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

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     /*
     * Timeline Controller
    */

    import Event from '../events';
    import EventHandler from '../event-handler';
    import Cea608Parser 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';

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

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

    class TimelineController extends EventHandler {
      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.LEVEL_SWITCHING,
          Event.INIT_PTS_FOUND);

        this.hls = hls;
        this.config = hls.config;
        this.enabled = true;
        this.Cues = hls.config.cueHandler;
        this.textTracks = [];
        this.tracks = [];
        this.unparsedVttFrags = [];
        this.initPTS = [];
        this.cueRanges = [];
        this.captionsTracks = {};

        this.captionsProperties = {
          textTrack1: {
            label: this.config.captionsTextTrack1Label,
            languageCode: this.config.captionsTextTrack1LanguageCode
          },
          textTrack2: {
            label: this.config.captionsTextTrack2Label,
            languageCode: this.config.captionsTextTrack2LanguageCode
          }
        };

        Eif (this.config.enableCEA708Captions) {
          let channel1 = new OutputFilter(this, 'textTrack1');
          let channel2 = new OutputFilter(this, 'textTrack2');

          this.cea608Parser = new Cea608Parser(0, channel1, channel2);
        }
      }

      addCues (trackName, startTime, endTime, screen) {
        // 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]);
        }

        this.Cues.newCue(this.captionsTracks[trackName], startTime, endTime, screen);
      }

      // Triggered when an initial PTS is found; used for synchronisation of WebVTT.
      onInitPtsFound (data) {
        if (data.id === 'main') {
          this.initPTS[data.frag.cc] = data.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 (this.unparsedVttFrags.length) {
          const unparsedVttFrags = this.unparsedVttFrags;
          this.unparsedVttFrags = [];
          unparsedVttFrags.forEach(frag => {
            this.onFragLoaded(frag);
          });
        }
      }

      getExistingTrack (trackName) {
        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) {
        const { label, languageCode } = this.captionsProperties[trackName];
        const captionsTracks = this.captionsTracks;
        if (!captionsTracks[trackName]) {
          // Enable reuse of existing text track.
          const existingTrack = this.getExistingTrack(trackName);
          if (!existingTrack) {
            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], this.media);
          }
        }
      }

      createTextTrack (kind, label, lang) {
        const media = this.media;
        Eif (media) {
          return media.addTextTrack(kind, label, lang);
        }
      }

      destroy () {
        EventHandler.prototype.destroy.call(this);
      }

      onMediaAttaching (data) {
        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 = { // Detect discontinuity in subtitle manifests
          ccOffset: 0,
          presentationOffset: 0,
          0: {
            start: 0, prevCC: -1, new: false
          }
        };
        this._cleanTracks();
      }

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

      onManifestLoaded (data) {
        this.textTracks = [];
        this.unparsedVttFrags = this.unparsedVttFrags || [];
        this.initPTS = [];
        this.cueRanges = [];

        Eif (this.config.enableWebVTT) {
          this.tracks = data.subtitles || [];
          const inUseTracks = this.media ? this.media.textTracks : [];

          this.tracks.forEach((track, index) => {
            let textTrack;
            if (index < inUseTracks.length) {
              const inUseTrack = [].slice.call(inUseTracks).find(inUseTrack => canReuseVttTextTrack(inUseTrack, track));
              // 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);
          });
        }
      }

      onLevelSwitching () {
        this.enabled = this.hls.currentLevel.closedCaptions !== 'NONE';
      }

      onFragLoaded (data) {
        let frag = data.frag,
          payload = data.payload;
        if (frag.type === 'main') {
          let 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 (sn !== this.lastSn + 1) {
            const cea608Parser = this.cea608Parser;
            Eif (cea608Parser) {
              cea608Parser.reset();
            }
          }
          this.lastSn = sn;
        } // 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(this.initPTS[frag.cc])) {
              this.unparsedVttFrags.push(data);
              if (this.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: 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: frag });
          }
        }
      }

      _parseVTTs (frag, payload) {
        let vttCCs = this.vttCCs;
        if (!vttCCs[frag.cc]) {
          vttCCs[frag.cc] = { start: frag.start, prevCC: this.prevCC, new: true };
          this.prevCC = frag.cc;
        }
        let textTracks = this.textTracks,
          hls = this.hls;

        // Parse the WebVTT file contents.
        WebVTTParser.parse(payload, this.initPTS[frag.cc], vttCCs, frag.cc, function (cues) {
          const currentTrack = textTracks[frag.trackId];
          // 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);
              } catch (err) {
                const textTrackCue = new window.TextTrackCue(cue.startTime, cue.endTime, cue.text);
                textTrackCue.id = cue.id;
                currentTrack.addCue(textTrackCue);
              }
            }
          }
          );
          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) {
        let decryptedData = data.payload,
          frag = data.frag;

        if (frag.type === 'subtitle') {
          if (!Number.isFinite(this.initPTS[frag.cc])) {
            this.unparsedVttFrags.push(data);
            return;
          }

          this._parseVTTs(frag, decryptedData);
        }
      }

      onFragParsingUserdata (data) {
        // push all of the CEA-708 messages into the interpreter
        // immediately. It will create the proper timestamps based on our PTS value
        if (this.enabled && this.config.enableCEA708Captions) {
          for (let i = 0; i < data.samples.length; i++) {
            let ccdatas = this.extractCea608Data(data.samples[i].bytes);
            this.cea608Parser.addData(data.samples[i].pts, ccdatas);
          }
        }
      }

      extractCea608Data (byteArray) {
        let count = byteArray[0] & 31;
        let position = 2;
        let tmpByte, ccbyte1, ccbyte2, ccValid, ccType;
        let actualCCBytes = [];

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

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

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

    export default TimelineController;