app.get('/tracks/:id', (req, res) => {
    const { id } = req.params;
    const _id = new mongoose.Types.ObjectId(id);

    const { range } = req.headers;

    if(!range) {
        res.statusCode = 416;
        res.end();
    }

    const cursor = bucket.find({ _id });

    cursor.on('data', document => {
        const positions = range.replace(/bytes=/, '').split('-');
        const start = parseInt(positions[0], 10);
        const end = positions[1] ? parseInt(positions[1], 10) : document.length - 1;
        const head = {
            'Accept-Ranges': 'bytes',
            'Content-Type': 'audio/mpeg',
            'Content-Length': (end - start) + 1,
            'Content-Range': `bytes ${start}-${end}/${document.length}`,
        };

        res.writeHead(206, head);

        bucket.openDownloadStream(_id, { start, end })
            .pipe(res)
            .on('error', () => {
                res.statusCode = 404;
                res.end();
            });
    });
});