[gnome-calendar/gbsneto/timezone-fixes: 1/3] event: Query client timezone on failure

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 0811242180be940df8351c52ac11e30eebd0283a
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Tue Dec 7 12:25:37 2021 -0300

    event: Query client timezone on failure
    
    If we can't find an appropriate timezone, query the ECalClient
    for it and give it an extra chance of finding the right timezone.
    
    Thanks to Milan Crha for proposing this fix.
    
    Related: https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/444

 src/core/gcal-event.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)
---
diff --git a/src/core/gcal-event.c b/src/core/gcal-event.c
index e752abfe..717b4e23 100644
--- a/src/core/gcal-event.c
+++ b/src/core/gcal-event.c
@@ -148,11 +148,12 @@ clear_range (GcalEvent *self)
 }
 
 static GTimeZone*
-get_timezone_from_ical (ECalComponentDateTime *comp)
+get_timezone_from_ical (GcalEvent             *self,
+                        ECalComponentDateTime *comp)
 {
+  g_autoptr (GTimeZone) tz = NULL;
   ICalTimezone *zone;
   ICalTime *itt;
-  GTimeZone *tz;
 
   itt = e_cal_component_datetime_get_value (comp);
   zone = i_cal_time_get_timezone (itt);
@@ -168,16 +169,29 @@ get_timezone_from_ical (ECalComponentDateTime *comp)
     }
   else if (e_cal_component_datetime_get_tzid (comp))
     {
-      const gchar *real_tzid;
+      const gchar *original_tzid, *tzid;
+
+      tzid = e_cal_component_datetime_get_tzid (comp);
+      original_tzid = tzid;
+
+      if (g_str_has_prefix (tzid, LIBICAL_TZID_PREFIX))
+        tzid += strlen (LIBICAL_TZID_PREFIX);
 
-      real_tzid = e_cal_component_datetime_get_tzid (comp);
+      tz = g_time_zone_new_identifier (tzid);
+
+      if (!tz && self->calendar)
+        {
+          ICalTimezone *tzone = NULL;
+          ECalClient *client;
 
-      if (g_str_has_prefix (real_tzid, LIBICAL_TZID_PREFIX))
-        real_tzid += strlen (LIBICAL_TZID_PREFIX);
+          client = gcal_calendar_get_client (self->calendar);
 
-      tz = g_time_zone_new_identifier (real_tzid);
+          if (client && e_cal_client_get_timezone_sync (client, original_tzid, &tzone, NULL, NULL))
+            zone = tzone;
+        }
     }
-  else if (zone)
+
+  if (!tz && zone)
     {
       g_autofree gchar *tzid = NULL;
       gint offset;
@@ -186,10 +200,6 @@ get_timezone_from_ical (ECalComponentDateTime *comp)
       tzid = format_utc_offset (offset);
       tz = g_time_zone_new_identifier (tzid);
     }
-  else
-    {
-      tz = g_time_zone_new_utc ();
-    }
 
   /*
    * If tz is NULL, the timezone identifier is invalid. Fallback to UTC
@@ -200,7 +210,7 @@ get_timezone_from_ical (ECalComponentDateTime *comp)
 
   GCAL_TRACE_MSG ("%s (%p)", g_time_zone_get_identifier (tz), tz);
 
-  return tz;
+  return g_steal_pointer (&tz);
 }
 
 static ECalComponentDateTime*
@@ -340,7 +350,7 @@ gcal_event_set_component_internal (GcalEvent     *self,
   GCAL_TRACE_MSG ("Retrieving start timezone");
 
   date = i_cal_time_normalize (e_cal_component_datetime_get_value (start));
-  zone_start = get_timezone_from_ical (start);
+  zone_start = get_timezone_from_ical (self, start);
   date_start = g_date_time_new (zone_start,
                                 i_cal_time_get_year (date),
                                 i_cal_time_get_month (date),
@@ -366,7 +376,7 @@ gcal_event_set_component_internal (GcalEvent     *self,
       GCAL_TRACE_MSG ("Retrieving end timezone");
 
       date = i_cal_time_normalize (e_cal_component_datetime_get_value (end));
-      zone_end = get_timezone_from_ical (end);
+      zone_end = get_timezone_from_ical (self, end);
       date_end = g_date_time_new (zone_end,
                                   i_cal_time_get_year (date),
                                   i_cal_time_get_month (date),