# All files / src/controller timeline-controller.ts

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     import Event from '../events';
    import EventHandler from '../event-handler';
    import Cea608Parser, { CaptionScreen } from '../utils/cea-608-parser';
    import OutputFilter from '../utils/output-filter';
    import WebVTTParser from '../utils/webvtt-parser';
    import { logger } from '../utils/logger';
    import { sendAddTrackEvent, clearCurrentCues } from '../utils/texttrack-utils';
    import Fragment from '../loader/fragment';
    import { HlsConfig } from '../config';
    import { CuesInterface } from '../utils/cues';
    import { MediaPlaylist } from '../types/media-playlist';

    type TrackProperties = {
      label: string,
      languageCode: string
    };

    type VTTCCs = {
      ccOffset: number,
      presentationOffset: number,
      [key: number]: {
        start: number,
        prevCC: number,
        new: boolean
      }
    };

    class TimelineController extends EventHandler {
      private media: HTMLMediaElement | null = null;
      private config: HlsConfig;
      private enabled: boolean = true;
      private Cues: CuesInterface;
      private textTracks: Array<TextTrack> = [];
      private tracks: Array<MediaPlaylist> = [];
      private initPTS: Array<number> = [];
      private unparsedVttFrags: Array<{ frag: Fragment, payload: ArrayBuffer }> = [];
      private cueRanges: Array<[number, number]> = [];
      private captionsTracks: Record<string, TextTrack> = {};
      private captionsProperties: {
        textTrack1: TrackProperties
        textTrack2: TrackProperties
        textTrack3: TrackProperties
        textTrack4: TrackProperties
      };
      private readonly cea608Parser!: Cea608Parser;
      private lastSn: number = -1;
      private prevCC: number = -1;
      private vttCCs: VTTCCs = newVTTCCs();

      constructor (hls) {
        super(hls,
          Event.MEDIA_ATTACHING,
          Event.MEDIA_DETACHING,
          Event.FRAG_PARSING_USERDATA,
          Event.FRAG_DECRYPTED,
          Event.MANIFEST_LOADING,
          Event.MANIFEST_LOADED,
          Event.FRAG_LOADED,
          Event.INIT_PTS_FOUND);

        this.hls = hls;
        this.config = hls.config;
        this.Cues = hls.config.cueHandler;

        this.captionsProperties = {
          textTrack1: {
            label: this.config.captionsTextTrack1Label,
            languageCode: this.config.captionsTextTrack1LanguageCode
          },
          textTrack2: {
            label: this.config.captionsTextTrack2Label,
            languageCode: this.config.captionsTextTrack2LanguageCode
          },
          textTrack3: {
            label: this.config.captionsTextTrack3Label,
            languageCode: this.config.captionsTextTrack3LanguageCode
          },
          textTrack4: {
            label: this.config.captionsTextTrack4Label,
            languageCode: this.config.captionsTextTrack4LanguageCode
          }
        };

        Eif (this.config.enableCEA708Captions) {
          const channel1 = new OutputFilter(this, 'textTrack1');
          const channel2 = new OutputFilter(this, 'textTrack2');
          const channel3 = new OutputFilter(this, 'textTrack3');
          const channel4 = new OutputFilter(this, 'textTrack4');
          this.cea608Parser = new Cea608Parser(channel1, channel2, channel3, channel4);
        }
      }

      addCues (trackName: string, startTime: number, endTime: number, screen: CaptionScreen) {
        // skip cues which overlap more than 50% with previously parsed time ranges
        const ranges = this.cueRanges;
        let merged = false;
        for (let i = ranges.length; i--;) {
          let cueRange = ranges[i];
          let overlap = intersection(cueRange[0], cueRange[1], startTime, endTime);
          if (overlap >= 0) {
            cueRange[0] = Math.min(cueRange[0], startTime);
            cueRange[1] = Math.max(cueRange[1], endTime);
            merged = true;
            if ((overlap / (endTime - startTime)) > 0.5) {
              return;
            }
          }
        }
        if (!merged) {
          ranges.push([startTime, endTime]);
        }

        if (this.config.renderTextTracksNatively) {
          this.Cues.newCue(this.captionsTracks[trackName], startTime, endTime, screen);
        } else {
          const cues = this.Cues.newCue(null, startTime, endTime, screen);
          this.hls.trigger(Event.CUES_PARSED, { type: 'captions', cues, track: trackName });
        }
      }

      // Triggered when an initial PTS is found; used for synchronisation of WebVTT.
      onInitPtsFound (data: { id: string, frag: Fragment, initPTS: number}) {
        const { frag, id, initPTS } = data;
        const { unparsedVttFrags } = this;
        if (id === 'main') {
          this.initPTS[frag.cc] = initPTS;
        }

        // Due to asynchronous processing, initial PTS may arrive later than the first VTT fragments are loaded.
        // Parse any unparsed fragments upon receiving the initial PTS.
        if (unparsedVttFrags.length) {
          this.unparsedVttFrags = [];
          unparsedVttFrags.forEach(frag => {
            this.onFragLoaded(frag);
          });
        }
      }

      getExistingTrack (trackName: string): TextTrack | null {
        const { media } = this;
        if (media) {
          for (let i = 0; i < media.textTracks.length; i++) {
            let textTrack = media.textTracks[i];
            if (textTrack[trackName]) {
              return textTrack;
            }
          }
        }
        return null;
      }

      createCaptionsTrack (trackName: string) {
        const { captionsProperties, captionsTracks, media } = this;
        if (!captionsTracks[trackName]) {
          // Enable reuse of existing text track.
          const existingTrack = this.getExistingTrack(trackName);
          if (!existingTrack) {
            const { label, languageCode } = captionsProperties[trackName];
            const textTrack = this.createTextTrack('captions', label, languageCode);
            if (textTrack) {
              // Set a special property on the track so we know it's managed by Hls.js
              textTrack[trackName] = true;
              captionsTracks[trackName] = textTrack;
            }
          } else {
            captionsTracks[trackName] = existingTrack;
            clearCurrentCues(captionsTracks[trackName]);
            sendAddTrackEvent(captionsTracks[trackName], media as HTMLMediaElement);
          }
        }
      }

      createTextTrack (kind: TextTrackKind, label: string, lang?: string): TextTrack | undefined {
        const media = this.media;
        Iif (!media) {
          return;
        }
        return media.addTextTrack(kind, label, lang);
      }

      destroy () {
        super.destroy();
      }

      onMediaAttaching (data: { media: HTMLMediaElement }) {
        this.media = data.media;
        this._cleanTracks();
      }

      onMediaDetaching () {
        const { captionsTracks } = this;
        Object.keys(captionsTracks).forEach(trackName => {
          clearCurrentCues(captionsTracks[trackName]);
          delete captionsTracks[trackName];
        });
      }

      onManifestLoading () {
        this.lastSn = -1; // Detect discontiguity in fragment parsing
        this.prevCC = -1;
        this.vttCCs = newVTTCCs(); // Detect discontinuity in subtitle manifests
        this._cleanTracks();
        this.tracks = [];
        this.captionsTracks = {};
      }

      _cleanTracks () {
        // clear outdated subtitles
        const { media } = this;
        if (!media) {
          return;
        }
        const textTracks = media.textTracks;
        if (textTracks) {
          for (let i = 0; i < textTracks.length; i++) {
            clearCurrentCues(textTracks[i]);
          }
        }
      }

      onManifestLoaded (data: { subtitles: Array<MediaPlaylist>, captions: Array<MediaPlaylist> }) {
        this.textTracks = [];
        this.unparsedVttFrags = this.unparsedVttFrags || [];
        this.initPTS = [];
        this.cueRanges = [];

        Eif (this.config.enableWebVTT) {
          const tracks = data.subtitles || [];
          const sameTracks = this.tracks && tracks && this.tracks.length === tracks.length;
          this.tracks = data.subtitles || [];

          Eif (this.config.renderTextTracksNatively) {
            const inUseTracks = this.media ? this.media.textTracks : [];

            this.tracks.forEach((track, index) => {
              let textTrack;
              if (index < inUseTracks.length) {
                let inUseTrack: TextTrack | null = null;

                for (let i = 0; i < inUseTracks.length; i++) {
                  if (canReuseVttTextTrack(inUseTracks[i], track)) {
                    inUseTrack = inUseTracks[i];
                    break;
                  }
                }

                // Reuse tracks with the same label, but do not reuse 608/708 tracks
                Eif (inUseTrack) {
                  textTrack = inUseTrack;
                }
              }
              if (!textTrack) {
                textTrack = this.createTextTrack('subtitles', track.name, track.lang);
              }

              if (track.default) {
                textTrack.mode = this.hls.subtitleDisplay ? 'showing' : 'hidden';
              } else {
                textTrack.mode = 'disabled';
              }

              this.textTracks.push(textTrack);
            });
          } else if (!sameTracks && this.tracks && this.tracks.length) {
            // Create a list of tracks for the provider to consume
            const tracksList = this.tracks.map((track) => {
              return {
                label: track.name,
                kind: track.type.toLowerCase(),
                default: track.default
              };
            });
            this.hls.trigger(Event.NON_NATIVE_TEXT_TRACKS_FOUND, { tracks: tracksList });
          }
        }

        Iif (this.config.enableCEA708Captions && data.captions) {
          data.captions.forEach(captionsTrack => {
            const instreamIdMatch = /(?:CC|SERVICE)([1-4])/.exec(captionsTrack.instreamId as string);

            if (!instreamIdMatch) {
              return;
            }

            const trackName = `textTrack${instreamIdMatch[1]}`;
            this.captionsProperties[trackName].label = captionsTrack.name;

            if (captionsTrack.lang) { // optional attribute
              this.captionsProperties[trackName].languageCode = captionsTrack.lang;
            }
          });
        }
      }

      onFragLoaded (data: { frag: Fragment, payload: ArrayBuffer }) {
        const { frag, payload } = data;
        const { cea608Parser, initPTS, lastSn, unparsedVttFrags } = this;
        if (frag.type === 'main') {
          const sn = frag.sn;
          // if this frag isn't contiguous, clear the parser so cues with bad start/end times aren't added to the textTrack
          if (frag.sn !== lastSn + 1) {
            Eif (cea608Parser) {
              cea608Parser.reset();
            }
          }
          this.lastSn = sn as number;
        } // eslint-disable-line brace-style
        // If fragment is subtitle type, parse as WebVTT.
        else Iif (frag.type === 'subtitle') {
          if (payload.byteLength) {
            // We need an initial synchronisation PTS. Store fragments as long as none has arrived.
            if (!Number.isFinite(initPTS[frag.cc])) {
              unparsedVttFrags.push(data);
              if (initPTS.length) {
                // finish unsuccessfully, otherwise the subtitle-stream-controller could be blocked from loading new frags.
                this.hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag });
              }
              return;
            }

            let decryptData = frag.decryptdata;
            // If the subtitles are not encrypted, parse VTTs now. Otherwise, we need to wait.
            if ((decryptData == null) || (decryptData.key == null) || (decryptData.method !== 'AES-128')) {
              this._parseVTTs(frag, payload);
            }
          } else {
            // In case there is no payload, finish unsuccessfully.
            this.hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag });
          }
        }
      }

      _parseVTTs (frag: Fragment, payload: ArrayBuffer) {
        const { hls, prevCC, textTracks, vttCCs } = this;
        if (!vttCCs[frag.cc]) {
          vttCCs[frag.cc] = { start: frag.start, prevCC, new: true };
          this.prevCC = frag.cc;
        }
        // Parse the WebVTT file contents.
        WebVTTParser.parse(payload, this.initPTS[frag.cc], vttCCs, frag.cc, (cues) => {
          if (this.config.renderTextTracksNatively) {
            const currentTrack = textTracks[frag.level];
            // WebVTTParser.parse is an async method and if the currently selected text track mode is set to "disabled"
            // before parsing is done then don't try to access currentTrack.cues.getCueById as cues will be null
            // and trying to access getCueById method of cues will throw an exception
            if (currentTrack.mode === 'disabled') {
              hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag: frag });
              return;
            }
            // Add cues and trigger event with success true.
            cues.forEach(cue => {
              // Sometimes there are cue overlaps on segmented vtts so the same
              // cue can appear more than once in different vtt files.
              // This avoid showing duplicated cues with same timecode and text.
              if (!currentTrack.cues.getCueById(cue.id)) {
                try {
                  currentTrack.addCue(cue);
                  if (!currentTrack.cues.getCueById(cue.id)) {
                    throw new Error(`addCue is failed for: ${cue}`);
                  }
                } catch (err) {
                  logger.debug(`Failed occurred on adding cues: ${err}`);
                  const textTrackCue = new (window as any).TextTrackCue(cue.startTime, cue.endTime, cue.text);
                  textTrackCue.id = cue.id;
                  currentTrack.addCue(textTrackCue);
                }
              }
            });
          } else {
            let trackId = this.tracks[frag.level].default ? 'default' : 'subtitles' + frag.level;
            hls.trigger(Event.CUES_PARSED, { type: 'subtitles', cues: cues, track: trackId });
          }
          hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: true, frag: frag });
        },
        function (e) {
          // Something went wrong while parsing. Trigger event with success false.
          logger.log(`Failed to parse VTT cue: ${e}`);
          hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag: frag });
        });
      }

      onFragDecrypted (data: { frag: Fragment, payload: any}) {
        const { frag, payload } = data;
        if (frag.type === 'subtitle') {
          if (!Number.isFinite(this.initPTS[frag.cc])) {
            this.unparsedVttFrags.push(data);
            return;
          }

          this._parseVTTs(frag, payload);
        }
      }

      onFragParsingUserdata (data: { samples: Array<any> }) {
        if (!this.enabled || !this.cea608Parser) {
          return;
        }

        // If the event contains captions (found in the bytes property), push all bytes into the parser immediately
        // It will create the proper timestamps based on the PTS value
        const cea608Parser = this.cea608Parser;
        for (let i = 0; i < data.samples.length; i++) {
          const ccBytes = data.samples[i].bytes;
          if (ccBytes) {
            const ccdatas = this.extractCea608Data(ccBytes);
            cea608Parser.addData(data.samples[i].pts, ccdatas[0], 1);
            cea608Parser.addData(data.samples[i].pts, ccdatas[1], 3);
          }
        }
      }

      extractCea608Data (byteArray: Uint8Array): number[][] {
        const count = byteArray[0] & 31;
        let position = 2;
        const actualCCBytes: number[][] = [[], []];

        for (let j = 0; j < count; j++) {
          const tmpByte = byteArray[position++];
          const ccbyte1 = 0x7F & byteArray[position++];
          const ccbyte2 = 0x7F & byteArray[position++];
          const ccValid = (4 & tmpByte) !== 0;
          const ccType = 3 & tmpByte;

          if (ccbyte1 === 0 && ccbyte2 === 0) {
            continue;
          }

          if (ccValid) {
            if (ccType === 0 || ccType === 1) {
              actualCCBytes[ccType].push(ccbyte1);
              actualCCBytes[ccType].push(ccbyte2);
            }
          }
        }
        return actualCCBytes;
      }
    }

    function canReuseVttTextTrack (inUseTrack, manifestTrack): boolean {
      return inUseTrack && inUseTrack.label === manifestTrack.name && !(inUseTrack.textTrack1 || inUseTrack.textTrack2);
    }

    function intersection (x1: number, x2: number, y1: number, y2: number): number {
      return Math.min(x2, y2) - Math.max(x1, y1);
    }

    function newVTTCCs (): VTTCCs {
      return {
        ccOffset: 0,
        presentationOffset: 0,
        0: {
          start: 0,
          prevCC: -1,
          new: false
        }
      };
    }

    export default TimelineController;