<?php

/**
 * dibi - tiny'n'smart database abstraction layer
 * ----------------------------------------------
 *
 * Copyright (c) 2005, 2008 David Grudl (http://www.davidgrudl.com)
 *
 * This source file is subject to the "dibi license" that is bundled
 * with this package in the file license.txt.
 *
 * For more information please see http://dibiphp.com/
 *
 * @copyright  Copyright (c) 2005, 2008 David Grudl
 * @license    http://dibiphp.com/license  dibi license
 * @link       http://dibiphp.com/
 * @package    dibi
 */



/**
 * Default implementation of IDataSource for dibi.
 *
 * @author     David Grudl
 * @copyright  Copyright (c) 2005, 2008 David Grudl
 * @package    dibi
 * @version    $Revision$ $Date$
 */
class DibiDataSource extends Nette_Object implements IDataSource
{
    /** @var DibiConnection */
    private $connection;

    /** @var string */
    private $sql;

    /** @var int */
    private $count;



    /**
     * @param  string  SQL command or table name, as data source
     * @param  DibiConnection  connection
     */
    public function __construct($sql, DibiConnection $connection = NULL)
    {
        if (strpos($sql, ' ') === FALSE) {
            // table name
            $this->sql = $sql;
        } else {
            // SQL command
            $this->sql = '(' . $sql . ') AS [source]';
        }

        $this->connection = $connection === NULL ? dibi::getConnection() : $connection;
    }



    /**
     * @param  int  offset
     * @param  int  limit
     * @param  array columns
     * @return ArrayIterator
     */
    public function getIterator($offset = NULL, $limit = NULL, $cols = NULL)
    {
        return $this->connection->query('
            SELECT *
            FROM', $this->sql, '
            %ofs %lmt', $offset, $limit
        );
    }



    /**
     * @return int
     */
    public function count()
    {
        if ($this->count === NULL) {
            $this->count = $this->connection->query('
                SELECT COUNT(*) FROM', $this->sql
            )->fetchSingle();
        }
        return $this->count;
    }

}