class DrupalTranslator

class DrupalTranslator implements TranslatorInterface {
    
    /**
     * The locale used for translating.
     *
     * @var string
     */
    protected $locale;
    
    /**
     * {@inheritdoc}
     */
    public function trans($id, array $parameters = [], $domain = NULL, $locale = NULL) {
        // If a TranslatableMarkup object is passed in as $id, return it since the
        // message has already been translated.
        if ($id instanceof TranslatableMarkup) {
            return $id;
        }
        return new TranslatableMarkup($id, $this->processParameters($parameters), $this->getOptions($domain, $locale));
    }
    
    /**
     * {@inheritdoc}
     */
    public function transChoice($id, $number, array $parameters = [], $domain = NULL, $locale = NULL) {
        // Violation messages can separated singular and plural versions by "|".
        $ids = explode('|', $id);
        if (!isset($ids[1])) {
            throw new \InvalidArgumentException(sprintf('The message "%s" cannot be pluralized, because it is missing a plural (e.g. "There is one apple|There are @count apples").', $id));
        }
        // Normally, calls to formatPlural() need to use literal strings, like
        // formatPlural($count, '1 item', '@count items')
        // so that the Drupal project POTX string extractor will correctly
        // extract the strings for translation and save them in a format that
        // formatPlural() can work with. However, this is a special case, because
        // Drupal is supporting a constraint message format from Symfony. So
        // although $id looks like a variable here, it is actually coming from a
        // static string in a constraint class that the POTX extractor knows about
        // and has processed to work with formatPlural(), so this specific call to
        // formatPlural() will work correctly.
        return \Drupal::translation()->formatPlural($number, $ids[0], $ids[1], $this->processParameters($parameters), $this->getOptions($domain, $locale));
    }
    
    /**
     * {@inheritdoc}
     */
    public function setLocale($locale) {
        $this->locale = $locale;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLocale() {
        return $this->locale ? $this->locale : \Drupal::languageManager()->getCurrentLanguage()
            ->getId();
    }
    
    /**
     * Processes the parameters array for use with TranslatableMarkup.
     */
    protected function processParameters(array $parameters) {
        $return = [];
        foreach ($parameters as $key => $value) {
            // We allow the values in the parameters to be safe string objects. This
            // can be useful when we want to use parameter values that are
            // TranslatableMarkup.
            if ($value instanceof MarkupInterface) {
                $value = (string) $value;
            }
            if (is_object($value)) {
                // TranslatableMarkup does not work with objects being passed as
                // replacement strings.
            }
            elseif (strpos($key, '{{ ') === 0 && strrpos($key, ' }}') == strlen($key) - 3) {
                // Transform it into a Drupal pattern using the format %name.
                $key = '%' . substr($key, 3, strlen($key) - 6);
                $return[$key] = $value;
            }
            else {
                $return[$key] = $value;
            }
        }
        return $return;
    }
    
    /**
     * Returns options suitable for use with TranslatableMarkup.
     */
    protected function getOptions($domain = NULL, $locale = NULL) {
        // We do not support domains, so we ignore this parameter.
        // If locale is left NULL, TranslatableMarkup will default to the interface
        // language.
        $locale = $locale ?? $this->locale;
        return [
            'langcode' => $locale,
        ];
    }

}