File ICal/Timezone/IanaTimezoneResolver.php

1:	<?php
2:	declare(strict_types=1);
3:
4:	namespace om\ICal\Timezone;
5:
6:	use DateTimeZone;
7:	use om\ICal\Component;
8:
9:	/**
10:	* Resolves IANA timezone names like "Europe/Prague" (case-insensitive).
11:	*/
12:	final class IanaTimezoneResolver implements TimezoneResolver {
13:	/** @var array<string, string>\|null lower-case name => name */
14:	private static ?array $names = null;
15:
16:	public function resolve(string $tzid, Component $calendar): ?ResolvedTimezone {
17:	self::$names ??= array_change_key_case(array_combine(
18:	$identifiers = DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC),
19:	$identifiers,
20:	));
21:	$name = self::$names[strtolower(trim($tzid))] ?? null;
22:	return $name === null ? null : new ResolvedTimezone($tzid, new DateTimeZone($name), TimezoneSource::Iana);
23:	}
24:	}
25: