<?php
/*
==============================================================================
	Dokeos - elearning and course management software
	
	Copyright (c) 2004-2005 Dokeos S.A.
	Copyright (c) 2003 Ghent University (UGent)
	Copyright (c) Roan Embrechts, Vrije Universiteit Brussel
	
	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: Zhong
	Mail: poopsoft@163.com
==============================================================================
*/
/**
============================================================================== 
*	This is the document library for Dokeos.
*	It is / will be used to provide a service layer to all document-using tools.
*	and eliminate code duplication fro group documents, scorm documents, main documents.
*	Include/require it in your code to use its functionality.
*
*	@version 1.1, January 2005
*	@package iilearn.library
============================================================================== 
*/

/*
============================================================================== 
	DOCUMENTATION
	use the functions like this: DocumentManager::get_course_quota()
============================================================================== 
*/

/*
============================================================================== 
		CONSTANTS
============================================================================== 
*/

define("DISK_QUOTA_FIELD", "disk_quota"); //name of the database field
/** default quota for the course documents folder */
define("DEFAULT_DOCUMENT_QUOTA", get_setting('default_document_quotum'));

/*
============================================================================== 
		VARIABLES
============================================================================== 
*/

$sys_course_path = api_get_path(SYS_COURSE_PATH);
$baseServDir = api_get_path(SYS_PATH);
$baseServUrl = $_configuration['url_append']."/";
$baseWorkDir = $sys_course_path.$courseDir;

/*
============================================================================== 
		DocumentManager CLASS
		the class and its functions
============================================================================== 
*/

/**
 *	@package iilearn.library
 */
class DocumentManager
{
	/**
	* @return the document folder quuta of the current course, in bytes
	* @todo eliminate globals
	*/
	function get_course_quota()
	{
		global $_course, $maxFilledSpace;
		$course_code = $_course['sysCode'];
		$course_table = Database :: get_main_table(TABLE_MAIN_COURSE);

		$sql_query = "SELECT `".DISK_QUOTA_FIELD."` FROM $course_table WHERE `code` = '$course_code'";
		$sql_result = api_sql_query($sql_query, __FILE__, __LINE__);
		$result = mysql_fetch_array($sql_result);
		$course_quota = $result[DISK_QUOTA_FIELD];

		if ($course_quota == NULL)
		{
			//course table entry for quota was null
			//use default value
			$course_quota = DEFAULT_DOCUMENT_QUOTA;
		}

		return $course_quota;
	}

	/**
	*	Get the content type of a file by checking the extension
	*	We could use mime_content_type() with php-versions > 4.3,
	*	but this doesn't work as it should on Windows installations
	*
	*	@param string $filename or boolean TRUE to return complete array
	*	@author ? first version
	*	@author Bert Vanderkimpen
	*
	*/
	function file_get_mime_type($filename)
	{
		//all mime types in an array (from 1.6, this is the authorative source)
		//please keep this alphabetical if you add something to this list!!!
	    $mime_types=array(
			"ai" => "application/postscript",
			"aif" => "audio/x-aiff",
    		"aifc" => "audio/x-aiff",
   			"aiff" => "audio/x-aiff",
		    "asf" => "video/x-ms-asf",
		    "asc" => "text/plain",
		    "au" => "audio/basic",
		    "avi" => "video/x-msvideo",
		    "bcpio" => "application/x-bcpio",
		    "bin" => "application/octet-stream",
		    "bmp" => "image/bmp",
		    "cdf" => "application/x-netcdf",
		    "class" => "application/octet-stream",
		    "cpio" => "application/x-cpio",
		    "cpt" => "application/mac-compactpro",
		    "csh" => "application/x-csh",
		    "css" => "text/css",
		    "dcr" => "application/x-director",
		    "dir" => "application/x-director",
		    "djv" => "image/vnd.djvu",
		    "djvu" => "image/vnd.djvu",
		    "dll" => "application/octet-stream",
		    "dmg" => "application/x-diskcopy",
		    "dms" => "application/octet-stream",
		    "doc" => "application/msword",
		    "dvi" => "application/x-dvi",
		    "dwg" => "application/vnd.dwg",
		    "dxf" => "application/vnd.dxf",
		    "dxr" => "application/x-director",
		    "eps" => "application/postscript",
		    "etx" => "text/x-setext",
		    "exe" => "application/octet-stream",
		    "ez" => "application/andrew-inset",
		    "gif" => "image/gif",
		    "gtar" => "application/x-gtar",
		    "gz" => "application/x-gzip",    
		    "hdf" => "application/x-hdf",
		    "hqx" => "application/mac-binhex40",
		    "htm" => "text/html",
		    "html" => "text/html",
		    "ice" => "x-conference-xcooltalk",
		    "ief" => "image/ief",
		    "iges" => "model/iges",
		    "igs" => "model/iges",
		    "jar" => "application/java-archiver",
		    "jpe" => "image/jpeg",
		    "jpeg" => "image/jpeg",
		    "jpg" => "image/jpeg",
		    "js" => "application/x-javascript",
		    "kar" => "audio/midi",
		    "latex" => "application/x-latex",
		    "lha" => "application/octet-stream",
		    "lzh" => "application/octet-stream",
		    "m1a" => "audio/mpeg",
		    "m2a" => "audio/mpeg",
		    "m3u" => "audio/x-mpegurl",
		    "man" => "application/x-troff-man",
		    "me" => "application/x-troff-me",
		    "mesh" => "model/mesh",
		    "mid" => "audio/midi",
		    "midi" => "audio/midi",
		    "mov" => "video/quicktime",
		    "movie" => "video/x-sgi-movie",
		    "mp2" => "audio/mpeg",
		    "mp3" => "audio/mpeg",
		    "mp4" => "video/mpeg4-generic",
		    "mpa" => "audio/mpeg",
		    "mpe" => "video/mpeg",
		    "mpeg" => "video/mpeg",
		    "mpg" => "video/mpeg",
		    "mpga" => "audio/mpeg",
		    "ms" => "application/x-troff-ms",
		    "msh" => "model/mesh",
		    "mxu" => "video/vnd.mpegurl",
		    "nc" => "application/x-netcdf",
		    "oda" => "application/oda",
		    "pbm" => "image/x-portable-bitmap",
		    "pct" => "image/pict",
		    "pdb" => "chemical/x-pdb",
		    "pdf" => "application/pdf",
		    "pgm" => "image/x-portable-graymap",
		    "pgn" => "application/x-chess-pgn",
		    "pict" => "image/pict",
		    "png" => "image/png",
		    "pnm" => "image/x-portable-anymap",
		    "ppm" => "image/x-portable-pixmap",
		    "ppt" => "application/vnd.ms-powerpoint",
		    "pps" => "application/vnd.ms-powerpoint",
		    "ps" => "application/postscript",
		    "qt" => "video/quicktime",
		    "ra" => "audio/x-realaudio",
		    "ram" => "audio/x-pn-realaudio",
		    "rar" => "image/x-rar-compressed",
		    "ras" => "image/x-cmu-raster",
		    "rgb" => "image/x-rgb",
		    "rm" => "audio/x-pn-realaudio",
		    "roff" => "application/x-troff",
		    "rpm" => "audio/x-pn-realaudio-plugin",
		    "rtf" => "text/rtf",
		    "rtx" => "text/richtext",
		    "sgm" => "text/sgml",
		    "sgml" => "text/sgml",
		    "sh" => "application/x-sh",
		    "shar" => "application/x-shar",
		    "silo" => "model/mesh",
		    "sib" => "application/X-Sibelius-Score",
		    "sit" => "application/x-stuffit",
		    "skd" => "application/x-koan",
		    "skm" => "application/x-koan",
		    "skp" => "application/x-koan",
		    "skt" => "application/x-koan",
		    "smi" => "application/smil",
		    "smil" => "application/smil",
		    "snd" => "audio/basic",
		    "so" => "application/octet-stream",
		    "spl" => "application/x-futuresplash",
		    "src" => "application/x-wais-source",
		    "sv4cpio" => "application/x-sv4cpio",
		    "sv4crc" => "application/x-sv4crc",
		    "svf" => "application/vnd.svf",
		    "swf" => "application/x-shockwave-flash",
		    "sxc" => "application/vnd.sun.xml.calc",
		    "sxi" => "application/vnd.sun.xml.impress",
		    "sxw" => "application/vnd.sun.xml.writer",
		    "t" => "application/x-troff",
		    "tar" => "application/x-tar",
		    "tcl" => "application/x-tcl",
		    "tex" => "application/x-tex",
		    "texi" => "application/x-texinfo",
		    "texinfo" => "application/x-texinfo",
		    "tga" => "image/x-targa",
		    "tif" => "image/tif",
		    "tiff" => "image/tiff",
		    "tr" => "application/x-troff",
		    "tsv" => "text/tab-seperated-values",
		    "txt" => "text/plain",
		    "ustar" => "application/x-ustar",
		    "vcd" => "application/x-cdlink",
		    "vrml" => "model/vrml",
		    "wav" => "audio/x-wav",
		    "wbmp" => "image/vnd.wap.wbmp",
		    "wbxml" => "application/vnd.wap.wbxml",
		    "wml" => "text/vnd.wap.wml",
		    "wmlc" => "application/vnd.wap.wmlc",
		    "wmls" => "text/vnd.wap.wmlscript",
		    "wmlsc" => "application/vnd.wap.wmlscriptc",
		    "wma" => "video/x-ms-wma",   
		    "wmv" => "video/x-ms-wmv",    
		    "wrl" => "model/vrml",
		    "xbm" => "image/x-xbitmap",
		    "xht" => "application/xhtml+xml",
		    "xhtml" => "application/xhtml+xml",
		    "xls" => "application/vnd.ms-excel",
		    "xml" => "text/xml",
		    "xpm" => "image/x-xpixmap",
		    "xsl" => "text/xml",
		    "xwd" => "image/x-windowdump",
		    "xyz" => "chemical/x-xyz",
		    "zip" => "application/zip"
		);
		
		if ($filename === TRUE) 
		{
			return $mime_types;
		}
		
		//get the extension of the file
		$extension = explode('.', $filename);

		//$filename will be an array if a . was found
		if (is_array($extension))
		{
			$extension = (strtolower($extension[sizeof($extension) - 1]));
		}
		//file without extension
		else
		{
			$extension = 'empty';
		}

		//if the extension is found, return the content type
		if (isset ($mime_types[$extension]))
			return $mime_types[$extension];
		//else return octet-stream
		return "application/octet-stream";
	}

	/**
	*	@return true if the user is allowed to see the document, false otherwise
	*	@author Sergio A Kessler, first version
	*	@author Roan Embrechts, bugfix
	*   @todo ??not only check if a file is visible, but also check if the user is allowed to see the file??
	*/
	function file_visible_to_user($this_course, $doc_url)
	{
		if (api_is_allowed_to_edit())
		{
			return true;
		}
		else
		{
			$tbl_document = Database::get_course_table(TABLE_DOCUMENT);
			$tbl_item_property = $this_course.'item_property';
			//$doc_url = addslashes($doc_url);
			$query = "SELECT 1 FROM `$tbl_document` AS docs,`$tbl_item_property` AS props WHERE props.tool = 'document' AND docs.id=props.ref AND props.visibility <> '1' AND docs.path = '$doc_url'";
			//echo $query;
			$result = api_sql_query($query, __FILE__, __LINE__);

			return (mysql_num_rows($result) == 0);
		}
	}

	/**
	* This function streams a file to the client
	*
	* @param string $full_file_name
	* @param boolean $forced
	* @param string $name
	* @return false if file doesn't exist, true if stream succeeded
	*/
	function file_send_for_download($full_file_name, $forced = false, $name = '')
	{
		if (!is_file($full_file_name))
		{
			return false;
		}
		$filename = ($name == '') ? basename($full_file_name) : $name;
		$len = filesize($full_file_name);

		if ($forced)
		{
			//force the browser to save the file instead of opening it

			header('Content-type: application/octet-stream');
			//header('Content-Type: application/force-download');
			header('Content-length: '.$len);
			if (preg_match("/MSIE 5.5/", $_SERVER['HTTP_USER_AGENT']))
			{
				header('Content-Disposition: filename= '.$filename);
			}
			else
			{
				header('Content-Disposition: attachment; filename= '.$filename);
			}
			if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE'))
			{
				header('Pragma: ');
				header('Cache-Control: ');
				header('Cache-Control: public'); // IE cannot download from sessions without a cache
			}
			header('Content-Description: '.$filename);
			header('Content-transfer-encoding: binary');

			$fp = fopen($full_file_name, 'r');
			fpassthru($fp);
			return true;
		}
		else
		{
			//no forced download, just let the browser decide what to do according to the mimetype

			$content_type = DocumentManager :: file_get_mime_type($filename);
			header('Expires: Wed, 01 Jan 1990 00:00:00 GMT');
			header('Last-Modified: '.gmdate('D, d M Y H:i:s').' GMT');
			header('Cache-Control: no-cache, must-revalidate');
			header('Pragma: no-cache');
			header('Content-type: '.$content_type);
			header('Content-Length: '.$len);
			$user_agent = strtolower($_SERVER['HTTP_USER_AGENT']);
			if (strpos($user_agent, 'msie'))
			{
				header('Content-Disposition: ; filename= '.$filename);
			}
			else
			{
				header('Content-Disposition: inline; filename= '.$filename);
			}
			readfile($full_file_name);
			return true;
		}
	}

	/**
	* Fetches all document data for the given user/group
	*
	* @param array $_course
	* @param string $path
	* @param int $to_group_id
	* @param int $to_user_id
	* @param boolean $can_see_invisible
	* @return array with all document data 
	*/
	function get_all_document_data($_course, $path = '/', $to_group_id = 0, $to_user_id = NULL, $can_see_invisible = false)
	{
		$TABLE_ITEMPROPERTY = Database :: get_course_table(TABLE_ITEM_PROPERTY, $_course['dbName']);
		$TABLE_DOCUMENT = Database :: get_course_table(TABLE_DOCUMENT, $_course['dbName']);

		if (!is_null($to_user_id))
		{
			$to_field = 'last.to_user_id';
			$to_value = $to_user_id;
		}
		else
		{
			$to_field = 'last.to_group_id';
			$to_value = $to_group_id;
		}

		//escape underscores in the path so they don't act as a wildcard
		$path = str_replace('_', '\_', $path);

		//if they can't see invisible files, they can only see files with visibility 1
		$visibility_bit = ' = 1';
		//if they can see invisible files, only deleted files (visibility 2) are filtered out
		if ($can_see_invisible)
		{
			$visibility_bit = ' <> 2';
		}

		//the given path will not end with a slash, unless it's the root '/'
		//so no root -> add slash
		$added_slash = ($path == '/') ? '' : '/';

		$sql = "SELECT *
						FROM  ".$TABLE_ITEMPROPERTY."  AS last, ".$TABLE_DOCUMENT."  AS docs
						WHERE docs.id = last.ref
						AND docs.path LIKE '".$path.$added_slash."%'
						AND docs.path NOT LIKE '".$path.$added_slash."%/%'
						AND last.tool = '".TOOL_DOCUMENT."' 
						AND ".$to_field." = ".$to_value."
						AND last.visibility".$visibility_bit;
		$result = api_sql_query($sql, __FILE__, __LINE__);

		if ($result && mysql_num_rows($result) != 0)
		{
			while ($row = mysql_fetch_assoc($result))
				//while ($row = mysql_fetch_array($result,MYSQL_NUM))
			{
				$document_data[$row['id']] = $row;
				//$document_data[] = $row;
			}
			return $document_data;
		}
		else
		{
			//display_error("Error getting document info from database (".mysql_error().")!");
			return false;
		}
	}

	/**
	 * Gets the paths of all folders in a course
	 * can show all folders (exept for the deleted ones) or only visible ones
	 * @param array $_course
	 * @param boolean $can_see_invisible
	 * @param int $to_group_id
	 * @return array with paths
	 */
	function get_all_document_folders($_course, $to_group_id = '0', $can_see_invisible = false)
	{
		$TABLE_ITEMPROPERTY = Database :: get_course_table(TABLE_ITEM_PROPERTY, $_course['dbName']);
		$TABLE_DOCUMENT = Database :: get_course_table(TABLE_DOCUMENT, $_course['dbName']);
		if(empty($to_group_id)){$to_group_id = '0';} //avoid empty strings in $to_group_id
		if ($can_see_invisible)
		{
			$sql = "SELECT path
								FROM  ".$TABLE_ITEMPROPERTY."  AS last, ".$TABLE_DOCUMENT."  AS docs
								WHERE docs.id = last.ref
								AND docs.filetype = 'folder' 
								AND last.tool = '".TOOL_DOCUMENT."' 
								AND last.to_group_id = ".$to_group_id." 
								AND last.visibility <> 2";

			$result = api_sql_query($sql, __FILE__, __LINE__);

			if ($result && mysql_num_rows($result) != 0)
			{
				while ($row = mysql_fetch_assoc($result))
				{
					$document_folders[] = $row['path'];
				}
				sort($document_folders, SORT_ASC);
				//return results
				return $document_folders;
			}
			else
			{
				return false;
			}
		}
		//no invisible folders
		else
		{
			//get visible folders
			$visible_sql = "SELECT path
						FROM  ".$TABLE_ITEMPROPERTY."  AS last, ".$TABLE_DOCUMENT."  AS docs
						WHERE docs.id = last.ref
						AND docs.filetype = 'folder' 
						AND last.tool = '".TOOL_DOCUMENT."' 
						AND last.to_group_id = ".$to_group_id." 
						AND last.visibility = 1";
			$visibleresult = api_sql_query($visible_sql, __FILE__, __LINE__);
			while ($all_visible_folders = mysql_fetch_assoc($visibleresult))
			{
				$visiblefolders[] = $all_visible_folders['path'];
				//echo "visible folders: ".$all_visible_folders['path']."<br>";
			}
			//get invisible folders
			$invisible_sql = "SELECT path 
						FROM  ".$TABLE_ITEMPROPERTY."  AS last, ".$TABLE_DOCUMENT."  AS docs
						WHERE docs.id = last.ref
						AND docs.filetype = 'folder' 
						AND last.tool = '".TOOL_DOCUMENT."' 
						AND last.to_group_id = ".$to_group_id." 
						AND last.visibility = 0";
			$invisibleresult = api_sql_query($invisible_sql, __FILE__, __LINE__);
			while ($invisible_folders = mysql_fetch_assoc($invisibleresult))
			{
				//get visible folders in the invisible ones -> they are invisible too
				//echo "invisible folders: ".$invisible_folders['path']."<br>";
				$folder_in_invisible_sql = "SELECT path 
								FROM  ".$TABLE_ITEMPROPERTY."  AS last, ".$TABLE_DOCUMENT."  AS docs
								WHERE docs.id = last.ref
								AND docs.path LIKE '".mysql_real_escape_string($invisible_folders['path'])."/%' 
								AND docs.filetype = 'folder' 
								AND last.tool = '".TOOL_DOCUMENT."' 
								AND last.to_group_id = ".$to_group_id." 
								AND last.visibility = 1";
				$folder_in_invisible_result = api_sql_query($folder_in_invisible_sql, __FILE__, __LINE__);
				while ($folders_in_invisible_folder = mysql_fetch_assoc($folder_in_invisible_result))
				{
					$invisiblefolders[] = $folders_in_invisible_folder['path'];
					//echo "<br>folders in invisible folders: ".$folders_in_invisible_folder['path']."<br><br><br>";
				}
			}
			//if both results are arrays -> //calculate the difference between the 2 arrays -> only visible folders are left :)
			if (is_array($visiblefolders) && is_array($invisiblefolders))
			{
				$document_folders = array_diff($visiblefolders, $invisiblefolders);
				sort($document_folders, SORT_ASC);
				return $document_folders;
			}
			//only visible folders found
			elseif (is_array($visiblefolders))
			{
				sort($visiblefolders, SORT_ASC);
				return $visiblefolders;
			}
			//no visible folders found
			else
			{
				return false;
			}
		}
	}

	/**
	 * This deletes a document by changing visibility to 2, renaming it to filename_DELETED_#id
	 * Files/folders that are inside a deleted folder get visibility 2
	 *
	 * @param array $_course
	 * @param string $path, path stored in the database
	 * @param string ,$base_work_dir, path to the documents folder
	 * @return boolean true/false
	 * @todo now only files/folders in a folder get visibility 2, we should rename them too.
	 */
	function delete_document($_course, $path, $base_work_dir)
	{
		$TABLE_DOCUMENT = Database :: get_course_table(TABLE_DOCUMENT);
		$TABLE_ITEMPROPERTY = Database :: get_course_table(TABLE_ITEM_PROPERTY);

		//first, delete the actual document...
		$document_id = DocumentManager :: get_document_id($_course, $path);
		$new_path = $path.'_DELETED_'.$document_id;

		if ($document_id)
		{
			if (get_setting('permanently_remove_deleted_files') == 'true') //deleted files are *really* deleted
			{
				$what_to_delete_sql = "SELECT id FROM ".$TABLE_DOCUMENT." WHERE path='".$path."' OR path LIKE '".$path."/%'";
				//get all id's of documents that are deleted
				$what_to_delete_result = api_sql_query($what_to_delete_sql, __FILE__, __LINE__);

				if ($what_to_delete_result && mysql_num_rows($what_to_delete_result) != 0)
				{
					//needed to deleted medadata
					require_once (api_get_path(INCLUDE_PATH)."../metadata/md_funcs.php");
					$mdStore = new mdstore(TRUE);

					//delete all item_property entries
					while ($row = mysql_fetch_array($what_to_delete_result))
					{
						//query to delete from item_property table
						$remove_from_item_property_sql = "DELETE FROM ".$TABLE_ITEMPROPERTY." WHERE ref = ".$row['id']." AND tool='".TOOL_DOCUMENT."'";
						//query to delete from document table
						$remove_from_document_sql = "DELETE FROM ".$TABLE_DOCUMENT." WHERE id = ".$row['id']."";

						//echo($remove_from_item_property_sql.'<br>');
						api_sql_query($remove_from_item_property_sql, __FILE__, __LINE__);
						//echo($remove_from_document_sql.'<br>');
						api_sql_query($remove_from_document_sql, __FILE__, __LINE__);

						//delete metadata
						$eid = 'Document'.'.'.$row['id'];
						$mdStore->mds_delete($eid);
						$mdStore->mds_delete_offspring($eid);

					}
					//delete documents, do it like this so metadata get's deleted too
					//update_db_info('delete', $path);
					//throw it away
					my_delete($base_work_dir.$path);

					return true;
				}
				else
				{
					return false;
				}
			}
			else //set visibility to 2 and rename file/folder to qsdqsd_DELETED_#id
				{
				if (api_item_property_update($_course, TOOL_DOCUMENT, $document_id, 'delete', $user_id))
				{
					//echo('item_property_update OK');
					if (rename($base_work_dir.$path, $base_work_dir.$new_path))
					{
						//echo('rename OK');
						$sql = "UPDATE $TABLE_DOCUMENT set path='".$new_path."' WHERE id='".$document_id."'";
						if (api_sql_query($sql, __FILE__, __LINE__))
						{
							//if it is a folder it can contain files
							$sql = "SELECT id,path FROM ".$TABLE_DOCUMENT." WHERE path LIKE '".$path."/%'";
							$result = api_sql_query($sql, __FILE__, __LINE__);
							if ($result && mysql_num_rows($result) > 0)
							{
								while ($deleted_items = mysql_fetch_assoc($result))
								{
									//echo('to delete also: id '.$deleted_items['id']);
									api_item_property_update($_course, TOOL_DOCUMENT, $deleted_items['id'], 'delete', $user_id);
									//Change path of subfolders and documents in database
									$old_item_path = $deleted_items['path'];
									$new_item_path = $new_path.substr($old_item_path, strlen($path));
									$sql = "UPDATE $TABLE_DOCUMENT set path = '".$new_item_path."' WHERE id = ".$deleted_items['id'];
									api_sql_query($sql, __FILE__, __LINE__);
								}
							}
							//echo('dbase update OK');
							return true;
						}
					}
				}
				else
				{
					return false;
				}
			}
		}
	}

	/**
	 * Gets the id of a document with a given path
	 *
	 * @param array $_course
	 * @param string $path
	 * @return int id of document / false if no doc found
	 */
	function get_document_id($_course, $path)
	{
		$TABLE_DOCUMENT = Database :: get_course_table(TABLE_DOCUMENT, $_course['dbName']);

		$sql = "SELECT id FROM $TABLE_DOCUMENT WHERE path = '$path'";
		$result = api_sql_query($sql, __FILE__, __LINE__);

		if ($result && mysql_num_rows($result) == 1)
		{
			$row = mysql_fetch_row($result);
			return $row[0];
		}
		else
		{
			return false;
		}
	}

}
//end class DocumentManager
?>