fix(datepicker): fix OS dependent time zone issue

- Fixes an issue with dates involving different OSes and timezones

Fixes #3079

src/datepicker/datepicker.js

@@ -128,6 +128,17 @@ angular.module('ui.bootstrap.datepicker', ['ui.bootstrap.dateparser', 'ui.bootst
     return arrays;
   };
 
+  // Fix a hard-reprodusible bug with timezones
+  // The bug depends on OS, browser, current timezone and current date
+  // i.e.
+  // var date = new Date(2014, 0, 1);
+  // console.log(date.getFullYear(), date.getMonth(), date.getDate(), date.getHours());
+  // can result in "2013 11 31 23" because of the bug.
+  this.fixTimeZone = function(date) {
+    var hours = date.getHours();
+    date.setHours(hours === 23 ? hours + 2 : 0);
+  };
+
   $scope.select = function( date ) {
     if ( $scope.datepickerMode === self.minMode ) {
       var dt = ngModelCtrl.$viewValue ? new Date( ngModelCtrl.$viewValue ) : new Date(0, 0, 0, 0, 0, 0, 0);
@@ -236,10 +247,11 @@ angular.module('ui.bootstrap.datepicker', ['ui.bootstrap.dateparser', 'ui.bootst
       }
 
       function getDates(startDate, n) {
-        var dates = new Array(n), current = new Date(startDate), i = 0;
-        current.setHours(12); // Prevent repeated dates because of timezone bug
+        var dates = new Array(n), current = new Date(startDate), i = 0, date;
         while ( i < n ) {
-          dates[i++] = new Date(current);
+          date = new Date(current);
+          ctrl.fixTimeZone(date);
+          dates[i++] = date;
           current.setDate( current.getDate() + 1 );
         }
         return dates;
@@ -341,10 +353,13 @@ angular.module('ui.bootstrap.datepicker', ['ui.bootstrap.dateparser', 'ui.bootst
 
       ctrl._refreshView = function() {
         var months = new Array(12),
-            year = ctrl.activeDate.getFullYear();
+            year = ctrl.activeDate.getFullYear(),
+            date;
 
         for ( var i = 0; i < 12; i++ ) {
-          months[i] = angular.extend(ctrl.createDateObject(new Date(year, i, 1), ctrl.formatMonth), {
+          date = new Date(year, i, 1);
+          ctrl.fixTimeZone(date);
+          months[i] = angular.extend(ctrl.createDateObject(date, ctrl.formatMonth), {
             uid: scope.uniqueId + '-' + i
           });
         }
@@ -401,10 +416,12 @@ angular.module('ui.bootstrap.datepicker', ['ui.bootstrap.dateparser', 'ui.bootst
       }
 
       ctrl._refreshView = function() {
-        var years = new Array(range);
+        var years = new Array(range), date;
 
         for ( var i = 0, start = getStartingYear(ctrl.activeDate.getFullYear()); i < range; i++ ) {
-          years[i] = angular.extend(ctrl.createDateObject(new Date(start + i, 0, 1), ctrl.formatYear), {
+          date = new Date(start + i, 0, 1);
+          ctrl.fixTimeZone(date);
+          years[i] = angular.extend(ctrl.createDateObject(date, ctrl.formatYear), {
             uid: scope.uniqueId + '-' + i
           });
         }

src/datepicker/test/datepicker.spec.js

@@ -284,6 +284,33 @@ describe('datepicker directive', function () {
       expect(getTitle()).toBe('January 2014');
     });
 
+    // issue #3079
+    describe('time zone bug', function () {
+
+      it('should deal with time zone bug', function() {
+        var ctrl = element.controller('datepicker'),
+            date = new Date('January 1, 2014');
+        spyOn(date, 'getHours').and.returnValue(23);
+        spyOn(date, 'setHours').and.returnValue();
+
+        ctrl.fixTimeZone(date);
+
+        expect(date.setHours).toHaveBeenCalledWith(25);
+      });
+
+      it('should not change hours if time zone bug does not occur', function() {
+        var ctrl = element.controller('datepicker'),
+            date = new Date('January 1, 2014');
+        spyOn(date, 'getHours').and.returnValue(0);
+        spyOn(date, 'setHours').and.returnValue();
+
+        ctrl.fixTimeZone(date);
+
+        expect(date.setHours).toHaveBeenCalledWith(0);
+      });
+
+    });
+
     describe('when `model` changes', function () {
       function testCalendar() {
         expect(getTitle()).toBe('November 2005');