import { orderBy, shuffle, throttle } from 'lodash'
import plyr from 'plyr'
import { nextTick } from 'vue'
import isMobile from 'ismobilejs'

import { eventBus, isAudioContextSupported } from '@/utils'

import {
  commonStore,
  preferenceStore as preferences,
  queueStore,
  recentlyPlayedStore,
  songStore,
  userStore
} from '@/stores'

import { audioService, socketService } from '@/services'
import router from '@/router'

/**
 * The number of seconds before the current song ends to start preload the next one.
 */
const PRELOAD_BUFFER = 30
const DEFAULT_VOLUME_VALUE = 7
const VOLUME_INPUT_SELECTOR = '#volumeInput'
const REPEAT_MODES: RepeatMode[] = ['NO_REPEAT', 'REPEAT_ALL', 'REPEAT_ONE']

export const playbackService = {
  player: null as Plyr | null,
  volumeInput: null as unknown as HTMLInputElement,
  repeatModes: REPEAT_MODES,
  initialized: false,

  init () {
    // We don't need to init this service twice, or the media events will be duplicated.
    if (this.initialized) {
      return
    }

    this.player = plyr.setup('.plyr', {
      controls: []
    })[0]

    this.volumeInput = document.querySelector<HTMLInputElement>(VOLUME_INPUT_SELECTOR)!
    this.listenToMediaEvents(this.player.media)

    if (isAudioContextSupported) {
      try {
        this.setVolume(preferences.volume)
      } catch (e) {
      }

      audioService.init(this.player.media)
      eventBus.emit('INIT_EQUALIZER')
    }

    this.setMediaSessionActionHandlers()

    this.listenToSocketEvents()
    this.initialized = true
  },

  listenToSocketEvents () {
    socketService.listen('SOCKET_TOGGLE_PLAYBACK', () => this.toggle())
      .listen('SOCKET_PLAY_NEXT', () => this.playNext())
      .listen('SOCKET_PLAY_PREV', () => this.playPrev())
      .listen('SOCKET_GET_STATUS', () => {
        const data = queueStore.current ? songStore.generateDataToBroadcast(queueStore.current) : {
          volume: this.volumeInput.value
        }
        socketService.broadcast('SOCKET_STATUS', data)
      })
      .listen('SOCKET_GET_CURRENT_SONG', () => {
        socketService.broadcast(
          'SOCKET_SONG',
          queueStore.current
            ? songStore.generateDataToBroadcast(queueStore.current)
            : { song: null }
        )
      })
      .listen('SOCKET_SET_VOLUME', ({ volume }: { volume: number }) => this.setVolume(volume))
  },

  setMediaSessionActionHandlers () {
    if (!navigator.mediaSession) {
      return
    }

    navigator.mediaSession.setActionHandler('play', () => this.resume())
    navigator.mediaSession.setActionHandler('pause', () => this.pause())
    navigator.mediaSession.setActionHandler('previoustrack', () => this.playPrev())
    navigator.mediaSession.setActionHandler('nexttrack', () => this.playNext())
  },

  listenToMediaEvents (mediaElement: HTMLMediaElement) {
    mediaElement.addEventListener('error', () => this.playNext(), true)

    mediaElement.addEventListener('ended', () => {
      if (commonStore.state.useLastfm && userStore.current.preferences.lastfm_session_key) {
        songStore.scrobble(queueStore.current!)
      }

      preferences.repeatMode === 'REPEAT_ONE' ? this.restart() : this.playNext()
    })

    let timeUpdateHandler = () => {
      const currentSong = queueStore.current!

      if (!currentSong.playCountRegistered && !this.isTranscoding) {
        // if we've passed 25% of the song, it's safe to say the song has been "played".
        // Refer to https://github.com/koel/koel/issues/1087
        if (!mediaElement.duration || mediaElement.currentTime * 4 >= mediaElement.duration) {
          this.registerPlay(currentSong)
        }
      }

      const nextSong = queueStore.next

      if (!nextSong || nextSong.preloaded || this.isTranscoding) {
        return
      }

      if (mediaElement.duration && mediaElement.currentTime + PRELOAD_BUFFER > mediaElement.duration) {
        this.preload(nextSong)
      }
    }

    if (process.env.NODE_ENV !== 'test') {
      timeUpdateHandler = throttle(timeUpdateHandler, 3000)
    }

    mediaElement.addEventListener('timeupdate', timeUpdateHandler)
  },

  get isTranscoding () {
    return isMobile.any && preferences.transcodeOnMobile
  },

  registerPlay (song: Song) {
    recentlyPlayedStore.add(song)
    songStore.registerPlay(song)
    recentlyPlayedStore.fetchAll()
    song.playCountRegistered = true
  },

  preload (song: Song) {
    const audioElement = document.createElement('audio')
    audioElement.setAttribute('src', songStore.getSourceUrl(song))
    audioElement.setAttribute('preload', 'auto')
    audioElement.load()
    song.preloaded = true
  },

  /**
   * Play a song. Because
   *
   * So many adventures couldn't happen today,
   * So many songs we forgot to play
   * So many dreams swinging out of the blue
   * We'll let them come true
   */
  async play (song?: Song) {
    if (!song) {
      return
    }

    document.title = `${song.title} ♫ Koel`
    this.player!.media.setAttribute('title', `${song.artist.name} - ${song.title}`)

    if (queueStore.current) {
      queueStore.current.playbackState = 'Stopped'
    }

    song.playbackState = 'Playing'
    queueStore.current = song

    // Manually set the `src` attribute of the audio to prevent plyr from resetting
    // the audio media object and cause our equalizer to malfunction.
    this.getPlayer().media.src = songStore.getSourceUrl(song)

    // We'll just "restart" playing the song, which will handle notification, scrobbling etc.
    // Fixes #898
    if (isAudioContextSupported) {
      await audioService.getContext().resume()
    }

    await this.restart()
  },

  showNotification (song: Song) {
    if (!window.Notification || !preferences.notify) {
      return
    }

    try {
      const notification = new window.Notification(`♫ ${song.title}`, {
        icon: song.album.cover,
        body: `${song.album.name} – ${song.artist.name}`
      })

      notification.onclick = () => window.focus()

      window.setTimeout(() => notification.close(), 5000)
    } catch (e) {
      // Notification fails.
      // @link https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerRegistration/showNotification
      console.error(e)
    }

    navigator.mediaSession.metadata = new MediaMetadata({
      title: song.title,
      artist: song.artist.name,
      album: song.album.name,
      artwork: [
        {
          src: song.album.cover,
          sizes: '256x256',
          type: 'image/png'
        }
      ]
    })
  },

  async restart () {
    const song = queueStore.current!

    this.showNotification(song)

    // Record the UNIX timestamp the song starts playing, for scrobbling purpose
    song.playStartTime = Math.floor(Date.now() / 1000)

    song.playCountRegistered = false

    eventBus.emit('SONG_STARTED', song)

    socketService.broadcast('SOCKET_SONG', songStore.generateDataToBroadcast(song))

    this.getPlayer().restart()

    try {
      await this.getPlayer().media.play()
    } catch (error) {
      // convert this into a warning, as an error will cause Cypress to fail the tests entirely
      console.warn(error)
    }
  },

  /**
   * The next song in the queue.
   * If we're in REPEAT_ALL mode and there's no next song, just get the first song.
   */
  get next () {
    if (queueStore.next) {
      return queueStore.next
    }

    if (preferences.repeatMode === 'REPEAT_ALL') {
      return queueStore.first
    }
  },

  /**
   * The previous song in the queue.
   * If we're in REPEAT_ALL mode and there's no prev song, get the last song.
   */
  get previous () {
    if (queueStore.previous) {
      return queueStore.previous
    }

    if (preferences.repeatMode === 'REPEAT_ALL') {
      return queueStore.last
    }
  },

  /**
   * Circle through the repeat mode.
   * The selected mode will be stored into local storage as well.
   */
  changeRepeatMode () {
    let index = this.repeatModes.indexOf(preferences.repeatMode) + 1

    if (index >= this.repeatModes.length) {
      index = 0
    }

    preferences.repeatMode = this.repeatModes[index]
  },

  /**
   * Play the prev song in the queue, if one is found.
   * If the prev song is not found and the current mode is NO_REPEAT, we stop completely.
   */
  async playPrev () {
    // If the song's duration is greater than 5 seconds and we've passed 5 seconds into it,
    // restart playing instead.
    if (this.getPlayer().media.currentTime > 5 && queueStore.current!.length > 5) {
      this.getPlayer().restart()

      return
    }

    if (!this.previous && preferences.repeatMode === 'NO_REPEAT') {
      this.stop()
    } else {
      await this.play(this.previous)
    }
  },

  /**
   * Play the next song in the queue, if one is found.
   * If the next song is not found and the current mode is NO_REPEAT, we stop completely.
   */
  async playNext () {
    if (!this.next && preferences.repeatMode === 'NO_REPEAT') {
      this.stop() //  Nothing lasts forever, even cold November rain.
    } else {
      await this.play(this.next)
    }
  },

  /**
   * @param {Number}     volume   0-10
   * @param {Boolean=true}   persist  Whether the volume should be saved into local storage
   */
  setVolume (volume: number, persist = true) {
    this.getPlayer().setVolume(volume)

    if (persist) {
      preferences.volume = volume
    }

    this.volumeInput.value = String(volume)
  },

  mute () {
    this.setVolume(0, false)
  },

  unmute () {
    preferences.volume = preferences.volume || DEFAULT_VOLUME_VALUE
    this.setVolume(preferences.volume)
  },

  stop () {
    document.title = 'Koel'
    this.getPlayer().pause()
    this.getPlayer().seek(0)

    if (queueStore.current) {
      queueStore.current.playbackState = 'Stopped'
    }

    socketService.broadcast('SOCKET_PLAYBACK_STOPPED')
  },

  pause () {
    this.getPlayer().pause()
    queueStore.current!.playbackState = 'Paused'
    socketService.broadcast('SOCKET_SONG', songStore.generateDataToBroadcast(queueStore.current!))
  },

  async resume () {
    try {
      await this.getPlayer().media.play()
    } catch (error) {
      console.error(error)
    }

    queueStore.current!.playbackState = 'Playing'
    eventBus.emit('SONG_STARTED', queueStore.current)
    socketService.broadcast('SOCKET_SONG', songStore.generateDataToBroadcast(queueStore.current!))
  },

  async toggle () {
    if (!queueStore.current) {
      await this.playFirstInQueue()
      return
    }

    if (queueStore.current.playbackState !== 'Playing') {
      await this.resume()
      return
    }

    this.pause()
  },

  /**
   * Queue up songs (replace them into the queue) and start playing right away.
   *
   * @param {?Song[]} songs  An array of song objects. Defaults to all songs if null.
   * @param {Boolean=false}   shuffled Whether to shuffle the songs before playing.
   */
  async queueAndPlay (songs?: Song[], shuffled = false) {
    if (!songs) {
      songs = shuffle(songStore.all)
    }

    if (!songs.length) {
      return
    }

    if (shuffled) {
      songs = shuffle(songs)
    }

    queueStore.replaceQueueWith(songs)

    // Wait for the DOM to complete updating and play the first song in the queue.
    await nextTick()
    router.go('queue')
    await this.play(queueStore.first)
  },

  async shuffleLibrary () {
    await this.queueAndPlay(songStore.all, true)
  },

  getPlayer () {
    return this.player!
  },

  /**
   * Play the first song in the queue.
   * If the current queue is empty, try creating it by shuffling all songs.
   */
  async playFirstInQueue () {
    queueStore.all.length ? await this.play(queueStore.first) : await this.shuffleLibrary()
  },

  async playAllByArtist (artist: Artist, shuffled = true) {
    shuffled
      ? await this.queueAndPlay(artist.songs, true /* shuffled */)
      : await this.queueAndPlay(orderBy(artist.songs, ['album_id', 'disc', 'track']))
  },

  async playAllInAlbum (album: Album, shuffled = true) {
    shuffled
      ? await this.queueAndPlay(album.songs, true /* shuffled */)
      : await this.queueAndPlay(orderBy(album.songs, ['disc', 'track']))
  }
}