[gnome-shell] calendar: Fix inclusion of zero-length events

[Marge Bot <marge-bot src gnome org>]

commit 225065367381252877bd54e25f7cdb8f71820ff5
Author: Sebastian Keller <skeller gnome org>
Date:   Thu Nov 4 14:09:03 2021 +0100

    calendar: Fix inclusion of zero-length events
    
    Events with a date time (not just a date) where the end time is missing
    or matching the start time were considered to not overlap the selected
    interval if they were happening on the start time of the interval. This
    was causing such zero-length events to be omitted from the calendar if
    they were starting at 0:00.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2023>

 js/ui/calendar.js | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)
---
diff --git a/js/ui/calendar.js b/js/ui/calendar.js
index ad83635589..a42d70ffb2 100644
--- a/js/ui/calendar.js
+++ b/js/ui/calendar.js
@@ -171,13 +171,26 @@ function _datesEqual(a, b) {
     return true;
 }
 
-function _dateIntervalsOverlap(a0, a1, b0, b1) {
-    if (a1 <= b0)
+/**
+ * Checks whether an event overlaps a given interval
+ *
+ * @param {Date} e0 Beginning of the event
+ * @param {Date} e1 End of the event
+ * @param {Date} i0 Beginning of the interval
+ * @param {Date} i1 End of the interval
+ * @returns {boolean} Whether there was an overlap
+ */
+function _eventOverlapsInterval(e0, e1, i0, i1) {
+    // This also ensures zero-length events are included
+    if (e0 >= i0 && e1 < i1)
+        return true;
+
+    if (e1 <= i0)
         return false;
-    else if (b1 <= a0)
+    if (i1 <= e0)
         return false;
-    else
-        return true;
+
+    return true;
 }
 
 // an implementation that reads data from a session bus service
@@ -343,7 +356,7 @@ class DBusEventSource extends EventSourceBase {
 
     *_getFilteredEvents(begin, end) {
         for (const event of this._events.values()) {
-            if (_dateIntervalsOverlap(event.date, event.end, begin, end))
+            if (_eventOverlapsInterval(event.date, event.end, begin, end))
                 yield event;
         }
     }