// Copyright 2023 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

function fetchArrayBuffer(method, url, body, callback) {
  var xhr = new XMLHttpRequest();
  xhr.responseType = 'arraybuffer';
  xhr.addEventListener('load', function() {
    callback(xhr.response);
  });
  xhr.open(method, url);
  xhr.send(body);
}

function extractLicense(licenseArrayBuffer) {
  var licenseArray = new Uint8Array(licenseArrayBuffer);
  var licenseStartIndex = licenseArray.length - 2;
  while (licenseStartIndex >= 0) {
    if (licenseArray[licenseStartIndex] == 13 &&
        licenseArray[licenseStartIndex + 1] == 10) {
      licenseStartIndex += 2;
      break;
    }
    --licenseStartIndex;
  }

  return licenseArray.subarray(licenseStartIndex);
}

var videoContentType = 'video/mp4; codecs="avc1.640028"';
var audioContentType = 'audio/mp4; codecs="mp4a.40.2"';

function play(videoElementId, keySystem) {
  navigator.requestMediaKeySystemAccess(keySystem, [{
    'initDataTypes': ['cenc'],
    'videoCapabilities': [{'contentType': videoContentType}],
    'audioCapabilities': [{'contentType': audioContentType}]
  }]).then(function(mediaKeySystemAccess) {
    return mediaKeySystemAccess.createMediaKeys();
  }).then(function(mediaKeys) {
    var videoElement = document.getElementById(videoElementId);

    if (videoElementId != 'primary-video') {
      videoElement.setMaxVideoCapabilities('width=1280; height=720');
    }

    if (mediaKeys.getMetrics) {
      console.log('Found getMetrics(), calling it ...');
      try {
        mediaKeys.getMetrics();
        console.log('Calling getMetrics() succeeded.');
      } catch(e) {
        console.log('Calling getMetrics() failed.');
      }
    }

    videoElement.setMediaKeys(mediaKeys);

    mediaKeySession = mediaKeys.createSession();
    mediaKeySession.addEventListener('message', function(messageEvent) {
      var licenseServerUrl = 'https://dash-mse-test.appspot.com/api/drm/widevine?drm_system=widevine&source=YOUTUBE&ip=0.0.0.0&ipbits=0&expire=19000000000&key=test_key1&sparams=ip,ipbits,expire,drm_system,source,video_id&video_id=03681262dc412c06&signature=9C4BE99E6F517B51FED1F0B3B31966D3C5DAB9D6.6A1F30BB35F3A39A4CA814B731450D4CBD198FFD';
      fetchArrayBuffer('POST', licenseServerUrl, messageEvent.message,
          function(licenseArrayBuffer) {
            mediaKeySession.update(extractLicense(licenseArrayBuffer));
          });
    });

    videoElement.addEventListener('encrypted', function(encryptedEvent) {
      mediaKeySession.generateRequest(
          encryptedEvent.initDataType, encryptedEvent.initData);
    });

    var mediaSource = new MediaSource();
    mediaSource.addEventListener('sourceopen', function() {
      var videoSourceBuffer = mediaSource.addSourceBuffer(videoContentType);
      fetchArrayBuffer('GET',
                      'http://yt-dash-mse-test.commondatastorage.googleapis.com/media/oops_cenc-20121114-145-no-clear-start.mp4',
                      null,
                      function(videoArrayBuffer) {
        videoSourceBuffer.appendBuffer(videoArrayBuffer);
      });

      var audioSourceBuffer = mediaSource.addSourceBuffer(audioContentType);
      fetchArrayBuffer('GET',
                      'http://yt-dash-mse-test.commondatastorage.googleapis.com/media/oops_cenc-20121114-148.mp4',
                      null,
                      function(audioArrayBuffer) {
        audioSourceBuffer.appendBuffer(audioArrayBuffer);
      });
    });

    videoElement.src = URL.createObjectURL(mediaSource);
    videoElement.play();
  });
}

play('primary-video', 'com.widevine.alpha');
window.setTimeout(function() {
  play('secondary-video-1', 'com.youtube.widevine.l3');
}, 10000);
window.setTimeout(function() {
  play('secondary-video-2', 'com.youtube.widevine.l3');
}, 20000);
window.setTimeout(function() {
  play('secondary-video-3', 'com.youtube.widevine.l3');
}, 30000);