europeana/media-player

/* global $ */

const languages = require('../languages/lang.js').default.locales;

function handleTranscriptionAnnotations(player, mediaItemLanguage) {
  if (player.manifest.__jsonld.items[0].annotations) {
    (async() => {
      await Promise.all(player.manifest.__jsonld.items[0].annotations.map(async(annotation) => {
        await fetchAnnotations(player, annotation, mediaItemLanguage);
      }));
      player.initLanguages(player.elem.find('video')[0].textTracks);
    })();
  }
}

async function fetchAnnotations(player, annotation, mediaItemLanguage) {
  return new Promise((resolve) => {
    $.get(annotation.id).then(async(response) => {
      let textResource = response.resources.find((resource) => {
        return (resource.dcType === 'Media') || (resource.textGranularity === 'media');
      });

      await fetchTextResource(player, response, textResource, annotation.language, annotation.source, mediaItemLanguage);
      resolve(true);
    });
  });
}

async function fetchTextResource(player, annotationResource, textResource, language, source, mediaItemLanguage) {
  // determine text, fetch, then loop over all entries and add them to a text track
  return new Promise((resolve) => {
    $.ajax({
      type: 'GET',
      url: textResource.resource['@id'],
      contentType: 'application/x-www-form-urlencoded;charset=utf-8',
      dataType: 'json'
    }).then((fullText) => {
      if (language === undefined) { // backwards compatibility with old format
        language = fullText.language;
      }

      let label = languages.find(lang => lang.code === language);
      label = label && label.name ? label.name : language;
      label += language === mediaItemLanguage ? ' [CC]' : '';
      label += source === undefined ? '' : ' (auto-generated)';

      const track = player.elem.find('video')[0].addTextTrack('subtitles', label, languages.find(lang => lang.code === language).iso);

      annotationResource.resources.forEach(element => {
        if ((element.dcType === 'Caption') || (element.textGranularity === 'caption')) {
          track.addCue(handleCaption(element, fullText));
        }
      });
    }).then(() => {
      resolve(true);
    });
  });
}

function handleCaption(element, fullText) {
  let characterRange = element.resource['@id'].substring(element.resource['@id'].lastIndexOf('=') + 1);
  let charRange = characterRange.split(',');
  let subtitleString = fullText.value.substring(charRange[0], charRange[1]);
  let timeRange = element.on[0].substring(element.on[0].lastIndexOf('=') + 1);
  let tRange = timeRange.split(',');

  let cue = new VTTCue(timeToSeconds(tRange[0]), timeToSeconds(tRange[1]), subtitleString);
  cue.id = element.resource['@id'];
  cue.line = -4;
  cue.size = 90;

  return cue;
}

function timeToSeconds(time) {
  let [hours, minutes, seconds] = time.split(':');
  hours = parseInt(hours);
  minutes = parseInt(minutes);
  let milliseconds;

  let parts = seconds.lastIndexOf('.') > -1 ? seconds.split('.') : [seconds, 0];
  seconds = parseInt(parts[0]);

  milliseconds = parts[1].length === 2 ? parseInt(parts[1]) * 10 : parseInt(parts[1]);

  return ((hours * 3600) + (minutes * 60) + seconds) + '.' + milliseconds;
}

module.exports = {
  handleTranscriptionAnnotations
};