ng-ScrollSpy.js support for custom element

/* ng-ScrollSpy.js v3.2.1
 * https://github.com/patrickmarabeas/ng-ScrollSpy.js
 *
 * Copyright 2014, Patrick Marabeas http://marabeas.io
 * Released under the MIT license
 * http://opensource.org/licenses/mit-license.php
 *
 * Date: 31/01/2015
 */

;(function(window, document, angular, undefined) {
  'use strict';
  angular.module('ngScrollSpy', [])

    .value('config', {
      'offset': 200,
      'delay': 100,
      'element': window
    })

    .run(['config', 'PositionFactory', function(config, PositionFactory) {
        angular.element(window).bind('load', function () {
            PositionFactory.refreshPositions();
            angular.element(document.getElementById('main')).bind('scroll', function() {
                PositionFactory.refreshPositions();
            });
        });
    }])

    .factory('PositionFactory', ['config', '$rootScope', function(config, $rootScope){
      return {
        'position': [],
        'refreshPositions': function() {
          this.position.documentHeight = Math.max(config.element.scrollHeight, config.element.offsetHeight, config.element.clientHeight);
          if (config.element.pageYOffset) {
              this.position.windowTop = config.element.pageYOffset;
          } else if (config.element.scrollTop) {
              this.position.windowTop = config.element.scrollTop;
          } else {
              this.position.windowTop = (document.documentElement || document.body.parentNode || document.body).scrollTop;
          }
          this.position.windowBottom = this.position.windowTop + window.innerHeight
        }
      }
    }])

    .factory('SpyFactory', ['$rootScope', function($rootScope){
      return {
        'spies': [],
        'addSpy': function(id) {
          var index = this.spies.map(function(e) { return e }).indexOf(id);
          if(index == -1) {
            this.spies.push(id);
            this.broadcast();
          }
        },
        'removeSpy': function(id) {
          var index = this.spies.map(function(e) { return e }).indexOf(id);
          if(index != -1) {
            this.spies.splice(index, 1);
            this.broadcast();
          }
        },
        'broadcast': function() {
          $rootScope.$broadcast('spied');
        }
      }
    }])

    .directive('scrollspyBroadcast', ['config', 'scrollspyConfig', 'SpyFactory', 'PositionFactory', function(config, scrollspyConfig, SpyFactory, PositionFactory) {
      return {
        restrict: 'A',
        scope: true,
        link: function(scope, element, attrs) {
          angular.extend(config, scrollspyConfig.config);
          var offset = parseInt(attrs.scrollspyOffset || config.offset);
          scope.checkActive = function() {
            scope.elementTop = element[0].offsetTop;
            scope.elementBottom = scope.elementTop + Math.max(element[0].scrollHeight, element[0].offsetHeight);

            if((scope.elementTop - offset) < (PositionFactory.position.documentHeight - window.innerHeight)) {
              if(scope.elementTop <= (PositionFactory.position.windowTop + offset)) {
                SpyFactory.addSpy(attrs.id);
              } else {
                SpyFactory.removeSpy(attrs.id);
              }

            } else {
              if(PositionFactory.position.windowBottom > (scope.elementBottom - offset)) {
                SpyFactory.addSpy(attrs.id);
              } else {
                SpyFactory.removeSpy(attrs.id);
              }
            }
          };

          config.throttle
            ? angular.element(config.element).bind('scroll', config.throttle(function() { scope.checkActive() }, config.delay))
            : angular.element(config.element).bind('scroll', function() { scope.checkActive() });

          angular.element(document).ready( function() { scope.checkActive() });
          angular.element(window).bind('resize', function () { scope.checkActive() });
        }
      }
    }])

    .directive('scrollspyListen', ['config', '$timeout', 'SpyFactory', function(config, $timeout, SpyFactory) {
      return {
        restrict: 'A',
        scope: {
          scrollspyListen: '@',
          enabled: '@'
        },
        replace: true,
        transclude: true,
        template: function(element) {
          var tag = element[0].nodeName;
          return '<' + tag + ' data-ng-transclude data-ng-class="{active: enabled}"></' + tag + '>';
        },
        link: function(scope) {
          scope.$on('spied', function() {
            $timeout(function() {
              var spies = scope.scrollspyListen.split("|");
              for(var i = 0; i < spies.length; i++)
                if(scope.enabled = spies[i] === SpyFactory.spies[SpyFactory.spies.length - 1])
                  break;
            });
          });
        }
      }
    }])

    .provider('scrollspyConfig', function() {
      var self = this;
      this.config = {};
      this.$get = function() {
        var extend = {};
        extend.config = self.config;
        return extend;
      };
      return this;
    });

})(window, document, angular);