timeline: Handle multiday events in calculate_changed_events

This patch do not sends ADD_EVENT for events that are multiday and are
part of the old_range when calling calculate_changed_events. This will
prevent multiday duplicate events to appear in the agenda widget when
using the week view.

If the event is a multiday and it was in the previous range, it won't
send the REMOVE_EVENT so multiday events won't dissapear when it's still
relevant.

See https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/898#note_1602391

src/core/gcal-event.c

@@ -1929,3 +1929,21 @@ gcal_event_format_date (GcalEvent *self)
 
   return g_steal_pointer (&formatted_string);
 }
+
+/**
+ * gcal_event_overlaps:
+ * @self: a #GcalEvent
+ * @range: a #GcalRange
+ *
+ * Returns: True if the event range overlaps the @range
+ */
+gboolean
+gcal_event_overlaps (GcalEvent *self,
+                     GcalRange *range)
+{
+  GcalRangeOverlap overlap;
+
+  g_return_val_if_fail (GCAL_IS_EVENT (self), FALSE);
+  overlap = gcal_range_calculate_overlap (gcal_event_get_range (self), range, NULL);
+  return overlap != GCAL_RANGE_NO_OVERLAP;
+}

src/core/gcal-event.h

@@ -136,6 +136,9 @@ void                 gcal_event_get_original_timezones           (GcalEvent
 
 gchar*               gcal_event_format_date                      (GcalEvent          *self);
 
+gboolean             gcal_event_overlaps                         (GcalEvent          *self,
+                                                                  GcalRange          *range);
+
 G_END_DECLS
 
 #endif /* GCAL_EVENT_H */

src/core/gcal-timeline.c

@@ -411,6 +411,9 @@ calculate_changed_events (GcalTimeline            *self,
   for (i = 0; events_to_remove && i < events_to_remove->len; i++)
     {
       GcalEvent *event = g_ptr_array_index (events_to_remove, i);
+      /* Do not re-remove multiday events that are part of new range */
+      if (gcal_event_is_multiday (event) && gcal_event_overlaps (event, new_range))
+        continue;
 
       GCAL_TRACE_MSG ("Removing event from subscriber %s due to time range change (event: '%s' (%s))",
                       G_OBJECT_TYPE_NAME (subscriber),
@@ -423,6 +426,9 @@ calculate_changed_events (GcalTimeline            *self,
   for (i = 0; events_to_add && i < events_to_add->len; i++)
     {
       GcalEvent *event = g_ptr_array_index (events_to_add, i);
+      /* Do not re-add multiday events that were part of old range */
+      if (gcal_event_is_multiday (event) && gcal_event_overlaps (event, old_range))
+        continue;
 
       GCAL_TRACE_MSG ("Queueing event addition for subscriber %s (event: '%s' (%s))",
                       G_OBJECT_TYPE_NAME (subscriber),