GcalScheduleValues: new struct to hold values from a GcalEvent for the schedule widges

We'll move GcalScheduleSection to operate without a backing GcalEvent,
so we can add tests.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-calendar/-/merge_requests/550>

src/gui/event-editor/gcal-schedule-section.c

@@ -771,3 +771,47 @@ gcal_schedule_section_day_changed (GcalScheduleSection *self)
   GCAL_RETURN (gcal_date_time_compare_date (start_date, gcal_event_get_date_start (self->event)) < 0 ||
                gcal_date_time_compare_date (end_date, gcal_event_get_date_end (self->event)) > 0);
 }
+
+/**
+ * Extracts the values from @event that are needed to populate #GcalScheduleSection.
+ *
+ * Returns: a #GcalscheduleValues ready for use.  Free it with
+ * gcal_schedule_values_free().
+ */
+GcalScheduleValues *
+gcal_schedule_values_from_event (GcalEvent *event)
+{
+  GcalScheduleValues *values = g_new0 (GcalScheduleValues, 1);
+
+  if (event)
+    {
+      GcalRecurrence *recur = gcal_event_get_recurrence (event);
+
+      values->all_day = gcal_event_get_all_day (event);
+      values->date_start = g_date_time_ref (gcal_event_get_date_start (event));
+      values->date_end = g_date_time_ref (gcal_event_get_date_end (event));
+
+      if (recur)
+        {
+          values->recur = gcal_recurrence_ref (recur);
+        }
+    }
+
+  return values;
+}
+
+/**
+ * Frees the contents of @values.  Does not free the @values pointer itself;
+ * this structure is meant to be allocated on the stack.
+ */
+void
+gcal_schedule_values_free (GcalScheduleValues *values)
+{
+  values->all_day = FALSE;
+
+  g_clear_pointer (&values->date_start, g_date_time_unref);
+  g_clear_pointer (&values->date_end, g_date_time_unref);
+  g_clear_pointer (&values->recur, gcal_recurrence_unref);
+
+  g_free (values);
+}

src/gui/event-editor/gcal-schedule-section.h

@@ -28,8 +28,26 @@ G_BEGIN_DECLS
 #define GCAL_TYPE_SCHEDULE_SECTION (gcal_schedule_section_get_type())
 G_DECLARE_FINAL_TYPE (GcalScheduleSection, gcal_schedule_section, GCAL, SCHEDULE_SECTION, GtkBox)
 
+/* Values from a GcalEvent that this widget can manipulate.
+ *
+ * We keep an immutable copy of the original event's values, and later generate
+ * a new GcalScheduleValues with the updated data from the widgetry.
+ */
+typedef struct
+{
+  gboolean all_day;
+  GDateTime *date_start;
+  GDateTime *date_end;
+  GcalRecurrence *recur;
+} GcalScheduleValues;
+
 gboolean             gcal_schedule_section_recurrence_changed    (GcalScheduleSection *self);
 
 gboolean             gcal_schedule_section_day_changed           (GcalScheduleSection *self);
 
+GcalScheduleValues  *gcal_schedule_values_from_event             (GcalEvent *event);
+void                 gcal_schedule_values_free                   (GcalScheduleValues *values);
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (GcalScheduleValues, gcal_schedule_values_free);
+
 G_END_DECLS