[evolution] I#1368 - itip-utils: Use Location as TZID instead of libical's TZID

[Milan Crha <mcrha src gnome org>]

commit 1ad4a6258dd146b17b0b8b420b8872fc1ce4b5bc
Author: Milan Crha <mcrha redhat com>
Date:   Thu Feb 18 14:00:40 2021 +0100

    I#1368 - itip-utils: Use Location as TZID instead of libical's TZID
    
    This helps with some servers, notably Exchange, which do not like
    real timezone IDs and prefer the Location instead.
    
    Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/1368

 src/calendar/gui/itip-utils.c | 49 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 6 deletions(-)
---
diff --git a/src/calendar/gui/itip-utils.c b/src/calendar/gui/itip-utils.c
index 1fae476214..0d922dac74 100644
--- a/src/calendar/gui/itip-utils.c
+++ b/src/calendar/gui/itip-utils.c
@@ -727,15 +727,23 @@ foreach_tzid_callback (ICalParameter *param,
                        gpointer data)
 {
        ItipUtilTZData *tz_data = data;
-       const gchar *tzid;
        ICalTimezone *zone = NULL;
-       ICalComponent *vtimezone_comp;
+       ICalComponent *vtimezone_comp, *tzcomp = NULL;
+       const gchar *tzid, *location;
+       gchar *tzid_dup = NULL;
 
        /* Get the TZID string from the parameter. */
        tzid = i_cal_parameter_get_tzid (param);
-       if (!tzid || g_hash_table_contains (tz_data->tzids, tzid))
+       if (!tzid)
                return;
 
+       if (g_hash_table_contains (tz_data->tzids, tzid)) {
+               location = g_hash_table_lookup (tz_data->tzids, tzid);
+               if (location)
+                       i_cal_parameter_set_tzid (param, location);
+               return;
+       }
+
        /* Look for the timezone */
        if (tz_data->zones != NULL)
                zone = i_cal_component_get_timezone (tz_data->zones, tzid);
@@ -752,9 +760,38 @@ foreach_tzid_callback (ICalParameter *param,
        if (!vtimezone_comp)
                return;
 
-       i_cal_component_take_component (
-               tz_data->icomp, i_cal_component_clone (vtimezone_comp));
-       g_hash_table_insert (tz_data->tzids, g_strdup (tzid), GINT_TO_POINTER (1));
+       location = i_cal_timezone_get_location (zone);
+       if (location && *location) {
+               ICalProperty *prop;
+
+               tzid_dup = g_strdup (tzid);
+               tzid = tzid_dup;
+
+               /* This frees the original 'tzid' */
+               i_cal_parameter_set_tzid (param, location);
+
+               if (g_hash_table_contains (tz_data->tzids, location)) {
+                       g_object_unref (vtimezone_comp);
+                       return;
+               }
+
+               tzcomp = i_cal_component_clone (vtimezone_comp);
+               prop = i_cal_component_get_first_property (tzcomp, I_CAL_TZID_PROPERTY);
+               if (prop) {
+                       i_cal_property_set_tzid (prop, location);
+                       g_object_unref (prop);
+               }
+
+               g_hash_table_insert (tz_data->tzids, g_strdup (location), NULL);
+       } else {
+               location = NULL;
+       }
+
+       if (!tzcomp)
+               tzcomp = i_cal_component_clone (vtimezone_comp);
+
+       i_cal_component_take_component (tz_data->icomp, tzcomp);
+       g_hash_table_insert (tz_data->tzids, tzid_dup ? tzid_dup : g_strdup (tzid), g_strdup (location));
        g_object_unref (vtimezone_comp);
 }