class.ilParticipants.php

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<?php
/* Copyright (c) 1998-2010 ILIAS open source, Extended GPL, see docs/LICENSE */

define("IL_CRS_ADMIN",1);
define("IL_CRS_TUTOR",3);
define("IL_CRS_MEMBER",2);

define('IL_GRP_ADMIN',4);
define('IL_GRP_MEMBER',5);


abstract class ilParticipants
{
        protected $component = '';
        
        protected $obj_id = 0;
        protected $type = '';
        protected $ref_id = 0;
        
        protected $roles = array();
        protected $role_data = array();
        
        protected $participants = array();
        protected $participants_status = array();
        protected $members = array();
        protected $tutors = array();
        protected $admins = array();
        
        protected $subscribers = array();
        
        protected $ilDB;
        protected $lng;
        

        public function __construct($a_component_name, $a_obj_id)
        {
                global $ilDB,$lng;
                
                $this->ilDB = $ilDB;
                $this->lng = $lng;
         
                $this->component = $a_component_name;
                
                $this->obj_id = $a_obj_id;
                $this->type = ilObject::_lookupType($a_obj_id);
                $ref_ids = ilObject::_getAllReferences($this->obj_id);
                $this->ref_id = current($ref_ids);
                
                $this->readParticipants();
                $this->readParticipantsStatus();
        }
        
        public static function getInstanceByObjId($a_obj_id)
        {
                $type = ilObject::_lookupType($a_obj_id);
                switch($type)
                {
                        case 'crs':
                                include_once './Modules/Course/classes/class.ilCourseParticipants.php';
                                return ilCourseParticipants::_getInstanceByObjId($a_obj_id);
                                
                        case 'grp':
                                include_once './Modules/Group/classes/class.ilGroupParticipants.php';
                                return ilGroupParticipants::_getInstanceByObjId($a_obj_id);
                                
                        case 'sess':
                                include_once './Modules/Session/classes/class.ilSessionParticipants.php';
                                return ilSessionParticipants::_getInstanceByObjId($a_obj_id);
                                
                        default:
                                $GLOBALS['ilLog']->logStack();
                                $GLOBALS['ilLog']->write(__METHOD__.': Invalid obj_id given: '.$a_obj_id);
                                throw new InvalidArgumentException('Invalid obj id given');
                }
        }
        
        protected function getComponent()
        {
                return $this->component;
        }


        
        public static function hasParticipantListAccess($a_obj_id, $a_usr_id = null)
        {
                if(!$a_usr_id)
                {
                        $a_usr_id = $GLOBALS['ilUser']->getId();
                }

                // if write access granted => return true
                $refs = ilObject::_getAllReferences($a_obj_id);
                $ref_id = end($refs);

                if($GLOBALS['ilAccess']->checkAccess('write','',$ref_id))
                {
                        return true;
                }
                $part = self::getInstanceByObjId($a_obj_id);
                if($part->isAssigned($a_usr_id))
                {
                        if($part->getType() == 'crs')
                        {
                                // Check for show_members
                                include_once './Modules/Course/classes/class.ilObjCourse.php';
                                if(!ilObjCourse::lookupShowMembersEnabled($a_obj_id))
                                {
                                        return false;
                                }
                        }
                        return true;
                }
                // User is not assigned to course/group => no read access
                return false;
        }
        
        public static function _getMembershipByType($a_usr_id,$a_type,$a_only_member_role = false)
        {
                global $ilDB;
                
                // this will also dismiss local roles!
                if ($a_only_member_role)
                {
                        $j2 = "JOIN object_data obd2 ON (ua.rol_id = obd2.obj_id) ";
                        $a2 = "AND obd2.title LIKE 'il_".$a_type."_mem%' ";
                }

                // #14290 - no role folder anymore
                $query = "SELECT DISTINCT obd.obj_id,obr.ref_id FROM rbac_ua ua ".
                        "JOIN rbac_fa fa ON ua.rol_id = fa.rol_id ".                    
                        "JOIN object_reference obr ON fa.parent = obr.ref_id ".
                        "JOIN object_data obd ON obr.obj_id = obd.obj_id ".
                        $j2.
                        "WHERE obd.type = ".$ilDB->quote($a_type,'text')." ".
                        "AND fa.assign = 'y' ".
                        "AND ua.usr_id = ".$ilDB->quote($a_usr_id,'integer')." ".
                        $a2;
                                
                $res = $ilDB->query($query);            
                while($row = $ilDB->fetchObject($res))
                {
                        $ref_ids[] = $row->obj_id;
                }
                
                return $ref_ids ? $ref_ids : array();                   
        }
        
        
        
        public static function _isParticipant($a_ref_id,$a_usr_id)
        {
                global $rbacreview,$ilObjDataCache,$ilDB,$ilLog;

                $local_roles = $rbacreview->getRolesOfRoleFolder($a_ref_id,false);
        
        return $rbacreview->isAssignedToAtLeastOneGivenRole($a_usr_id, $local_roles);
        }

        public static function lookupNumberOfParticipants($a_ref_id)
        {
                global $rbacreview;

                $lroles = $rbacreview->getRolesOfRoleFolder($a_ref_id,false);
                return $rbacreview->getNumberOfAssignedUsers($lroles);
        }

        public static function lookupNumberOfMembers($a_ref_id)
        {
                global $rbacreview, $ilObjDataCache;

                $has_policies = $rbacreview->getLocalPolicies($a_ref_id);

                if(!$has_policies)
                {
                        return 0;
                }
                $lroles = $rbacreview->getRolesOfRoleFolder($a_ref_id,false);

                $memberRoles = array();
                foreach($lroles as $role_id)
                {
                        $title = $ilObjDataCache->lookupTitle($role_id);
                        switch(substr($title,0,8))
                        {
                                case 'il_crs_a':
                                case 'il_crs_t':
                                case 'il_grp_a':
                                        break;

                                default:
                                        $memberRoles[] = $role_id;
                                        break;
                        }
                }
                return $rbacreview->getNumberOfAssignedUsers($memberRoles);
        }


        public static function _isBlocked($a_obj_id,$a_usr_id)
        {
                global $ilDB;

                $query = "SELECT * FROM obj_members ".
                        "WHERE obj_id = ".$ilDB->quote($a_obj_id,'integer')." ".
                        "AND usr_id = ".$ilDB->quote($a_usr_id,'integer')." ".
                        "AND blocked = ".$ilDB->quote(1,'integer');
                $res = $ilDB->query($query);
                return $res->numRows() ? true : false; 
        }
        
        public static function _hasPassed($a_obj_id,$a_usr_id)
        {
                global $ilDB;

                $query = "SELECT * FROM obj_members ".
                        "WHERE obj_id = ".$ilDB->quote($a_obj_id ,'integer')." ".
                        "AND usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND passed = '1'";
                $res = $ilDB->query($query);
                return $res->numRows() ? true : false; 
        }       
        
        public static function _deleteAllEntries($a_obj_id)
        {
                global $ilDB;

                $query = "DELETE FROM obj_members ".
                        "WHERE obj_id = ".$ilDB->quote($a_obj_id ,'integer')." ";
                $res = $ilDB->manipulate($query);

                $query = "DELETE FROM il_subscribers ".
                        "WHERE obj_id = ".$ilDB->quote($a_obj_id ,'integer')."";
                $res = $ilDB->manipulate($query);
                
                $query = 'DELETE FROM crs_waiting_list '.
                                'WHERE obj_id = '.$ilDB->quote($a_obj_id,'integer');
                $ilDB->manipulate($query);

                return true;
        }
        
        public static function _deleteUser($a_usr_id)
        {
                global $ilDB;

                $query = "DELETE FROM obj_members WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')."";
                $res = $ilDB->manipulate($query);

                $query = "DELETE FROM il_subscribers WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')."";
                $res = $ilDB->manipulate($query);

                include_once './Modules/Course/classes/class.ilCourseWaitingList.php';
                ilCourseWaitingList::_deleteUser($a_usr_id);
        }
        
        public static function getDefaultMemberRole($a_ref_id)
        {
                global $ilCtrl;
                
                $obj_id = ilObject::_lookupObjId($a_ref_id);
                $type = ilObject::_lookupType($obj_id);
                
                if(!in_array($type,array('crs','grp')))
                {
                        return 0;
                }
                
                global $rbacreview;
                

                $roles = $rbacreview->getRolesOfRoleFolder($a_ref_id,false);
                
                foreach($roles as $role)
                {
                        $title = ilObject::_lookupTitle($role);
                        if(substr($title, 0, 13) == ('il_'.$type.'_member'))
                        {
                                return $role;
                        }
                }
                return 0;
        }
        
        public function getObjId()
        {
                return $this->obj_id;
        }
        
        public function getType()
        {
                return $this->type;
        }
        
        public function getNotificationRecipients()
        {
                global $ilDB;
                
                $query = "SELECT * FROM obj_members ".
                        "WHERE notification = 1 ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id)." ";
                $res = $ilDB->query($query);
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        if($this->isAdmin($row->usr_id) or $this->isTutor($row->usr_id))
                        {
                                $recp[] = $row->usr_id;
                        }
                }
                return $recp ? $recp : array();
        }
        
        public function getCountMembers()
        {
                return count($this->members);
        }
        
        public function getCountParticipants()
        {
                return count($this->participants);
        }
        
        
        
        
        public function getParticipants()
        {
                return $this->participants ? $this->participants : array();
        }
        
        public function getMembers()
        {
                return $this->members ? $this->members : array();
        }
        public function getAdmins()
        {
                return $this->admins ? $this->admins : array();
        }
        
        public function getCountAdmins()
        {
                return count($this->getAdmins());
        }
        
        
        public function getTutors()
        {
                return $this->tutors ? $this->tutors : array();
        }
        
        public function isAdmin($a_usr_id)
        {
                return in_array($a_usr_id,$this->admins) ? true : false;        
        }
        
        public function isTutor($a_usr_id)
        {
                return in_array($a_usr_id,$this->tutors) ? true : false;        
        }
        
        public function isMember($a_usr_id)
        {
                return in_array($a_usr_id,$this->members) ? true : false;       
        }
        
        
        
        
        public function isAssigned($a_usr_id)
        {
                return in_array($a_usr_id,$this->participants);
        }
        
        public function isLastAdmin($a_usr_id)
        {
                return in_array($a_usr_id,$this->getAdmins()) and count($this->getAdmins()) == 1;
        }
        
        
        public function getRoles()
        {
                return $this->roles ? $this->roles : array();
        }
        
        public function getAssignedRoles($a_usr_id)
        {
                global $rbacreview;
                
                foreach($this->roles as $role)
                {
                        if($rbacreview->isAssigned($a_usr_id,$role))
                        {
                                $assigned[] = $role;
                        }
                }
                return $assigned ? $assigned : array();
        }
        
        public function updateRoleAssignments($a_usr_id,$a_roles)
        {
                global $rbacreview,$rbacadmin;
                
                $roles = $a_roles ? $a_roles : array();
                
                foreach($this->getRoles() as $role_id)
                {
                        if($rbacreview->isAssigned($a_usr_id,$role_id))
                        {
                                if(!in_array($role_id,$roles))
                                {
                                        $rbacadmin->deassignUser($role_id,$a_usr_id);
                                }
                        }
                        else
                        {
                                if(in_array($role_id,$roles))
                                {
                                        $rbacadmin->assignUser($role_id,$a_usr_id);
                                }
                        }
                }
                $this->readParticipants();
                $this->readParticipantsStatus();
        }
        
        public function checkLastAdmin($a_usr_ids)
        {
                foreach($this->getAdmins() as $admin_id)
                {
                        if(!in_array($admin_id,$a_usr_ids))
                        {
                                return true;
                        }
                }
                return false;
        }
        
        public function isBlocked($a_usr_id)
        {
                if(isset($this->participants_status[$a_usr_id]))
                {
                        return $this->participants_status[$a_usr_id]['blocked'] ? true : false; 
                }
                return false;
        }
        
        public function hasPassed($a_usr_id)
        {
                if(isset($this->participants_status[$a_usr_id]))
                {
                        return $this->participants_status[$a_usr_id]['passed'] ? true : false;
                }
                return false;
        }
        
        public function delete($a_usr_id)
        {
                global $rbacadmin,$ilDB;
                
                $this->dropDesktopItem($a_usr_id);
                foreach($this->roles as $role_id)
                {
                        $rbacadmin->deassignUser($role_id,$a_usr_id);
                }
                
                $query = "DELETE FROM obj_members ".
                        "WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id ,'integer');
                $res = $ilDB->manipulate($query);
                
                $this->readParticipants();
                $this->readParticipantsStatus();
                
                $GLOBALS['ilAppEventHandler']->raise(
                                $this->getComponent(),
                                "deleteParticipant", 
                                array(
                                        'obj_id' => $this->obj_id, 
                                        'usr_id' => $a_usr_id)
                );
                
                return true;
        }

        public function updateBlocked($a_usr_id,$a_blocked)
        {
                global $ilDB;
                
                $this->participants_status[$a_usr_id]['blocked'] = (int) $a_blocked;

                $query = "SELECT * FROM obj_members ".
                "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ".
                "AND usr_id = ".$ilDB->quote($a_usr_id ,'integer');
                $res = $ilDB->query($query);
                if($res->numRows())
                {
                        $query = "UPDATE obj_members SET ".
                                "blocked = ".$ilDB->quote((int) $a_blocked ,'integer')." ".
                                "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ".
                                "AND usr_id = ".$ilDB->quote($a_usr_id ,'integer');
                }
                else
                {
                        $query = "INSERT INTO obj_members (blocked,obj_id,usr_id,notification,passed) ".
                                "VALUES ( ".
                                $ilDB->quote((int) $a_blocked ,'integer').", ".
                                $ilDB->quote($this->obj_id ,'integer').", ".
                                $ilDB->quote($a_usr_id ,'integer').", ".
                                $ilDB->quote(0,'integer').", ".
                                $ilDB->quote(0,'integer').
                                ")";
                        
                }
                $res = $ilDB->manipulate($query);
                return true;
        }

        public function updateNotification($a_usr_id,$a_notification)
        {
                global $ilDB;
                
                $this->participants_status[$a_usr_id]['notification'] = (int) $a_notification;

                $query = "SELECT * FROM obj_members ".
                "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ".
                "AND usr_id = ".$ilDB->quote($a_usr_id ,'integer');
                $res = $ilDB->query($query);
                if($res->numRows())
                {
                        $query = "UPDATE obj_members SET ".
                                "notification = ".$ilDB->quote((int) $a_notification ,'integer')." ".
                                "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ".
                                "AND usr_id = ".$ilDB->quote($a_usr_id ,'integer');
                }
                else
                {
                        $query = "INSERT INTO obj_members (notification,obj_id,usr_id,passed,blocked) ".
                                "VALUES ( ".
                                $ilDB->quote((int) $a_notification ,'integer').", ".
                                $ilDB->quote($this->obj_id ,'integer').", ".
                                $ilDB->quote($a_usr_id ,'integer').", ".
                                $ilDB->quote(0,'integer').", ".
                                $ilDB->quote(0,'integer').
                                ")";
                        
                }
                $res = $ilDB->manipulate($query);
                return true;
        }
        

        
        
        public function add($a_usr_id,$a_role)
        {
                global $rbacadmin,$ilLog,$ilAppEventHandler;
                
                if($this->isAssigned($a_usr_id))
                {
                        return false;
                }
                
                switch($a_role)
                {
                        case IL_CRS_ADMIN:
                                $this->admins[] = $a_usr_id;
                                break;

                        case IL_CRS_TUTOR:
                                $this->tutors[] = $a_usr_id;
                                break;

                        case IL_CRS_MEMBER:
                                $this->members[] = $a_usr_id;
                                break;
                                
                        case IL_GRP_ADMIN:
                                $this->admins[] = $a_usr_id;
                                break;
                                
                        case IL_GRP_MEMBER:
                                $this->members[] = $a_usr_id;
                                break;
                }
                
                $this->participants[] = $a_usr_id;
                $rbacadmin->assignUser($this->role_data[$a_role],$a_usr_id);
                $this->addDesktopItem($a_usr_id);
                
                // Delete subscription request
                $this->deleteSubscriber($a_usr_id);
                
                include_once './Services/Membership/classes/class.ilWaitingList.php';
                ilWaitingList::deleteUserEntry($a_usr_id,$this->obj_id);

                $ilLog->write(__METHOD__.': Raise new event: Modules/Course|Group addParticipant');
                $ilAppEventHandler->raise(
                                $this->getComponent(),
                                "addParticipant", 
                                array(
                                        'obj_id' => $this->obj_id,
                                        'usr_id' => $a_usr_id,
                                        'role_id' => $a_role)
                );
                return true;
        }
        

        public function deleteParticipants($a_user_ids)
        {
                foreach($a_user_ids as $user_id)
                {
                        $this->delete($user_id);
                }
                return true;
        }
        
        public function addDesktopItem($a_usr_id)
        {
                if(!ilObjUser::_isDesktopItem($a_usr_id, $this->ref_id,$this->type))
                {
                        ilObjUser::_addDesktopItem($a_usr_id, $this->ref_id,$this->type);
                }
                return true;
        }
        
        function dropDesktopItem($a_usr_id)
        {
                if(ilObjUser::_isDesktopItem($a_usr_id, $this->ref_id,$this->type))
                {
                        ilObjUser::_dropDesktopItem($a_usr_id, $this->ref_id,$this->type);
                }

                return true;
        }
        
        
        
        public function isNotificationEnabled($a_usr_id)
        {
                if(isset($this->participants_status[$a_usr_id]))
                {
                        return $this->participants_status[$a_usr_id]['notification'] ? true : false;
                }
                return false;
        }
        
        
        protected function readParticipants()
        {
                global $rbacreview,$ilObjDataCache,$ilLog;
                
                $GLOBALS['rbacreview']->clearCaches();
                $this->roles = $rbacreview->getRolesOfRoleFolder($this->ref_id,false);

                $users = array();
                $this->participants = array();
                $this->members = $this->admins = $this->tutors = array();

                foreach($this->roles as $role_id)
                {
                        $title = $ilObjDataCache->lookupTitle($role_id);
                        switch(substr($title,0,8))
                        {
                                case 'il_crs_m':
                                        $this->role_data[IL_CRS_MEMBER] = $role_id;
                                        $this->participants = array_unique(array_merge($assigned = $rbacreview->assignedUsers($role_id),$this->participants));
                                        $this->members = array_unique(array_merge($assigned,$this->members));
                                        break;

                                case 'il_crs_a':
                                        $this->role_data[IL_CRS_ADMIN] = $role_id;
                                        $this->participants = array_unique(array_merge($assigned = $rbacreview->assignedUsers($role_id),$this->participants));
                                        $this->admins = $rbacreview->assignedUsers($role_id);
                                        break;
                
                                case 'il_crs_t':
                                        $this->role_data[IL_CRS_TUTOR] = $role_id;
                                        $this->participants = array_unique(array_merge($assigned = $rbacreview->assignedUsers($role_id),$this->participants));
                                        $this->tutors = $rbacreview->assignedUsers($role_id);
                                        break;
                                        
                                case 'il_grp_a':
                                        $this->role_data[IL_GRP_ADMIN] = $role_id;
                                        $this->participants = array_unique(array_merge($assigned = $rbacreview->assignedUsers($role_id),$this->participants));
                                        $this->admins = $rbacreview->assignedUsers($role_id);
                                        break;
                                        
                                case 'il_grp_m':
                                        $this->role_data[IL_GRP_MEMBER] = $role_id;
                                        $this->participants = array_unique(array_merge($assigned = $rbacreview->assignedUsers($role_id),$this->participants));
                                        $this->members = $rbacreview->assignedUsers($role_id);
                                        break;
                                
                                default:
                                        $this->participants = array_unique(array_merge($assigned = $rbacreview->assignedUsers($role_id),$this->participants));
                                        $this->members = array_unique(array_merge($assigned,$this->members));
                                        break;
                        }
                }
        }
        
        protected function readParticipantsStatus()
        {
                global $ilDB;
                
                $query = "SELECT * FROM obj_members ".
                        "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ";
                $res = $ilDB->query($query);
                $this->participants_status = array();
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        $this->participants_status[$row->usr_id]['blocked'] = $row->blocked;
                        $this->participants_status[$row->usr_id]['notification']  = $row->notification;
                        $this->participants_status[$row->usr_id]['passed'] = $row->passed;
                }
        }
        
        public function isGroupingMember($a_usr_id,$a_field = '')
        {
                global $rbacreview,$ilObjDataCache,$ilDB;

                // Used for membership limitations -> check membership by given field
                if($a_field)
                {
                        include_once './Services/User/classes/class.ilObjUser.php';

                        $tmp_user =& ilObjectFactory::getInstanceByObjId($a_usr_id);
                        switch($a_field)
                        {
                                case 'login':
                                        $and = "AND login = ".$ilDB->quote($tmp_user->getLogin(),'text')." ";
                                        break;
                                case 'email':
                                        $and = "AND email = ".$ilDB->quote($tmp_user->getEmail(),'text')." ";
                                        break;
                                case 'matriculation':
                                        $and = "AND matriculation = ".$ilDB->quote($tmp_user->getMatriculation(),'text')." ";
                                        break;

                                default:
                                        $and = "AND usr_id = ".$ilDB->quote($a_usr_id,'integer'). " ";
                                        break;
                        }
                        
                        if(!$this->getParticipants())
                        {
                                return false;
                        }

                        $query = "SELECT * FROM usr_data ud ".
                                "WHERE ".$ilDB->in('usr_id',$this->getParticipants(),false,'integer')." ".
                                $and;

                        $res = $ilDB->query($query);
                        return $res->numRows() ? true : false;
                }
        }

        public static function lookupSubscribers($a_obj_id)
        {
                global $ilDB;

                $subscribers = array();
                $query = "SELECT usr_id FROM il_subscribers ".
                        "WHERE obj_id = ".$ilDB->quote($a_obj_id ,'integer')." ".
                        "ORDER BY sub_time ";

                $res = $ilDB->query($query);
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        $subscribers[] = $row->usr_id;
                }
                return $subscribers;
        }
        
        public function getSubscribers()
        {
                $this->readSubscribers();

                return $this->subscribers;
        }

        
        public function getCountSubscribers()
        {
                return count($this->getSubscribers());
        }

        public function getSubscriberData($a_usr_id)
        {
                return $this->readSubscriberData($a_usr_id);
        }



        public function assignSubscribers($a_usr_ids)
        {
                if(!is_array($a_usr_ids) or !count($a_usr_ids))
                {
                        return false;
                }
                foreach($a_usr_ids as $id)
                {
                        if(!$this->assignSubscriber($id))
                        {
                                return false;
                        }
                }
                return true;
        }

        public function assignSubscriber($a_usr_id)
        {
                global $ilErr;
                
                $ilErr->setMessage("");
                if(!$this->isSubscriber($a_usr_id))
                {
                        $ilErr->appendMessage($this->lng->txt("crs_user_notsubscribed"));

                        return false;
                }
                if($this->isAssigned($a_usr_id))
                {
                        $tmp_obj = ilObjectFactory::getInstanceByObjId($a_usr_id);
                        $ilErr->appendMessage($tmp_obj->getLogin().": ".$this->lng->txt("crs_user_already_assigned"));

                        return false;
                }

                if(!$tmp_obj =& ilObjectFactory::getInstanceByObjId($a_usr_id))
                {
                        $ilErr->appendMessage($this->lng->txt("crs_user_not_exists"));

                        return false;
                }

                // TODO: must be group or course member role
                $this->add($tmp_obj->getId(),IL_CRS_MEMBER);
                $this->deleteSubscriber($a_usr_id);

                return true;
        }

        public function autoFillSubscribers()
        {
                $this->readSubscribers();

                $counter = 0;
                foreach($this->subscribers as $subscriber)
                {
                        if(!$this->assignSubscriber($subscriber))
                        {
                                continue;
                        }
                        else
                        {
                                // TODO: notification
                                #$this->sendNotification($this->NOTIFY_ACCEPT_SUBSCRIBER,$subscriber);
                        }
                        ++$counter;
                }

                return $counter;
        }

        public function addSubscriber($a_usr_id)
        {
                global $ilDB;

                $query = "INSERT INTO il_subscribers (usr_id,obj_id,subject,sub_time) ".
                        " VALUES (".
                        $ilDB->quote($a_usr_id ,'integer').",".
                        $ilDB->quote($this->obj_id ,'integer').", ".
                        $ilDB->quote('','text').", ".
                        $ilDB->quote(time() ,'integer').
                        ")";
                $res = $ilDB->manipulate($query);

                return true;
        }


        public function updateSubscriptionTime($a_usr_id,$a_subtime)
        {
                global $ilDB;

                $query = "UPDATE il_subscribers ".
                        "SET sub_time = ".$ilDB->quote($a_subtime ,'integer')." ".
                        "WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ";
                $res = $ilDB->manipulate($query);

                return true;
        }
        
        public function updateSubject($a_usr_id,$a_subject)
        {
                global $ilDB;
                
                $query = "UPDATE il_subscribers ".
                        "SET subject = ".$ilDB->quote($a_subject ,'text')." ".
                        "WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ";
                $res = $ilDB->manipulate($query);
                return true;
        }

        
        public function deleteSubscriber($a_usr_id)
        {
                global $ilDB;

                $query = "DELETE FROM il_subscribers ".
                        "WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ";
                $res = $ilDB->manipulate($query);

                return true;
        }

        
        public function deleteSubscribers($a_usr_ids)
        {
                global $ilErr,$ilDB;
                
                if(!is_array($a_usr_ids) or !count($a_usr_ids))
                {
                        $ilErr->setMessage('');
                        $ilErr->appendMessage($this->lng->txt("no_usr_ids_given"));

                        return false;
                }
                $query = "DELETE FROM il_subscribers ".
                        "WHERE ".$ilDB->in('usr_id',(array) $a_usr_ids,false,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id,'integer');
                $res = $ilDB->query($query);
                return true;
        }
        
        
        public function isSubscriber($a_usr_id)
        {
                global $ilDB;

                $query = "SELECT * FROM il_subscribers ".
                        "WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($this->obj_id ,'integer')."";

                $res = $ilDB->query($query);
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        return true;
                }
                return false;
        }

        public static function _isSubscriber($a_obj_id,$a_usr_id)
        {
                global $ilDB;

                $query = "SELECT * FROM il_subscribers ".
                        "WHERE usr_id = ".$ilDB->quote($a_usr_id ,'integer')." ".
                        "AND obj_id = ".$ilDB->quote($a_obj_id ,'integer')."";

                $res = $ilDB->query($query);
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        return true;
                }
                return false;
        }
        
        protected function readSubscribers()
        {
                global $ilDB;

                $this->subscribers = array();

                $query = "SELECT usr_id FROM il_subscribers ".
                        "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ".
                        "ORDER BY sub_time ";

                $res = $this->ilDB->query($query);
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        // DELETE SUBSCRIPTION IF USER HAS BEEN DELETED
                        if(!ilObjectFactory::getInstanceByObjId($row->usr_id,false))
                        {
                                $this->deleteSubscriber($row->usr_id);
                        }
                        $this->subscribers[] = $row->usr_id;
                }
                return true;
        }

        protected function readSubscriberData($a_usr_id)
        {
                global $ilDB;

                $query = "SELECT * FROM il_subscribers ".
                        "WHERE obj_id = ".$ilDB->quote($this->obj_id ,'integer')." ".
                        "AND usr_id = ".$ilDB->quote($a_usr_id ,'integer')."";

                $res = $this->ilDB->query($query);
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        $data["time"] = $row->sub_time;
                        $data["usr_id"] = $row->usr_id;
                        $data['subject'] = $row->subject;
                }
                return $data ? $data : array();
        }

        public static function lookupSubscribersData($a_obj_id)
        {
                global $ilDB;

                $query = 'SELECT * FROM il_subscribers '.
                        'WHERE obj_id = '.$ilDB->quote($a_obj_id,'integer');
                $res = $ilDB->query($query);

                $data = array();
                while($row = $res->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        $data[$row->usr_id]['time'] = $row->sub_time;
                        $data[$row->usr_id]['usr_id'] = $row->usr_id;
                        $data[$row->usr_id]['subject'] = $row->subject;
                }
                return $data;
        }
}
?>