'use strict';

/**
 * @ngdoc filter
 * @name orderBy
 * @function
 *
 * @description
 * Orders a specified `array` by the `expression` predicate.
 *
 * @param {Array} array The array to sort.
 * @param {function(*)|string|Array.<(function(*)|string)>} expression A predicate to be
 *    used by the comparator to determine the order of elements.
 *
 *    Can be one of:
 *
 *    - `function`: Getter function. The result of this function will be sorted using the
 *      `<`, `=`, `>` operator.
 *    - `string`: An Angular expression which evaluates to an object to order by, such as 'name'
 *      to sort by a property called 'name'. Optionally prefixed with `+` or `-` to control
 *      ascending or descending sort order (for example, +name or -name).
 *    - `Array`: An array of function or string predicates. The first predicate in the array
 *      is used for sorting, but when two items are equivalent, the next predicate is used.
 *
 * @param {boolean=} reverse Reverse the order of the array.
 * @returns {Array} Sorted copy of the source array.
 *
 * @example
   <example>
     <file name="index.html">
       <script>
         function Ctrl($scope) {
           $scope.friends =
               [{name:'John', phone:'555-1212', age:10},
                {name:'Mary', phone:'555-9876', age:19},
                {name:'Mike', phone:'555-4321', age:21},
                {name:'Adam', phone:'555-5678', age:35},
                {name:'Julie', phone:'555-8765', age:29}]
           $scope.predicate = '-age';
         }
       </script>
       <div ng-controller="Ctrl">
         <pre>Sorting predicate = {{predicate}}; reverse = {{reverse}}</pre>
         <hr/>
         [ <a href="" ng-click="predicate=''">unsorted</a> ]
         <table class="friend">
           <tr>
             <th><a href="" ng-click="predicate = 'name'; reverse=false">Name</a>
                 (<a href="" ng-click="predicate = '-name'; reverse=false">^</a>)</th>
             <th><a href="" ng-click="predicate = 'phone'; reverse=!reverse">Phone Number</a></th>
             <th><a href="" ng-click="predicate = 'age'; reverse=!reverse">Age</a></th>
           </tr>
           <tr ng-repeat="friend in friends | orderBy:predicate:reverse">
             <td>{{friend.name}}</td>
             <td>{{friend.phone}}</td>
             <td>{{friend.age}}</td>
           </tr>
         </table>
       </div>
     </file>
   </example>
 */
orderByFilter.$inject = ['$parse'];
function orderByFilter($parse){
  return function(array, sortPredicate, reverseOrder) {
    if (!isArray(array)) return array;
    if (!sortPredicate) return array;
    sortPredicate = isArray(sortPredicate) ? sortPredicate: [sortPredicate];
    sortPredicate = map(sortPredicate, function(predicate){
      var descending = false, get = predicate || identity;
      if (isString(predicate)) {
        if ((predicate.charAt(0) == '+' || predicate.charAt(0) == '-')) {
          descending = predicate.charAt(0) == '-';
          predicate = predicate.substring(1);
        }
        get = $parse(predicate);
        if (get.constant) {
          var key = get();
          return reverseComparator(function(a,b) {
            return compare(a[key], b[key]);
          }, descending);
        }
      }
      return reverseComparator(function(a,b){
        return compare(get(a),get(b));
      }, descending);
    });
    var arrayCopy = [];
    for ( var i = 0; i < array.length; i++) { arrayCopy.push(array[i]); }
    return arrayCopy.sort(reverseComparator(comparator, reverseOrder));

    function comparator(o1, o2){
      for ( var i = 0; i < sortPredicate.length; i++) {
        var comp = sortPredicate[i](o1, o2);
        if (comp !== 0) return comp;
      }
      return 0;
    }
    function reverseComparator(comp, descending) {
      return toBoolean(descending)
          ? function(a,b){return comp(b,a);}
          : comp;
    }
    function compare(v1, v2){
      var t1 = typeof v1;
      var t2 = typeof v2;
      if (t1 == t2) {
        if (t1 == "string") {
           v1 = v1.toLowerCase();
           v2 = v2.toLowerCase();
        }
        if (v1 === v2) return 0;
        return v1 < v2 ? -1 : 1;
      } else {
        return t1 < t2 ? -1 : 1;
      }
    }
  };
}

@@ -138,16 +138,220 @@
 edicate.
+ It is ordered alphabetically%0A * for strings and numerically for numbers. Note: if you notice numbers are not being sorted%0A * correctly, make sure they are actually being saved as numbers and not strings.
 %0A *%0A * @

clarify how sorting is processed