fix(datepicker): disable title button when in max mode

When the calendar is in the maximum configured mode, clicking the title
button has no effect.  To convey this to users, make the non-functional
button non-clickable, and take the button out of focus order, disable
the button when in the maximum mode.

Closes #3012

src/datepicker/datepicker.js

@@ -44,6 +44,7 @@ angular.module('ui.bootstrap.datepicker', ['ui.bootstrap.dateparser', 'ui.bootst
   });
 
   $scope.datepickerMode = $scope.datepickerMode || datepickerConfig.datepickerMode;
+  $scope.maxMode = self.maxMode;
   $scope.uniqueId = 'datepicker-' + $scope.$id + '-' + Math.floor(Math.random() * 10000);
 
   if(angular.isDefined($attrs.initDate)) {

src/datepicker/test/datepicker.spec.js

@@ -32,12 +32,16 @@ describe('datepicker directive', function () {
     $rootScope.date = new Date('September 30, 2010 15:30:00');
   }));
 
+  function getTitleButton() {
+    return element.find('th').eq(1).find('button').first();
+  }
+
   function getTitle() {
-    return element.find('th').eq(1).find('button').first().text();
+    return getTitleButton().text();
   }
 
   function clickTitleButton() {
-    element.find('th').eq(1).find('button').first().click();
+    getTitleButton().click();
   }
 
   function clickPreviousButton(times) {
@@ -1905,6 +1909,14 @@ describe('datepicker directive', function () {
       clickTitleButton();
       expect(getTitle()).toBe('2013');
     });
+
+    it('disables the title button at it', function() {
+      expect(getTitleButton().prop('disabled')).toBe(false);
+      clickTitleButton();
+      expect(getTitleButton().prop('disabled')).toBe(true);
+      clickTitleButton();
+      expect(getTitleButton().prop('disabled')).toBe(true);
+    });
   });
 
   describe('with an ngModelController having formatters and parsers', function() {

template/datepicker/day.html

@@ -2,7 +2,7 @@
   <thead>
     <tr>
       <th><button type="button" class="btn btn-default btn-sm pull-left" ng-click="move(-1)" tabindex="-1"><i class="glyphicon glyphicon-chevron-left"></i></button></th>
-      <th colspan="{{5 + showWeeks}}"><button id="{{uniqueId}}-title" role="heading" aria-live="assertive" aria-atomic="true" type="button" class="btn btn-default btn-sm" ng-click="toggleMode()" tabindex="-1" style="width:100%;"><strong>{{title}}</strong></button></th>
+      <th colspan="{{5 + showWeeks}}"><button id="{{uniqueId}}-title" role="heading" aria-live="assertive" aria-atomic="true" type="button" class="btn btn-default btn-sm" ng-click="toggleMode()" ng-disabled="datepickerMode === maxMode" tabindex="-1" style="width:100%;"><strong>{{title}}</strong></button></th>
       <th><button type="button" class="btn btn-default btn-sm pull-right" ng-click="move(1)" tabindex="-1"><i class="glyphicon glyphicon-chevron-right"></i></button></th>
     </tr>
     <tr>

template/datepicker/month.html

@@ -2,7 +2,7 @@
   <thead>
     <tr>
       <th><button type="button" class="btn btn-default btn-sm pull-left" ng-click="move(-1)" tabindex="-1"><i class="glyphicon glyphicon-chevron-left"></i></button></th>
-      <th><button id="{{uniqueId}}-title" role="heading" aria-live="assertive" aria-atomic="true" type="button" class="btn btn-default btn-sm" ng-click="toggleMode()" tabindex="-1" style="width:100%;"><strong>{{title}}</strong></button></th>
+      <th><button id="{{uniqueId}}-title" role="heading" aria-live="assertive" aria-atomic="true" type="button" class="btn btn-default btn-sm" ng-click="toggleMode()" ng-disabled="datepickerMode === maxMode" tabindex="-1" style="width:100%;"><strong>{{title}}</strong></button></th>
       <th><button type="button" class="btn btn-default btn-sm pull-right" ng-click="move(1)" tabindex="-1"><i class="glyphicon glyphicon-chevron-right"></i></button></th>
     </tr>
   </thead>

template/datepicker/year.html

@@ -2,7 +2,7 @@
   <thead>
     <tr>
       <th><button type="button" class="btn btn-default btn-sm pull-left" ng-click="move(-1)" tabindex="-1"><i class="glyphicon glyphicon-chevron-left"></i></button></th>
-      <th colspan="3"><button id="{{uniqueId}}-title" role="heading" aria-live="assertive" aria-atomic="true" type="button" class="btn btn-default btn-sm" ng-click="toggleMode()" tabindex="-1" style="width:100%;"><strong>{{title}}</strong></button></th>
+      <th colspan="3"><button id="{{uniqueId}}-title" role="heading" aria-live="assertive" aria-atomic="true" type="button" class="btn btn-default btn-sm" ng-click="toggleMode()" ng-disabled="datepickerMode === maxMode" tabindex="-1" style="width:100%;"><strong>{{title}}</strong></button></th>
       <th><button type="button" class="btn btn-default btn-sm pull-right" ng-click="move(1)" tabindex="-1"><i class="glyphicon glyphicon-chevron-right"></i></button></th>
     </tr>
   </thead>