<!--
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">

<!--
`iron-media-query` can be used to data bind to a CSS media query.
The `query` property is a bare CSS media query.
The `query-matches` property is a boolean representing whether the page matches that media query.

Example:

    <iron-media-query query="(min-width: 600px)" query-matches="{{queryMatches}}"></iron-media-query>

@group Iron Elements
@demo demo/index.html
@hero hero.svg
@element iron-media-query
-->

<script>

  Polymer({

    is: 'iron-media-query',

    properties: {

      /**
       * The Boolean return value of the media query.
       */
      queryMatches: {
        type: Boolean,
        value: false,
        readOnly: true,
        notify: true
      },

      /**
       * The CSS media query to evaluate.
       */
      query: {
        type: String,
        observer: 'queryChanged'
      }

    },

    created: function() {
      this._mqHandler = this.queryHandler.bind(this);
    },

    queryChanged: function(query) {
      if (this._mq) {
        this._mq.removeListener(this._mqHandler);
      }
      if (query[0] !== '(') {
        query = '(' + query + ')';
      }
      this._mq = window.matchMedia(query);
      this._mq.addListener(this._mqHandler);
      this.queryHandler(this._mq);
    },

    queryHandler: function(mq) {
      this._setQueryMatches(mq.matches);
    }

  });

</script>