utils: Add GDateTime utils

This will greatly help with the transition to GDateTime.
In the future, we can propose these APIs to GLib itself.

src/meson.build

@@ -20,6 +20,7 @@ gcal_deps = [
 ]
 
 sources = files(
+  'utils/gcal-date-time-utils.c',
   'utils/gcal-utils.c',
   'views/gcal-month-cell.c',
   'views/gcal-month-popover.c',

src/utils/gcal-date-time-utils.c

@@ -0,0 +1,116 @@
+/* gcal-date-time-utils.c
+ *
+ * Copyright 2019 Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "gcal-date-time-utils.h"
+#include "gcal-utils.h"
+
+/**
+ * gcal_set_datetime:
+ * @dest: location to a #GDateTime pointer
+ * @src: (nullable): a #GDateTime
+ *
+ * Performs the same of g_set_object(), but with #GDateTime
+ * instances.
+ *
+ * Returns: %TRUE if the value of @dest changed, %FALSE otherwise
+ */
+gboolean
+gcal_set_date_time (GDateTime **dest,
+                    GDateTime  *src)
+{
+  gboolean changed = *dest != src;
+
+  gcal_clear_datetime (dest);
+
+  if (src)
+    *dest = g_date_time_ref (src);
+
+  return changed;
+}
+
+/**
+ * gcal_date_time_get_days_in_month:
+ * @date: a #GDateTime
+ *
+ * Retrieves the number of days in the month and year
+ * represented by @date.
+ *
+ * Returns: number of days in month during the year of @date
+ */
+guint8
+gcal_date_time_get_days_in_month (GDateTime *date)
+{
+  return g_date_get_days_in_month (g_date_time_get_month (date),
+                                   g_date_time_get_year (date));
+}
+
+/**
+ * gcal_date_time_get_start_of_week:
+ * @date: a #GDateTime
+ *
+ * Retrieves the first day of the week @date is in, at 00:00
+ * of the local timezone.
+ *
+ * This date is inclusive.
+ *
+ * Returns: (transfer full): a #GDateTime
+ */
+GDateTime*
+gcal_date_time_get_start_of_week (GDateTime *date)
+{
+  g_autoptr (GDateTime) start_of_week = NULL;
+  gint n_days_after_week_start;
+  gint first_weekday;
+  gint weekday;
+
+  g_assert (date != NULL);
+
+  first_weekday = get_first_weekday ();
+  weekday = g_date_time_get_day_of_week (date) - 1;
+  n_days_after_week_start = (weekday - first_weekday) % 7;
+
+  start_of_week = g_date_time_add_days (date, -n_days_after_week_start);
+
+  return g_date_time_new_local (g_date_time_get_year (start_of_week),
+                                g_date_time_get_month (start_of_week),
+                                g_date_time_get_day_of_month (start_of_week),
+                                0, 0, 0);
+}
+
+/**
+ * gcal_date_time_get_end_of_week:
+ * @date: a #GDateTime
+ *
+ * Retrieves the last day of the week @date is in, at 23:59:59
+ * of the local timezone.
+ *
+ * Because this date is exclusive, it actually is start of the
+ * next week.
+ *
+ * Returns: (transfer full): a #GDateTime
+ */
+GDateTime*
+gcal_date_time_get_end_of_week (GDateTime *date)
+{
+  g_autoptr (GDateTime) week_start = NULL;
+
+  week_start = gcal_date_time_get_start_of_week (date);
+  return g_date_time_add_weeks (week_start, 1);
+}

src/utils/gcal-date-time-utils.h

@@ -0,0 +1,44 @@
+/* gcal-date-time-utils.h
+ *
+ * Copyright 2019 Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+/**
+ * gcal_clear_datetime:
+ * @dt: location of a #GDateTime pointer
+ *
+ * Unreferences @dt if not %NULL, and set it to %NULL.
+ */
+#define gcal_clear_datetime(dt) g_clear_pointer (dt, g_date_time_unref)
+
+gboolean             gcal_set_date_time                          (GDateTime         **dest,
+                                                                  GDateTime          *src);
+
+guint8               gcal_date_time_get_days_in_month            (GDateTime          *date);
+
+GDateTime*           gcal_date_time_get_start_of_week            (GDateTime          *date);
+
+GDateTime*           gcal_date_time_get_end_of_week              (GDateTime          *date);
+
+G_END_DECLS

src/utils/gcal-utils.h

@@ -19,7 +19,9 @@
 #ifndef __GCAL_UTILS_H__
 #define __GCAL_UTILS_H__
 
+#include "gcal-date-time-utils.h"
 #include "gcal-manager.h"
+
 #include <gtk/gtk.h>
 #include <libecal/libecal.h>
 #include <libgweather/gweather.h>
@@ -31,7 +33,6 @@
 #define MINUTES_PER_DAY 1440
 #define MAX_MINUTES     (7 * MINUTES_PER_DAY)
 
-#define gcal_clear_datetime(dt) g_clear_pointer (dt, g_date_time_unref)
 #define gcal_clear_timeout(pp) { if (pp && *pp) { g_source_remove (*pp); *pp = 0; } }
 
 #if !EDS_CHECK_VERSION (3, 31, 90)

tests/test-event.c

@@ -18,7 +18,7 @@
 
 #include <glib.h>
 
-#include "gcal-utils.h"
+#include "utils/gcal-utils.h"
 #include "gcal-event.h"
 
 #define STUB_EVENT "BEGIN:VEVENT\n"             \