owntone-server/web-src/src/lib/Artists.js

export default class Artists {
  constructor (items, options = { hideSingles: false, hideSpotify: false, sort: 'Name', group: false }) {
    this.items = items
    this.options = options
    this.grouped = {}
    this.sortedAndFiltered = []
    this.indexList = []

    this.init()
  }

  init () {
    this.createSortedAndFilteredList()
    this.createGroupedList()
    this.createIndexList()
  }

  getArtistIndex (artist) {
    if (this.options.sort === 'Name') {
      return artist.name_sort.charAt(0).toUpperCase()
    }
    return artist.time_added.substring(0, 4)
  }

  isArtistVisible (artist) {
    if (this.options.hideSingles && artist.track_count <= (artist.album_count * 2)) {
      return false
    }
    if (this.options.hideSpotify && artist.data_kind === 'spotify') {
      return false
    }
    return true
  }

  createIndexList () {
    this.indexList = [...new Set(this.sortedAndFiltered
      .map(artist => this.getArtistIndex(artist)))]
  }

  createSortedAndFilteredList () {
    let artistsSorted = this.items
    if (this.options.hideSingles || this.options.hideSpotify || this.options.hideOther) {
      artistsSorted = artistsSorted.filter(artist => this.isArtistVisible(artist))
    }
    if (this.options.sort === 'Recently added') {
      artistsSorted = [...artistsSorted].sort((a, b) => b.time_added.localeCompare(a.time_added))
    }
    this.sortedAndFiltered = artistsSorted
  }

  createGroupedList () {
    if (!this.options.group) {
      this.grouped = {}
    }
    this.grouped = this.sortedAndFiltered.reduce((r, artist) => {
      const idx = this.getArtistIndex(artist)
      r[idx] = [...r[idx] || [], artist]
      return r
    }, {})
  }
}