timeline-chart.ts

import Chart from 'chart.js';
import 'chartjs-plugin-zoom';
import { applyChartInstanceOverrides, hhmmss } from './chartjs-horizontal-bar';
import { TrackSet } from '../../src/types/track';
import Fragment from '../../src/loader/fragment';

declare global {
  interface Window {
    Hls: any;
    hls: any;
    chart: any;
  }
}

const X_AXIS_SECONDS = 'x-axis-seconds';

export class TimelineChart {
  private readonly chart: Chart;
  private rafDebounceRequestId: number = -1;
  private imageDataBuffer: ImageData | null = null;
  private media: HTMLMediaElement | null = null;
  private tracksChangeHandler?: (e) => void;
  private cuesChangeHandler?: (e) => void;
  private hidden: boolean = true;

  constructor (canvas: HTMLCanvasElement, chartJsOptions?: any) {
    const ctx = canvas.getContext('2d');
    const chart = this.chart = self.chart = new Chart(ctx, {
      type: 'horizontalBar',
      data: {
        labels: [],
        datasets: []
      },
      options: Object.assign(getChartOptions(), chartJsOptions),
      plugins: [{
        afterRender: () => {
          this.imageDataBuffer = null;
          this.drawCurrentTime();
        }
      }]
    });

    applyChartInstanceOverrides(chart);

    // Log object on click and seek to position
    canvas.onclick = (event: MouseEvent) => {
      const element = chart.getElementAtEvent(event);
      if (element.length) {
        const dataset = chart.data.datasets[element[0]._datasetIndex];
        const obj = dataset.data[element[0]._index];
        console.log(obj);
        if (self.hls && self.hls.media) {
          const scale = chart.scales[X_AXIS_SECONDS];
          const pos = Chart.helpers.getRelativePosition(event, chart);
          const time = scale.getValueForPixel(pos.x);
          self.hls.media.currentTime = time;
        }
      }
    };

    canvas.ondblclick = (event: MouseEvent) => {
      const chartArea: { left, top, right, bottom } = chart.chartArea;
      const element = chart.getElementAtEvent(event);
      const pos = Chart.helpers.getRelativePosition(event, chart);
      const scale = chart.scales[X_AXIS_SECONDS];
      const range = scale.max - scale.min;
      const newDiff = range * (event.getModifierState('Shift') ? -1.0 : 0.5);
      const minPercent = (scale.getValueForPixel(pos.x) - scale.min) / range;
      const maxPercent = 1 - minPercent;
      const minDelta = newDiff * minPercent;
      const maxDelta = newDiff * maxPercent;
      // zoom in when double clicking near elements in chart area
      if (element.length || pos.x > chartArea.left) {
        scale.options.ticks.min = Math.max(this.minZoom, scale.min + minDelta);
        scale.options.ticks.max = Math.min(this.maxZoom, scale.max - maxDelta);
      } else {
        // chart.resetZoom();
        scale.options.ticks.min = this.minZoom;
        scale.options.ticks.max = this.maxZoom;
      }
      this.update();
    };

    // TODO: Prevent zoom over y axis labels
  }

  reset () {
    const { labels, datasets } = this.chart.data;
    const scale = this.chart.scales[X_AXIS_SECONDS];
    scale.options.ticks.min = 0;
    scale.options.ticks.max = 60;
    const config = this.chart.config;
    if (config?.options) {
      config.options.plugins.zoom.zoom.rangeMax.x = 60;
    }
    labels.length = 0;
    datasets.length = 0;
    this.resize(datasets);
  }

  update () {
    if (this.hidden || !this.chart.ctx.canvas.width) {
      return;
    }
    this.chart.update({
      duration: 0,
      lazy: true
    });
  }

  resize (datasets?) {
    if (this.hidden) {
      return;
    }
    if (datasets?.length) {
      const scale = this.chart.scales[X_AXIS_SECONDS];
      const { top } = this.chart.chartArea;
      const height = top + datasets.reduce((val, dataset) => val + dataset.barThickness, 0) + scale.height + 5;
      this.chart.canvas.parentNode.style.height = `${height}px`;
    }
    self.cancelAnimationFrame(this.rafDebounceRequestId);
    this.rafDebounceRequestId = self.requestAnimationFrame(() => {
      this.chart.resize();
    });
  }

  show () {
    this.hidden = false;
  }

  hide () {
    this.hidden = true;
  }

  updateLevels (levels: any[]) {
    const { labels, datasets } = this.chart.data;
    levels.forEach((level, i) => {
      labels.push(getLevelName(level, level.level || level.id || i));
      datasets.push(datasetWithDefaults({
        url: Array.isArray(level.url) ? level.url[0] : level.url,
        trackType: 'level',
        level: level.level
      }));
      if (level.details) {
        this.updateLevelOrTrack(level.details);
      }
    });
    this.resize(datasets);
  }

  updateAudioTracks (audioTracks: any[]) {
    const { labels, datasets } = this.chart.data;
    audioTracks.forEach((track, i) => {
      labels.push(getAudioTrackName(track, i));
      datasets.push(datasetWithDefaults({
        url: Array.isArray(track.url) ? track.url[0] : track.url,
        trackType: 'audioTrack',
        audioTrack: i
      }));
      if (track.details) {
        this.updateLevelOrTrack(track.details);
      }
    });
    this.resize(datasets);
  }

  updateSubtitleTracks (subtitles: any[]) {
    const { labels, datasets } = this.chart.data;
    subtitles.forEach((track, i) => {
      labels.push(getSubtitlesName(track, i));
      datasets.push(datasetWithDefaults({
        url: Array.isArray(track.url) ? track.url[0] : track.url,
        trackType: 'subtitleTrack',
        subtitleTrack: i
      }));
      if (track.details) {
        this.updateLevelOrTrack(track.details);
      }
    });
    this.resize(datasets);
  }

  removeType (trackType: 'level' | 'audioTrack' | 'subtitleTrack' | 'textTrack') {
    const { labels, datasets } = this.chart.data;
    let i = datasets.length;
    while (i--) {
      if (datasets[i].trackType === trackType) {
        datasets.splice(i, 1);
        labels.splice(i, 1);
      }
    }
  }

  updateLevelOrTrack (details: any) {
    const { targetduration, totalduration, url } = details;
    const { datasets } = this.chart.data;
    // eslint-disable-next-line no-restricted-properties
    const levelDataSet = arrayFind(datasets, dataset => dataset.url && dataset.url.toString() === url);
    if (!levelDataSet) {
      return;
    }
    const data = levelDataSet.data;
    data.length = 0;
    if (details.fragments) {
      details.fragments.forEach((fragment) => {
        // TODO: keep track of initial playlist start and duration so that we can show drift and pts offset
        // (Make that a feature of hls.js v1.0.0 fragments)
        data.push(Object.assign({
          dataType: 'fragment'
        }, fragment));
      });
    }
    const start = details.fragments && details.fragments.length ? details.fragments[0].start : 0;
    this.maxZoom = Math.max(start + totalduration + targetduration, this.maxZoom);
    if (this.hidden) {
      return;
    }
    this.rafDebounceRequestId = self.requestAnimationFrame(() => this.update());
  }

  // @ts-ignore
  get minZoom (): number {
    if (this.chart.config && this.chart.config.options) {
      return this.chart.config.options.plugins.zoom.zoom.rangeMin.x;
    }
    return 60;
  }

  // @ts-ignore
  get maxZoom (): number {
    if (this.chart.config && this.chart.config.options) {
      return this.chart.config.options.plugins.zoom.zoom.rangeMax.x;
    }
    return 60;
  }

  // @ts-ignore
  set maxZoom (x: number) {
    const { chart } = this;
    const { config } = chart;
    if (config?.options) {
      const currentZoom = config.options.plugins.zoom.zoom.rangeMax.x;
      const newZoom = Math.max(x, currentZoom);
      if (currentZoom === 60 && newZoom !== currentZoom) {
        const scale = chart.scales[X_AXIS_SECONDS];
        scale.options.ticks.max = newZoom;
      }
      config.options.plugins.zoom.zoom.rangeMax.x = newZoom;
    }
  }

  updateFragment (data: any) {
    const { datasets } = this.chart.data;
    const frag: Fragment = data.frag;
    const levelDataSet = arrayFind(datasets, dataset => dataset.url === frag.baseurl);
    if (!levelDataSet) {
      return;
    }
    // eslint-disable-next-line no-restricted-properties
    const fragData = arrayFind(levelDataSet.data, fragData => fragData.relurl === frag.relurl);
    if (fragData && fragData !== frag) {
      Object.assign(fragData, frag);
    }
    if (this.hidden) {
      return;
    }
    this.rafDebounceRequestId = self.requestAnimationFrame(() => this.update());
  }

  updateSourceBuffers (tracks: TrackSet, media: HTMLMediaElement) {
    const { labels, datasets } = this.chart.data;
    const trackTypes = Object.keys(tracks).sort((type) => type === 'video' ? 1 : -1);
    const mediaBufferData = [];

    this.media = media;

    trackTypes.forEach((type) => {
      const track = tracks[type];
      const data = [];
      const sourceBuffer = track.buffer;
      const backgroundColor = {
        video: 'rgba(0, 0, 255, 0.2)',
        audio: 'rgba(128, 128, 0, 0.2)',
        audiovideo: 'rgba(128, 128, 255, 0.2)'
      }[type];
      labels.unshift(`${type} buffer (${track.id})`);
      datasets.unshift(datasetWithDefaults({
        data,
        categoryPercentage: 0.5,
        backgroundColor,
        sourceBuffer
      }));
      sourceBuffer.onupdate = () => {
        try {
          replaceTimeRangeTuples(sourceBuffer.buffered, data);
        } catch (error) {
          console.warn(error);
          return;
        }
        replaceTimeRangeTuples(media.buffered, mediaBufferData);
        this.update();
      };
    });

    if (trackTypes.length === 0) {
      media.onprogress = () => {
        replaceTimeRangeTuples(media.buffered, mediaBufferData);
        this.update();
      };
    }

    labels.unshift('media buffer');
    datasets.unshift(datasetWithDefaults({
      data: mediaBufferData,
      categoryPercentage: 0.5,
      backgroundColor: 'rgba(0, 255, 0, 0.2)',
      media
    }));

    media.ontimeupdate = () => this.drawCurrentTime();

    // TextTrackList
    const { textTracks } = media;
    this.tracksChangeHandler = this.tracksChangeHandler || ((e) => this.setTextTracks(e.currentTarget));
    textTracks.removeEventListener('addtrack', this.tracksChangeHandler);
    textTracks.removeEventListener('removetrack', this.tracksChangeHandler);
    textTracks.removeEventListener('change', this.tracksChangeHandler);
    textTracks.addEventListener('addtrack', this.tracksChangeHandler);
    textTracks.addEventListener('removetrack', this.tracksChangeHandler);
    textTracks.addEventListener('change', this.tracksChangeHandler);
    this.setTextTracks(textTracks);
    this.resize(datasets);
  }

  setTextTracks (textTracks) {
    const { labels, datasets } = this.chart.data;
    this.removeType('textTrack');
    [].forEach.call(textTracks, (textTrack, i) => {
      if (textTrack.kind === 'subtitles' || textTrack.kind === 'captions') {
        return;
      }
      const data = [];
      labels.push(`${textTrack.name || textTrack.label} ${textTrack.kind} (${textTrack.mode})`);
      datasets.push(datasetWithDefaults({
        data,
        categoryPercentage: 0.5,
        url: '',
        trackType: 'textTrack',
        textTrack: i
      }));
      this.cuesChangeHandler = this.cuesChangeHandler || ((e) => this.updateTextTrackCues(e.currentTarget));
      textTrack._data = data;
      textTrack.removeEventListener('cuechange', this.cuesChangeHandler);
      textTrack.addEventListener('cuechange', this.cuesChangeHandler);
      this.updateTextTrackCues(textTrack);
    });
    this.resize(datasets);
  }

  updateTextTrackCues (textTrack) {
    const data = textTrack._data;
    if (!data) {
      return;
    }
    const { activeCues, cues } = textTrack;
    data.length = 0;
    if (!cues) {
      return;
    }
    const length = cues.length;

    let activeLength = 0;
    let activeMin = Infinity;
    let activeMax = 0;
    if (activeCues) {
      activeLength = activeCues.length;
      for (let i = 0; i < activeLength; i++) {
        let cue = activeCues[i];
        if (!cue && activeCues.item) {
          cue = activeCues.item(i);
        }
        if (cue) {
          activeMin = Math.min(activeMin, cue.startTime);
          activeMax = cue.endTime ? Math.max(activeMax, cue.endTime) : activeMax;
        } else {
          activeLength--;
        }
      }
    }
    for (let i = 0; i < length; i++) {
      let cue = cues[i];
      if (!cue && cues.item) {
        cue = cues.item(i);
      }
      if (!cue) {
        continue;
      }
      const start = cue.startTime;
      const end = cue.endTime;
      const content = getCueLabel(cue);
      let active = false;
      if (activeLength && end >= activeMin && start <= activeMax) {
        active = [].some.call(activeCues, (activeCue) => cuesMatch(activeCue, cue));
      }
      data.push({
        start,
        end,
        content,
        active,
        dataType: 'cue'
      });
    }
    if (this.hidden) {
      return;
    }
    self.cancelAnimationFrame(this.rafDebounceRequestId);
    this.rafDebounceRequestId = self.requestAnimationFrame(() => {
      this.update();
    });
  }

  drawCurrentTime () {
    const chart = this.chart;
    if (self.hls && self.hls.media && chart.data.datasets.length) {
      const currentTime = self.hls.media.currentTime;
      const scale = chart.scales[X_AXIS_SECONDS];
      const ctx: CanvasRenderingContext2D = chart.ctx;
      if (this.hidden || !ctx.canvas.width) {
        return;
      }
      const chartArea: { left, top, right, bottom } = chart.chartArea;
      const x = scale.getPixelForValue(currentTime);
      ctx.restore();
      ctx.save();
      this.drawLineX(ctx, x, chartArea);
      if (x > chartArea.left && x < chartArea.right) {
        ctx.fillStyle = this.getCurrentTimeColor(self.hls.media);
        const y = chartArea.top + chart.data.datasets[0].barThickness + 1;
        ctx.fillText(hhmmss(currentTime, 5), x + 2, y, 100);
      }
      ctx.restore();
    }
  }

  getCurrentTimeColor (video: HTMLMediaElement): string {
    if (!video.readyState || video.ended) {
      return 'rgba(0, 0, 0, 0.9)';
    }
    if (video.seeking || video.readyState < 3) {
      return 'rgba(255, 128, 0, 0.9)';
    }
    if (video.paused) {
      return 'rgba(128, 0, 255, 0.9)';
    }
    return 'rgba(0, 0, 255, 0.9)';
  }

  drawLineX (ctx, x, chartArea) {
    if (!this.imageDataBuffer) {
      const devicePixelRatio = self.devicePixelRatio || 1;
      this.imageDataBuffer = ctx.getImageData(0, 0, chartArea.right * devicePixelRatio, chartArea.bottom * devicePixelRatio);
    } else {
      ctx.fillStyle = '#ffffff';
      ctx.fillRect(0, 0, chartArea.right, chartArea.bottom);
      ctx.putImageData(this.imageDataBuffer, 0, 0);
    }
    if (x > chartArea.left && x < chartArea.right) {
      ctx.lineWidth = 1;
      ctx.strokeStyle = this.getCurrentTimeColor(self.hls.media); // alpha '0.5'
      ctx.beginPath();
      ctx.moveTo(x, chartArea.top);
      ctx.lineTo(x, chartArea.bottom);
      ctx.stroke();
    }
  }
}

function datasetWithDefaults (options) {
  return Object.assign({
    data: [],
    xAxisID: X_AXIS_SECONDS,
    barThickness: 35,
    categoryPercentage: 1
  }, options);
}

function getLevelName (level: any, index: number) {
  let label = '(main playlist)';
  if (level.attrs && level.attrs.BANDWIDTH) {
    label = `${getMainLevelAttribute(level)}@${level.attrs.BANDWIDTH}`;
    if (level.name) {
      label = `${label} (${level.name})`;
    }
  } else if (level.name) {
    label = level.name;
  }
  return `${label} L-${index}`;
}

function getMainLevelAttribute (level: any) {
  return level.attrs.RESOLUTION || level.attrs.CODECS || level.attrs.AUDIO;
}

function getAudioTrackName (track: any, index: number) {
  const label = track.lang ? `${track.name}/${track.lang}` : track.name;
  return `${label} (${track.groupId || track.attrs['GROUP-ID']}) A-${index}`;
}

function getSubtitlesName (track: any, index: number) {
  const label = track.lang ? `${track.name}/${track.lang}` : track.name;
  return `${label} (${track.groupId || track.attrs['GROUP-ID']}) S-${index}`;
}

function replaceTimeRangeTuples (timeRanges, data) {
  data.length = 0;
  const { length } = timeRanges;
  for (let i = 0; i < length; i++) {
    data.push([timeRanges.start(i), timeRanges.end(i)]);
  }
}

function cuesMatch (cue1, cue2) {
  return cue1.startTime === cue2.startTime &&
    cue1.endTime === cue2.endTime &&
    cue1.text === cue2.text &&
    cue1.data === cue2.data &&
    JSON.stringify(cue1.value) === JSON.stringify(cue2.value);
}

function getCueLabel (cue) {
  if (cue.text) {
    return cue.text;
  }
  const result = parseDataCue(cue);
  return JSON.stringify(result);
}

function parseDataCue (cue) {
  const data = {};
  const { value } = cue;
  if (value) {
    if (value.info) {
      let collection = data[value.key];
      if (collection !== Object(collection)) {
        collection = {};
        data[value.key] = collection;
      }
      collection[value.info] = value.data;
    } else {
      data[value.key] = value.data;
    }
  }
  return data;
}

function getChartOptions () {
  return {
    animation: {
      duration: 0
    },
    elements: {
      rectangle: {
        borderWidth: 1,
        borderColor: 'rgba(20, 20, 20, 1)'
      }
    },
    events: [
      'click', 'touchstart'
    ],
    hover: {
      mode: null,
      animationDuration: 0
    },
    legend: {
      display: false
    },
    maintainAspectRatio: false,

    responsiveAnimationDuration: 0,
    scales: {
      // TODO: additional xAxes for PTS and PDT
      xAxes: [{
        id: X_AXIS_SECONDS,
        ticks: {
          beginAtZero: true,
          sampleSize: 0,
          maxRotation: 0,
          callback: (tickValue, i, ticks) => {
            if (i === 0 || i === ticks.length - 1) {
              return tickValue ? '' : '0';
            } else {
              return hhmmss(tickValue, 2);
            }
          }
        }
      }],
      yAxes: [{
        gridLines: {
          display: false
        }
      }]
    },
    tooltips: {
      enabled: false
    },
    plugins: {
      zoom: {
        pan: {
          enabled: true,
          mode: 'x',
          rangeMin: {
            x: -10, y: null
          },
          rangeMax: {
            x: null, y: null
          }
        },
        zoom: {
          enabled: true,
          speed: 0.1,
          mode: 'x',
          rangeMin: {
            x: 0, y: null
          },
          rangeMax: {
            x: 60, y: null
          }
        }
      }
    }
  };
}

function arrayFind (array, predicate) {
  const len = array.length >>> 0;
  if (typeof predicate !== 'function') {
    throw TypeError('predicate must be a function');
  }
  const thisArg = arguments[2];
  let k = 0;
  while (k < len) {
    const kValue = array[k];
    if (predicate.call(thisArg, kValue, k, array)) {
      return kValue;
    }
    k++;
  }
  return undefined;
}