class BlockTranslation

class BlockTranslation extends Block {
    
    /**
     * {@inheritdoc}
     */
    public function query() {
        // Let the parent set the block table to use, but do not use the parent
        // query. Instead build a query so can use an inner join to the selected
        // block table.
        parent::query();
        $query = $this->select('i18n_string', 'i18n')
            ->fields('i18n')
            ->fields('b', [
            'bid',
            'module',
            'delta',
            'theme',
            'status',
            'weight',
            'region',
            'custom',
            'visibility',
            'pages',
            'title',
            'cache',
            'i18n_mode',
        ])
            ->fields('lt', [
            'lid',
            'translation',
            'language',
            'plid',
            'plural',
        ])
            ->condition('i18n_mode', 1);
        $query->leftJoin($this->blockTable, 'b', '[b].[delta] = [i18n].[objectid]');
        $query->innerJoin('locales_target', 'lt', '[lt].[lid] = [i18n].[lid]');
        // The i18n_string module adds a status column to locale_target. It was
        // originally 'status' in a later revision it was named 'i18n_status'.
        
        /** @var \Drupal\Core\Database\Schema $db */
        if ($this->getDatabase()
            ->schema()
            ->fieldExists('locales_target', 'status')) {
            $query->addField('lt', 'status', 'i18n_status');
        }
        if ($this->getDatabase()
            ->schema()
            ->fieldExists('locales_target', 'i18n_status')) {
            $query->addField('lt', 'i18n_status', 'i18n_status');
        }
        return $query;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fields() {
        return [
            'bid' => $this->t('The block numeric identifier.'),
            'module' => $this->t('The module providing the block.'),
            'delta' => $this->t("The block's delta."),
            'theme' => $this->t('Which theme the block is placed in.'),
            'status' => $this->t('Block enabled status'),
            'weight' => $this->t('Block weight within region'),
            'region' => $this->t('Theme region within which the block is set'),
            'visibility' => $this->t('Visibility'),
            'pages' => $this->t('Pages list.'),
            'title' => $this->t('Block title.'),
            'cache' => $this->t('Cache rule.'),
            'i18n_mode' => $this->t('Multilingual mode'),
            'lid' => $this->t('Language string ID'),
            'textgroup' => $this->t('A module defined group of translations'),
            'context' => $this->t('Full string ID for quick search: type:objectid:property.'),
            'objectid' => $this->t('Object ID'),
            'type' => $this->t('Object type for this string'),
            'property' => $this->t('Object property for this string'),
            'objectindex' => $this->t('Integer value of Object ID'),
            'format' => $this->t('The {filter_format}.format of the string'),
            'translation' => $this->t('Translation'),
            'language' => $this->t('Language code'),
            'plid' => $this->t('Parent lid'),
            'plural' => $this->t('Plural index number'),
            'i18n_status' => $this->t('Translation needs update'),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIds() {
        $ids['delta']['type'] = 'string';
        $ids['delta']['alias'] = 'b';
        $ids['language']['type'] = 'string';
        return $ids;
    }

}