + track.id + '\' and album \'' + album.id + '\' > ' + err);
        }
    }

    async linkAlbumToArtists(album, artists) {
        if (album === undefined || artists === undefined || artists.length === 0) {
            return;
        }
        for (let index = 0; index < artists.length; index++) {
            await new AlbumToArtist(album, artists[index]).save();
        }
    }

    getFilter() {
        let filter = config?.library?.formats || ['.mp3'];
        for (let index = 0; index < filter.length; index++) {
            if (filter[index].startsWith(".")) {
                continue;
            }
            filter[index] = '.' + filter[index];
        }
        return filter;
    }

}

module.exports = Queue;