<?php
/*
============================================================================== 
	Dokeos - elearning and course management software
	
	Copyright (c) 2004 Dokeos S.A.
	Copyright (c) 2003 Ghent University (UGent)
	Copyright (c) 2001 Universite catholique de Louvain (UCL)
	Copyright (c) Bart Mollet (bart.mollet@hogent.be)
	
	For a full list of contributors, see "credits.txt".
	The full license can be read in "license.txt".
	
	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.
	
	See the GNU General Public License for more details.
	
	Contact address: Dokeos, 44 rue des palais, B-1030 Brussels, Belgium
	Mail: info@dokeos.com
============================================================================== 
*/
/**
============================================================================== 
*	This is a library with some functions to sort tabular data
*
*	@package dokeos.library
============================================================================== 
*/
define('SORT_DATE', 3);
define('SORT_IMAGE',4);
class TableSort
{
	/**
	 * String to lowercase (keep accents).
	 * @param string $txt The string to convert
	 * @author René Haentjens
	 * This  function is 8859-1 specific and should be adapted when Dokeos is
	 * used with other charsets. 
	 */
	function strtolower_keepaccents($txt)
	{
		return strtolower(strtr($txt, "ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞ", "àáâãäåæçèéêëìíîïðñòóôõöøùúûüýþ"));
	}
	/**
	 * String to lowercase.
	 * @param string $txt The string to convert
	 * @author René Haentjens
	 * This  function is 8859-1 specific and should be adapted when Dokeos is
	 * used with other charsets.
	 */
	function strtolower_eorlatin($txt)
	{
		return str_replace(array ("æ", "ß"), array ("ae", "ss"), strtr(TableSort::strtolower_keepaccents($txt), "àáâãäåçèéêëìíîïðñòóôõöøùúûüýÿ", "aaaaaaceeeeiiiidnoooooouuuuyy"));
		// do not replace "þ" by "th", leave it at the end of the alphabet...
		// do not replace any of "$&¢£¥©ª®µº", though they resemble letters...
	}
	/**
	 * Create a string to use in sorting.
	 * @param string $txt The string to convert
	 * @author René Haentjens
	 * This  function is 8859-1 specific and should be adapted when Dokeos is
	 * used with other charsets. 
	 * See http://anubis.dkuug.dk/CEN/TC304/EOR/eorhome.html 
	 * Function 'orderingstring' can be used to implement EOR level 1 ordering,
	 * for 8859- 1.
	 */
	function orderingstring($txt)
	{
		return ereg_replace("[^0-9a-zþ]", "", TableSort::strtolower_eorlatin($txt));
	}
	/**
	 * Sort 2-dimensional table.
	 * @param array $data The data to be sorted.
	 * @param int $column The column on which the data should be sorted (default =
	 * 0)
	 * @param string $direction The direction to sort (SORT_ASC (default) or
	 * SORT_DESC)
	 * @param constant $type How should data be sorted (SORT_REGULAR, SORT_NUMERIC,
	 * SORT_STRING,SORT_DATE,SORT_IMAGE)
	 * @return array The sorted dataset
	 * @author bart.mollet@hogent.be
	 */
	function sort_table($data, $column = 0, $direction = SORT_ASC, $type = SORT_REGULAR)
	{
		switch ($type)
		{
			case SORT_REGULAR :
				if (TableSort::is_image_column($data, $column))
				{
					return TableSort::sort_table($data, $column, $direction, SORT_IMAGE);
				}
				elseif (TableSort::is_date_column($data, $column))
				{
					return TableSort::sort_table($data, $column, $direction, SORT_DATE);
				}
				elseif (TableSort::is_numeric_column($data, $column))
				{
					return TableSort::sort_table($data, $column, $direction, SORT_NUMERIC);
				}

				return TableSort::sort_table($data, $column, $direction, SORT_STRING);
				break;
			case SORT_NUMERIC :
				$compare_function = 'strip_tags($el1) > strip_tags($el2)';
				break;
			case SORT_STRING :
				$compare_function = 'strnatcmp(TableSort::orderingstring(strip_tags($el1)),TableSort::orderingstring(strip_tags($el2))) > 0';
				break;
			case SORT_IMAGE :
				$compare_function = 'strnatcmp(TableSort::orderingstring(strip_tags($el1,"<img>")),TableSort::orderingstring(strip_tags($el2,"<img>"))) > 0';
				break;
			case SORT_DATE :
				$compare_function = 'strtotime(strip_tags($el1)) > strtotime(strip_tags($el2))';
		}
		$function_body = '$el1 = $a['.$column.']; $el2 = $b['.$column.']; return ('.$direction.' == SORT_ASC ? ('.$compare_function.') : !('.$compare_function.'));';
		// Sort the content
		usort($data, create_function('$a,$b', $function_body));
		return $data;
	}
	/**
	 * Checks if a column of a 2D-array contains only numeric values
	 * @param array $data The data-array
	 * @param int $column The index of the column to check
	 * @return bool true if column contains only dates, false otherwise
	 * @todo Take locale into account (eg decimal point or comma ?)
	 * @author bart.mollet@hogent.be
	 */
	function is_numeric_column($data, $column)
	{
		$is_numeric = true;
		foreach ($data as $index => $row)
		{
			$is_numeric &= is_numeric(strip_tags($row[$column]));
		}
		return $is_numeric;
	}
	/**
	 * Checks if a column of a 2D-array contains only dates (GNU date syntax)
	 * @param array $data The data-array
	 * @param int $column The index of the column to check
	 * @return bool true if column contains only dates, false otherwise
	 * @author bart.mollet@hogent.be
	 */
	function is_date_column($data, $column)
	{
		$is_date = true;
		foreach ($data as $index => $row)
		{
			if(strlen(strip_tags($row[$column])) != 0 )
			{
				$check_date = strtotime(strip_tags($row[$column]));
				// strtotime Returns a timestamp on success, FALSE otherwise. 
				// Previous to PHP 5.1.0, this function would return -1 on failure. 
				$is_date &= ($check_date != -1 && $check_date != false);
			}
			else
			{
				$is_date &= false;	
			}
		}
		return $is_date;
	}
	/**
	 * Checks if a column of a 2D-array contains only images (<img src="
	 * path/file.ext" alt=".."/>)
	 * @param array $data The data-array
	 * @param int $column The index of the column to check
	 * @return bool true if column contains only images, false otherwise
	 * @author bart.mollet@hogent.be
	 */
	function is_image_column($data, $column)
	{
		$is_image = true;
		foreach ($data as $index => $row)
		{
			$is_image &= strlen(trim(strip_tags($row[$column],'<img>'))) > 0; // at least one img-tag
			$is_image &= strlen(trim(strip_tags($row[$column]))) == 0; // and no text outside attribute-values
		}
		return $is_image;
	}
}
?>