<?php
/**
 * Piwik - Open source web analytics
 * 
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
 * 
 * @category Piwik
 * @package Piwik
 */

/**
 * Delete all rows from the table that are not in the offset,offset+limit range
 * 
 * @package Piwik
 * @subpackage Piwik_DataTable
 */
class Piwik_DataTable_Filter_Limit extends Piwik_DataTable_Filter
{
	/**
	 * Filter constructor.
	 * 
	 * @param Piwik_DataTable  $table
	 * @param int              $offset          Starting row (indexed from 0)
	 * @param int              $limit           Number of rows to keep (specify -1 to keep all rows)
	 * @param bool             $keepSummaryRow  Whether to keep the summary row or not.
	 */
	public function __construct( $table, $offset, $limit = null, $keepSummaryRow = false )
	{
		parent::__construct($table);
		$this->offset = $offset;
		
		if(is_null($limit))
		{
			$limit = -1;
		}
		$this->limit = $limit;
		$this->keepSummaryRow = $keepSummaryRow;
	}

	/**
	 * Limits the given data table
	 *
	 * @param Piwik_DataTable  $table
	 */
	public function filter($table)
	{
		$table->setRowsCountBeforeLimitFilter();
		
		if ($this->keepSummaryRow)
		{
			$summaryRow = $table->getRowFromId(Piwik_DataTable::ID_SUMMARY_ROW);
		}
		
		// we delete from 0 to offset
		if($this->offset > 0) 
		{
			$table->deleteRowsOffset( 0, $this->offset );
		}
		// at this point the array has offset less elements. We delete from limit to the end
		if( $this->limit >= 0 )
		{
			$table->deleteRowsOffset( $this->limit );
		}
		
		if ($this->keepSummaryRow && $summaryRow)
		{
			$table->addSummaryRow($summaryRow);
		}
	}
}
