import Vue from 'vue'
import slugify from 'slugify'
import { without, map, take, remove, orderBy, each, union } from 'lodash'

import { secondsToHis, alerts } from '../utils'
import { http, ls } from '../services'
import { sharedStore, favoriteStore, albumStore, artistStore } from '.'
import stub from '../stubs/song'

export const songStore = {
  stub,
  albums: [],
  cache: {},

  state: {
    /**
     * All songs in the store
     *
     * @type {Array}
     */
    songs: [stub],

    /**
     * The recently played songs **in the current session**
     *
     * @type {Array}
     */
    recent: []
  },

  /**
   * Init the store.
   *
   * @param  {Array.<Object>} albums The array of albums to extract our songs from
   */
  init (albums) {
    // Iterate through the albums. With each, add its songs into our master song list.
    // While doing so, we populate some other information into the songs as well.
    this.all = albums.reduce((songs, album) => {
      each(album.songs, song => {
        this.setupSong(song, album)
      })

      return songs.concat(album.songs)
    }, [])
  },

  setupSong (song, album) {
    song.fmtLength = secondsToHis(song.length)

    // Manually set these additional properties to be reactive
    Vue.set(song, 'playCount', 0)
    Vue.set(song, 'album', album)
    Vue.set(song, 'liked', false)
    Vue.set(song, 'lyrics', null)
    Vue.set(song, 'playbackState', 'stopped')

    if (song.contributing_artist_id) {
      const artist = artistStore.byId(song.contributing_artist_id)
      artist.albums = union(artist.albums, [album])
      artistStore.setupArtist(artist)
      Vue.set(song, 'artist', artist)
    } else {
      Vue.set(song, 'artist', artistStore.byId(song.album.artist.id))
    }

    // Cache the song, so that byId() is faster
    this.cache[song.id] = song
  },

  /**
   * Initializes the interaction (like/play count) information.
   *
   * @param  {Array.<Object>} interactions The array of interactions of the current user
   */
  initInteractions (interactions) {
    favoriteStore.clear()

    each(interactions, interaction => {
      const song = this.byId(interaction.song_id)

      if (!song) {
        return
      }

      song.liked = interaction.liked
      song.playCount = interaction.play_count
      song.album.playCount += song.playCount
      song.artist.playCount += song.playCount

      if (song.liked) {
        favoriteStore.add(song)
      }
    })
  },

  /**
   * Get the total duration of some songs.
   *
   * @param {Array.<Object>}  songs
   * @param {Boolean}     toHis Whether to convert the duration into H:i:s format
   *
   * @return {Float|String}
   */
  getLength (songs, toHis) {
    const duration = songs.reduce((length, song) => length + song.length, 0)

    return toHis ? secondsToHis(duration) : duration
  },

  /**
   * Get all songs.
   *
   * @return {Array.<Object>}
   */
  get all () {
    return this.state.songs
  },

  /**
   * Set all songs.
   *
   * @param  {Array.<Object>} value
   */
  set all (value) {
    this.state.songs = value
  },

  /**
   * Get a song by its ID.
   *
   * @param  {String} id
   *
   * @return {Object}
   */
  byId (id) {
    return this.cache[id]
  },

  /**
   * Get songs by their IDs.
   *
   * @param  {Array.<String>} ids
   *
   * @return {Array.<Object>}
   */
  byIds (ids) {
    return ids.map(id => this.byId(id))
  },

  /**
   * Guess a song by its title and album.
   * Forget about Levenshtein distance, this implementation is good enough.
   *
   * @param  {string} title
   * @param  {Object} album
   *
   * @return {Object|false}
   */
  guess (title, album) {
    title = slugify(title.toLowerCase())
    let found = false
    album.songs.forEach(song => {
      if (slugify(song.title.toLowerCase()) === title) {
        found = song
      }
    })

    return found
  },

  /**
   * Increase a play count for a song.
   *
   * @param {Object} song
   */
  registerPlay (song) {
    return new Promise((resolve, reject) => {
      const oldCount = song.playCount

      http.post('interaction/play', { song: song.id }, data => {
        // Use the data from the server to make sure we don't miss a play from another device.
        song.playCount = data.play_count
        song.album.playCount += song.playCount - oldCount
        song.artist.playCount += song.playCount - oldCount

        resolve(data)
      }, r => reject(r))
    })
  },

  /**
   * Add a song into the "recently played" list.
   *
   * @param {Object}
   */
  addRecent (song) {
    // First we make sure that there's no duplicate.
    this.state.recent = without(this.state.recent, song)

    // Then we prepend the song into the list.
    this.state.recent.unshift(song)
  },

  /**
   * Scrobble a song (using Last.fm).
   *
   * @param  {Object}   song
   */
  scrobble (song) {
    return new Promise((resolve, reject) => {
      http.post(`${song.id}/scrobble/${song.playStartTime}`, {}, data => resolve(data), r => reject(r))
    })
  },

  /**
   * Update song data.
   *
   * @param  {Array.<Object>} songs   An array of song
   * @param  {Object}     data
   */
  update (songs, data) {
    return new Promise((resolve, reject) => {
      http.put('songs', {
        data,
        songs: map(songs, 'id')
      }, songs => {
        each(songs, song => this.syncUpdatedSong(song))
        alerts.success(`Updated ${songs.length} song${songs.length === 1 ? '' : 's'}.`)
        resolve(songs)
      }, r => reject(r))
    })
  },

  /**
   * Sync an updated song into our current library.
   *
   * This is one of the most ugly functions I've written, if not the worst itself.
   * Sorry, future me.
   * Sorry guys.
   * Forgive me.
   *
   * @param  {Object} updatedSong The updated song, with albums and whatnot.
   *
   * @return {?Object}       The updated song.
   */
  syncUpdatedSong (updatedSong) {
    // Cases:
    // 1. Album doesn't change (and then, artist doesn't either)
    // 2. Album changes (note that a new album might have been created) and
    //    2.a. Artist remains the same.
    //    2.b. Artist changes as well. Note that an artist might have been created.

    // Find the original song,
    const originalSong = this.byId(updatedSong.id)

    if (!originalSong) {
      return
    }

    // and keep track of original album/artist.
    const originalAlbumId = originalSong.album.id
    const originalArtistId = originalSong.artist.id

    // First, we update the title, lyrics, and track #
    originalSong.title = updatedSong.title
    originalSong.lyrics = updatedSong.lyrics
    originalSong.track = updatedSong.track

    if (updatedSong.album.id === originalAlbumId) { // case 1
      // Nothing to do
    } else { // case 2
      // First, remove it from its old album
      albumStore.removeSongsFromAlbum(originalSong.album, originalSong)

      const existingAlbum = albumStore.byId(updatedSong.album.id)
      const newAlbumCreated = !existingAlbum

      if (!newAlbumCreated) {
        // The song changed to an existing album. We now add it to such album.
        albumStore.addSongsIntoAlbum(existingAlbum, originalSong)
      } else {
        // A new album was created. We:
        // - Add the new album into our collection
        // - Add the song into it
        albumStore.addSongsIntoAlbum(updatedSong.album, originalSong)
        albumStore.add(updatedSong.album)
      }

      if (updatedSong.album.artist.id === originalArtistId) { // case 2.a
        // Same artist, but what if the album is new?
        if (newAlbumCreated) {
          artistStore.addAlbumsIntoArtist(artistStore.byId(originalArtistId), updatedSong.album)
        }
      } else { // case 2.b
        // The artist changes.
        const existingArtist = artistStore.byId(updatedSong.album.artist.id)

        if (existingArtist) {
          originalSong.artist = existingArtist
        } else {
          // New artist created. We:
          // - Add the album into it, because now it MUST BE a new album
          // (there's no "new artist with existing album" in our system).
          // - Add the new artist into our collection
          artistStore.addAlbumsIntoArtist(updatedSong.album.artist, updatedSong.album)
          artistStore.add(updatedSong.album.artist)
          originalSong.artist = updatedSong.album.artist
        }
      }

      // As a last step, we purify our library of empty albums/artists.
      if (albumStore.isAlbumEmpty(albumStore.byId(originalAlbumId))) {
        albumStore.remove(albumStore.byId(originalAlbumId))
      }

      if (artistStore.isArtistEmpty(artistStore.byId(originalArtistId))) {
        artistStore.remove(artistStore.byId(originalArtistId))
      }

      // Now we make sure the next call to info() get the refreshed, correct info.
      originalSong.infoRetrieved = false
    }

    return originalSong
  },

  /**
   * Get a song's playable source URL.
   *
   * @param  {Object} song
   *
   * @return {string} The source URL, with JWT token appended.
   */
  getSourceUrl (song) {
    return `${sharedStore.state.cdnUrl}api/${song.id}/play?jwt-token=${ls.get('jwt-token')}`
  },

  /**
   * Get a song's shareable URL.
   * Visiting this URL will automatically queue the song and play it.
   *
   * @param  {Object} song
   *
   * @return {string}
   */
  getShareableUrl (song) {
    return `${window.location.origin}/#!/song/${song.id}`
  },

  /**
   * Get the last n recently played songs.
   *
   * @param  {Number} n
   *
   * @return {Array.<Object>}
   */
  getRecent (n = 10) {
    return take(this.state.recent, n)
  },

  /**
   * Get top n most-played songs.
   *
   * @param  {Number} n
   *
   * @return {Array.<Object>}
   */
  getMostPlayed (n = 10) {
    const songs = take(orderBy(this.all, 'playCount', 'desc'), n)

    // Remove those with playCount=0
    remove(songs, song => !song.playCount)

    return songs
  },

  /**
   * Get n most recently added songs.
   * @param  {Number} n
   * @return {Array.<Object>}
   */
  getRecentlyAdded (n = 10) {
    return take(orderBy(this.all, 'created_at', 'desc'), n)
  },

  /**
   * Called when the application is torn down.
   * Reset stuff.
   */
  teardown () {
    this.state.recent = []
  }
}