class Insert

class Insert extends QueryInsert {
    
    /**
     * {@inheritdoc}
     */
    public function execute() {
        if (!$this->preExecute()) {
            return NULL;
        }
        // If we're selecting from a SelectQuery, finish building the query and
        // pass it back, as any remaining options are irrelevant.
        if (!empty($this->fromQuery)) {
            // The SelectQuery may contain arguments, load and pass them through.
            return $this->connection
                ->query((string) $this, $this->fromQuery
                ->getArguments(), $this->queryOptions);
        }
        // If there are any fields in the query, execute normal INSERT statements.
        if (count($this->insertFields)) {
            $stmt = $this->connection
                ->prepareStatement((string) $this, $this->queryOptions);
            if (count($this->insertValues) === 1) {
                // Inserting a single row does not require a transaction to be atomic,
                // and executes faster without a transaction wrapper.
                $insert_values = $this->insertValues[0];
                try {
                    $stmt->execute($insert_values, $this->queryOptions);
                } catch (\Exception $e) {
                    $this->connection
                        ->exceptionHandler()
                        ->handleExecutionException($e, $stmt, $insert_values, $this->queryOptions);
                }
            }
            else {
                // Inserting multiple rows requires a transaction to be atomic, and
                // executes faster as a single transaction.
                try {
                    $transaction = $this->connection
                        ->startTransaction();
                } catch (\PDOException $e) {
                    // $this->connection->exceptionHandler()->handleExecutionException()
                    // requires a $statement argument, so we cannot use that.
                    throw new DatabaseExceptionWrapper($e->getMessage(), 0, $e);
                }
                foreach ($this->insertValues as $insert_values) {
                    try {
                        $stmt->execute($insert_values, $this->queryOptions);
                    } catch (\Exception $e) {
                        // One of the INSERTs failed, rollback the whole batch.
                        $transaction->rollBack();
                        $this->connection
                            ->exceptionHandler()
                            ->handleExecutionException($e, $stmt, $insert_values, $this->queryOptions);
                    }
                }
            }
            // Re-initialize the values array so that we can re-use this query.
            $this->insertValues = [];
        }
        else {
            $stmt = $this->connection
                ->prepareStatement("INSERT INTO {{$this->table}} DEFAULT VALUES", $this->queryOptions);
            try {
                $stmt->execute(NULL, $this->queryOptions);
            } catch (\Exception $e) {
                $this->connection
                    ->exceptionHandler()
                    ->handleExecutionException($e, $stmt, [], $this->queryOptions);
            }
        }
        return $this->connection
            ->lastInsertId();
    }
    
    /**
     * {@inheritdoc}
     */
    public function __toString() {
        // Create a sanitized comment string to prepend to the query.
        $comments = $this->connection
            ->makeComment($this->comments);
        // Produce as many generic placeholders as necessary.
        $placeholders = [];
        if (!empty($this->insertFields)) {
            $placeholders = array_fill(0, count($this->insertFields), '?');
        }
        $insert_fields = array_map(function ($field) {
            return $this->connection
                ->escapeField($field);
        }, $this->insertFields);
        // If we're selecting from a SelectQuery, finish building the query and
        // pass it back, as any remaining options are irrelevant.
        if (!empty($this->fromQuery)) {
            $insert_fields_string = $insert_fields ? ' (' . implode(', ', $insert_fields) . ') ' : ' ';
            return $comments . 'INSERT INTO {' . $this->table . '}' . $insert_fields_string . $this->fromQuery;
        }
        return $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') VALUES (' . implode(', ', $placeholders) . ')';
    }

}