<?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, Hogeschool Gent

	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 the class library for Dokeos.
*	@package	 dokeos.library
==============================================================================
*/
require_once (api_get_path(LIBRARY_PATH).'course.lib.php');
/**
 * This library contains some functions for class-management.
 * @author Bart Mollet
 * @package dokeos.library
 */
class ClassManager
{
	/**
	 * Get class information
	 * @note This function can't be named get_class() because that's a standard
	 * php-function.
	 */
	function get_class_info($class_id)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$sql = "SELECT * FROM $table_class WHERE id='".$class_id."'";
		$res = Database::query($sql, __FILE__, __LINE__);
		return mysql_fetch_array($res, MYSQL_ASSOC);
	}
	/**
	 * Change the name of a class
	 * @param string $name The new name
	 * @param int $class_id The class id
	 */
	function set_name($name, $class_id)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$sql = "UPDATE $table_class SET name='".mysql_real_escape_string($name)."' WHERE id='".$class_id."'";
		$res = Database::query($sql, __FILE__, __LINE__);
	}
	/**
	 * Create a class
	 * @param string $name
	 */
	function create_class($name)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$sql = "INSERT INTO $table_class SET name='".mysql_real_escape_string($name)."'";
		Database::query($sql, __FILE__, __LINE__);
		return mysql_affected_rows() == 1;
	}
	/**
	 * Check if a classname is allready in use
	 * @param string $name
	 */
	function class_name_exists($name)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$sql = "SELECT * FROM $table_class WHERE name='".mysql_real_escape_string($name)."'";
		$res = Database::query($sql, __FILE__, __LINE__);
		return mysql_num_rows($res) != 0;
	}
	/**
	 * Delete a class
	 * @param int $class_id
	 * @todo Add option to unsubscribe class-members from the courses where the
	 * class was subscibed to
	 */
	function delete_class($class_id)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$table_class_course = Database :: get_main_table(TABLE_MAIN_COURSE_CLASS);
		$table_class_user = Database :: get_main_table(TABLE_MAIN_CLASS_USER);
		$sql = "DELETE FROM $table_class_user WHERE class_id = '".$class_id."'";
		Database::query($sql, __FILE__, __LINE__);
		$sql = "DELETE FROM $table_class_course WHERE class_id = '".$class_id."'";
		Database::query($sql, __FILE__, __LINE__);
		$sql = "DELETE FROM $table_class WHERE id = '".$class_id."'";
		Database::query($sql, __FILE__, __LINE__);
	}
	/**
	 * Get all users from a class
	 * @param int $class_id
	 * @return array
	 */
	function get_users($class_id)
	{
		$table_class_user = Database :: get_main_table(TABLE_MAIN_CLASS_USER);
		$table_user = Database :: get_main_table(TABLE_MAIN_USER);
		$sql = "SELECT * FROM $table_class_user cu, $table_user u WHERE cu.class_id = '".$class_id."' AND cu.user_id = u.user_id";
		$res = Database::query($sql, __FILE__, __LINE__);
		$users = array ();
		while ($user = mysql_fetch_array($res, MYSQL_ASSOC))
		{
			$users[] = $user;
		}
		return $users;
	}
	/**
	 * Add a user to a class. If the class is subscribed to a course, the new
	 * user will also be subscribed to that course.
	 * @param int $user_id The user id
	 * @param int $class_id The class id
	 */
	function add_user($user_id, $class_id)
	{
		$table_class_user = Database :: get_main_table(TABLE_MAIN_CLASS_USER);
		$sql = "INSERT IGNORE INTO $table_class_user SET user_id = '".$user_id."', class_id='".$class_id."'";
		Database::query($sql, __FILE__, __LINE__);
		$courses = ClassManager :: get_courses($class_id);
		foreach ($courses as $index => $course)
		{
			CourseManager :: subscribe_user($user_id, $course['course_code']);
		}
	}
	/**
	 * Unsubscribe a user from a class. If the class is also subscribed in a
	 * course, the user will be unsubscribed from that course
	 * @param int $user_id The user id
	 * @param int $class_id The class id
	 */
	function unsubscribe_user($user_id, $class_id)
	{
		$table_class_user = Database :: get_main_table(TABLE_MAIN_CLASS_USER);
		$table_course_class = Database :: get_main_table(TABLE_MAIN_COURSE_CLASS);
		$courses = ClassManager :: get_courses($class_id);
		if (count($courses) != 0)
		{
			$course_codes = array ();
			foreach ($courses as $index => $course)
			{
				$course_codes[] = $course['course_code'];
				$sql = "SELECT DISTINCT user_id FROM $table_class_user t1, $table_course_class t2 WHERE t1.class_id=t2.class_id AND course_code = '".$course['course_code']."' AND user_id = $user_id AND t2.class_id<>'$class_id'";
				$res = Database::query($sql, __FILE__, __LINE__);
				if (mysql_num_rows($res) == 0 && CourseManager :: get_user_in_course_status($user_id, $course['course_code']) == STUDENT)
				{
					CourseManager :: unsubscribe_user($user_id, $course['course_code']);
				}
			}
		}
		$sql = "DELETE FROM $table_class_user WHERE user_id='".$user_id."' AND class_id = '".$class_id."'";
		Database::query($sql, __FILE__, __LINE__);
	}
	/**
	 * Get all courses in which a class is subscribed
	 * @param int $class_id
	 * @return array
	 */
	function get_courses($class_id)
	{
		$table_class_course = Database :: get_main_table(TABLE_MAIN_COURSE_CLASS);
		$table_course = Database :: get_main_table(TABLE_MAIN_COURSE);
		$sql = "SELECT * FROM $table_class_course cc, $table_course c WHERE cc.class_id = '".$class_id."' AND cc.course_code = c.code";
		$res = Database::query($sql, __FILE__, __LINE__);
		$courses = array ();
		while ($course = mysql_fetch_array($res, MYSQL_ASSOC))
		{
			$courses[] = $course;
		}
		return $courses;
	}
	/**
	 * Subscribe all members of a class to a course
	 * @param  int $class_id The class id
	 * @param string $course_code The course code
	 */
	function subscribe_to_course($class_id, $course_code)
	{
		$tbl_course_class = Database :: get_main_table(TABLE_MAIN_COURSE_CLASS);
		$tbl_class_user = Database :: get_main_table(TABLE_MAIN_CLASS_USER);
		$tbl_course_user = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
		$sql = "INSERT IGNORE INTO $tbl_course_class SET course_code = '".mysql_real_escape_string($course_code)."', class_id = '".mysql_real_escape_string($class_id)."'";
		Database::query($sql, __FILE__, __LINE__);
		$sql = "SELECT user_id FROM $tbl_class_user WHERE class_id = '".mysql_real_escape_string($class_id)."'";
		$res = Database::query($sql, __FILE__, __LINE__);
		while ($user = mysql_fetch_object($res))
		{
			CourseManager :: subscribe_user($user->user_id, $course_code);
		}
	}
	/**
	 * Unsubscribe a class from a course.
	 * Only students are unsubscribed. If a user is member of 2 classes which
	 * are both subscribed to the course, the user stays in the course.
	 * @param int $class_id The class id
	 * @param string $course_code The course code
	 */
	function unsubscribe_from_course($class_id, $course_code)
	{
		$tbl_course_class = Database :: get_main_table(TABLE_MAIN_COURSE_CLASS);
		$tbl_class_user = Database :: get_main_table(TABLE_MAIN_CLASS_USER);
		$sql = "SELECT cu.user_id,COUNT(cc.class_id) FROM $tbl_course_class cc, $tbl_class_user cu WHERE  cc.class_id = cu.class_id AND cc.course_code = '".mysql_real_escape_string($course_code)."' GROUP BY cu.user_id HAVING COUNT(cc.class_id) = 1";
		$single_class_users = Database::query($sql, __FILE__, __LINE__);
		while ($single_class_user = mysql_fetch_object($single_class_users))
		{
			$sql = "SELECT * FROM $tbl_class_user WHERE class_id = '".mysql_real_escape_string($class_id)."' AND user_id = '".mysql_real_escape_string($single_class_user->user_id)."'";
			$res = Database::query($sql, __FILE__, __LINE__);
			if (mysql_num_rows($res) > 0)
			{
				if (CourseManager :: get_user_in_course_status($single_class_user->user_id, $course_code) == STUDENT)
				{
					CourseManager :: unsubscribe_user($single_class_user->user_id, $course_code);
				}
			}
		}
		$sql = "DELETE FROM $tbl_course_class WHERE course_code = '".mysql_real_escape_string($course_code)."' AND class_id = '".mysql_real_escape_string($class_id)."'";
		Database::query($sql, __FILE__, __LINE__);
	}

	/**
	 * Get the class-id
	 * @param string $name The class name
	 * @return int the ID of the class
	 */
	function get_class_id($name)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$sql = "SELECT * FROM $table_class WHERE name='".$name."'";
		$res = Database::query($sql, __FILE__, __LINE__);
		$obj = mysql_fetch_object($res);
		return $obj->id;
	}
	/**
	 * Get all classes subscribed in a course
	 * @param string $course_code
	 * @return array An array with all classes (keys: 'id','code','name')
	 */
	function get_classes_in_course($course_code)
	{
		$table_class = Database :: get_main_table(TABLE_MAIN_CLASS);
		$table_course_class = Database :: get_main_table(TABLE_MAIN_COURSE_CLASS);
		$sql = "SELECT cl.* FROM $table_class cl, $table_course_class cc WHERE cc.course_code = '".mysql_real_escape_string($course_code)."' AND cc.class_id = cl.id";
		$res = Database::query($sql, __FILE__, __LINE__);
		$classes = array ();
		while ($class = mysql_fetch_array($res, MYSQL_ASSOC))
		{
			$classes[] = $class;
		}
		return $classes;
	}
}
?>