72 lines
2.4 KiB
PHP
Executable File
72 lines
2.4 KiB
PHP
Executable File
<?php
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declare(strict_types=1);
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namespace Sabre\VObject\TimezoneGuesser;
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use DateTimeZone;
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use Exception;
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/**
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* Some clients add 'X-LIC-LOCATION' with the olson name.
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*/
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class FindFromTimezoneIdentifier implements TimezoneFinder
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{
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public function find(string $tzid, bool $failIfUncertain = false): ?DateTimeZone
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{
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// First we will just see if the tzid is a support timezone identifier.
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//
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// The only exception is if the timezone starts with (. This is to
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// handle cases where certain microsoft products generate timezone
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// identifiers that for instance look like:
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//
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// (GMT+01.00) Sarajevo/Warsaw/Zagreb
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//
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// Since PHP 5.5.10, the first bit will be used as the timezone and
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// this method will return just GMT+01:00. This is wrong, because it
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// doesn't take DST into account
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if (!isset($tzid[0])) {
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return null;
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}
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if ('(' === $tzid[0]) {
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return null;
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}
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// PHP has a bug that logs PHP warnings even it shouldn't:
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// https://bugs.php.net/bug.php?id=67881
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//
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// That's why we're checking if we'll be able to successfully instantiate
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// \DateTimeZone() before doing so. Otherwise we could simply instantiate
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// and catch the exception.
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$tzIdentifiers = DateTimeZone::listIdentifiers();
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try {
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if (
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(in_array($tzid, $tzIdentifiers)) ||
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(preg_match('/^GMT(\+|-)([0-9]{4})$/', $tzid, $matches)) ||
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(in_array($tzid, $this->getIdentifiersBC()))
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) {
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return new DateTimeZone($tzid);
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}
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} catch (Exception $e) {
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}
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return null;
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}
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/**
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* This method returns an array of timezone identifiers, that are supported
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* by DateTimeZone(), but not returned by DateTimeZone::listIdentifiers().
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*
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* We're not using DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC) because:
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* - It's not supported by some PHP versions as well as HHVM.
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* - It also returns identifiers, that are invalid values for new DateTimeZone() on some PHP versions.
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* (See timezonedata/php-bc.php and timezonedata php-workaround.php)
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*
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* @return array
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*/
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private function getIdentifiersBC()
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{
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return include __DIR__.'/../timezonedata/php-bc.php';
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}
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}
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