class DrupalDateTime

class DrupalDateTime extends DateTimePlus {
    use StringTranslationTrait;
    use DependencySerializationTrait {
        __sleep as defaultSleep;
    }
    
    /**
     * Formatted strings translation cache.
     *
     * Translation cache represents an instance storage for formatted date
     * strings. It contains a multidimensional array where:
     * - first level keys - are drupal language codes;
     * - second level keys - are each symbols of given format string (like 'F');
     * - third level keys - are original matched strings related to the symbol;
     * - values - are translated or not-translated original strings (depends on
     *   if a particular symbol represents translatable value according to PHP's
     *   date() format character).
     *
     * For example:
     * @code
     *   [
     *     'en' => [
     *       'F' => [
     *         'November' => t('November'),
     *         'December' => t('December'),
     *       ],
     *       'd' => [
     *         '10' => '10',
     *         '31' => '31',
     *       ],
     *     ],
     *   ]
     * @endcode
     *
     * @var array
     */
    protected $formatTranslationCache = [];
    
    /**
     * Constructs a date object.
     *
     * @param string $time
     *   A date/input_time_adjusted string. Defaults to 'now'.
     * @param mixed $timezone
     *   PHP DateTimeZone object, string or NULL allowed.
     *   Defaults to NULL. Note that the $timezone parameter and the current
     *   timezone are ignored when the $time parameter either is a UNIX timestamp
     *   (e.g. @946684800) or specifies a timezone
     *   (e.g. 2010-01-28T15:00:00+02:00).
     *   @see http://php.net/manual/datetime.construct.php
     * @param array $settings
     *   - validate_format: (optional) Boolean choice to validate the
     *     created date using the input format. The format used in
     *     createFromFormat() allows slightly different values than format().
     *     Using an input format that works in both functions makes it
     *     possible to a validation step to confirm that the date created
     *     from a format string exactly matches the input. This option
     *     indicates the format can be used for validation. Defaults to TRUE.
     *   - langcode: (optional) Used to control the result of the format() method.
     *     Defaults to NULL.
     *   - debug: (optional) Boolean choice to leave debug values in the
     *     date object for debugging purposes. Defaults to FALSE.
     */
    public function __construct($time = 'now', $timezone = NULL, $settings = []) {
        if (!isset($settings['langcode'])) {
            $settings['langcode'] = \Drupal::languageManager()->getCurrentLanguage()
                ->getId();
        }
        // Instantiate the parent class.
        parent::__construct($time, $timezone, $settings);
    }
    
    /**
     * Overrides prepareTimezone().
     *
     * Override basic component timezone handling to use Drupal's
     * knowledge of the preferred user timezone.
     */
    protected function prepareTimezone($timezone) {
        if (empty($timezone)) {
            // Fallback to user or system default timezone.
            $timezone = date_default_timezone_get();
        }
        return parent::prepareTimezone($timezone);
    }
    
    /**
     * Overrides format().
     *
     * @param string $format
     *   A format string using either PHP's date().
     * @param array $settings
     *   - timezone: (optional) String timezone name. Defaults to the timezone
     *     of the date object.
     *   - langcode: (optional) String two letter language code used to control
     *     the result of the format() method. Defaults to NULL.
     *
     * @return string
     *   The formatted value of the date. Since the format may contain user input,
     *   this value should be escaped when output.
     */
    public function format($format, $settings = []) {
        $langcode = !empty($settings['langcode']) ? $settings['langcode'] : $this->langcode;
        $value = '';
        // Format the date and catch errors.
        try {
            // Encode markers that should be translated. 'A' becomes
            // '\xEF\AA\xFF'. xEF and xFF are invalid UTF-8 sequences,
            // and we assume they are not in the input string.
            // Paired backslashes are isolated to prevent errors in
            // read-ahead evaluation. The read-ahead expression ensures that
            // A matches, but not \A.
            $format = preg_replace([
                '/\\\\\\\\/',
                '/(?<!\\\\)([AaeDlMTF])/',
            ], [
                "\xef\\\\\\\\\xff",
                "\xef\\\\\$1\$1\xff",
            ], $format);
            // Call date_format().
            $format = parent::format($format, $settings);
            // $format will be NULL if there are any errors.
            if ($format !== NULL) {
                // Translates a formatted date string.
                $translation_callback = function ($matches) use ($langcode) {
                    $code = $matches[1];
                    $string = $matches[2];
                    if (!isset($this->formatTranslationCache[$langcode][$code][$string])) {
                        $options = [
                            'langcode' => $langcode,
                        ];
                        if ($code == 'F') {
                            $options['context'] = 'Long month name';
                        }
                        if ($code == '') {
                            $this->formatTranslationCache[$langcode][$code][$string] = $string;
                        }
                        else {
                            $this->formatTranslationCache[$langcode][$code][$string] = $this->t($string, [], $options);
                        }
                    }
                    return $this->formatTranslationCache[$langcode][$code][$string];
                };
                // Translate the marked sequences.
                $value = preg_replace_callback('/\\xEF([AaeDlMTF]?)(.*?)\\xFF/', $translation_callback, $format);
            }
        } catch (\Exception $e) {
            $this->errors[] = $e->getMessage();
        }
        return $value;
    }
    
    /**
     * {@inheritdoc}
     */
    public function __sleep() : array {
        return array_diff($this->defaultSleep(), [
            'formatTranslationCache',
        ]);
    }

}