ID3 music tags

id3.js

const { promisify } = require('util');
const fs = require('fs');
const path = require('path');
const jimp = require('jimp');
const mm = require('music-metadata');
const Id3Writer = require('browser-id3-writer');

const start = Date.now();

const writeFile = promisify(fs.writeFile);
const readFile = promisify(fs.readFile);
const readdir = promisify(fs.readdir);

const getMp3Files = async dir => {
  const allFiles = await readdir(dir);
  return allFiles.filter(file => /\.mp3$/.test(file));
};

const resolveFeat = rawArtistsOrTitle => {
  const trim = str => str.trim();
  const truthy = item => !!item;

  const [artistsOrTitle, rawFeatArtists] = rawArtistsOrTitle
    .split(/ fe?a?t\. /g)
    .map(trim)
    .filter(truthy);

  const [artistOrTitle, ...otherArtists] = artistsOrTitle
    ? artistsOrTitle
        .split('&')
        .map(trim)
        .filter(truthy)
    : [];

  const featArtists = rawFeatArtists
    ? rawFeatArtists
        .split('&')
        .map(trim)
        .filter(truthy)
    : [];

  return [artistOrTitle, [...otherArtists, ...featArtists]];
};

const updateId3Tags = async (fileName, fileContent) => {
  // Load data into parsers.
  const writer = new Id3Writer(fileContent);
  const metadata = await mm.parseBuffer(fileContent);

  // Update thumbnail to have square shape.
  const oldThumbnail = metadata.common.picture[0].data;
  const img = await jimp.read(oldThumbnail);
  const newThumbnail = await img.cover(512, 512).getBufferAsync(jimp.MIME_JPEG);
  writer.setFrame('APIC', {
    type: 3,
    description: 'Album cover',
    data: newThumbnail
  });

  // Parse song title and
  const artists = [];

  const [rawArtists, rawTitleWithId] = fileName.split(' - ', 2);

  const [mainArtist, featArtists] = resolveFeat(rawArtists);
  artists.push(mainArtist, ...featArtists);

  const [rawTitleWithRemix] = rawTitleWithId.split('-', 1);
  const [rawTitle, rawRemix] = rawTitleWithRemix.split(' (', 2);
  const [title, featArtistsFromTitle] = resolveFeat(rawTitle);
  artists.push(...featArtistsFromTitle);

  // Set song artists.
  writer.setFrame('TPE1', artists);
  // Set song title.
  writer.setFrame('TIT2', rawRemix ? `${title} (${rawRemix.trim()}` : title);
  // Set album artist.
  writer.setFrame('TPE2', artists[0]);
  // Set album title.
  writer.setFrame('TALB', rawRemix ? `${title} (${rawRemix.trim()}` : title);

  // Add tag to MP3 buffer.
  writer.addTag();

  return Buffer.from(writer.arrayBuffer);
};

(async () => {
  let counter = 0;
  const directory = path.resolve(process.argv[2] || '.');

  process.stdout.write(`Scanning directory: ${directory}\n`);

  const mp3FileNames = await getMp3Files(directory);
  const total = mp3FileNames.length;
  const digits = total.toString().length;

  const promises = mp3FileNames.map(async mp3FileName => {
    // Normalize path.
    const normalizedPath = path.resolve(
      path.normalize(path.join(directory, mp3FileName))
    );

    // Read MP3 file from disk.
    const mp3File = await readFile(normalizedPath);

    // Update ID3 tags.
    const updatedMp3File = await updateId3Tags(mp3FileName, mp3File);

    // Write file to disk.
    await writeFile(normalizedPath, updatedMp3File);

    // Update progress.
    const current = (++counter).toString().padStart(digits, ' ');
    process.stdout.write(`\rConverting ID3 tags: ${current}/${total}`);
  });

  await Promise.all(promises);

  if (total) {
    process.stdout.write('\n');
  }
  process.stdout.write(`Processed ${total} in ${Date.now() - start}ms.\n`);
})();