EWS calendar: Do not link against Evolution libraries

Replace Evolution functions with newly added libecal functions
and copy/adapt the rest Evolution functions, to not link against
Evolution, thus to not load Evolution (and GUI) libraries into
the evolution-calendar-factory process.

The code duplication is not ideal, but it does worth it in this case.

This way the distribution packagers can split evolution-ews into packages
which require evolution (the configuration part) and which not, and let
the users install evolution-ews core parts without Evolution itself, thus
for example Exchange accounts configured in GNOME Online Accounts can
provide data to GNOME Calendar without a need to install Evolution itself.

src/EWS/calendar/CMakeLists.txt

@@ -34,7 +34,6 @@ target_compile_definitions(ews-m365 PRIVATE
 
 target_compile_options(ews-m365 PUBLIC
 	${CAMEL_CFLAGS}
-	${EVOLUTION_CALENDAR_CFLAGS}
 	${LIBEBACKEND_CFLAGS}
 	${LIBECAL_CFLAGS}
 	${LIBEDATACAL_CFLAGS}
@@ -50,7 +49,6 @@ target_include_directories(ews-m365 PUBLIC
 	${CMAKE_SOURCE_DIR}/src/Microsoft365
 	${CMAKE_CURRENT_BINARY_DIR}
 	${CAMEL_INCLUDE_DIRS}
-	${EVOLUTION_CALENDAR_INCLUDE_DIRS}
 	${LIBEBACKEND_INCLUDE_DIRS}
 	${LIBECAL_INCLUDE_DIRS}
 	${LIBEDATACAL_INCLUDE_DIRS}
@@ -60,7 +58,6 @@ target_include_directories(ews-m365 PUBLIC
 target_link_libraries(ews-m365
 	${DEPENDENCIES}
 	${CAMEL_LDFLAGS}
-	${EVOLUTION_CALENDAR_LDFLAGS}
 	${LIBEBACKEND_LDFLAGS}
 	${LIBECAL_LDFLAGS}
 	${LIBEDATACAL_LDFLAGS}
@@ -104,7 +101,6 @@ target_compile_definitions(ecalbackendews PRIVATE
 
 target_compile_options(ecalbackendews PUBLIC
 	${CAMEL_CFLAGS}
-	${EVOLUTION_CALENDAR_CFLAGS}
 	${LIBEBACKEND_CFLAGS}
 	${LIBECAL_CFLAGS}
 	${LIBEDATACAL_CFLAGS}
@@ -118,7 +114,6 @@ target_include_directories(ecalbackendews PUBLIC
 	${CMAKE_SOURCE_DIR}/src/EWS
 	${CMAKE_CURRENT_BINARY_DIR}
 	${CAMEL_INCLUDE_DIRS}
-	${EVOLUTION_CALENDAR_INCLUDE_DIRS}
 	${LIBEBACKEND_INCLUDE_DIRS}
 	${LIBECAL_INCLUDE_DIRS}
 	${LIBEDATACAL_INCLUDE_DIRS}
@@ -128,7 +123,6 @@ target_include_directories(ecalbackendews PUBLIC
 target_link_libraries(ecalbackendews
 	${DEPENDENCIES}
 	${CAMEL_LDFLAGS}
-	${EVOLUTION_CALENDAR_LDFLAGS}
 	${LIBEBACKEND_LDFLAGS}
 	${LIBECAL_LDFLAGS}
 	${LIBEDATACAL_LDFLAGS}

src/EWS/calendar/e-cal-backend-ews-utils.c

@@ -2388,3 +2388,44 @@ e_cal_backend_ews_get_datetime_with_zone (ETimezoneCache *timezone_cache,
 
 	return dt;
 }
+
+/* This is adapted copy of calendar_config_get_icaltimezone(), to avoid dependency
+   on the evolution code in the backend. */
+ICalTimezone *
+e_cal_backend_ews_get_configured_evolution_icaltimezone (void)
+{
+	GSettingsSchemaSource *schema_source;
+	ICalTimezone *zone = NULL;
+	gchar *location = NULL;
+
+	schema_source = g_settings_schema_source_get_default ();
+	if (schema_source) {
+		GSettingsSchema *schema;
+
+		schema = g_settings_schema_source_lookup (schema_source, "org.gnome.evolution.calendar", TRUE);
+		if (schema) {
+			GSettings *settings;
+
+			settings = g_settings_new ("org.gnome.evolution.calendar");
+
+			if (g_settings_get_boolean (settings, "use-system-timezone"))
+				location = e_cal_util_get_system_timezone_location ();
+			else
+				location = g_settings_get_string (settings, "timezone");
+
+			g_clear_object (&settings);
+			g_settings_schema_unref (schema);
+		}
+	}
+
+	if (!location)
+		location = e_cal_util_get_system_timezone_location ();
+
+	if (location) {
+		zone = i_cal_timezone_get_builtin_timezone (location);
+
+		g_free (location);
+	}
+
+	return zone;
+}

src/EWS/calendar/e-cal-backend-ews-utils.h

@@ -68,6 +68,8 @@ ICalTime *	e_cal_backend_ews_get_datetime_with_zone	(ETimezoneCache *timezone_ca
 								 ICalComponent *comp,
 								 ICalPropertyKind prop_kind,
 								 ICalTime * (* get_func) (ICalProperty *prop));
+ICalTimezone *	e_cal_backend_ews_get_configured_evolution_icaltimezone
+								(void);
 
 G_END_DECLS