TimezoneController.php

<?php

namespace Drupal\system\Controller;

use Symfony\Component\HttpFoundation\JsonResponse;

/**
 * Provides a callback for finding a time zone identifier.
 */
class TimezoneController {
    
    /**
     * Returns a time zone identifier given a time zone abbreviation.
     *
     * @param string $abbreviation
     *   Time zone abbreviation.
     * @param int $offset
     *   Offset from GMT in seconds. Defaults to -1 which means that first found
     *   time zone corresponding to abbreviation is returned. Otherwise exact
     *   offset is searched and only if not found then the first time zone with
     *   any offset is returned.
     * @param null|int $is_daylight_saving_time
     *   Daylight saving time indicator. If abbreviation does not exist then the
     *   time zone is searched solely by offset and is DST.
     *
     * @return \Symfony\Component\HttpFoundation\JsonResponse
     *   The time zone identifier or 'false' in JsonResponse object.
     */
    public function getTimezone($abbreviation = '', $offset = -1, $is_daylight_saving_time = NULL) {
        $offset = intval($offset);
        // Out of bounds check for offset. Offset +/- UTC is typically no
        // smaller/larger than -12/+14.
        if ($offset < -60000 || $offset > 60000) {
            return new JsonResponse(FALSE);
        }
        if (isset($is_daylight_saving_time)) {
            $original = intval($is_daylight_saving_time);
            $is_daylight_saving_time = min(1, max(-1, intval($is_daylight_saving_time)));
            // Catch if out of boundary.
            if ($original !== $is_daylight_saving_time) {
                return new JsonResponse(FALSE);
            }
        }
        // An abbreviation of "0" passed in the callback arguments should be
        // interpreted as the empty string.
        $abbreviation = $abbreviation ? $abbreviation : '';
        $timezone = timezone_name_from_abbr($abbreviation, $offset, $is_daylight_saving_time);
        return new JsonResponse($timezone);
    }

}