SoundWave/server/Converter.js

import EventEmitter from 'events';
import fs from 'fs';
import ytdl from 'ytdl-core';
import ffmpeg from 'fluent-ffmpeg';

class Converter extends EventEmitter {
	constructor(url) {
		super();
		this.ytdl = null;
		this.totalSeconds = 0;
		ytdl.getInfo(url, {}, (err, info) => {
			if (err)
				this.emit('unavailable', err);
			else {
				this.totalSeconds = info ? info.length_seconds : 0;
				this.ytdl = ytdl(url);
				this.emit('available', info);
			}
		});
	}
}

export class VideoConverter extends Converter {
	constructor(url) { super(url); }

	initResponse(res, path) {
		const totalSize = res.headers['content-length'];
		let dataRead = 0;
		res.on('data', data => {
			dataRead += data.length;
			let percent = dataRead / totalSize;
			this.emit('progress', (percent * 100).toFixed(0));
		})
		   .on('end', () => this.emit('end'))
		   .on('error', () => fs.unlink(path, err => this.emit('error', error)));
	}

	download(path) {
		if (this.ytdl)
			this.ytdl.on('response', res => this.initResponse(res, path)).pipe(fs.createWriteStream(path));
	}
}

export class AudioConverter extends Converter {
	constructor(url) { super(url); }

	audio_percent(date) {
		const time = moment(new Date(...[0, 0, 0, ...date.split(':')]));
		const seconds = time.hours() * 3600 + time.minutes() * 60 + time.seconds();
		return ((seconds / this.totalSeconds) * 100).toFixed(0);
	}

	download(path) {
		if (this.ytdl)
			ffmpeg(this.ytdl)
				.noVideo().format('mp3')
				.output(fs.createWriteStream(path))
				.on('end', () => this.emit('end'))
				.on('start', () => this.emit('start'))
				.on('progress', params => this.emit('progress', this.audio_percent(params.timemark)))
				.on('error', (err, stdout, stderr) => fs.unlink(path, () => this.emit('error', err, stdout, stderr)))
				.run();
	}
}