<?php
/**
 * @package angifw
 * @copyright Copyright (C) 2009-2013 Nicholas K. Dionysopoulos. All rights reserved.
 * @author Nicholas K. Dionysopoulos - http://www.dionysopoulos.me
 * @license http://www.gnu.org/copyleft/gpl.html GNU/GPL v3 or later
 *
 * Akeeba Next Generation Installer Framework
 *
 * This file may contain code from the Joomla! Platform, Copyright (c) 2005 -
 * 2012 Open Source Matters, Inc. This file is NOT part of the Joomla! Platform.
 * It is derivative work and clearly marked as such as per the provisions of the
 * GNU General Public License.
 */

defined('_AKEEBA') or die();


/**
 * Query Building Class.
 */
class ADatabaseQueryMysqli extends ADatabaseQuery implements ADatabaseQueryLimitable
{
	/**
	 * @var    interger  The offset for the result set.
	 */
	protected $offset;

	/**
	 * @var    integer  The limit for the result set.
	 */
	protected $limit;

	/**
	 * Method to modify a query already in string format with the needed
	 * additions to make the query limited to a particular number of
	 * results, or start at a particular offset.
	 *
	 * @param   string   $query   The query in string format
	 * @param   integer  $limit   The limit for the result set
	 * @param   integer  $offset  The offset for the result set
	 *
	 * @return string
	 *
	 */
	public function processLimit($query, $limit, $offset = 0)
	{
		if ($limit > 0 || $offset > 0)
		{
			$query .= ' LIMIT ' . $offset . ', ' . $limit;
		}

		return $query;
	}

	/**
	 * Concatenates an array of column names or values.
	 *
	 * @param   array   $values     An array of values to concatenate.
	 * @param   string  $separator  As separator to place between each value.
	 *
	 * @return  string  The concatenated values.
	 *
	 */
	public function concatenate($values, $separator = null)
	{
		if ($separator)
		{
			$concat_string = 'CONCAT_WS(' . $this->quote($separator);

			foreach ($values as $value)
			{
				$concat_string .= ', ' . $value;
			}

			return $concat_string . ')';
		}
		else
		{
			return 'CONCAT(' . implode(',', $values) . ')';
		}
	}

	/**
	 * Sets the offset and limit for the result set, if the database driver supports it.
	 *
	 * Usage:
	 * $query->setLimit(100, 0); (retrieve 100 rows, starting at first record)
	 * $query->setLimit(50, 50); (retrieve 50 rows, starting at 50th record)
	 *
	 * @param   integer  $limit   The limit for the result set
	 * @param   integer  $offset  The offset for the result set
	 *
	 * @return  ADatabaseQuery  Returns this object to allow chaining.
	 *
	 */
	public function setLimit($limit = 0, $offset = 0)
	{
		$this->limit  = (int) $limit;
		$this->offset = (int) $offset;

		return $this;
	}
}