# All files / src/loader playlist-loader.ts

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     /**
     * PlaylistLoader - delegate for media manifest/playlist loading tasks. Takes care of parsing media to internal data-models.
     *
     * Once loaded, dispatches events with parsed data-models of manifest/levels/audio/subtitle tracks.
     *
     * Uses loader(s) set in config to do actual internal loading of resource tasks.
     *
     * @module
     *
     */

    import Event from '../events';
    import EventHandler from '../event-handler';
    import { ErrorTypes, ErrorDetails } from '../errors';
    import { logger } from '../utils/logger';
    import { Loader, PlaylistContextType, PlaylistLoaderContext, PlaylistLevelType, LoaderCallbacks, LoaderResponse, LoaderStats, LoaderConfiguration } from '../types/loader';
    import MP4Demuxer from '../demux/mp4demuxer';
    import M3U8Parser from './m3u8-parser';

    const { performance } = window;

    /**
     * @constructor
     */
    class PlaylistLoader extends EventHandler {
      private loaders: Partial<Record<PlaylistContextType, Loader<PlaylistLoaderContext>>> = {};

      /**
       * @constructs
       * @param {Hls} hls
       */
      constructor (hls) {
        super(hls,
          Event.MANIFEST_LOADING,
          Event.LEVEL_LOADING,
          Event.AUDIO_TRACK_LOADING,
          Event.SUBTITLE_TRACK_LOADING);
      }

      /**
       * @param {PlaylistContextType} type
       * @returns {boolean}
       */
      static canHaveQualityLevels (type: PlaylistContextType): boolean {
        return (type !== PlaylistContextType.AUDIO_TRACK &&
          type !== PlaylistContextType.SUBTITLE_TRACK);
      }

      /**
       * Map context.type to LevelType
       * @param {PlaylistLoaderContext} context
       * @returns {LevelType}
       */
      static mapContextToLevelType (context: PlaylistLoaderContext): PlaylistLevelType {
        const { type } = context;

        switch (type) {
        case PlaylistContextType.AUDIO_TRACK:
          return PlaylistLevelType.AUDIO;
        case PlaylistContextType.SUBTITLE_TRACK:
          return PlaylistLevelType.SUBTITLE;
        default:
          return PlaylistLevelType.MAIN;
        }
      }

      static getResponseUrl (response: LoaderResponse, context: PlaylistLoaderContext): string {
        let url = response.url;
        // responseURL not supported on some browsers (it is used to detect URL redirection)
        // data-uri mode also not supported (but no need to detect redirection)
        if (url === undefined || url.indexOf('data:') === 0) {
          // fallback to initial URL
          url = context.url;
        }
        return url;
      }

      /**
       * Returns defaults or configured loader-type overloads (pLoader and loader config params)
       * Default loader is XHRLoader (see utils)
       * @param {PlaylistLoaderContext} context
       * @returns {Loader} or other compatible configured overload
       */
      createInternalLoader (context: PlaylistLoaderContext): Loader<PlaylistLoaderContext> {
        const config = this.hls.config;
        const PLoader = config.pLoader;
        const Loader = config.loader;
        // TODO(typescript-config): Verify once config is typed that InternalLoader always returns a Loader
        const InternalLoader = PLoader || Loader;

        const loader = new InternalLoader(config);

        // TODO - Do we really need to assign the instance or if the dep has been lost
        context.loader = loader;
        this.loaders[context.type] = loader;

        return loader;
      }

      getInternalLoader (context: PlaylistLoaderContext): Loader<PlaylistLoaderContext> | undefined {
        return this.loaders[context.type];
      }

      resetInternalLoader (contextType: PlaylistContextType) {
        Eif (this.loaders[contextType]) {
          delete this.loaders[contextType];
        }
      }

      /**
       * Call `destroy` on all internal loader instances mapped (one per context type)
       */
      destroyInternalLoaders () {
        for (let contextType in this.loaders) {
          let loader = this.loaders[contextType];
          Eif (loader) {
            loader.destroy();
          }

          this.resetInternalLoader(contextType as PlaylistContextType);
        }
      }

      destroy () {
        this.destroyInternalLoaders();

        super.destroy();
      }

      onManifestLoading (data: { url: string; }) {
        this.load({
          url: data.url,
          type: PlaylistContextType.MANIFEST,
          level: 0,
          id: null,
          responseType: 'text'
        });
      }

      onLevelLoading (data: { url: string; level: number | null; id: number | null; }) {
        this.load({
          url: data.url,
          type: PlaylistContextType.LEVEL,
          level: data.level,
          id: data.id,
          responseType: 'text'
        });
      }

      onAudioTrackLoading (data: { url: string; id: number | null; }) {
        this.load({
          url: data.url,
          type: PlaylistContextType.AUDIO_TRACK,
          level: null,
          id: data.id,
          responseType: 'text'
        });
      }

      onSubtitleTrackLoading (data: { url: string; id: number | null; }) {
        this.load({
          url: data.url,
          type: PlaylistContextType.SUBTITLE_TRACK,
          level: null,
          id: data.id,
          responseType: 'text'
        });
      }

      load (context: PlaylistLoaderContext): boolean {
        const config = this.hls.config;

        logger.debug(`Loading playlist of type ${context.type}, level: ${context.level}, id: ${context.id}`);

        // Check if a loader for this context already exists
        let loader = this.getInternalLoader(context);
        Iif (loader) {
          const loaderContext = loader.context;
          if (loaderContext && loaderContext.url === context.url) { // same URL can't overlap
            logger.trace('playlist request ongoing');
            return false;
          } else {
            logger.warn(`aborting previous loader for type: ${context.type}`);
            loader.abort();
          }
        }

        let maxRetry: number;
        let timeout: number;
        let retryDelay: number;
        let maxRetryDelay: number;

        // apply different configs for retries depending on
        // context (manifest, level, audio/subs playlist)
        switch (context.type) {
        case PlaylistContextType.MANIFEST:
          maxRetry = config.manifestLoadingMaxRetry;
          timeout = config.manifestLoadingTimeOut;
          retryDelay = config.manifestLoadingRetryDelay;
          maxRetryDelay = config.manifestLoadingMaxRetryTimeout;
          break;
        case PlaylistContextType.LEVEL:
          // Disable internal loader retry logic, since we are managing retries in Level Controller
          maxRetry = 0;
          maxRetryDelay = 0;
          retryDelay = 0;
          timeout = config.levelLoadingTimeOut;
          // TODO Introduce retry settings for audio-track and subtitle-track, it should not use level retry config
          break;
        default:
          maxRetry = config.levelLoadingMaxRetry;
          timeout = config.levelLoadingTimeOut;
          retryDelay = config.levelLoadingRetryDelay;
          maxRetryDelay = config.levelLoadingMaxRetryTimeout;
          break;
        }

        loader = this.createInternalLoader(context);

        const loaderConfig: LoaderConfiguration = {
          timeout,
          maxRetry,
          retryDelay,
          maxRetryDelay
        };

        const loaderCallbacks: LoaderCallbacks<PlaylistLoaderContext> = {
          onSuccess: this.loadsuccess.bind(this),
          onError: this.loaderror.bind(this),
          onTimeout: this.loadtimeout.bind(this)
        };

        logger.debug(`Calling internal loader delegate for URL: ${context.url}`);
        loader.load(context, loaderConfig, loaderCallbacks);

        return true;
      }

      loadsuccess (response: LoaderResponse, stats: LoaderStats, context: PlaylistLoaderContext, networkDetails: unknown = null) {
        if (context.isSidxRequest) {
          this._handleSidxRequest(response, context);
          this._handlePlaylistLoaded(response, stats, context, networkDetails);
          return;
        }

        this.resetInternalLoader(context.type);
        if (typeof response.data !== 'string') {
          throw new Error('expected responseType of "text" for PlaylistLoader');
        }

        const string = response.data;

        stats.tload = performance.now();
        // stats.mtime = new Date(target.getResponseHeader('Last-Modified'));

        // Validate if it is an M3U8 at all
        if (string.indexOf('#EXTM3U') !== 0) {
          this._handleManifestParsingError(response, context, 'no EXTM3U delimiter', networkDetails);
          return;
        }

        // Check if chunk-list or master. handle empty chunk list case (first EXTINF not signaled, but TARGETDURATION present)
        if (string.indexOf('#EXTINF:') > 0 || string.indexOf('#EXT-X-TARGETDURATION:') > 0) {
          this._handleTrackOrLevelPlaylist(response, stats, context, networkDetails);
        } else {
          this._handleMasterPlaylist(response, stats, context, networkDetails);
        }
      }

      loaderror (response: LoaderResponse, context: PlaylistLoaderContext, networkDetails = null) I{
        this._handleNetworkError(context, networkDetails, false, response);
      }

      loadtimeout (stats: LoaderStats, context: PlaylistLoaderContext, networkDetails = null) {
        this._handleNetworkError(context, networkDetails, true);
      }

      // TODO(typescript-config): networkDetails can currently be a XHR or Fetch impl,
      // but with custom loaders it could be generic investigate this further when config is typed
      _handleMasterPlaylist (response: LoaderResponse, stats: LoaderStats, context: PlaylistLoaderContext, networkDetails: unknown) {
        const hls = this.hls;
        const string = response.data;

        const url = PlaylistLoader.getResponseUrl(response, context);

        const levels = M3U8Parser.parseMasterPlaylist(string, url);
        if (!levels.length) {
          this._handleManifestParsingError(response, context, 'no level found in manifest', networkDetails);
          return;
        }

        // multi level playlist, parse level info

        const audioGroups = levels.map(level => ({
          id: level.attrs.AUDIO,
          codec: level.audioCodec
        }));

        let audioTracks = M3U8Parser.parseMasterPlaylistMedia(string, url, 'AUDIO', audioGroups);
        let subtitles = M3U8Parser.parseMasterPlaylistMedia(string, url, 'SUBTITLES');

        if (audioTracks.length) {
          // check if we have found an audio track embedded in main playlist (audio track without URI attribute)
          let embeddedAudioFound = false;
          audioTracks.forEach(audioTrack => {
            if (!audioTrack.url) {
              embeddedAudioFound = true;
            }
          });

          // if no embedded audio track defined, but audio codec signaled in quality level,
          // we need to signal this main audio track this could happen with playlists with
          // alt audio rendition in which quality levels (main)
          // contains both audio+video. but with mixed audio track not signaled
          if (embeddedAudioFound === false && levels[0].audioCodec && !levels[0].attrs.AUDIO) {
            logger.log('audio codec signaled in quality level, but no embedded audio track signaled, create one');
            audioTracks.unshift({
              type: 'main',
              name: 'main'
            });
          }
        }

        hls.trigger(Event.MANIFEST_LOADED, {
          levels,
          audioTracks,
          subtitles,
          url,
          stats,
          networkDetails
        });
      }

      _handleTrackOrLevelPlaylist (response: LoaderResponse, stats: LoaderStats, context: PlaylistLoaderContext, networkDetails: unknown) {
        const hls = this.hls;

        const { id, level, type } = context;

        const url = PlaylistLoader.getResponseUrl(response, context);

        // if the values are null, they will result in the else conditional
        const levelUrlId = Number.isFinite(id as number) ? id : 0;
        const levelId = Number.isFinite(level as number) ? level : levelUrlId;

        const levelType = PlaylistLoader.mapContextToLevelType(context);
        const levelDetails = M3U8Parser.parseLevelPlaylist(response.data, url, levelId, levelType, levelUrlId);

        // set stats on level structure
        // TODO(jstackhouse): why? mixing concerns, is it just treated as value bag?
        (levelDetails as any).tload = stats.tload;

        // We have done our first request (Manifest-type) and receive
        // not a master playlist but a chunk-list (track/level)
        // We fire the manifest-loaded event anyway with the parsed level-details
        // by creating a single-level structure for it.
        if (type === PlaylistContextType.MANIFEST) {
          const singleLevel = {
            url,
            details: levelDetails
          };

          hls.trigger(Event.MANIFEST_LOADED, {
            levels: [singleLevel],
            audioTracks: [],
            url,
            stats,
            networkDetails
          });
        }

        // save parsing time
        stats.tparsed = performance.now();

        // in case we need SIDX ranges
        // return early after calling load for
        // the SIDX box.
        if (levelDetails.needSidxRanges) {
          const sidxUrl = levelDetails.initSegment.url;
          this.load({
            url: sidxUrl,
            isSidxRequest: true,
            type,
            level,
            levelDetails,
            id,
            rangeStart: 0,
            rangeEnd: 2048,
            responseType: 'arraybuffer'
          });
          return;
        }

        // extend the context with the new levelDetails property
        context.levelDetails = levelDetails;

        this._handlePlaylistLoaded(response, stats, context, networkDetails);
      }

      _handleSidxRequest (response: LoaderResponse, context: PlaylistLoaderContext) {
        if (typeof response.data === 'string') {
          throw new Error('sidx request must be made with responseType of array buffer');
        }

        const sidxInfo = MP4Demuxer.parseSegmentIndex(new Uint8Array(response.data));
        // if provided fragment does not contain sidx, early return
        if (!sidxInfo) {
          return;
        }
        const sidxReferences = sidxInfo.references;
        const levelDetails = context.levelDetails;
        sidxReferences.forEach((segmentRef, index) => {
          const segRefInfo = segmentRef.info;
          if (!levelDetails) {
            return;
          }
          const frag = levelDetails.fragments[index];
          if (frag.byteRange.length === 0) {
            frag.setByteRange(String(1 + segRefInfo.end - segRefInfo.start) + '@' + String(segRefInfo.start));
          }
        });

        if (levelDetails) {
          levelDetails.initSegment.setByteRange(String(sidxInfo.moovEndOffset) + '@0');
        }
      }

      _handleManifestParsingError (response: LoaderResponse, context: PlaylistLoaderContext, reason: string, networkDetails: unknown) {
        this.hls.trigger(Event.ERROR, {
          type: ErrorTypes.NETWORK_ERROR,
          details: ErrorDetails.MANIFEST_PARSING_ERROR,
          fatal: true,
          url: response.url,
          reason,
          networkDetails
        });
      }

      _handleNetworkError (context: PlaylistLoaderContext, networkDetails: unknown, timeout: boolean = false, response: LoaderResponse | null = null) I{
        logger.info(`A network error occured while loading a ${context.type}-type playlist`);

        let details;
        let fatal;

        const loader = this.getInternalLoader(context);

        switch (context.type) {
        case PlaylistContextType.MANIFEST:
          details = (timeout ? ErrorDetails.MANIFEST_LOAD_TIMEOUT : ErrorDetails.MANIFEST_LOAD_ERROR);
          fatal = true;
          break;
        case PlaylistContextType.LEVEL:
          details = (timeout ? ErrorDetails.LEVEL_LOAD_TIMEOUT : ErrorDetails.LEVEL_LOAD_ERROR);
          fatal = false;
          break;
        case PlaylistContextType.AUDIO_TRACK:
          details = (timeout ? ErrorDetails.AUDIO_TRACK_LOAD_TIMEOUT : ErrorDetails.AUDIO_TRACK_LOAD_ERROR);
          fatal = false;
          break;
        default:
          // details = ...?
          fatal = false;
        }

        Eif (loader) {
          loader.abort();
          this.resetInternalLoader(context.type);
        }

        // TODO(typescript-events): when error events are handled, type this
        let errorData: any = {
          type: ErrorTypes.NETWORK_ERROR,
          details,
          fatal,
          url: context.url,
          loader,
          context,
          networkDetails
        };

        Eif (response) {
          errorData.response = response;
        }

        this.hls.trigger(Event.ERROR, errorData);
      }

      _handlePlaylistLoaded (response: LoaderResponse, stats: LoaderStats, context: PlaylistLoaderContext, networkDetails: unknown) {
        const { type, level, id, levelDetails } = context;

        if (!levelDetails || !levelDetails.targetduration) {
          this._handleManifestParsingError(response, context, 'invalid target duration', networkDetails);
          return;
        }

        const canHaveLevels = PlaylistLoader.canHaveQualityLevels(context.type);
        if (canHaveLevels) {
          this.hls.trigger(Event.LEVEL_LOADED, {
            details: levelDetails,
            level: level || 0,
            id: id || 0,
            stats,
            networkDetails
          });
        } else {
          switch (type) {
          case PlaylistContextType.AUDIO_TRACK:
            this.hls.trigger(Event.AUDIO_TRACK_LOADED, {
              details: levelDetails,
              id,
              stats,
              networkDetails
            });
            break;
          case PlaylistContextType.SUBTITLE_TRACK:
            this.hls.trigger(Event.SUBTITLE_TRACK_LOADED, {
              details: levelDetails,
              id,
              stats,
              networkDetails
            });
            break;
          }
        }
      }
    }

    export default PlaylistLoader;