/**
 * @file master-playlist-controller.js
 */
import PlaylistLoader from './playlist-loader';
import SegmentLoader from './segment-loader';
import Ranges from './ranges';
import videojs from 'video.js';
import HlsAudioTrack from './hls-audio-track';

// 5 minute blacklist
const BLACKLIST_DURATION = 5 * 60 * 1000;
let Hls;

const parseCodecs = function(codecs) {
  let result = {
    codecCount: 0,
    videoCodec: null,
    audioProfile: null
  };

  result.codecCount = codecs.split(',').length;
  result.codecCount = result.codecCount || 2;

  // parse the video codec but ignore the version
  result.videoCodec = (/(^|\s|,)+(avc1)[^ ,]*/i).exec(codecs);
  result.videoCodec = result.videoCodec && result.videoCodec[2];

  // parse the last field of the audio codec
  result.audioProfile = (/(^|\s|,)+mp4a.\d+\.(\d+)/i).exec(codecs);
  result.audioProfile = result.audioProfile && result.audioProfile[2];

  return result;
};

/**
 * the master playlist controller controller all interactons
 * between playlists and segmentloaders. At this time this mainly
 * involves a master playlist and a series of audio playlists
 * if they are available
 *
 * @class MasterPlaylistController
 * @extends videojs.EventTarget
 */
export default class MasterPlaylistController extends videojs.EventTarget {
  constructor({
    url,
    withCredentials,
    mode,
    tech,
    bandwidth,
    externHls
  }) {
    super();

    Hls = externHls;

    this.withCredentials = withCredentials;
    this.tech_ = tech;
    this.hls_ = tech.hls;
    this.mode_ = mode;
    this.audioTracks_ = [];

    this.mediaSource = new videojs.MediaSource({ mode });
    this.mediaSource.on('audioinfo', (e) => this.trigger(e));
    // load the media source into the player
    this.mediaSource.addEventListener('sourceopen', this.handleSourceOpen_.bind(this));

    let segmentLoaderOptions = {
      hls: this.hls_,
      mediaSource: this.mediaSource,
      currentTime: this.tech_.currentTime.bind(this.tech_),
      withCredentials: this.withCredentials,
      seekable: () => this.seekable(),
      seeking: () => this.tech_.seeking(),
      setCurrentTime: (a) => this.setCurrentTime(a),
      hasPlayed: () => this.tech_.played().length !== 0,
      bandwidth
    };

    // combined audio/video or just video when alternate audio track is selected
    this.mainSegmentLoader_ = new SegmentLoader(segmentLoaderOptions);
    // alternate audio track
    this.audioSegmentLoader_ = new SegmentLoader(segmentLoaderOptions);

    if (!url) {
      throw new Error('A non-empty playlist URL is required');
    }

    this.masterPlaylistLoader_ = new PlaylistLoader(url, this.hls_, this.withCredentials);

    this.masterPlaylistLoader_.on('loadedmetadata', () => {
      let media = this.masterPlaylistLoader_.media();

      // if this isn't a live video and preload permits, start
      // downloading segments
      if (media.endList && this.tech_.preload() !== 'none') {
        this.mainSegmentLoader_.playlist(media);
        this.mainSegmentLoader_.expired(this.masterPlaylistLoader_.expired_);
        this.mainSegmentLoader_.load();
      }

      this.setupSourceBuffer_();
      this.setupFirstPlay();
      this.useAudio();
    });

    this.masterPlaylistLoader_.on('loadedplaylist', () => {
      let updatedPlaylist = this.masterPlaylistLoader_.media();
      let seekable;

      if (!updatedPlaylist) {
        // select the initial variant
        this.initialMedia_ = this.selectPlaylist();
        this.masterPlaylistLoader_.media(this.initialMedia_);
        this.fillAudioTracks_();

        this.trigger('selectedinitialmedia');
        return;
      }

      this.mainSegmentLoader_.playlist(updatedPlaylist);
      this.mainSegmentLoader_.expired(this.masterPlaylistLoader_.expired_);
      this.updateDuration();

      // update seekable
      seekable = this.seekable();
      if (!updatedPlaylist.endList && seekable.length !== 0) {
        this.mediaSource.addSeekableRange_(seekable.start(0), seekable.end(0));
      }
    });

    this.masterPlaylistLoader_.on('error', () => {
      this.blacklistCurrentPlaylist(this.masterPlaylistLoader_.error);
    });

    this.masterPlaylistLoader_.on('mediachanging', () => {
      this.mainSegmentLoader_.pause();
    });

    this.masterPlaylistLoader_.on('mediachange', () => {
      this.mainSegmentLoader_.abort();
      this.mainSegmentLoader_.load();
      this.tech_.trigger({
        type: 'mediachange',
        bubbles: true
      });
    });

    this.mainSegmentLoader_.on('progress', () => {
      // figure out what stream the next segment should be downloaded from
      // with the updated bandwidth information
      this.masterPlaylistLoader_.media(this.selectPlaylist());

      this.trigger('progress');
    });

    this.mainSegmentLoader_.on('error', () => {
      this.blacklistCurrentPlaylist(this.mainSegmentLoader_.error());
    });

    this.audioSegmentLoader_.on('error', () => {
      videojs.log.warn('Problem encountered with the current alternate audio track' +
                       '. Switching back to default.');
      this.audioSegmentLoader_.abort();
      this.audioPlaylistLoader_ = null;
      this.useAudio();
    });

    this.masterPlaylistLoader_.load();
  }

  /**
   * fill our internal list of HlsAudioTracks with data from
   * the master playlist or use a default
   *
   * @private
   */
  fillAudioTracks_() {
    let master = this.master();
    let mediaGroups = master.mediaGroups || {};

    // force a default if we have none or we are not
    // in html5 mode (the only mode to support more than one
    // audio track)
    if (!mediaGroups ||
        !mediaGroups.AUDIO ||
        Object.keys(mediaGroups.AUDIO).length === 0 ||
        this.mode_ !== 'html5') {
      // "main" audio group, track name "default"
      mediaGroups.AUDIO = {main: {default: {default: true }}};
    }

    let tracks = {};

    for (let mediaGroup in mediaGroups.AUDIO) {
      for (let label in mediaGroups.AUDIO[mediaGroup]) {
        let properties = mediaGroups.AUDIO[mediaGroup][label];

        // if the track already exists add a new "location"
        // since tracks in different mediaGroups are actually the same
        // track with different locations to download them from
        if (tracks[label]) {
          tracks[label].addLoader(mediaGroup, properties.resolvedUri);
          continue;
        }

        let track = new HlsAudioTrack(videojs.mergeOptions(properties, {
          hls: this.hls_,
          withCredentials: this.withCredential,
          mediaGroup,
          label
        }));

        tracks[label] = track;
        this.audioTracks_.push(track);
      }
    }
  }

  /**
   * Call load on our SegmentLoaders
   */
  load() {
    this.mainSegmentLoader_.load();
    if (this.audioPlaylistLoader_) {
      this.audioSegmentLoader_.load();
    }
  }

  /**
   * Get the current active Media Group for Audio
   * given the selected playlist and its attributes
   */
  activeAudioGroup() {
    let media = this.masterPlaylistLoader_.media();
    let mediaGroup = 'main';

    if (media && media.attributes && media.attributes.AUDIO) {
      mediaGroup = media.attributes.AUDIO;
    }

    return mediaGroup;
  }

  /**
   * Use any audio track that we have, and start to load it
   */
  useAudio() {
    let track;

    this.audioTracks_.forEach((t) => {
      if (!track && t.enabled) {
        track = t;
      }
    });

    // called too early or no track is enabled
    if (!track) {
      return;
    }

    // Pause any alternative audio
    if (this.audioPlaylistLoader_) {
      this.audioPlaylistLoader_.pause();
      this.audioPlaylistLoader_ = null;
      this.audioSegmentLoader_.pause();
    }

    // If the audio track for the active audio group has
    // a playlist loader than it is an alterative audio track
    // otherwise it is a part of the mainSegmenLoader
    let loader = track.getLoader(this.activeAudioGroup());

    if (!loader) {
      this.mainSegmentLoader_.clearBuffer();
      return;
    }

    // TODO: it may be better to create the playlist loader here
    // when we can change an audioPlaylistLoaders src
    this.audioPlaylistLoader_ = loader;

    if (this.audioPlaylistLoader_.started) {
      this.audioPlaylistLoader_.load();
      this.audioSegmentLoader_.load();
      this.audioSegmentLoader_.clearBuffer();
      return;
    }

    this.audioPlaylistLoader_.on('loadedmetadata', () => {
      /* eslint-disable no-shadow */
      let media = this.audioPlaylistLoader_.media();
      /* eslint-enable no-shadow */

      this.audioSegmentLoader_.playlist(media);
      this.addMimeType_(this.audioSegmentLoader_, 'mp4a.40.2', media);

      // if the video is already playing, or if this isn't a live video and preload
      // permits, start downloading segments
      if (!this.tech_.paused() ||
          (media.endList && this.tech_.preload() !== 'none')) {
        this.audioSegmentLoader_.load();
      }

      if (!media.endList) {
        // trigger the playlist loader to start "expired time"-tracking
        this.audioPlaylistLoader_.trigger('firstplay');
      }
    });

    this.audioPlaylistLoader_.on('loadedplaylist', () => {
      let updatedPlaylist;

      if (this.audioPlaylistLoader_) {
        updatedPlaylist = this.audioPlaylistLoader_.media();
      }

      if (!updatedPlaylist) {
        // only one playlist to select
        this.audioPlaylistLoader_.media(
          this.audioPlaylistLoader_.playlists.master.playlists[0]);
        return;
      }

      this.audioSegmentLoader_.playlist(updatedPlaylist);
    });

    this.audioPlaylistLoader_.on('error', () => {
      videojs.log.warn('Problem encountered loading the alternate audio track' +
                       '. Switching back to default.');
      this.audioSegmentLoader_.abort();
      this.audioPlaylistLoader_ = null;
      this.useAudio();
    });

    this.audioSegmentLoader_.clearBuffer();
    this.audioPlaylistLoader_.start();
  }

  /**
   * Re-tune playback quality level for the current player
   * conditions. This method may perform destructive actions, like
   * removing already buffered content, to readjust the currently
   * active playlist quickly.
   *
   * @private
   */
  fastQualityChange_() {
    let media = this.selectPlaylist();

    if (media !== this.masterPlaylistLoader_.media()) {
      this.masterPlaylistLoader_.media(media);
      this.mainSegmentLoader_.sourceUpdater_.remove(this.tech_.currentTime() + 5, Infinity);
    }
  }

  /**
   * Begin playback.
   */
  play() {
    if (this.setupFirstPlay()) {
      return;
    }

    if (this.tech_.ended()) {
      this.tech_.setCurrentTime(0);
    }

    this.load();

    // if the viewer has paused and we fell out of the live window,
    // seek forward to the earliest available position
    if (this.tech_.duration() === Infinity) {
      if (this.tech_.currentTime() < this.tech_.seekable().start(0)) {
        return this.tech_.setCurrentTime(this.tech_.seekable().start(0));
      }
    }

  }

  /**
   * Seek to the latest media position if this is a live video and the
   * player and video are loaded and initialized.
   */
  setupFirstPlay() {
    let seekable;
    let media = this.masterPlaylistLoader_.media();

    // check that everything is ready to begin buffering
    // 1) the active media playlist is available
    if (media &&
        // 2) the video is a live stream
        !media.endList &&

        // 3) the player is not paused
        !this.tech_.paused() &&

        // 4) the player has not started playing
        !this.hasPlayed_) {

      this.load();

      // trigger the playlist loader to start "expired time"-tracking
      this.masterPlaylistLoader_.trigger('firstplay');
      this.hasPlayed_ = true;

      // seek to the latest media position for live videos
      seekable = this.seekable();
      if (seekable.length) {
        this.tech_.setCurrentTime(seekable.end(0));
      }

      return true;
    }
    return false;
  }

  /**
   * handle the sourceopen event on the MediaSource
   *
   * @private
   */
  handleSourceOpen_() {
    // Only attempt to create the source buffer if none already exist.
    // handleSourceOpen is also called when we are "re-opening" a source buffer
    // after `endOfStream` has been called (in response to a seek for instance)
    this.setupSourceBuffer_();

    // if autoplay is enabled, begin playback. This is duplicative of
    // code in video.js but is required because play() must be invoked
    // *after* the media source has opened.
    if (this.tech_.autoplay()) {
      this.tech_.play();
    }

    this.trigger('sourceopen');
  }

  /**
   * Blacklists a playlist when an error occurs for a set amount of time
   * making it unavailable for selection by the rendition selection algorithm
   * and then forces a new playlist (rendition) selection.
   *
   * @param {Object=} error an optional error that may include the playlist
   * to blacklist
   */
  blacklistCurrentPlaylist(error = {}) {
    let currentPlaylist;
    let nextPlaylist;

    // If the `error` was generated by the playlist loader, it will contain
    // the playlist we were trying to load (but failed) and that should be
    // blacklisted instead of the currently selected playlist which is likely
    // out-of-date in this scenario
    currentPlaylist = error.playlist || this.masterPlaylistLoader_.media();

    // If there is no current playlist, then an error occurred while we were
    // trying to load the master OR while we were disposing of the tech
    if (!currentPlaylist) {
      this.error = error;
      return this.mediaSource.endOfStream('network');
    }

    // Blacklist this playlist
    currentPlaylist.excludeUntil = Date.now() + BLACKLIST_DURATION;

    // Select a new playlist
    nextPlaylist = this.selectPlaylist();

    if (nextPlaylist) {
      videojs.log.warn('Problem encountered with the current ' +
                       'HLS playlist. Switching to another playlist.');

      return this.masterPlaylistLoader_.media(nextPlaylist);
    }
    videojs.log.warn('Problem encountered with the current ' +
                     'HLS playlist. No suitable alternatives found.');
    // We have no more playlists we can select so we must fail
    this.error = error;
    return this.mediaSource.endOfStream('network');
  }

  /**
   * Pause all segment loaders
   */
  pauseLoading() {
    this.mainSegmentLoader_.pause();
    if (this.audioPlaylistLoader_) {
      this.audioSegmentLoader_.pause();
    }
  }

  /**
   * set the current time on all segment loaders
   *
   * @param {TimeRange} currentTime the current time to set
   * @return {TimeRange} the current time
   */
  setCurrentTime(currentTime) {
    let buffered = Ranges.findRange(this.tech_.buffered(), currentTime);

    if (!(this.masterPlaylistLoader_ && this.masterPlaylistLoader_.media())) {
      // return immediately if the metadata is not ready yet
      return 0;
    }

    // it's clearly an edge-case but don't thrown an error if asked to
    // seek within an empty playlist
    if (!this.masterPlaylistLoader_.media().segments) {
      return 0;
    }

    // if the seek location is already buffered, continue buffering as
    // usual
    if (buffered && buffered.length) {
      return currentTime;
    }

    // cancel outstanding requests so we begin buffering at the new
    // location
    this.mainSegmentLoader_.abort();
    if (this.audioPlaylistLoader_) {
      this.audioSegmentLoader_.abort();
    }

    if (!this.tech_.paused()) {
      this.mainSegmentLoader_.load();
      if (this.audioPlaylistLoader_) {
        this.audioSegmentLoader_.load();
      }
    }
  }

  /**
   * get the current duration
   *
   * @return {TimeRange} the duration
   */
  duration() {
    if (!this.masterPlaylistLoader_) {
      return 0;
    }

    if (this.mediaSource) {
      return this.mediaSource.duration;
    }

    return Hls.Playlist.duration(this.masterPlaylistLoader_.media());
  }

  /**
   * check the seekable range
   *
   * @return {TimeRange} the seekable range
   */
  seekable() {
    let media;
    let mainSeekable;
    let audioSeekable;

    if (!this.masterPlaylistLoader_) {
      return videojs.createTimeRanges();
    }
    media = this.masterPlaylistLoader_.media();
    if (!media) {
      return videojs.createTimeRanges();
    }

    mainSeekable = Hls.Playlist.seekable(media,
                                         this.masterPlaylistLoader_.expired_);
    if (mainSeekable.length === 0) {
      return mainSeekable;
    }

    if (this.audioPlaylistLoader_) {
      audioSeekable = Hls.Playlist.seekable(this.audioPlaylistLoader_.media(),
                                            this.audioPlaylistLoader_.expired_);
      if (audioSeekable.length === 0) {
        return audioSeekable;
      }
    }

    if (!audioSeekable) {
      // seekable has been calculated based on buffering video data so it
      // can be returned directly
      return mainSeekable;
    }

    return videojs.createTimeRanges([[
      (audioSeekable.start(0) > mainSeekable.start(0)) ? audioSeekable.start(0) :
                                                         mainSeekable.start(0),
      (audioSeekable.end(0) < mainSeekable.end(0)) ? audioSeekable.end(0) :
                                                     mainSeekable.end(0)
    ]]);
  }

  /**
   * Update the player duration
   */
  updateDuration() {
    let oldDuration = this.mediaSource.duration;
    let newDuration = Hls.Playlist.duration(this.masterPlaylistLoader_.media());
    let buffered = this.tech_.buffered();
    let setDuration = () => {
      this.mediaSource.duration = newDuration;
      this.tech_.trigger('durationchange');

      this.mediaSource.removeEventListener('sourceopen', setDuration);
    };

    if (buffered.length > 0) {
      newDuration = Math.max(newDuration, buffered.end(buffered.length - 1));
    }

    // if the duration has changed, invalidate the cached value
    if (oldDuration !== newDuration) {
      // update the duration
      if (this.mediaSource.readyState !== 'open') {
        this.mediaSource.addEventListener('sourceopen', setDuration);
      } else {
        setDuration();
      }
    }
  }

  /**
   * dispose of the MasterPlaylistController and everything
   * that it controls
   */
  dispose() {
    this.masterPlaylistLoader_.dispose();
    this.audioTracks_.forEach((track) => {
      track.dispose();
    });
    this.audioTracks_.length = 0;
    this.mainSegmentLoader_.dispose();
    this.audioSegmentLoader_.dispose();
  }

  /**
   * return the master playlist object if we have one
   *
   * @return {Object} the master playlist object that we parsed
   */
  master() {
    return this.masterPlaylistLoader_.master;
  }

  /**
   * return the currently selected playlist
   *
   * @return {Object} the currently selected playlist object that we parsed
   */
  media() {
    // playlist loader will not return media if it has not been fully loaded
    return this.masterPlaylistLoader_.media() || this.initialMedia_;
  }

  /**
   * setup our internal source buffers on our segment Loaders
   *
   * @private
   */
  setupSourceBuffer_() {
    let media = this.masterPlaylistLoader_.media();

    // wait until a media playlist is available and the Media Source is
    // attached
    if (!media || this.mediaSource.readyState !== 'open') {
      return;
    }

    this.addMimeType_(this.mainSegmentLoader_, 'avc1.4d400d, mp4a.40.2', media);

    // exclude any incompatible variant streams from future playlist
    // selection
    this.excludeIncompatibleVariants_(media);
  }

  /**
   * add a time type to a segmentLoader
   *
   * @param {SegmentLoader} segmentLoader the segmentloader to work on
   * @param {String} codecs to use by default
   * @param {Object} the parsed media object
   * @private
   */
  addMimeType_(segmentLoader, defaultCodecs, media) {
    let mimeType = 'video/mp2t';

    // if the codecs were explicitly specified, pass them along to the
    // source buffer
    if (media.attributes && media.attributes.CODECS) {
      mimeType += '; codecs="' + media.attributes.CODECS + '"';
    } else {
      mimeType += '; codecs="' + defaultCodecs + '"';
    }
    segmentLoader.mimeType(mimeType);
  }

  /**
   * Blacklist playlists that are known to be codec or
   * stream-incompatible with the SourceBuffer configuration. For
   * instance, Media Source Extensions would cause the video element to
   * stall waiting for video data if you switched from a variant with
   * video and audio to an audio-only one.
   *
   * @param {Object} media a media playlist compatible with the current
   * set of SourceBuffers. Variants in the current master playlist that
   * do not appear to have compatible codec or stream configurations
   * will be excluded from the default playlist selection algorithm
   * indefinitely.
   * @private
   */
  excludeIncompatibleVariants_(media) {
    let master = this.masterPlaylistLoader_.master;
    let codecCount = 2;
    let videoCodec = null;
    let audioProfile = null;
    let codecs;

    if (media.attributes && media.attributes.CODECS) {
      codecs = parseCodecs(media.attributes.CODECS);
      videoCodec = codecs.videoCodec;
      audioProfile = codecs.audioProfile;
      codecCount = codecs.codecCount;
    }
    master.playlists.forEach(function(variant) {
      let variantCodecs = {
        codecCount: 2,
        videoCodec: null,
        audioProfile: null
      };

      if (variant.attributes && variant.attributes.CODECS) {
        variantCodecs = parseCodecs(variant.attributes.CODECS);
      }

      // if the streams differ in the presence or absence of audio or
      // video, they are incompatible
      if (variantCodecs.codecCount !== codecCount) {
        variant.excludeUntil = Infinity;
      }

      // if h.264 is specified on the current playlist, some flavor of
      // it must be specified on all compatible variants
      if (variantCodecs.videoCodec !== videoCodec) {
        variant.excludeUntil = Infinity;
      }
      // HE-AAC ("mp4a.40.5") is incompatible with all other versions of
      // AAC audio in Chrome 46. Don't mix the two.
      if ((variantCodecs.audioProfile === '5' && audioProfile !== '5') ||
          (audioProfile === '5' && variantCodecs.audioProfile !== '5')) {
        variant.excludeUntil = Infinity;
      }
    });
  }
}