Nitro-Cool-UI-Renderer/packages/sound/src/music/MusicPlayer.ts

import { GetEventDispatcher, SoundManagerEvent } from '@nitrots/events';
import { NitroLogger } from '@nitrots/utils';
import { Howl, Howler } from 'howler';
import { TraxData } from '../trax/TraxData';

export class MusicPlayer
{
    private _currentSong: TraxData | undefined;
    private _currentSongId: number;
    private _startPos: number;
    private _playLength: number;
    private _isPlaying: boolean;
    private _currentPos: number;
    private _cache: Map<number, Howl>;
    private _sampleUrl: string;

    private _tickerInterval: number | undefined;
    private _sequence: ISequenceEntry[][];

    constructor(sampleUrl: string)
    {
        this._sampleUrl = sampleUrl;
        this._isPlaying = false;
        this._startPos = 0;
        this._currentPos = 0;
        this._playLength = 0;
        this._sequence = [];
        this._cache = new Map<number, Howl>();
    }

    public async play(song: string, currentSongId: number, startPos: number = 0, playLength: number = -1): Promise<void>
    {
        this.reset();

        this._currentSong = new TraxData(song);
        this._startPos = Math.trunc(startPos);
        this._playLength = playLength;
        this._currentPos = this._startPos;
        this._currentSongId = currentSongId;
        //this.emit('loading');
        await this.preload();
        this._isPlaying = true;
        //this.emit('playing', this._currentPos, this._playLength - 1);
        this.tick(); // to evade initial 1 sec delay
        this._tickerInterval = window.setInterval(() => this.tick(), 1000);
    }

    private reset(): void
    {
        this._isPlaying = false;
        window.clearInterval(this._tickerInterval);

        Howler.stop();
        this._currentSongId = -1;
        this._currentSong = undefined;
        this._tickerInterval = undefined;
        this._startPos = 0;
        this._playLength = 0;
        this._sequence = [];
        this._currentPos = 0;
    }

    public pause(): void
    {
        this._isPlaying = false;
        //this.emit('paused', this._currentPos);

        Howler.stop();
    }

    public resume(): void
    {
        this._isPlaying = true;
        //this.emit('playing', this._currentPos, this._playLength - 1 );
    }

    public stop(): void
    {
        const songId = this._currentSongId;
        this.reset();
        GetEventDispatcher().dispatchEvent(new SoundManagerEvent(SoundManagerEvent.TRAX_SONG_COMPLETE, songId));
        //this.emit('stopped');
    }

    /**
     * Sets global howler volume for all sounds
     * @param volume value from 0.0 to 1.0
     */
    public setVolume(volume: number): void
    {
        Howler.volume(volume);
    }

    /**
     * Gets global howler volume for all sounds
     * @returns value from 0.0 to 1.0
     */
    public getVolume(): number
    {
        return Howler.volume();
    }

    /**
     * Gets sample from cache or loads it if not in cache
     * @param id sample id
     * @returns howl sound object
     */
    public async getSample(id: number): Promise<Howl>
    {
        let sample = this._cache.get(id);

        if(!sample) sample = await this.loadSong(id);

        return Promise.resolve(sample);
    }

    private async preload(): Promise<void>
    {
        this._sequence = [];

        if(!this._currentSong) return;

        for(const channel of this._currentSong.channels)
        {
            const sequenceEntryArray: ISequenceEntry[] = [];
            for(const sample of channel.items)
            {
                const sampleSound = await this.getSample(sample.id);

                const sampleCount = Math.ceil((sample.length * 2) / Math.ceil(sampleSound.duration()));

                for(let i = 0; i < sampleCount; i++)
                {
                    for(let j = 0; j < Math.ceil(sampleSound.duration()); j++)
                    {
                        sequenceEntryArray.push({ sampleId: sample.id, offset: j });
                    }
                }
            }

            this._sequence.push(sequenceEntryArray);
        }

        if(this._playLength <= 0) this._playLength = Math.max(...this._sequence.map((value: ISequenceEntry[]) => value.length));
    }

    public async preloadSamplesForSong(song: string): Promise<void>
    {
        const traxData = new TraxData(song);

        await Promise.all(traxData.getSampleIds().map(id => this.getSample(id)));
    }

    private async loadSong(songId: number): Promise<Howl>
    {
        return new Promise<Howl>((resolve, reject) =>
        {
            const sample = new Howl({
                src: [this._sampleUrl.replace('%sample%', songId.toString())],
                preload: true,
            });

            sample.once('load', () =>
            {
                this._cache.set(songId, sample);
                resolve(sample);
            });

            sample.once('loaderror', () =>
            {
                NitroLogger.error('failed to load sample ' + songId);
                reject('failed to load sample ' + songId);
            });
        });
    }


    private tick(): void
    {
        if(this._currentPos > this._playLength - 1)
        {
            this.stop();
        }

        if(this._isPlaying)
        {
            if(this._currentSong)
            {
                //this.emit('time', this._currentPos);
                this.playPosition(this._currentPos);
            }

            this._currentPos++;
        }
    }

    private playPosition(pos: number): void
    {
        if(!this._currentSong || !this._sequence) return;

        //@ts-ignore
        if(!Howler._audioUnlocked)
        {
            //console.log('skipping due to locked audio');
            return;
        }

        for(const sequencyEntry of this._sequence)
        {
            const entry = sequencyEntry[pos];

            if(!entry) continue;

            // sample -1 is play none
            // sample 0 is 1 second of empty noise
            if(entry.sampleId === -1 || entry.sampleId === 0) continue;

            const sampleAudio = this._cache.get(entry.sampleId);

            if(!sampleAudio) continue;

            if(entry.offset === 0)
            {
                sampleAudio.play();
            }
            else if(!sampleAudio.playing())
            {
                sampleAudio.seek(entry.offset);
                sampleAudio.play();
            }
        }
    }

}

interface ISequenceEntry
{
    sampleId: number;
    offset: number;
}