Merge branch 'MDL-75627_m400_v1' of https://github.com/sbourget/moodle …

…into MOODLE_400_STABLE

calendar/lib.php

@@ -3072,11 +3072,21 @@ function calendar_import_events_from_ical(iCalendar $ical, int $subscriptionid =
         \core_php_time_limit::raise(300);
     }
 
+    // Start with a safe default timezone.
+    $timezone = 'UTC';
+
     // Grab the timezone from the iCalendar file to be used later.
     if (isset($ical->properties['X-WR-TIMEZONE'][0]->value)) {
         $timezone = $ical->properties['X-WR-TIMEZONE'][0]->value;
-    } else {
-        $timezone = 'UTC';
+
+    } else if (isset($ical->properties['PRODID'][0]->value)) {
+        // If the timezone was not found, check to se if this is MS exchange / Office 365 which uses Windows timezones.
+        if (strncmp($ical->properties['PRODID'][0]->value, 'Microsoft', 9) == 0) {
+            if (isset($ical->components['VTIMEZONE'][0]->properties['TZID'][0]->value)) {
+                $tzname = $ical->components['VTIMEZONE'][0]->properties['TZID'][0]->value;
+                $timezone = IntlTimeZone::getIDForWindowsID($tzname);
+            }
+        }
     }
 
     $icaluuids = [];