feat(datepicker): add keyboard navigation

The following shortcuts are available:
Arrow left/right: previous/next day
Arrow up/down: previous/next week
Page up/down: previous/next month
Shift+page up/down: previous/next year
Home/end: beginning/end of the current view
Shift+home/end: min/max selectable date

demo/src/app/components/datepicker/demos/customday/datepicker-customday.html

@@ -12,8 +12,8 @@
   </div>
 </form>
 
-<ng-template #customDay let-date="date" let-currentMonth="currentMonth" let-selected="selected" let-disabled="disabled">
-  <span class="custom-day" [class.weekend]="isWeekend(date)"
+<ng-template #customDay let-date="date" let-currentMonth="currentMonth" let-selected="selected" let-disabled="disabled" let-focused="focused">
+  <span class="custom-day" [class.weekend]="isWeekend(date)" [class.focused]="focused"
         [class.bg-primary]="selected" [class.hidden]="date.month !== currentMonth" [class.text-muted]="disabled">
     {{ date.day }}
   </span>

demo/src/app/components/datepicker/demos/customday/datepicker-customday.ts

@@ -12,7 +12,7 @@ import {NgbDateStruct} from '@ng-bootstrap/ng-bootstrap';
       display: inline-block;
       width: 2rem;
     }
-    .custom-day:hover {
+    .custom-day:hover, .custom-day.focused {
       background-color: #e6e6e6;
     }
     .weekend {

src/datepicker/datepicker-day-template-context.ts

@@ -18,6 +18,11 @@ export interface DayTemplateContext {
    */
   disabled: boolean;
 
+  /**
+   * True if current date is focused
+   */
+  focused: boolean;
+
   /**
    * True if current date is selected
    */

src/datepicker/datepicker-day-view.ts

@@ -20,14 +20,16 @@ import {NgbDateStruct} from './ngb-date-struct';
     '[class.text-white]': 'selected',
     '[class.text-muted]': 'isMuted()',
     '[class.outside]': 'isMuted()',
-    '[class.btn-secondary]': '!disabled'
+    '[class.btn-secondary]': 'true',
+    '[class.active]': 'focused'
   },
   template: `{{ date.day }}`
 })
 export class NgbDatepickerDayView {
   @Input() currentMonth: number;
   @Input() date: NgbDateStruct;
   @Input() disabled: boolean;
+  @Input() focused: boolean;
   @Input() selected: boolean;
 
   isMuted() { return !this.selected && (this.date.month !== this.currentMonth || this.disabled); }

src/datepicker/datepicker-month-view.ts

@@ -13,7 +13,7 @@ import {DayTemplateContext} from './datepicker-day-template-context';
     }
     .ngb-dp-day, .ngb-dp-weekday, .ngb-dp-week-number {
       width: 2rem;
-      height: 2rem;      
+      height: 2rem;
     }
     .ngb-dp-day {
       cursor: pointer;
@@ -37,6 +37,10 @@ import {DayTemplateContext} from './datepicker-day-template-context';
           <ng-template [ngIf]="!isHidden(day)">
             <ng-template [ngTemplateOutlet]="dayTemplate"
             [ngOutletContext]="_getDayContext(day, month)">
+              currentMonth: month.number,
+              disabled: isDisabled(day),
+              focused: isFocused(day.date),
+              selected: isSelected(day.date)}">
             </ng-template>
           </ng-template>
         </div>
@@ -47,6 +51,7 @@ import {DayTemplateContext} from './datepicker-day-template-context';
 export class NgbDatepickerMonthView {
   @Input() dayTemplate: TemplateRef<DayTemplateContext>;
   @Input() disabled: boolean;
+  @Input() focusedDate: NgbDate;
   @Input() month: MonthViewModel;
   @Input() outsideDays: 'visible' | 'hidden' | 'collapsed';
   @Input() selectedDate: NgbDate;
@@ -72,16 +77,20 @@ export class NgbDatepickerMonthView {
     };
   }
 
-  isDisabled(day: DayViewModel) { return this.disabled || day.disabled; }
-
-  isSelected(date: NgbDate) { return this.selectedDate && this.selectedDate.equals(date); }
-
   isCollapsed(week: WeekViewModel) {
     return this.outsideDays === 'collapsed' && week.days[0].date.month !== this.month.number &&
         week.days[week.days.length - 1].date.month !== this.month.number;
   }
 
+  isDisabled(day: DayViewModel) { return this.disabled || day.disabled; }
+
+  isFocused(date: NgbDate) {
+    return !!(this.focusedDate && this.focusedDate.equals(date) && this.month.number === date.month);
+  }
+
   isHidden(day: DayViewModel) {
     return (this.outsideDays === 'hidden' || this.outsideDays === 'collapsed') && this.month.number !== day.date.month;
   }
+
+  isSelected(date: NgbDate) { return !!(this.selectedDate && this.selectedDate.equals(date)); }
 }

src/datepicker/datepicker-navigation-select.ts

@@ -18,11 +18,20 @@ import {NgbCalendar} from './ngb-calendar';
     }
   `],
   template: `
-    <select [disabled]="disabled" class="custom-select d-inline-block" [value]="date?.month" (change)="changeMonth($event.target.value)">
-      <option *ngFor="let m of months" [value]="m">{{ i18n.getMonthShortName(m) }}</option>
-    </select>` +
-      `<select [disabled]="disabled" class="custom-select d-inline-block" [value]="date?.year" (change)="changeYear($event.target.value)">
-      <option *ngFor="let y of years" [value]="y">{{ y }}</option>
+    <select
+      [disabled]="disabled"
+      class="custom-select d-inline-block"
+      [value]="date?.month"
+      (change)="changeMonth($event.target.value)"
+      tabindex="-1">
+        <option *ngFor="let m of months" [value]="m">{{ i18n.getMonthShortName(m) }}</option>
+    </select><select
+      [disabled]="disabled"
+      class="custom-select d-inline-block"
+      [value]="date?.year"
+      (change)="changeYear($event.target.value)"
+      tabindex="-1">
+        <option *ngFor="let y of years" [value]="y">{{ y }}</option>
     </select> 
   `  // template needs to be formatted in a certain way so we don't add empty text nodes
 })

src/datepicker/datepicker-navigation.ts

@@ -43,7 +43,7 @@ import {NgbCalendar} from './ngb-calendar';
     }    
   `],
   template: `
-    <button type="button" class="btn-link" (click)="!!doNavigate(navigation.PREV)" [disabled]="prevDisabled()">
+    <button type="button" class="btn-link" (click)="!!doNavigate(navigation.PREV)" [disabled]="prevDisabled()" tabindex="-1">
       <span class="ngb-dp-navigation-chevron"></span>    
     </button>
     
@@ -55,7 +55,7 @@ import {NgbCalendar} from './ngb-calendar';
       (select)="selectDate($event)">
     </ngb-datepicker-navigation-select>
     
-    <button type="button" class="btn-link" (click)="!!doNavigate(navigation.NEXT)" [disabled]="nextDisabled()">
+    <button type="button" class="btn-link" (click)="!!doNavigate(navigation.NEXT)" [disabled]="nextDisabled()" tabindex="-1">
       <span class="ngb-dp-navigation-chevron right"></span>
     </button>
   `

src/datepicker/datepicker.spec.ts

@@ -2,7 +2,7 @@ import {TestBed, ComponentFixture, async, inject} from '@angular/core/testing';
 import {createGenericTestComponent} from '../test/common';
 import {getMonthSelect, getYearSelect, getNavigationLinks} from '../test/datepicker/common';
 
-import {Component, TemplateRef} from '@angular/core';
+import {Component, TemplateRef, DebugElement} from '@angular/core';
 import {By} from '@angular/platform-browser';
 import {FormsModule, ReactiveFormsModule, FormGroup, FormControl, Validators} from '@angular/forms';
 
@@ -13,6 +13,7 @@ import {NgbDatepicker} from './datepicker';
 import {DayTemplateContext} from './datepicker-day-template-context';
 import {NgbDateStruct} from './ngb-date-struct';
 import {NgbDatepickerMonthView} from './datepicker-month-view';
+import {NgbDatepickerDayView} from './datepicker-day-view';
 import {NgbDatepickerNavigationSelect} from './datepicker-navigation-select';
 import {NgbDatepickerNavigation} from './datepicker-navigation';
 
@@ -31,6 +32,36 @@ function getDatepicker(element: HTMLElement): HTMLElement {
   return element.querySelector('ngb-datepicker') as HTMLElement;
 }
 
+function triggerKeyDown(element: DebugElement, keyCode: number, shiftKey = false) {
+  let event = {
+    keyCode: keyCode,
+    shiftKey: shiftKey,
+    defaultPrevented: false,
+    propagationStopped: false,
+    stopPropagation: function() { this.propagationStopped = true; },
+    preventDefault: function() { this.defaultPrevented = true; }
+  };
+  element.triggerEventHandler('keydown', event);
+  return event;
+}
+
+function expectFilteredDaysToBe(
+    element: DebugElement, expectedDates: NgbDate[],
+    filterFn: (dayView: NgbDatepickerDayView, element: DebugElement) => boolean) {
+  const days = element.queryAll(By.directive(NgbDatepickerDayView))
+                   .filter((day: DebugElement) => { return filterFn(day.componentInstance, day); })
+                   .map((value: DebugElement) => NgbDate.from(value.componentInstance.date));
+  expect(days).toEqual(expectedDates);
+}
+
+function expectSelectedDate(element: DebugElement, date: NgbDate) {
+  expectFilteredDaysToBe(element, date ? [date] : [], (dayView: NgbDatepickerDayView) => dayView.selected);
+}
+
+function expectFocusedDate(element: DebugElement, date: NgbDate) {
+  expectFilteredDaysToBe(element, date ? [date] : [], (dayView: NgbDatepickerDayView) => dayView.focused);
+}
+
 function expectSameValues(datepicker: NgbDatepicker, config: NgbDatepickerConfig) {
   expect(datepicker.dayTemplate).toBe(config.dayTemplate);
   expect(datepicker.displayMonths).toBe(config.displayMonths);
@@ -541,6 +572,143 @@ describe('ngb-datepicker', () => {
       expect(getYearSelect(fixture.nativeElement).value).toBe(`${today.getFullYear()}`);
     });
 
+    it('should correctly navigate with keyboard', () => {
+      const fixture = createTestComponent(`<ngb-datepicker #dp
+        [startDate]="date" [minDate]="minDate"
+        [maxDate]="maxDate" [displayMonths]="2"
+        [markDisabled]="markDisabled"></ngb-datepicker>`);
+
+      const datepicker = fixture.debugElement.query(By.directive(NgbDatepicker));
+      expectFocusedDate(datepicker, null);
+      expectSelectedDate(datepicker, null);
+
+      datepicker.triggerEventHandler('focus', {});
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 1));
+      expectSelectedDate(datepicker, null);
+
+      triggerKeyDown(datepicker, 40 /* down arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 8));
+      expectSelectedDate(datepicker, null);
+
+      triggerKeyDown(datepicker, 32 /* space */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 8));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 8));
+
+      triggerKeyDown(datepicker, 39 /* right arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 9));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 8));
+
+      triggerKeyDown(datepicker, 38 /* up arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 2));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 8));
+
+      triggerKeyDown(datepicker, 37 /* left arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 1));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 8));
+
+      triggerKeyDown(datepicker, 33 /* page up */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 7, 1));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 8));
+
+      triggerKeyDown(datepicker, 35 /* end */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 31));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 8));
+
+      triggerKeyDown(datepicker, 13 /* enter */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 31));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));
+
+      triggerKeyDown(datepicker, 36 /* home */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 7, 1));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));
+
+      triggerKeyDown(datepicker, 33 /* page up */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 6, 1));
+      expectSelectedDate(datepicker, null);  // selection is no longer visible
+
+      triggerKeyDown(datepicker, 34 /* page down */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 7, 1));
+      expectSelectedDate(datepicker, null);  // selection is still no longer visible
+
+      triggerKeyDown(datepicker, 35 /* end */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 7, 31));
+      expectSelectedDate(datepicker, null);  // selection is still no longer visible
+
+      triggerKeyDown(datepicker, 39 /* right arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 1));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));  // selection is visible again
+
+      triggerKeyDown(datepicker, 40 /* down arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 8));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));
+
+      triggerKeyDown(datepicker, 40 /* down arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 15));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));
+
+      triggerKeyDown(datepicker, 40 /* down arrow */);
+      fixture.detectChanges();
+      // we can reach the disabled date
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 22));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));
+
+      triggerKeyDown(datepicker, 32 /* space */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 22));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));  // space on a disabled date does not select it
+
+      triggerKeyDown(datepicker, 13 /* enter */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2016, 8, 22));
+      expectSelectedDate(datepicker, new NgbDate(2016, 8, 31));  // enter on a disabled date does not select it
+
+      triggerKeyDown(datepicker, 35 /* end */, true /* with shift */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2020, 12, 31));  // maximum date
+      expectSelectedDate(datepicker, null);                      // selection is again no longer visible
+
+      triggerKeyDown(datepicker, 39 /* right arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2020, 12, 31));  // stays at the maximum date
+
+      triggerKeyDown(datepicker, 36 /* home */, true /* with shift */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2010, 1, 1));  // minimum date
+
+      triggerKeyDown(datepicker, 37 /* left arrow */);
+      fixture.detectChanges();
+      expectFocusedDate(datepicker, new NgbDate(2010, 1, 1));  // stays at the minimum date
+
+      triggerKeyDown(datepicker, 34 /* page down */, true /* with shift */);
+      fixture.detectChanges();
+
+      expectFocusedDate(datepicker, new NgbDate(2011, 1, 1));
+      triggerKeyDown(datepicker, 33 /* page up */, true /* with shift */);
+      fixture.detectChanges();
+
+      expectFocusedDate(datepicker, new NgbDate(2010, 1, 1));
+      datepicker.triggerEventHandler('blur', {});
+      fixture.detectChanges();
+
+      expectFocusedDate(datepicker, null);
+    });
+
     it('should support disabling all dates and navigation via the disabled attribute', async(() => {
          const fixture = createTestComponent(
              `<ngb-datepicker [(ngModel)]="model" [startDate]="date" [disabled]="true"></ngb-datepicker>`);