Per RFC 5545, includes VTIMEZONE data in iCal exports

Signed-off-by: Jon Stovell <jonstovell@gmail.com>

Author: Sesquipedalian

Sources/Actions/Calendar.php

@@ -24,6 +24,7 @@
 use SMF\Calendar\Event;
 use SMF\Calendar\EventOccurrence;
 use SMF\Calendar\Holiday;
+use SMF\Calendar\VTimeZone;
 use SMF\Config;
 use SMF\Db\DatabaseApi as Db;
 use SMF\ErrorHandler;
@@ -626,8 +627,10 @@ public function export(): void
 				&& ($occurrence = $event->getOccurrence($_REQUEST['recurrenceid'])) !== false
 			) {
 				$file['content'][] = $occurrence->export();
+				$file['content'][] = VTimeZone::load($occurrence->tzid)->export($occurrence->start, $occurrence->end);
 			} else {
 				$file['content'][] = $event->export();
+				$file['content'][] = VTimeZone::load($event->tzid)->export($event->start, $event->end);
 			}
 
 			$file['filename'] = $event->title . '.ics';
@@ -656,6 +659,7 @@ public function export(): void
 			$high_date = (clone $low_date)->add($duration);
 
 			$full_event_uids = [];
+			$tzids = [];
 
 			foreach (Event::getOccurrencesInRange($low_date->format('Y-m-d'), $high_date->format('Y-m-d'), true) as $occurrence) {
 				$event = $occurrence->getParentEvent();
@@ -674,17 +678,41 @@ public function export(): void
 						&& $event->getRecurrenceEnd() <= $high_date
 					)
 				) {
+					if (!isset($tzids[$event->tzid])) {
+						$tzids[$event->tzid] = [
+							'min' => $event->start,
+							'max' => $event->end,
+						];
+					}
+
+					$tzids[$event->tzid]['min'] = $tzids[$event->tzid]['min'] > $event->start ? $event->start : $tzids[$event->tzid]['min'];
+					$tzids[$event->tzid]['max'] = $tzids[$event->tzid]['max'] < $event->end ? $event->end : $tzids[$event->tzid]['max'];
+
 					$file['content'][] = $event->export();
 					$full_event_ids[] = $event->uid;
 				}
 				// Otherwise, export just this occurrence.
 				else {
+					if (!isset($tzids[$occurrence->tzid])) {
+						$tzids[$occurrence->tzid] = [
+							'min' => $occurrence->start,
+							'max' => $occurrence->end,
+						];
+					}
+
+					$tzids[$occurrence->tzid]['min'] = $tzids[$occurrence->tzid]['min'] > $occurrence->start ? $occurrence->start : $tzids[$occurrence->tzid]['min'];
+					$tzids[$occurrence->tzid]['max'] = $tzids[$occurrence->tzid]['max'] < $occurrence->end ? $occurrence->end : $tzids[$occurrence->tzid]['max'];
+
 					$file['content'][] = $occurrence->export();
 				}
 
 				$file['mtime'] = max($file['mtime'], $event->modified_time);
 			}
 
+			foreach ($tzids as $tzid => $range) {
+				$file['content'][] = VTimeZone::load($tzid)->export($range['min'], $range['max']);
+			}
+
 			$file['filename'] = implode(' ', [Utils::$context['forum_name'], Lang::$txt['events'], $low_date->format('Y-m-d'), $high_date->format('Y-m-d')]) . '.ics';
 		}