Add the Chronological

vendor/sabre/vobject/lib/TimezoneGuesser/FindFromTimezoneIdentifier.php

@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sabre\VObject\TimezoneGuesser;
+
+use DateTimeZone;
+use Exception;
+
+/**
+ * Some clients add 'X-LIC-LOCATION' with the olson name.
+ */
+class FindFromTimezoneIdentifier implements TimezoneFinder
+{
+    public function find(string $tzid, bool $failIfUncertain = false): ?DateTimeZone
+    {
+        // First we will just see if the tzid is a support timezone identifier.
+        //
+        // The only exception is if the timezone starts with (. This is to
+        // handle cases where certain microsoft products generate timezone
+        // identifiers that for instance look like:
+        //
+        // (GMT+01.00) Sarajevo/Warsaw/Zagreb
+        //
+        // Since PHP 5.5.10, the first bit will be used as the timezone and
+        // this method will return just GMT+01:00. This is wrong, because it
+        // doesn't take DST into account
+        if (!isset($tzid[0])) {
+            return null;
+        }
+        if ('(' === $tzid[0]) {
+            return null;
+        }
+        // PHP has a bug that logs PHP warnings even it shouldn't:
+        // https://bugs.php.net/bug.php?id=67881
+        //
+        // That's why we're checking if we'll be able to successfully instantiate
+        // \DateTimeZone() before doing so. Otherwise we could simply instantiate
+        // and catch the exception.
+        $tzIdentifiers = DateTimeZone::listIdentifiers();
+
+        try {
+            if (
+                (in_array($tzid, $tzIdentifiers)) ||
+                (preg_match('/^GMT(\+|-)([0-9]{4})$/', $tzid, $matches)) ||
+                (in_array($tzid, $this->getIdentifiersBC()))
+            ) {
+                return new DateTimeZone($tzid);
+            }
+        } catch (Exception $e) {
+        }
+
+        return null;
+    }
+
+    /**
+     * This method returns an array of timezone identifiers, that are supported
+     * by DateTimeZone(), but not returned by DateTimeZone::listIdentifiers().
+     *
+     * We're not using DateTimeZone::listIdentifiers(DateTimeZone::ALL_WITH_BC) because:
+     * - It's not supported by some PHP versions as well as HHVM.
+     * - It also returns identifiers, that are invalid values for new DateTimeZone() on some PHP versions.
+     * (See timezonedata/php-bc.php and timezonedata php-workaround.php)
+     *
+     * @return array
+     */
+    private function getIdentifiersBC()
+    {
+        return include __DIR__.'/../timezonedata/php-bc.php';
+    }
+}