2024-12-16 17:24:37 +03:00

142 lines
4.7 KiB
PHP

<?php
/*
* *
* * calendar App
* *
* * @copyright 2023 Anna Larch <anna.larch@gmx.net>
* *
* * @author Anna Larch <anna.larch@gmx.net>
* *
* * This library is free software; you can redistribute it and/or
* * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
* * License as published by the Free Software Foundation; either
* * version 3 of the License, or any later version.
* *
* * This library is distributed in the hope that it will be useful,
* * but WITHOUT ANY WARRANTY; without even the implied warranty of
* * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
* *
* * You should have received a copy of the GNU Affero General Public
* * License along with this library. If not, see <http://www.gnu.org/licenses/>.
* *
*
*/
declare(strict_types=1);
/*
* @copyright 2023 Anna Larch <anna.larch@gmx.net>
*
* @author 2023 Anna Larch <anna.larch@gmx.net>
*
* @license GNU AGPL version 3 or any later version
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
namespace OCA\Calendar\Service\Appointments;
use Sabre\VObject\Component;
use Sabre\VObject\Component\VCalendar;
use Sabre\VObject\Component\VTimeZone;
use Sabre\VObject\TimeZoneUtil;
use function max;
use function min;
class TimezoneGenerator {
/**
* Returns a VTIMEZONE component for a Olson timezone identifier
* with daylight transitions covering the given date range.
*
* @link https://gist.github.com/thomascube/47ff7d530244c669825736b10877a200
*
* @param string $timezone Timezone
* @param integer $from Unix timestamp with first date/time in this timezone
* @param integer $to Unix timestap with last date/time in this timezone
* @psalm-suppress NoValue
*
* @return null|VTimeZone A Sabre\VObject\Component object representing a VTIMEZONE definition
* or null if no timezone information is available
*/
public function generateVtimezone(string $timezone, int $from, int $to): ?VTimeZone {
try {
$tz = new \DateTimeZone($timezone);
} catch (\Exception $e) {
return null;
}
// get all transitions for one year back/ahead
$year = 86400 * 360;
$transitions = $tz->getTransitions($from - $year, $to + $year);
$vcalendar = new VCalendar();
$vtimezone = $vcalendar->createComponent('VTIMEZONE');
$vtimezone->TZID = $timezone;
$standard = $daylightStart = null;
foreach ($transitions as $i => $trans) {
$component = null;
// daylight saving time definition
if ($trans['isdst']) {
$daylightDefinition = $trans['ts'];
$daylightStart = $vcalendar->createComponent('DAYLIGHT');
$component = $daylightStart;
}
// standard time definition
else {
$standardDefinition = $trans['ts'];
$standard = $vcalendar->createComponent('STANDARD');
$component = $standard;
}
if ($component) {
if ($i === 0) {
$date = new \DateTime('19700101T000000');
$tzfrom = $trans['offset'] / 3600;
$offset = $tzfrom;
} else {
$date = new \DateTime($trans['time']);
$offset = $trans['offset'] / 3600;
}
$component->DTSTART = $date->format('Ymd\THis');
$component->TZOFFSETFROM = sprintf('%s%02d%02d', $tzfrom >= 0 ? '+' : '-', abs(floor($tzfrom)), ($tzfrom - floor($tzfrom)) * 60);
$component->TZOFFSETTO = sprintf('%s%02d%02d', $offset >= 0 ? '+' : '-', abs(floor($offset)), ($offset - floor($offset)) * 60);
// add abbreviated timezone name if available
if (!empty($trans['abbr'])) {
$component->TZNAME = $trans['abbr'];
}
$tzfrom = $offset;
$vtimezone->add($component);
}
// we covered the entire date range
if ($standard && $daylightStart && min($standardDefinition, $daylightDefinition) < $from && max($standardDefinition, $daylightDefinition) > $to) {
break;
}
}
// add X-MICROSOFT-CDO-TZID if available
$microsoftExchangeMap = array_flip(TimeZoneUtil::$microsoftExchangeMap);
if (!empty($microsoftExchangeMap) && array_key_exists($tz->getName(), $microsoftExchangeMap)) {
$vtimezone->add('X-MICROSOFT-CDO-TZID', $microsoftExchangeMap[$tz->getName()]);
}
return $vtimezone;
}
}