'use strict';

/**
 * !!! This is an undocumented "private" service !!!
 *
 * @name ng.$sniffer
 * @requires $window
 * @requires $document
 *
 * @property {boolean} history Does the browser support html5 history api ?
 * @property {boolean} hashchange Does the browser support hashchange event ?
 * @property {boolean} transitions Does the browser support CSS transition events ?
 * @property {boolean} animations Does the browser support CSS animation events ?
 *
 * @description
 * This is very simple implementation of testing browser's features.
 */
function $SnifferProvider() {
  this.$get = ['$window', '$document', function($window, $document) {
    var eventSupport = {},
        android = int((/android (\d+)/.exec(lowercase(($window.navigator || {}).userAgent)) || [])[1]),
        document = $document[0] || {},
        vendorPrefix,
        vendorRegex = /^(Moz|webkit|O|ms)(?=[A-Z])/,
        bodyStyle = document.body && document.body.style,
        transitions = false,
        animations = false,
        match;

    if (bodyStyle) {
      for(var prop in bodyStyle) {
        if(match = vendorRegex.exec(prop)) {
          vendorPrefix = match[0];
          vendorPrefix = vendorPrefix.substr(0, 1).toUpperCase() + vendorPrefix.substr(1);
          break;
        }
      }
      transitions = !!(('transition' in bodyStyle) || (vendorPrefix + 'Transition' in bodyStyle));
      animations  = !!(('animation' in bodyStyle) || (vendorPrefix + 'Animation' in bodyStyle));
      
      if (android && (!transitions||!animations)) {
        transitions = isString(document.body.style.webkitTransition); 
        animations = isString(document.body.style.webkitAnimation); 
      }
    }


    return {
      // Android has history.pushState, but it does not update location correctly
      // so let's not use the history API at all.
      // http://code.google.com/p/android/issues/detail?id=17471
      // https://github.com/angular/angular.js/issues/904
      history: !!($window.history && $window.history.pushState && !(android < 4)),
      hashchange: 'onhashchange' in $window &&
                  // IE8 compatible mode lies
                  (!document.documentMode || document.documentMode > 7),
      hasEvent: function(event) {
        // IE9 implements 'input' event it's so fubared that we rather pretend that it doesn't have
        // it. In particular the event is not fired when backspace or delete key are pressed or
        // when cut operation is performed.
        if (event == 'input' && msie == 9) return false;

        if (isUndefined(eventSupport[event])) {
          var divElm = document.createElement('div');
          eventSupport[event] = 'on' + event in divElm;
        }

        return eventSupport[event];
      },
      csp: document.securityPolicy ? document.securityPolicy.isActive : false,
      vendorPrefix: vendorPrefix,
      transitions : transitions,
      animations : animations
    };
  }];
}
