File ICal/Timezone/AliasTimezoneResolver.php

1:	<?php
2:	declare(strict_types=1);
3:
4:	namespace om\ICal\Timezone;
5:
6:	use DateTimeZone;
7:	use Exception;
8:	use IntlTimeZone;
9:	use om\ICal\Component;
10:	use om\TimezoneResolver as NameResolver;
11:
12:	/**
13:	* Resolves Windows timezone names ("W. Europe Standard Time"), Outlook display names
14:	* ("(UTC+01:00) Amsterdam, Berlin, ..."), prefixed names ("/mozilla.org/20070129_1/Europe/Paris"),
15:	* quoted names and IANA names without their first part ("Argentina/Buenos_Aires").
16:	*
17:	* The bundled map (CLDR plus aliases) is used first, so results do not depend on the ICU version;
18:	* IntlTimeZone::getIDForWindowsID() of the intl extension is a fallback for newer Windows names.
19:	*/
20:	final class AliasTimezoneResolver implements TimezoneResolver {
21:	private readonly NameResolver $names;
22:
23:	/**
24:	* @param ?array<string, string> $windowsTimezones Windows name => IANA name, the bundled mapping by default
25:	*/
26:	public function __construct(?array $windowsTimezones = null) {
27:	$this->names = new NameResolver($windowsTimezones ?? self::windowsTimezones());
28:	}
29:
30:	public function resolve(string $tzid, Component $calendar): ?ResolvedTimezone {
31:	$timezone = $this->names->resolve($tzid) ?? self::fromIntl($tzid) ?? self::bySuffix($tzid);
32:	return $timezone === null ? null : new ResolvedTimezone($tzid, $timezone, TimezoneSource::Alias);
33:	}
34:
35:	private static function fromIntl(string $tzid): ?DateTimeZone {
36:	if (!class_exists(IntlTimeZone::class)) {
37:	return null;
38:	}
39:	// returns false for unknown names, although the stubs say string
40:	$name = (string) IntlTimeZone::getIDForWindowsID(trim($tzid, " \t'\""));
41:	try {
42:	return $name !== '' ? new DateTimeZone($name) : null;
43:	} catch (Exception) {
44:	return null;
45:	}
46:	}
47:
48:	/**
49:	* An IANA name missing its first part, e.g. "Argentina/Buenos_Aires", when the match is unique.
50:	*/
51:	private static function bySuffix(string $tzid): ?DateTimeZone {
52:	$suffix = '/' . strtolower(trim($tzid, " \t'\"/"));
53:	if (strlen($suffix) < 4) {
54:	return null;
55:	}
56:	$matches = array_filter(DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC), static fn(string $name): bool => str_ends_with(strtolower($name), $suffix));
57:	return count($matches) === 1 ? new DateTimeZone(reset($matches)) : null;
58:	}
59:
60:	/**
61:	* @return array<string, string>
62:	*/
63:	public static function windowsTimezones(): array {
64:	static $map;
65:	return $map ??= require __DIR__ . '/../../WindowsTimezones.php';
66:	}
67:	}
68:

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