utils: Add GDateTime utils

This will greatly help with the transition to GDateTime. In the future, we can propose these APIs to GLib itself.
2019-04-26 12:59:29 -03:00
parent 3bff2b8981
commit 68943eec57
5 changed files with 164 additions and 2 deletions
@@ -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);
+}