class ForumIndexStorage

class ForumIndexStorage implements ForumIndexStorageInterface {
    
    /**
     * The active database connection.
     *
     * @var \Drupal\Core\Database\Connection
     */
    protected $database;
    
    /**
     * Constructs a ForumIndexStorage object.
     *
     * @param \Drupal\Core\Database\Connection $database
     *   The current database connection.
     */
    public function __construct(Connection $database) {
        $this->database = $database;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getOriginalTermId(NodeInterface $node) {
        return $this->database
            ->queryRange("SELECT f.tid FROM {forum} f INNER JOIN {node} n ON f.vid = n.vid WHERE n.nid = :nid ORDER BY f.vid DESC", 0, 1, [
            ':nid' => $node->id(),
        ])
            ->fetchField();
    }
    
    /**
     * {@inheritdoc}
     */
    public function create(NodeInterface $node) {
        $this->database
            ->insert('forum')
            ->fields([
            'tid' => $node->forum_tid,
            'vid' => $node->getRevisionId(),
            'nid' => $node->id(),
        ])
            ->execute();
    }
    
    /**
     * {@inheritdoc}
     */
    public function read(array $vids) {
        return $this->database
            ->select('forum', 'f')
            ->fields('f', [
            'nid',
            'tid',
        ])
            ->condition('f.vid', $vids, 'IN')
            ->execute();
    }
    
    /**
     * {@inheritdoc}
     */
    public function delete(NodeInterface $node) {
        $this->database
            ->delete('forum')
            ->condition('nid', $node->id())
            ->execute();
    }
    
    /**
     * {@inheritdoc}
     */
    public function deleteRevision(NodeInterface $node) {
        $this->database
            ->delete('forum')
            ->condition('nid', $node->id())
            ->condition('vid', $node->getRevisionId())
            ->execute();
    }
    
    /**
     * {@inheritdoc}
     */
    public function update(NodeInterface $node) {
        $this->database
            ->update('forum')
            ->fields([
            'tid' => $node->forum_tid,
        ])
            ->condition('vid', $node->getRevisionId())
            ->execute();
    }
    
    /**
     * {@inheritdoc}
     */
    public function updateIndex(NodeInterface $node) {
        $nid = $node->id();
        $count = $this->database
            ->query("SELECT COUNT(cid) FROM {comment_field_data} c INNER JOIN {forum_index} i ON c.entity_id = i.nid WHERE c.entity_id = :nid AND c.field_name = 'comment_forum' AND c.entity_type = 'node' AND c.status = :status AND c.default_langcode = 1", [
            ':nid' => $nid,
            ':status' => CommentInterface::PUBLISHED,
        ])
            ->fetchField();
        if ($count > 0) {
            // Comments exist.
            $last_reply = $this->database
                ->queryRange("SELECT cid, name, created, uid FROM {comment_field_data} WHERE entity_id = :nid AND field_name = 'comment_forum' AND entity_type = 'node' AND status = :status AND default_langcode = 1 ORDER BY cid DESC", 0, 1, [
                ':nid' => $nid,
                ':status' => CommentInterface::PUBLISHED,
            ])
                ->fetchObject();
            $this->database
                ->update('forum_index')
                ->fields([
                'comment_count' => $count,
                'last_comment_timestamp' => $last_reply->created,
            ])
                ->condition('nid', $nid)
                ->execute();
        }
        else {
            // Comments do not exist.
            // @todo This should be actually filtering on the desired node language
            $this->database
                ->update('forum_index')
                ->fields([
                'comment_count' => 0,
                'last_comment_timestamp' => $node->getCreatedTime(),
            ])
                ->condition('nid', $nid)
                ->execute();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function createIndex(NodeInterface $node) {
        $query = $this->database
            ->insert('forum_index')
            ->fields([
            'nid',
            'title',
            'tid',
            'sticky',
            'created',
            'comment_count',
            'last_comment_timestamp',
        ]);
        foreach ($node->getTranslationLanguages() as $langcode => $language) {
            $translation = $node->getTranslation($langcode);
            foreach ($translation->taxonomy_forums as $item) {
                $query->values([
                    'nid' => $node->id(),
                    'title' => $translation->label(),
                    'tid' => $item->target_id,
                    'sticky' => (int) $node->isSticky(),
                    'created' => $node->getCreatedTime(),
                    'comment_count' => 0,
                    'last_comment_timestamp' => $node->getCreatedTime(),
                ]);
            }
        }
        $query->execute();
        // The logic for determining last_comment_count is fairly complex, so
        // update the index too.
        if ($node->isNew()) {
            $this->updateIndex($node);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function deleteIndex(NodeInterface $node) {
        $this->database
            ->delete('forum_index')
            ->condition('nid', $node->id())
            ->execute();
    }

}