// Copyright 2017 Google Inc. 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"';

navigator.requestMediaKeySystemAccess('com.widevine.alpha', [{
  'initDataTypes': ['cenc'],
  'videoCapabilities': [{'contentType': videoContentType}],
  'audioCapabilities': [{'contentType': audioContentType}]
}]).then(function(mediaKeySystemAccess) {
  return mediaKeySystemAccess.createMediaKeys();
}).then(function(mediaKeys) {
  var videoElement = document.querySelector('video');

  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-20121114-142.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();
});