common/date-chooser: Increment or decrement year when GcalMultiChoice wraps

Closes: https://gitlab.gnome.org/GNOME/gnome-calendar/-/work_items/97
Closes: https://gitlab.gnome.org/GNOME/gnome-calendar/-/work_items/1484

Co-authored-by: mindonwarp <mind.on.warp@gmail.com>
Co-authored-by: Koc13 <ilija.kocinac@proton.me>
Part-of: <https://gitlab.gnome.org/GNOME/gnome-calendar/-/merge_requests/853>

src/gui/common/gcal-date-chooser.blp

@@ -17,6 +17,7 @@ template $GcalDateChooser: Adw.Bin {
       next-button-tooltip: _("Next Month");
       visible: bind $get_split_choice_visible(template.show-heading, template.split-month-year) as <bool>;
       user-changed => $on_split_multi_choice_user_changed() swapped;
+      wrapped => $on_split_multi_choice_wrapped() swapped;
 
       layout {
         column: 0;
@@ -93,6 +94,7 @@ Popover popover {
       next-button-tooltip: bind month_choice.next-button-tooltip;
       string-list: bind month_choice.string-list;
       user-changed => $on_split_multi_choice_user_changed() swapped;
+      wrapped => $on_split_multi_choice_wrapped() swapped;
     }
 
     $GcalMultiChoice {

src/gui/common/gcal-date-chooser.c

@@ -889,6 +889,29 @@ on_split_multi_choice_user_changed (GcalDateChooser *self)
   multi_choice_changed (self, year, month, 1);
 }
 
+static void
+on_split_multi_choice_wrapped (GcalDateChooser *self)
+{
+  int year, month;
+
+  year = gcal_multi_choice_get_value (GCAL_MULTI_CHOICE (self->year_choice));
+  month = gcal_multi_choice_get_value (GCAL_MULTI_CHOICE (self->month_choice)) + 1;
+
+  switch (month)
+    {
+    case G_DATE_JANUARY:
+      year++;
+      break;
+    case G_DATE_DECEMBER:
+      year--;
+      break;
+    default:
+      g_assert_not_reached ();
+    }
+
+  multi_choice_changed (self, year, month, 1);
+}
+
 static gboolean
 on_drop_target_drop_cb (GtkDropTarget   *target,
                         const GValue    *value,
@@ -1021,6 +1044,7 @@ gcal_date_chooser_class_init (GcalDateChooserClass *class)
   gtk_widget_class_bind_template_child (widget_class, GcalDateChooser, gizmo);
 
   gtk_widget_class_bind_template_callback (widget_class, on_combined_multi_choice_user_changed);
+  gtk_widget_class_bind_template_callback (widget_class, on_split_multi_choice_wrapped);
   gtk_widget_class_bind_template_callback (widget_class, get_combined_choice_visible);
   gtk_widget_class_bind_template_callback (widget_class, get_split_choice_visible);
   gtk_widget_class_bind_template_callback (widget_class, on_split_multi_choice_user_changed);