itunes-album-disc.js

/*

An OSA script to replace disc numbers in album names with the disc number attribute.

Accepts album names in any of these formats:

LCD Soundsystem (Disc 1)
Mellon Collie and the Infinite Sadness (Disc 1: Dawn to Dusk)
The Wall: Live in Berlin (Disc 2) [Live]

*/

function getMultiDiscAlbums () {
  let albums = {}
  const tracks = library.whose({ album: { _contains: '(Disc ' } })

  tracks().forEach(function (track) {
    const albumNameWithDisc = track.album()
    const albumName = albumNameWithDisc.replace(/ \(Disc .*\).*/i, '') // this ignores '[Live]'

    albums[albumName] = albums[albumName] || {}
    albums[albumName][albumNameWithDisc] = albums[albumName][albumNameWithDisc] || []
    albums[albumName][albumNameWithDisc].push(track)
  })

  return albums
}

function replaceAlbumNames (albums) {
  for (const albumName in albums) {
    if (albums.hasOwnProperty(albumName)) {
      const albumNames = Object.keys(albums[albumName]).sort()
      const discCount = albumNames.length

      albumNames.forEach(function (albumNameWithDisc, index) {
        const discNumber = index + 1
        const album = albumNameWithDisc.replace(/ \(Disc .*\)/i, '')

        albums[albumName][albumNameWithDisc].forEach(function (track) {
          track.discNumber.set(discNumber)
          track.discCount.set(discCount)
          track.album.set(album)
        })
      })
    }
  }
}

const app = Application('iTunes')
const library = app.sources[0].libraryPlaylists[0].fileTracks

const albums = getMultiDiscAlbums()
replaceAlbumNames(albums)