TimeZoneExtension.php

<?php

use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
use Acme\Example\Auth\AppUser;

/**
 * Replaces the `date` filter with one that uses the user's timezone if a
 * user is present.
 */
final class TimeZoneExtension extends \Twig_Extension
{
    /**
     * @var TokenStorageInterface
     */
    private $security;

    public function __construct(TokenStorageInterface $security)
    {
        $this->security = $security;
    }

    /**
     * {@inheritdoc}
     */
    public function getFilters()
    {
        return [
            new \Twig_SimpleFilter('date', [$this, 'formatDate'], [
                'needs_environment'     => true,
            ]),
        ];
    }

    public function formatDate(\Twig_Environment $env, $date, $format=null, $timezone=null)
    {
        if (null === $timezone) {
            $timezone = $this->getUserTimezone();
        }

        return \twig_date_format_filter($env, $date, $format, $timezone);
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'storeroom_tz';
    }

    private function getUserTimezone()
    {
        $token = $this->security->getToken();
        if ($token && ($user = $token->getUser()) && $user instanceof AppUser) {
            return $user->getTimeZone();
        }

        return null;
    }
}