class StatementWrapper

class StatementWrapper implements \IteratorAggregate, StatementInterface {
    
    /**
     * The Drupal database connection object.
     *
     * @var \Drupal\Core\Database\Connection
     */
    protected $connection;
    
    /**
     * The client database Statement object.
     *
     * For a \PDO client connection, this will be a \PDOStatement object.
     *
     * @var object
     */
    protected $clientStatement;
    
    /**
     * Is rowCount() execution allowed.
     *
     * @var bool
     */
    protected $rowCountEnabled = FALSE;
    
    /**
     * Constructs a StatementWrapper object.
     *
     * @param \Drupal\Core\Database\Connection $connection
     *   Drupal database connection object.
     * @param object $client_connection
     *   Client database connection object, for example \PDO.
     * @param string $query
     *   The SQL query string.
     * @param array $options
     *   Array of query options.
     * @param bool $row_count_enabled
     *   (optional) Enables counting the rows matched. Defaults to FALSE.
     */
    public function __construct(Connection $connection, $client_connection, string $query, array $options, bool $row_count_enabled = FALSE) {
        $this->connection = $connection;
        $this->clientStatement = $client_connection->prepare($query, $options);
        $this->rowCountEnabled = $row_count_enabled;
        $this->setFetchMode(\PDO::FETCH_OBJ);
    }
    
    /**
     * Returns the client-level database statement object.
     *
     * This method should normally be used only within database driver code.
     *
     * @return object
     *   The client-level database statement, for example \PDOStatement.
     */
    public function getClientStatement() {
        return $this->clientStatement;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConnectionTarget() : string {
        return $this->connection
            ->getTarget();
    }
    
    /**
     * {@inheritdoc}
     */
    public function execute($args = [], $options = []) {
        if (isset($options['fetch'])) {
            if (is_string($options['fetch'])) {
                // \PDO::FETCH_PROPS_LATE tells __construct() to run before properties
                // are added to the object.
                $this->setFetchMode(\PDO::FETCH_CLASS | \PDO::FETCH_PROPS_LATE, $options['fetch']);
            }
            else {
                $this->setFetchMode($options['fetch']);
            }
        }
        if ($this->connection
            ->isEventEnabled(StatementExecutionStartEvent::class)) {
            $startEvent = new StatementExecutionStartEvent(spl_object_id($this), $this->connection
                ->getKey(), $this->connection
                ->getTarget(), $this->getQueryString(), $args ?? [], $this->connection
                ->findCallerFromDebugBacktrace());
            $this->connection
                ->dispatchEvent($startEvent);
        }
        $return = $this->clientStatement
            ->execute($args);
        if (isset($startEvent) && $this->connection
            ->isEventEnabled(StatementExecutionEndEvent::class)) {
            $this->connection
                ->dispatchEvent(new StatementExecutionEndEvent($startEvent->statementObjectId, $startEvent->key, $startEvent->target, $startEvent->queryString, $startEvent->args, $startEvent->caller, $startEvent->time));
        }
        return $return;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getQueryString() {
        return $this->clientStatement->queryString;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchCol($index = 0) {
        return $this->fetchAll(\PDO::FETCH_COLUMN, $index);
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAllAssoc($key, $fetch = NULL) {
        $return = [];
        if (isset($fetch)) {
            if (is_string($fetch)) {
                $this->setFetchMode(\PDO::FETCH_CLASS, $fetch);
            }
            else {
                $this->setFetchMode($fetch);
            }
        }
        foreach ($this as $record) {
            $record_key = is_object($record) ? $record->{$key} : $record[$key];
            $return[$record_key] = $record;
        }
        return $return;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAllKeyed($key_index = 0, $value_index = 1) {
        $return = [];
        $this->setFetchMode(\PDO::FETCH_NUM);
        foreach ($this as $record) {
            $return[$record[$key_index]] = $record[$value_index];
        }
        return $return;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchField($index = 0) {
        // Call \PDOStatement::fetchColumn to fetch the field.
        return $this->clientStatement
            ->fetchColumn($index);
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAssoc() {
        // Call \PDOStatement::fetch to fetch the row.
        return $this->fetch(\PDO::FETCH_ASSOC);
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchObject(?string $class_name = NULL, array $constructor_arguments = []) {
        if ($class_name) {
            return $this->clientStatement
                ->fetchObject($class_name, $constructor_arguments);
        }
        return $this->clientStatement
            ->fetchObject();
    }
    
    /**
     * {@inheritdoc}
     */
    public function rowCount() {
        // SELECT query should not use the method.
        if ($this->rowCountEnabled) {
            return $this->clientStatement
                ->rowCount();
        }
        else {
            throw new RowCountException();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function setFetchMode($mode, $a1 = NULL, $a2 = []) {
        // Call \PDOStatement::setFetchMode to set fetch mode.
        // \PDOStatement is picky about the number of arguments in some cases so we
        // need to be pass the exact number of arguments we where given.
        switch (func_num_args()) {
            case 1:
                return $this->clientStatement
                    ->setFetchMode($mode);
            case 2:
                return $this->clientStatement
                    ->setFetchMode($mode, $a1);
            case 3:
            default:
                return $this->clientStatement
                    ->setFetchMode($mode, $a1, $a2);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetch($mode = NULL, $cursor_orientation = NULL, $cursor_offset = NULL) {
        // Call \PDOStatement::fetchAll to fetch all rows.
        // \PDOStatement is picky about the number of arguments in some cases so we
        // need to be pass the exact number of arguments we where given.
        switch (func_num_args()) {
            case 0:
                return $this->clientStatement
                    ->fetch();
            case 1:
                return $this->clientStatement
                    ->fetch($mode);
            case 2:
                return $this->clientStatement
                    ->fetch($mode, $cursor_orientation);
            case 3:
            default:
                return $this->clientStatement
                    ->fetch($mode, $cursor_orientation, $cursor_offset);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAll($mode = NULL, $column_index = NULL, $constructor_arguments = NULL) {
        // Call \PDOStatement::fetchAll to fetch all rows.
        // \PDOStatement is picky about the number of arguments in some cases so we
        // need to be pass the exact number of arguments we where given.
        switch (func_num_args()) {
            case 0:
                return $this->clientStatement
                    ->fetchAll();
            case 1:
                return $this->clientStatement
                    ->fetchAll($mode);
            case 2:
                return $this->clientStatement
                    ->fetchAll($mode, $column_index);
            case 3:
            default:
                return $this->clientStatement
                    ->fetchAll($mode, $column_index, $constructor_arguments);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIterator() {
        return new \ArrayIterator($this->fetchAll());
    }

}