<!--
@license
Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->

<link rel="import" href="../../polymer/polymer.html">
<link rel="import" href="../neon-shared-element-animation-behavior.html">
<link rel="import" href="../web-animations.html">

<!--
`<hero-animation>` is a shared element animation that scales and transform an element such that it
appears to be shared between two pages. Use this in `<neon-animated-pages>`. The source page
should use this animation in an 'exit' animation and set the `fromPage` configuration property to
itself, and the destination page should use this animation in an `entry` animation and set the
`toPage` configuration property to itself. They should also define the hero elements in the
`sharedElements` property (not a configuration property, see
`Polymer.NeonSharedElementAnimatableBehavior`).

Configuration:
```
{
  name: 'hero-animation',
  id: <shared-element-id>,
  timing: <animation-timing>,
  toPage: <node>, /* define for the destination page */
  fromPage: <node>, /* define for the source page */
}
```
-->

<script>

  Polymer({

    is: 'hero-animation',

    behaviors: [
      Polymer.NeonSharedElementAnimationBehavior
    ],

    configure: function(config) {
      var shared = this.findSharedElements(config);
      if (!shared) {
        return;
      }

      var fromRect = shared.from.getBoundingClientRect();
      var toRect = shared.to.getBoundingClientRect();

      var deltaLeft = fromRect.left - toRect.left;
      var deltaTop = fromRect.top - toRect.top;
      var deltaWidth = fromRect.width / toRect.width;
      var deltaHeight = fromRect.height / toRect.height;

      this.setPrefixedProperty(shared.to, 'transformOrigin', '0 0');
      shared.to.style.zIndex = 10000;
      shared.from.style.visibility = 'hidden';

      this._effect = new KeyframeEffect(shared.to, [
        {'transform': 'translate(' + deltaLeft + 'px,' + deltaTop + 'px) scale(' + deltaWidth + ',' + deltaHeight + ')'},
        {'transform': 'none'}
      ], this.timingFromConfig(config));

      return this._effect;
    },

    complete: function(config) {
      var shared = this.findSharedElements(config);
      if (!shared) {
        return null;
      }
      shared.to.style.zIndex = '';
      shared.from.style.visibility = '';
    }

  });

</script>