Fix: Navigation to invisible days of week in VAADIN calendar (#12243)

Some changes in BasicBackwardHandler and BasicForwardHandler.
Also test was added (CalendarBackwardForwardTest).
Changes after review.

Change-Id: Ibe0283534b784e3c18134619e1843440ca74e65c

2 files changed, 32 insertions, 0 deletions

diff --git a/server/src/com/vaadin/ui/components/calendar/handler/BasicBackwardHandler.java b/server/src/com/vaadin/ui/components/calendar/handler/BasicBackwardHandler.java
index f4d47f89d4..0e99b26856 100644
--- a/server/src/com/vaadin/ui/components/calendar/handler/BasicBackwardHandler.java
+++ b/server/src/com/vaadin/ui/components/calendar/handler/BasicBackwardHandler.java
@@ -47,6 +47,7 @@ public class BasicBackwardHandler implements BackwardHandler {
         // calculate amount to move back
         int durationInDays = (int) (((end.getTime()) - start.getTime()) / DateConstants.DAYINMILLIS);
         durationInDays++;
+        // for week view durationInDays = -7, for day view durationInDays = -1
         durationInDays = -durationInDays;
 
         // set new start and end times
@@ -59,6 +60,21 @@ public class BasicBackwardHandler implements BackwardHandler {
         javaCalendar.add(java.util.Calendar.DATE, durationInDays);
         Date newEnd = javaCalendar.getTime();
 
+        if (start.equals(end)) { // day view
+            int firstDay = event.getComponent().getFirstVisibleDayOfWeek();
+            int lastDay = event.getComponent().getLastVisibleDayOfWeek();
+            int dayOfWeek = javaCalendar.get(Calendar.DAY_OF_WEEK);
+
+            // we suppose that 7 >= lastDay >= firstDay >= 1
+            while (!(firstDay <= dayOfWeek && dayOfWeek <= lastDay)) {
+                javaCalendar.add(java.util.Calendar.DATE, -1);
+                dayOfWeek = javaCalendar.get(Calendar.DAY_OF_WEEK);
+            }
+
+            newStart = javaCalendar.getTime();
+            newEnd = javaCalendar.getTime();
+        }
+
         setDates(event, newStart, newEnd);
     }
 
diff --git a/server/src/com/vaadin/ui/components/calendar/handler/BasicForwardHandler.java b/server/src/com/vaadin/ui/components/calendar/handler/BasicForwardHandler.java
index 96c3c097dc..45b44cb673 100644
--- a/server/src/com/vaadin/ui/components/calendar/handler/BasicForwardHandler.java
+++ b/server/src/com/vaadin/ui/components/calendar/handler/BasicForwardHandler.java
@@ -45,6 +45,7 @@ public class BasicForwardHandler implements ForwardHandler {
 
         // calculate amount to move forward
         int durationInDays = (int) (((end.getTime()) - start.getTime()) / DateConstants.DAYINMILLIS);
+        // for week view durationInDays = 7, for day view durationInDays = 1
         durationInDays++;
 
         // set new start and end times
@@ -57,6 +58,21 @@ public class BasicForwardHandler implements ForwardHandler {
         javaCalendar.add(java.util.Calendar.DATE, durationInDays);
         Date newEnd = javaCalendar.getTime();
 
+        if (start.equals(end)) { // day view
+            int firstDay = event.getComponent().getFirstVisibleDayOfWeek();
+            int lastDay = event.getComponent().getLastVisibleDayOfWeek();
+            int dayOfWeek = javaCalendar.get(Calendar.DAY_OF_WEEK);
+
+            // we suppose that 7 >= lastDay >= firstDay >= 1
+            while (!(firstDay <= dayOfWeek && dayOfWeek <= lastDay)) {
+                javaCalendar.add(java.util.Calendar.DATE, 1);
+                dayOfWeek = javaCalendar.get(Calendar.DAY_OF_WEEK);
+            }
+
+            newStart = javaCalendar.getTime();
+            newEnd = javaCalendar.getTime();
+        }
+
         setDates(event, newStart, newEnd);
     }