<?php //$id: $
/* For licensing terms, see /license.txt */
/**
* This is the session library for Chamilo.
* All main sessions functions should be placed here.
* @package chamilo.library
*/

/* LIBRARIES */
require_once 'display.lib.php';
require_once(dirname(__FILE__).'/course.lib.php');

/**
*	This class provides methods for sessions management.
*	Include/require it in your code to use its features.
*
*	@package chamilo.library
*/
class SessionManager {
	private function __construct() {

	}
    /**
     * Fetches a session from the database
     * @param   int     Session ID
     * @return  array   Session details (id, id_coach, name, nbr_courses, nbr_users, nbr_classes, date_start, date_end, nb_days_access_before_beginning,nb_days_access_after_end, session_admin_id)
     */
    public static function fetch($id) {
    	$t = Database::get_main_table(TABLE_MAIN_SESSION);
        if ($id != strval(intval($id))) { return array(); }
        $s = "SELECT * FROM $t WHERE id = $id";
        $r = Database::query($s);
        if (Database::num_rows($r) != 1) { return array(); }
        return Database::fetch_array($r,'ASSOC');
    }
	 /**
	  * Create a session
	  * @author Carlos Vargas <carlos.vargas@dokeos.com>,from existing code
	  * @param	string 		name
	  * @param 	integer		year_start
	  * @param 	integer		month_start
	  * @param 	integer		day_start
	  * @param 	integer		year_end
	  * @param 	integer		month_end
	  * @param 	integer		day_end
	  * @param 	integer		nb_days_acess_before
	  * @param 	integer		nb_days_acess_after
	  * @param 	integer		nolimit
	  * @param 	string		coach_username
	  * @param 	integer		id_session_category
	  * @return $id_session;
	  **/
	public static function create_session ($sname,$syear_start,$smonth_start,$sday_start,$syear_end,$smonth_end,$sday_end,$snb_days_acess_before,$snb_days_acess_after,$nolimit,$coach_username, $id_session_category,$id_visibility) {
		global $_user;
		$name= trim($sname);
		$year_start= intval($syear_start);
		$month_start=intval($smonth_start);
		$day_start=intval($sday_start);
		$year_end=intval($syear_end);
		$month_end=intval($smonth_end);
		$day_end=intval($sday_end);
		$nb_days_acess_before = intval($snb_days_acess_before);
		$nb_days_acess_after = intval($snb_days_acess_after);
		$id_session_category = intval($id_session_category);
		$id_visibility = intval($id_visibility);
		$tbl_user		= Database::get_main_table(TABLE_MAIN_USER);
		$tbl_session	= Database::get_main_table(TABLE_MAIN_SESSION);

		if(is_int($coach_username)) {
			$id_coach = $coach_username;
		} else {
			$sql = 'SELECT user_id FROM '.$tbl_user.' WHERE username="'.Database::escape_string($coach_username).'"';
			$rs = Database::query($sql);
			$id_coach = Database::result($rs,0,'user_id');
		}

		if (empty($nolimit)) {
			$date_start="$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
			$date_end="$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);
		} else {
			$id_visibility = 1; // by default is read only
			$date_start="0000-00-00";
			$date_end="0000-00-00";
		}
		if (empty($name)) {
			$msg=get_lang('SessionNameIsRequired');
			return $msg;
		} elseif (empty($coach_username))   {
			$msg=get_lang('CoachIsRequired');
			return $msg;
		} elseif (empty($nolimit) && (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start))) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (empty($nolimit) && (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end))) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif(empty($nolimit) && $date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		} else {
			$rs = Database::query("SELECT 1 FROM $tbl_session WHERE name='".addslashes($name)."'");
			if(Database::num_rows($rs)) {
				$msg=get_lang('SessionNameAlreadyExists');
				return $msg;
			} else {
				$sql_insert = "INSERT INTO $tbl_session(name,date_start,date_end,id_coach,session_admin_id, nb_days_access_before_beginning, nb_days_access_after_end, session_category_id,visibility)
							   VALUES('".Database::escape_string($name)."','$date_start','$date_end','$id_coach',".intval($_user['user_id']).",".$nb_days_acess_before.", ".$nb_days_acess_after.", ".$id_session_category.", ".$id_visibility.")";
				Database::query($sql_insert);
				$id_session=Database::insert_id();

				// add event to system log
				$time = time();
				$user_id = api_get_user_id();
				event_system(LOG_SESSION_CREATE, LOG_SESSION_ID, $id_session, $time, $user_id);

				return $id_session;
			}
		}
	}
	/**
	 * Edit a session
	 * @author Carlos Vargas <carlos.vargas@dokeos.com>,from existing code
	 * @param	integer		id
	 * @param	string 		name
	 * @param 	integer		year_start
	 * @param 	integer		month_start
	 * @param 	integer		day_start
	 * @param 	integer		year_end
	 * @param 	integer		month_end
	 * @param 	integer		day_end
	 * @param 	integer		nb_days_acess_before
	 * @param 	integer		nb_days_acess_after
	 * @param 	integer		nolimit
	 * @param 	integer		id_coach
	 * @param 	integer		id_session_category
	 * @return $id;
	 * The parameter id is a primary key
	**/
	public static function edit_session ($id,$name,$year_start,$month_start,$day_start,$year_end,$month_end,$day_end,$nb_days_acess_before,$nb_days_acess_after,$nolimit,$id_coach, $id_session_category, $id_visibility) {
		global $_user;
		$name=trim(stripslashes($name));
		$year_start=intval($year_start);
		$month_start=intval($month_start);
		$day_start=intval($day_start);
		$year_end=intval($year_end);
		$month_end=intval($month_end);
		$day_end=intval($day_end);
		$id_coach= intval($id_coach);
		$nb_days_acess_before= intval($nb_days_acess_before);
		$nb_days_acess_after = intval($nb_days_acess_after);
		$id_session_category = intval($id_session_category);
		$id_visibility = intval($id_visibility);

		$tbl_user		= Database::get_main_table(TABLE_MAIN_USER);
		$tbl_session	= Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_rel_course = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);


		if (empty($nolimit)) {
			$date_start="$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
			$date_end="$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);
		} else {
			$date_start="000-00-00";
			$date_end="000-00-00";
			$id_visibility = 1;//force read only
		}
		if (empty($name)) {
			$msg=get_lang('SessionNameIsRequired');
			return $msg;
		} elseif (empty($id_coach))   {
			$msg=get_lang('CoachIsRequired');
			return $msg;
		} elseif (empty($nolimit) && (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start))) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (empty($nolimit) && (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end))) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif (empty($nolimit) && $date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		} else {
			$rs = Database::query("SELECT id FROM $tbl_session WHERE name='".Database::escape_string($name)."'");
			$exists = false;
			while ($row = Database::fetch_array($rs)) {
				if($row['id']!=$id)
					$exists = true;
			}
			if ($exists) {
				$msg=get_lang('SessionNameAlreadyExists');
				return $msg;
			} else {
				$sql="UPDATE $tbl_session " .
					"SET name='".Database::escape_string($name)."',
						date_start='".$date_start."',
						date_end='".$date_end."',
						id_coach='".$id_coach."',
						nb_days_access_before_beginning = ".$nb_days_acess_before.",
						nb_days_access_after_end = ".$nb_days_acess_after.",
						session_category_id = ".$id_session_category." ,
						visibility= ".$id_visibility."
					  WHERE id='$id'";
				Database::query($sql);
				/*$sqlu = "UPDATE $tbl_session_rel_course " .
						  " SET id_coach='$id_coach'" .
						  " WHERE id_session='$id'";
				Database::query($sqlu);*/
				return $id;
			}
		}
	}
	/**
	 * Delete session
	 * @author Carlos Vargas <carlos.vargas@dokeos.com>, from existing code
	 * @param	array	id_checked
	 * @param   boolean  optional, true if the function is called by a webservice, false otherwise.
     * @return	void	Nothing, or false on error
	 * The parameters is a array to delete sessions
	 **/
	public static function delete_session ($id_checked,$from_ws = false) {
		$tbl_session=						Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_rel_course=			Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_course_rel_user=	Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session_rel_user=				Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_user = 						Database::get_main_table(TABLE_MAIN_USER);
		global $_user;
		if(is_array($id_checked)) {
			$id_checked=Database::escape_string(implode(',',$id_checked));
		} else {
			$id_checked=intval($id_checked);
		}

		if (!api_is_platform_admin() && !$from_ws) {
			$sql = 'SELECT session_admin_id FROM '.Database :: get_main_table(TABLE_MAIN_SESSION).' WHERE id='.$id_checked;
			$rs = Database::query($sql);
			if (Database::result($rs,0,0)!=$_user['user_id']) {
				api_not_allowed(true);
			}
		}
		Database::query("DELETE FROM $tbl_session WHERE id IN($id_checked)");
		Database::query("DELETE FROM $tbl_session_rel_course WHERE id_session IN($id_checked)");
		Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session IN($id_checked)");
		Database::query("DELETE FROM $tbl_session_rel_user WHERE id_session IN($id_checked)");

		// delete extra session fields
		$t_sf 		= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$t_sfv 		= Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);

		// Delete extra fields from session where field variable is "SECCION"
		$sql = "SELECT t_sfv.field_id FROM $t_sfv t_sfv, $t_sf t_sf  WHERE t_sfv.session_id = '$id_checked' AND t_sf.field_variable = 'SECCION' ";
		$rs_field = Database::query($sql);

		$field_id = 0;
		if (Database::num_rows($rs_field) == 1) {
			$row_field = Database::fetch_row($rs_field);
			$field_id = $row_field[0];

			$sql_delete_sfv = "DELETE FROM $t_sfv WHERE session_id = '$id_checked' AND field_id = '$field_id'";
			$rs_delete_sfv = Database::query($sql_delete_sfv);
		}

		$sql = "SELECT * FROM $t_sfv WHERE field_id = '$field_id' ";
		$rs_field_id = Database::query($sql);

		if (Database::num_rows($rs_field_id) == 0) {
			$sql_delete_sf = "DELETE FROM $t_sf WHERE id = '$field_id'";
			$rs_delete_sf = Database::query($sql_delete_sf);
		}

		/*
		$sql = "SELECT distinct field_id FROM $t_sfv  WHERE session_id = '$id_checked'";
		$res_field_ids = @Database::query($sql);

		if (Database::num_rows($res_field_ids) > 0) {
			while($row_field_id = Database::fetch_row($res_field_ids)){
				$field_ids[] = $row_field_id[0];
			}
		}

		//delete from table_session_field_value from a given session id

		$sql_session_field_value = "DELETE FROM $t_sfv WHERE session_id = '$id_checked'";
		@Database::query($sql_session_field_value);

		$sql = "SELECT distinct field_id FROM $t_sfv";
		$res_field_all_ids = @Database::query($sql);

		if (Database::num_rows($res_field_all_ids) > 0) {
			while($row_field_all_id = Database::fetch_row($res_field_all_ids)){
				$field_all_ids[] = $row_field_all_id[0];
			}
		}

		if (count($field_ids) > 0 && count($field_all_ids) > 0) {
			foreach($field_ids as $field_id) {
				// check if field id is used into table field value
				if (in_array($field_id,$field_all_ids)) {
					continue;
				} else {
					$sql_session_field = "DELETE FROM $t_sf WHERE id = '$field_id'";
					Database::query($sql_session_field);
				}
			}
		}
		*/
		// add event to system log
		$time = time();
		$user_id = api_get_user_id();
		event_system(LOG_SESSION_DELETE, LOG_SESSION_ID, $id_checked, $time, $user_id);

	}


	 /**
	  * Subscribes users to the given session and optionally (default) unsubscribes previous users
	  * @author Carlos Vargas <carlos.vargas@dokeos.com>,from existing code
	  * @param	integer		Session ID
	  * @param	array		List of user IDs
	  * @param	bool		Whether to unsubscribe existing users (true, default) or not (false)
	  * @return	void		Nothing, or false on error
	  **/
	public static function suscribe_users_to_session ($id_session,$user_list, $visibility=SESSION_VISIBLE_READ_ONLY, $empty_users=true,$send_email=false) {

	  	if ($id_session!= strval(intval($id_session))) return false;
	   	foreach($user_list as $intUser){
	   		if ($intUser!= strval(intval($intUser))) return false;
	   	}
	   	$tbl_session_rel_course				= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
	   	$tbl_session_rel_user 				= Database::get_main_table(TABLE_MAIN_SESSION_USER);
	   	$tbl_session						= Database::get_main_table(TABLE_MAIN_SESSION);

		$session_info 		= api_get_session_info($id_session);
		$session_name 		= $session_info['name'];

		//from function parameter
		$session_visibility = $visibility;
	   	if (empty($session_visibility)) {
	   		$session_visibility = $session_info['name'];
	   		$session_visivility	= $session_info['visibility']; //loaded from DB
	   		//default status loaded if empty
			if (empty($session_visivility))
				$session_visibility = SESSION_VISIBLE_READ_ONLY; // by default readonly 1
	   	}
		$session_info = api_get_session_info($id_session);
		$session_name = $session_info['name'];

	   	//$sql = "SELECT id_user FROM $tbl_session_rel_user WHERE id_session='$id_session' AND relation_type<>".SESSION_RELATION_TYPE_RRHH."";
        $sql = "SELECT id_user FROM $tbl_session_rel_course_rel_user WHERE id_session='$id_session' ";
        
		$result = Database::query($sql);
		$existingUsers = array();
		while($row = Database::fetch_array($result)){
			$existingUsers[] = $row['id_user'];
		}
		$sql = "SELECT course_code FROM $tbl_session_rel_course WHERE id_session='$id_session'";
		$result=Database::query($sql);
		$course_list=array();

		while($row=Database::fetch_array($result)) {
			$course_list[]=$row['course_code'];
		}


		if ($send_email) {
		    global $_configuration;
			//sending emails only
			if(is_array($user_list) && count($user_list)>0) {
				foreach($user_list as $enreg_user) {
				    if (!in_array($enreg_user,$existingUsers )) {
					    //send email
					    $emailbody 	= '';
					    $emailheaders = '';

					    $user_info 	= UserManager::get_user_info_by_id($enreg_user);
					    $firstname 	= $user_info['firstname'];
					    $lastname 	= $user_info['lastname'];
					    $email 		= $user_info['email'];

					    $emailto = '"'.$firstname.' '.$lastname.'" <'.$email.'>';
					    $emailsubject = '['.get_setting('siteName').'] '.get_lang('YourReg').' '.get_setting('siteName');
					    $emailheaders = 'From: '.get_setting('administratorName').' '.get_setting('administratorSurname').' <'.get_setting('emailAdministrator').">\n";
					    $emailheaders .= 'Reply-To: '.get_setting('emailAdministrator');

					    if ($_configuration['multiple_access_urls']) {
				            $access_url_id = api_get_current_access_url_id();
				            if ($access_url_id != -1 ){
				            	$url 		= api_get_access_url($access_url_id);
				            	$emailbody	= get_lang('Dear')." ".stripslashes(api_get_person_name($firstname, $lastname)).",\n\n".get_lang('YouAreRegisterToSession')." : ". $session_name  ." \n\n" .get_lang('Address') ." ". get_setting('siteName') ." ". get_lang('Is') ." : ". $url['url'] ."\n\n". get_lang('Problem'). "\n\n". get_lang('Formula').",\n\n".get_setting('administratorName')." ".get_setting('administratorSurname')."\n". get_lang('Manager'). " ".get_setting('siteName')."\nT. ".get_setting('administratorTelephone')."\n" .get_lang('Email') ." : ".get_setting('emailAdministrator');
				            }
					    } else {
					    	$emailbody	= get_lang('Dear')." ".stripslashes(api_get_person_name($firstname, $lastname)).",\n\n".get_lang('YouAreRegisterToSession')." : ". $session_name ." \n\n" .get_lang('Address') ." ". get_setting('siteName') ." ". get_lang('Is') ." : ". $_configuration['root_web'] ."\n\n". get_lang('Problem'). "\n\n". get_lang('Formula').",\n\n".get_setting('administratorName')." ".get_setting('administratorSurname')."\n". get_lang('Manager'). " ".get_setting('siteName')."\nT. ".get_setting('administratorTelephone')."\n" .get_lang('Email') ." : ".get_setting('emailAdministrator');
					    }

					    @api_send_mail($emailto, $emailsubject, $emailbody, $emailheaders);

					}
				}
			}
		}

		foreach ($course_list as $enreg_course) {
			// for each course in the session
			$nbr_users=0;
	        $enreg_course = Database::escape_string($enreg_course);
				// delete existing users
			if ($empty_users!==false) {
				foreach ($existingUsers as $existing_user) {
					if(!in_array($existing_user, $user_list)) {
						$sql = "DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session='$id_session' AND course_code='$enreg_course' AND id_user='$existing_user' AND status != 2 ";
						Database::query($sql);
						if(Database::affected_rows()) {
							$nbr_users--;
						}
					}
				}
			}
			// insert new users into session_rel_course_rel_user and ignore if they already exist
			foreach ($user_list as $enreg_user) {
				if(!in_array($enreg_user, $existingUsers)) {
	                $enreg_user = Database::escape_string($enreg_user);
					$insert_sql = "INSERT IGNORE INTO $tbl_session_rel_course_rel_user(id_session,course_code,id_user,visibility) VALUES('$id_session','$enreg_course','$enreg_user','$session_visivility')";
					Database::query($insert_sql);
					if(Database::affected_rows()) {
						$nbr_users++;
					}
				}
			}
			// count users in this session-course relation
			$sql = "SELECT COUNT(id_user) as nbUsers FROM $tbl_session_rel_course_rel_user WHERE id_session='$id_session' AND course_code='$enreg_course' AND status<>2";
			$rs = Database::query($sql);
			list($nbr_users) = Database::fetch_array($rs);
			// update the session-course relation to add the users total
			$update_sql = "UPDATE $tbl_session_rel_course SET nbr_users=$nbr_users WHERE id_session='$id_session' AND course_code='$enreg_course'";
			Database::query($update_sql);
		}
		// delete users from the session
		if ($empty_users===true){
			Database::query("DELETE FROM $tbl_session_rel_user WHERE id_session = $id_session AND relation_type<>".SESSION_RELATION_TYPE_RRHH."");
		}
			// insert missing users into session
		$nbr_users = 0;
		foreach ($user_list as $enreg_user) {
	        $enreg_user = Database::escape_string($enreg_user);
			$nbr_users++;
			$insert_sql = "INSERT IGNORE INTO $tbl_session_rel_user(id_session, id_user) VALUES('$id_session','$enreg_user')";
			Database::query($insert_sql);
		}

		// update number of users in the session
		$nbr_users = count($user_list);		
        if ($empty_users) {
            // update number of users in the session            
            $update_sql = "UPDATE $tbl_session SET nbr_users= $nbr_users WHERE id='$id_session' ";
            Database::query($update_sql);
        } else {
            echo $update_sql = "UPDATE $tbl_session SET nbr_users= nbr_users + $nbr_users WHERE id='$id_session' ";
            Database::query($update_sql);           
        }
        
	}

	/**
	 * Unsubscribe user from session
	 *
	 * @param int Session id
	 * @param int User id
	 * @return bool True in case of success, false in case of error
	 */
	public static function unsubscribe_user_from_session($session_id, $user_id) {
		$session_id = (int)$session_id;
		$user_id = (int)$user_id;

		$tbl_session_rel_course_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session_rel_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);

		$delete_sql = "DELETE FROM $tbl_session_rel_user WHERE id_session = '$session_id' AND id_user ='$user_id' AND relation_type<>".SESSION_RELATION_TYPE_RRHH."";
		Database::query($delete_sql);
		$return = Database::affected_rows();

		// Update number of users
		$update_sql = "UPDATE $tbl_session SET nbr_users= nbr_users - $return WHERE id='$session_id' ";
		Database::query($update_sql);

		// Get the list of courses related to this session
		$course_list = SessionManager::get_course_list_by_session_id($session_id);
		if(!empty($course_list)) {
			foreach($course_list as $course) {
				$course_code = $course['code'];
				// Delete user from course
				Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session='$session_id' AND course_code='$course_code' AND id_user='$user_id'");
				if(Database::affected_rows()) {
					// Update number of users in this relation
					Database::query("UPDATE $tbl_session_rel_course SET nbr_users=nbr_users - 1 WHERE id_session='$session_id' AND course_code='$course_code'");
				}
			}
		}

		return true;

	}

	 /** Subscribes courses to the given session and optionally (default) unsubscribes previous users
	 * @author Carlos Vargas <carlos.vargas@dokeos.com>,from existing code
     * @param	int		Session ID
     * @param	array	List of courses IDs
     * @param	bool	Whether to unsubscribe existing users (true, default) or not (false)
     * @return	void	Nothing, or false on error
     **/
     public static function add_courses_to_session ($id_session, $course_list, $empty_courses=true) {
     	// security checks
     	if ($id_session!= strval(intval($id_session))) { return false; }
	   	foreach($course_list as $intCourse){
	   		if ($intCourse!= strval(intval($intCourse))) { return false; }
	   	}
	   	// initialisation
		$tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session						= Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_rel_user				= Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_session_rel_course				= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_course							= Database::get_main_table(TABLE_MAIN_COURSE);
     	// get general coach ID
		$id_coach = Database::query("SELECT id_coach FROM $tbl_session WHERE id=$id_session");
		$id_coach = Database::fetch_array($id_coach);
		$id_coach = $id_coach[0];
		// get list of courses subscribed to this session
		$rs = Database::query("SELECT course_code FROM $tbl_session_rel_course WHERE id_session=$id_session");
		$existingCourses = Database::store_result($rs);
		$nbr_courses=count($existingCourses);
		// get list of users subscribed to this session
		$sql="SELECT id_user
			FROM $tbl_session_rel_user
			WHERE id_session = $id_session AND relation_type<>".SESSION_RELATION_TYPE_RRHH."";
		$result=Database::query($sql);
		$user_list=Database::store_result($result);

		// remove existing courses from the session
		if ($empty_courses===true) {
			foreach ($existingCourses as $existingCourse) {
				if (!in_array($existingCourse['course_code'], $course_list)){
					Database::query("DELETE FROM $tbl_session_rel_course WHERE course_code='".$existingCourse['course_code']."' AND id_session=$id_session");
					Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE course_code='".$existingCourse['course_code']."' AND id_session=$id_session");

				}
			}
			$nbr_courses=0;
		}

		// Pass through the courses list we want to add to the session
		foreach ($course_list as $enreg_course) {
			$enreg_course = Database::escape_string($enreg_course);
			$exists = false;
			// check if the course we want to add is already subscribed
			foreach ($existingCourses as $existingCourse) {
				if ($enreg_course == $existingCourse['course_code']) {
					$exists=true;
				}
			}
			if (!$exists) {
				//if the course isn't subscribed yet
				$sql_insert_rel_course= "INSERT INTO $tbl_session_rel_course (id_session,course_code) VALUES ('$id_session','$enreg_course')";
				Database::query($sql_insert_rel_course);
				//We add the current course in the existing courses array, to avoid adding another time the current course
				$existingCourses[]=array('course_code'=>$enreg_course);
				$nbr_courses++;

				// subscribe all the users from the session to this course inside the session
				$nbr_users=0;
				foreach ($user_list as $enreg_user) {
					$enreg_user_id = Database::escape_string($enreg_user['id_user']);
					$sql_insert = "INSERT IGNORE INTO $tbl_session_rel_course_rel_user (id_session,course_code,id_user) VALUES ('$id_session','$enreg_course','$enreg_user_id')";
					Database::query($sql_insert);
					if (Database::affected_rows()) {
						$nbr_users++;
					}
				}
				Database::query("UPDATE $tbl_session_rel_course SET nbr_users=$nbr_users WHERE id_session='$id_session' AND course_code='$enreg_course'");
			}
		}
		Database::query("UPDATE $tbl_session SET nbr_courses=$nbr_courses WHERE id='$id_session'");
     }

	/**
	 * Unsubscribe course from a session
	 *
	 * @param int Session id
	 * @param int Course id
	 * @return bool True in case of success, false otherwise
	 */
	public static function unsubscribe_course_from_session($session_id, $course_id) {
		$session_id = (int)$session_id;
		$course_id = (int)$course_id;

		$tbl_session_rel_course = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);

		// Get course code
		$course_code = CourseManager::get_course_code_from_course_id($course_id);
		if($course_code == 0) {
			return false;
		}

		// Unsubscribe course
	    Database::query("DELETE FROM $tbl_session_rel_course WHERE course_code='$course_code' AND id_session='$session_id'");
	    $nb_affected = Database::affected_rows();

	    Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE course_code='$course_code' AND id_session='$session_id'");
	    if($nb_affected > 0) {
			// Update number of courses in the session
			Database::query("UPDATE $tbl_session SET nbr_courses= nbr_courses + $nb_affected WHERE id='$session_id' ");
			return true;
		} else {
			return false;
		}
	}


  /**
  * Creates a new extra field for a given session
  * @param	string	Field's internal variable name
  * @param	int		Field's type
  * @param	string	Field's language var name
  * @return int     new extra field id
  */
	public static function create_session_extra_field ($fieldvarname, $fieldtype, $fieldtitle) {
		// database table definition
		$t_sf 			= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$fieldvarname 	= Database::escape_string($fieldvarname);
		$fieldtitle 	= Database::escape_string($fieldtitle);
		$fieldtype = (int)$fieldtype;
		$time = time();
		$sql_field = "SELECT id FROM $t_sf WHERE field_variable = '$fieldvarname'";
		$res_field = Database::query($sql_field);

		$r_field = Database::fetch_row($res_field);

		if (Database::num_rows($res_field)>0) {
			$field_id = $r_field[0];
		} else {
			// save new fieldlabel into course_field table
			$sql = "SELECT MAX(field_order) FROM $t_sf";
			$res = Database::query($sql);

			$order = 0;
			if (Database::num_rows($res)>0) {
				$row = Database::fetch_row($res);
				$order = $row[0]+1;
			}

			$sql = "INSERT INTO $t_sf
						                SET field_type = '$fieldtype',
						                field_variable = '$fieldvarname',
						                field_display_text = '$fieldtitle',
						                field_order = '$order',
						                tms = FROM_UNIXTIME($time)";
			$result = Database::query($sql);

			$field_id=Database::insert_id();
		}
		return $field_id;
	}

/**
 * Update an extra field value for a given session
 * @param	integer	Course ID
 * @param	string	Field variable name
 * @param	string	Field value
 * @return	boolean	true if field updated, false otherwise
 */
	public static function update_session_extra_field_value ($session_id,$fname,$fvalue='') {

		$t_sf 			= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$t_sfv 			= Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);
		$fname = Database::escape_string($fname);
		$session_id = (int)$session_id;
		$fvalues = '';
		if(is_array($fvalue))
		{
			foreach($fvalue as $val)
			{
				$fvalues .= Database::escape_string($val).';';
			}
			if(!empty($fvalues))
			{
				$fvalues = substr($fvalues,0,-1);
			}
		}
		else
		{
			$fvalues = Database::escape_string($fvalue);
		}

		$sqlsf = "SELECT * FROM $t_sf WHERE field_variable='$fname'";
		$ressf = Database::query($sqlsf);
		if(Database::num_rows($ressf)==1)
		{ //ok, the field exists
			//	Check if enumerated field, if the option is available
			$rowsf = Database::fetch_array($ressf);

			$tms = time();
			$sqlsfv = "SELECT * FROM $t_sfv WHERE session_id = '$session_id' AND field_id = '".$rowsf['id']."' ORDER BY id";
			$ressfv = Database::query($sqlsfv);
			$n = Database::num_rows($ressfv);
			if ($n>1) {
				//problem, we already have to values for this field and user combination - keep last one
				while($rowsfv = Database::fetch_array($ressfv))
				{
					if($n > 1)
					{
						$sqld = "DELETE FROM $t_sfv WHERE id = ".$rowsfv['id'];
						$resd = Database::query($sqld);
						$n--;
					}
					$rowsfv = Database::fetch_array($ressfv);
					if($rowsfv['field_value'] != $fvalues)
					{
						$sqlu = "UPDATE $t_sfv SET field_value = '$fvalues', tms = FROM_UNIXTIME($tms) WHERE id = ".$rowsfv['id'];
						$resu = Database::query($sqlu);
						return($resu?true:false);
					}
					return true;
				}
			} else if ($n==1) {
				//we need to update the current record
				$rowsfv = Database::fetch_array($ressfv);
				if($rowsfv['field_value'] != $fvalues)
				{
					$sqlu = "UPDATE $t_sfv SET field_value = '$fvalues', tms = FROM_UNIXTIME($tms) WHERE id = ".$rowsfv['id'];
					//error_log('UM::update_extra_field_value: '.$sqlu);
					$resu = Database::query($sqlu);
					return($resu?true:false);
				}
				return true;
			} else {
				$sqli = "INSERT INTO $t_sfv (session_id,field_id,field_value,tms) " .
					"VALUES ('$session_id',".$rowsf['id'].",'$fvalues',FROM_UNIXTIME($tms))";
				//error_log('UM::update_extra_field_value: '.$sqli);
				$resi = Database::query($sqli);
				return($resi?true:false);
			}
		} else {
			return false; //field not found
		}
	}

	/**
	* Checks the relationship between a session and a course.
	* @param int $session_id
	* @param int $course_id
	* @return bool				Returns TRUE if the session and the course are related, FALSE otherwise.
	* */
	public static function relation_session_course_exist ($session_id, $course_id) {
		$tbl_session_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$return_value = false;
		$sql= "SELECT course_code FROM $tbl_session_course WHERE id_session = ".Database::escape_string($session_id)." AND course_code = '".Database::escape_string($course_id)."'";
		$result = Database::query($sql);
		$num = Database::num_rows($result);
		if ($num>0) {
			$return_value = true;
		}
		return $return_value;
	}

	/**
	* Get the session information by name
	* @param string session name
	* @return mixed false if the session does not exist, array if the session exist
	* */
	public static function get_session_by_name ($session_name) {
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
		$sql = 'SELECT id, id_coach, date_start, date_end FROM '.$tbl_session.' WHERE name="'.Database::escape_string($session_name).'"';
		$result = Database::query($sql);
		$num = Database::num_rows($result);
		if ($num>0){
			return Database::fetch_array($result);
		} else {
			return false;
		}
	}

	/**
	  * Create a session category
	  * @author Jhon Hinojosa <jhon.hinojosa@dokeos.com>, from existing code
	  * @param	string 		name
	  * @param 	integer		year_start
	  * @param 	integer		month_start
	  * @param 	integer		day_start
	  * @param 	integer		year_end
	  * @param 	integer		month_end
	  * @param 	integer		day_end
	  * @return $id_session;
	  **/
	public static function create_category_session($sname,$syear_start,$smonth_start,$sday_start,$syear_end,$smonth_end, $sday_end){
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$name= trim($sname);
		$year_start= intval($syear_start);
		$month_start=intval($smonth_start);
		$day_start=intval($sday_start);
		$year_end=intval($syear_end);
		$month_end=intval($smonth_end);
		$day_end=intval($sday_end);

		$date_start = "$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
		$date_end = "$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);

		if (empty($name)) {
			$msg=get_lang('SessionCategoryNameIsRequired');
			return $msg;
		} elseif (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start)) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end)) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif($date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		} else {
			$sql = "INSERT INTO $tbl_session_category(name, date_start, date_end) VALUES('".Database::escape_string($name)."','$date_start','$date_end')";
			Database::query($sql);
			$id_session=Database::insert_id();
			// add event to system log
			$time = time();
			$user_id = api_get_user_id();
			event_system(LOG_SESSION_CATEGORY_CREATE, LOG_SESSION_CATEGORY_ID, $id_session, $time, $user_id);
			return $id_session;
		}
	}

	/**
	 * Edit a sessions categories
	 * @author Jhon Hinojosa <jhon.hinojosa@dokeos.com>,from existing code
	 * @param	integer		id
	 * @param	string 		name
	 * @param 	integer		year_start
	 * @param 	integer		month_start
	 * @param 	integer		day_start
	 * @param 	integer		year_end
	 * @param 	integer		month_end
	 * @param 	integer		day_end
	 * @return $id;
	 * The parameter id is a primary key
	**/
	public static function edit_category_session($id, $sname,$syear_start,$smonth_start,$sday_start,$syear_end,$smonth_end, $sday_end){
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$name= trim($sname);
		$year_start= intval($syear_start);
		$month_start=intval($smonth_start);
		$day_start=intval($sday_start);
		$year_end=intval($syear_end);
		$month_end=intval($smonth_end);
		$day_end=intval($sday_end);
		$id=intval($id);
		$date_start = "$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
		$date_end = "$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);

		if (empty($name)) {
			$msg=get_lang('SessionCategoryNameIsRequired');
			return $msg;
		} elseif (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start)) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end)) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif($date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		} else {
			$sql = "UPDATE $tbl_session_category SET name = '".Database::escape_string($name)."', date_start = '$date_start', date_end = '$date_end'
					WHERE id= '".$id."' ";
			$result = Database::query($sql);
			return ($result? true:false);
		}
	}

	/**
	 * Delete sessions categories
	 * @author Jhon Hinojosa <jhon.hinojosa@dokeos.com>, from existing code
	 * @param	array	id_checked
	 * @param	bool	include delete session
	 * @param	bool	optional, true if the function is called by a webservice, false otherwise.
     * @return	void	Nothing, or false on error
	 * The parameters is a array to delete sessions
	 **/
	public static function delete_session_category($id_checked, $delete_session = false,$from_ws = false){
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
		if(is_array($id_checked)) {
			$id_checked=Database::escape_string(implode(',',$id_checked));
		} else {
			$id_checked=intval($id_checked);
		}
		$sql = "SELECT id FROM $tbl_session WHERE session_category_id IN (".$id_checked.")";
		$result = @Database::query($sql);
		while ($rows = Database::fetch_array($result)) {
			$session_id = $rows['id'];
			if ($delete_session) {
				if ($from_ws) {
					SessionManager::delete_session($session_id,true);
				} else {
					SessionManager::delete_session($session_id);
				}
			}
		}
		$sql = "DELETE FROM $tbl_session_category WHERE id IN (".$id_checked.")";
		$rs = @Database::query($sql);
		$result = Database::affected_rows();

		// add event to system log
		$time = time();
		$user_id = api_get_user_id();
		event_system(LOG_SESSION_CATEGORY_DELETE, LOG_SESSION_CATEGORY_ID, $id_checked, $time, $user_id);


		// delete extra session fields where field variable is "PERIODO"
		$t_sf 		= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$t_sfv 		= Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);

		$sql = "SELECT t_sfv.field_id FROM $t_sfv t_sfv, $t_sf t_sf  WHERE t_sfv.session_id = '$id_checked' AND t_sf.field_variable = 'PERIODO' ";
		$rs_field = Database::query($sql);

		$field_id = 0;
		if (Database::num_rows($rs_field) > 0) {
			$row_field = Database::fetch_row($rs_field);
			$field_id = $row_field[0];
			$sql_delete_sfv = "DELETE FROM $t_sfv WHERE session_id = '$id_checked' AND field_id = '$field_id'";
			$rs_delete_sfv = Database::query($sql_delete_sfv);
		}

		$sql = "SELECT * FROM $t_sfv WHERE field_id = '$field_id' ";
		$rs_field_id = Database::query($sql);

		if (Database::num_rows($rs_field_id) == 0) {
			$sql_delete_sf = "DELETE FROM $t_sf WHERE id = '$field_id'";
			$rs_delete_sf = Database::query($sql_delete_sf);
		}

		return true;
	}

	/**
     * Get a list of sessions of which the given conditions match with an = 'cond'
	 * @param array $conditions a list of condition (exemple : status=>STUDENT)
	 * @param array $order_by a list of fields on which sort
	 * @return array An array with all sessions of the platform.
	 * @todo optional course code parameter, optional sorting parameters...
	*/
	public static function get_sessions_list ($conditions = array(), $order_by = array()) {

		$session_table =Database::get_main_table(TABLE_MAIN_SESSION);
		$session_category_table = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$user_table = Database::get_main_table(TABLE_MAIN_USER);

		$return_array = array();

		$sql_query = " SELECT s.id, s.name, s.nbr_courses, s.date_start, s.date_end, u.firstname, u.lastname , sc.name as category_name
				FROM $session_table s
				INNER JOIN $user_table u ON s.id_coach = u.user_id
				LEFT JOIN  $session_category_table sc ON s.session_category_id = sc.id ";

		if (count($conditions)>0) {
			$sql_query .= ' WHERE ';
			foreach ($conditions as $field=>$value) {
                $field = Database::escape_string($field);
                $value = Database::escape_string($value);
				$sql_query .= $field.' = '.$value;
			}
		}
		if (count($order_by)>0) {
			$sql_query .= ' ORDER BY '.Database::escape_string(implode(',',$order_by));
		}
		$sql_result = Database::query($sql_query);
		while ($result = Database::fetch_array($sql_result)) {
			$return_array[$result['id']] = $result;
		}
		return $return_array;
	}
	/**
	 * Get the session category information by id
	 * @param string session category ID
	 * @return mixed false if the session category does not exist, array if the session category exists
	 */
	public static function get_session_category ($id) {
		$id = intval($id);
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$sql = 'SELECT id, name, date_start, date_end FROM '.$tbl_session_category.' WHERE id="'.$id.'"';
		$result = Database::query($sql);
		$num = Database::num_rows($result);
		if ($num>0){
			return Database::fetch_array($result);
		} else {
			return false;
		}
	}

	/**
	 * Assign a coach to course in session with status = 2
	 * @param int  		- user id
	 * @param int  		- session id
	 * @param string  	- course code
	 * @param bool  	- optional, if is true the user don't be a coach now, otherwise it'll assign a coach
	 * @return bool true if there are affected rows, otherwise false
	 */
	public static function set_coach_to_course_session($user_id, $session_id = 0, $course_code = '',$nocoach = false) {

		// Definition of variables
		$user_id = intval($user_id);

		if (!empty($session_id)) {
			$session_id = intval($session_id);
		} else {
			$session_id = api_get_session_id();
		}

		if (!empty($course_code)) {
			$course_code = Database::escape_string($course_code);
		} else {
			$course_code = api_get_course_id();
		}

		// definitios of tables
		$tbl_session_rel_course_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_user	= Database::get_main_table(TABLE_MAIN_USER);

		// check if user is a teacher
		$sql= "SELECT * FROM $tbl_user WHERE status='1' AND user_id = '$user_id'";

		$rs_check_user = Database::query($sql);

		if (Database::num_rows($rs_check_user) > 0) {

			if ($nocoach) {

				// check if user_id exits int session_rel_user
				$sql = "SELECT id_user FROM $tbl_session_rel_user WHERE id_session = '$session_id' AND id_user = '$user_id'";
				$res = Database::query($sql);

				if (Database::num_rows($res) > 0) {
					// The user don't be a coach now
					$sql = "UPDATE $tbl_session_rel_course_rel_user SET status = 0 WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id' ";
					$rs_update = Database::query($sql);
					if (Database::affected_rows() > 0) return true;
					else return false;
				} else {
					// The user don't be a coach now
					$sql = "DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id' ";
					$rs_delete = Database::query($sql);
					if (Database::affected_rows() > 0) return true;
					else return false;
				}

			} else {
				// Assign user like a coach to course
				// First check if the user is registered in the course
				$sql = "SELECT id_user FROM $tbl_session_rel_course_rel_user WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id'";
				$rs_check = Database::query($sql);

				//Then update or insert
				if (Database::num_rows($rs_check) > 0) {
					$sql = "UPDATE $tbl_session_rel_course_rel_user SET status = 2 WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id' ";
					$rs_update = Database::query($sql);
					if (Database::affected_rows() > 0) return true;
					else return false;
				} else {
					$sql = " INSERT INTO $tbl_session_rel_course_rel_user(id_session, course_code, id_user, status) VALUES('$session_id', '$course_code', '$user_id', 2)";
					$rs_insert = Database::query($sql);
					if (Database::affected_rows() > 0) return true;
					else return false;
				}
			}
		} else {
			return false;
		}
	}

	/**
	  * Subscribes sessions to human resource manager (Dashboard feature)
	  *	@param	int 		Human Resource Manager id
	  * @param	array 		Sessions id
	  * @param	int			Relation type
	  **/
	public static function suscribe_sessions_to_hr_manager($hr_manager_id,$sessions_list) {
        global $_configuration;
        // Database Table Definitions
        $tbl_session                    =   Database::get_main_table(TABLE_MAIN_SESSION);
        $tbl_session_rel_user           =   Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $tbl_session_rel_course_user    =   Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);        
        $tbl_session_rel_access_url     =   Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);        

        $hr_manager_id = intval($hr_manager_id);
        $affected_rows = 0;

        //Deleting assigned sessions to hrm_id
        if ($_configuration['multiple_access_urls']) {  
            $sql = "SELECT id_session FROM $tbl_session_rel_user s INNER JOIN $tbl_session_rel_access_url a ON (a.session_id = s.id_session) WHERE id_user = $hr_manager_id AND relation_type=".SESSION_RELATION_TYPE_RRHH." AND access_url_id = ".api_get_current_access_url_id()."";
        } else {
            $sql = "SELECT id_session FROM $tbl_session_rel_user s WHERE id_user = $hr_manager_id AND relation_type=".SESSION_RELATION_TYPE_RRHH."";
        }
        $result = Database::query($sql);  

        if (Database::num_rows($result) > 0) {
            while ($row = Database::fetch_array($result))   {
                 $sql = "DELETE FROM $tbl_session_rel_user WHERE id_session = {$row['id_session']} AND id_user = $hr_manager_id AND relation_type=".SESSION_RELATION_TYPE_RRHH." ";
                 Database::query($sql);
            }
        }

		/*
		//Deleting assigned courses in sessions to hrm_id
	   	$sql = "SELECT * FROM $tbl_session_rel_course_user WHERE id_user = $hr_manager_id ";
		$result = Database::query($sql);

		if (Database::num_rows($result) > 0) {
			$sql = "DELETE FROM $tbl_session_rel_course_user WHERE id_user = $hr_manager_id ";
			Database::query($sql);
		}
		*/

		// inserting new sessions list
		if (is_array($sessions_list)) {
			foreach ($sessions_list as $session_id) {
				$session_id = intval($session_id);
				$insert_sql = "INSERT IGNORE INTO $tbl_session_rel_user(id_session, id_user, relation_type) VALUES($session_id, $hr_manager_id, '".SESSION_RELATION_TYPE_RRHH."')";
				Database::query($insert_sql);
				$affected_rows = Database::affected_rows();
			}
		}
		return $affected_rows;

	}

	/**
	 * Get sessions followed by human resources manager
	 * @param int		Human resources manager id
	 * @return array 	sessions
	 */
	public static function get_sessions_followed_by_drh($hr_manager_id) {
        global $_configuration;
		// Database Table Definitions
		$tbl_session 			= 	Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_rel_user 	= 	Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $tbl_session_rel_access_url =   Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

		$hr_manager_id = intval($hr_manager_id);
		$assigned_sessions_to_hrm = array();

		if ($_configuration['multiple_access_urls']) {   
           $sql = "SELECT * FROM $tbl_session s INNER JOIN $tbl_session_rel_user sru ON (sru.id_session = s.id) LEFT JOIN $tbl_session_rel_access_url a  ON (s.id = a.session_id)
                   WHERE sru.id_user = '$hr_manager_id' AND sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."' AND access_url_id = ".api_get_current_access_url_id()."";
        } else {
            $sql = "SELECT * FROM $tbl_session s
                     INNER JOIN $tbl_session_rel_user sru ON sru.id_session = s.id AND sru.id_user = '$hr_manager_id' AND sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."' ";   
        }
		$rs_assigned_sessions = Database::query($sql);
		if (Database::num_rows($rs_assigned_sessions) > 0) {
			while ($row_assigned_sessions = Database::fetch_array($rs_assigned_sessions))	{
				$assigned_sessions_to_hrm[$row_assigned_sessions['id']] = $row_assigned_sessions;
			}
		}
		return $assigned_sessions_to_hrm;
	}

	/**
	 * Gets the list of courses by session
	 * @param int session id
	 * @return array list of courses
	 */
	public static function get_course_list_by_session_id ($session_id) {
		$tbl_course				= Database::get_main_table(TABLE_MAIN_COURSE);
		$tbl_session_rel_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		// select the courses
		$sql = "SELECT * FROM $tbl_course c INNER JOIN $tbl_session_rel_course src ON c.code = src.course_code WHERE src.id_session = '$session_id' ORDER BY title;";
		$result 	= Database::query($sql);
		$num_rows 	= Database::num_rows($result);
		$courses = array();
		if ($num_rows > 0) {
			while ($row = Database::fetch_array($result,'ASSOC'))	{
				$courses[$row['id']] = $row;
			}
		}
		return $courses;
	}

	/**
	 * Get the session id based on the original id and field name in the extra fields. Returns 0 if session was not found
	 *
	 * @param string Original session id
	 * @param string Original field name
	 * @return int Session id
	 */
	public static function get_session_id_from_original_id($original_session_id_value, $original_session_id_name) {
		$t_sfv = Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);
		$table_field = Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$sql_session = "SELECT session_id FROM $table_field sf INNER JOIN $t_sfv sfv ON sfv.field_id=sf.id WHERE field_variable='$original_session_id_name' AND field_value='$original_session_id_value'";
		$res_session = Database::query($sql_session);
		$row = Database::fetch_object($res_session);
		if ($row) {
			return $row->session_id;
		} else {
			return 0;
		}
	}
    
    /**
     * Get users by session
     * @param   int sesssion id
     * @return  array a list with the user info
     */
    public static function get_users_by_session($id) {
        $tbl_user                           = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_session_rel_user               = Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $order_clause ='';
        $sql = 'SELECT '.$tbl_user.'.user_id, lastname, firstname, username
        FROM '.$tbl_user.'
        INNER JOIN '.$tbl_session_rel_user.'
            ON '.$tbl_user.'.user_id = '.$tbl_session_rel_user.'.id_user 
            AND '.$tbl_session_rel_user.'.id_session = '.$id.$order_clause;

        $result=Database::query($sql);
        //$users=Database::store_result($result);
        while ($row = Database::fetch_array($result,'ASSOC')) {
            $return_array[] = $row;
        }
        
        return $return_array;
    }
    
}