/**
  * @see EventListenerInterface::listen_events()
  * @param object $event_object
  * @return bool
  */
 public static function listen_events($event_object)
 {
     global $transaction;
     if ($event_object instanceof ItemAddHolderEvent) {
         $type = $event_object->get_type();
         if ($type == "project") {
             $project_id = $event_object->get_id();
             $item_id = $event_object->get_item_id();
             $gid = $event_object->get_gid();
             $transaction_id = $transaction->begin();
             if (self::create($project_id, $item_id, $gid, null, null) == false) {
                 if ($transaction_id != null) {
                     $transaction->rollback($transaction_id);
                 }
                 return false;
             } else {
                 if ($transaction_id != null) {
                     $transaction->commit($transaction_id);
                 }
             }
         }
     }
     if ($event_object instanceof ItemAddEvent) {
         $get_array = $event_object->get_get_array();
         $post_array = $event_object->get_post_array();
         $item_holder = $event_object->get_item_holder();
         $item_holder_name = $event_object->get_item_holder_name();
         if ($get_array['nav'] == "project" and is_numeric($get_array['project_id']) and !$get_array['parent']) {
             $transaction_id = $transaction->begin();
             if ($item_holder == true and $item_holder_name) {
                 $item_holder_class = Item::get_holder_handling_class_by_name($item_holder_name);
                 $item_holder_instance = $item_holder_class::get_instance_by_item_id($event_object->get_item_id());
                 if (self::$project_instance_array[$get_array['project_id']]) {
                     $project = self::$project_instance_array[$get_array['project_id']];
                 } else {
                     $project = new Project($get_array['project_id']);
                     self::$project_instance_array[$get_array['project_id']] = $project;
                 }
                 $required_sub_item_array = $project->list_required_sub_items($get_array['key']);
                 if (is_array($required_sub_item_array) and count($required_sub_item_array) >= 1) {
                     if ($required_sub_item_array[0] == "all") {
                         $sub_item_array = $item_holder_instance->get_item_holder_items(null);
                         if (is_array($sub_item_array) and count($sub_item_array)) {
                             foreach ($sub_item_array as $sub_item_key => $sub_item_value) {
                                 if (self::create($get_array['project_id'], $sub_item_value, null, null, null, $event_object->get_item_id()) == false) {
                                     if ($transaction_id != null) {
                                         $transaction->rollback($transaction_id);
                                     }
                                     return false;
                                 }
                                 if (DataEntity::is_kind_of("file", $sub_item_value) or DataEntity::is_kind_of("value", $sub_item_value) or DataEntity::is_kind_of("parameter", $sub_item_value)) {
                                     $data_entity_id = DataEntity::get_entry_by_item_id($sub_item_value);
                                     $folder_id = $project->get_item_holder_value("folder_id", null, $value['status_id']);
                                     $parent_data_entity_id = Folder::get_data_entity_id_by_folder_id($folder_id);
                                     $child_data_entity = new DataEntity($data_entity_id);
                                     if ($child_data_entity->set_as_child_of($parent_data_entity_id, true, $parent_item_id) == false) {
                                         return false;
                                     }
                                 }
                             }
                         }
                     } else {
                         foreach ($required_sub_item_array as $key => $value) {
                             $sub_item_array = $item_holder_instance->get_item_holder_items($value['position_id']);
                             if (is_array($sub_item_array) and count($sub_item_array)) {
                                 foreach ($sub_item_array as $sub_item_key => $sub_item_value) {
                                     if (self::create($get_array['project_id'], $sub_item_value, null, null, null, $event_object->get_item_id(), $value['status_id']) == false) {
                                         if ($transaction_id != null) {
                                             $transaction->rollback($transaction_id);
                                         }
                                         return false;
                                     }
                                     if (DataEntity::is_kind_of("file", $sub_item_value) or DataEntity::is_kind_of("value", $sub_item_value) or DataEntity::is_kind_of("parameter", $sub_item_value)) {
                                         $data_entity_id = DataEntity::get_entry_by_item_id($sub_item_value);
                                         $folder_id = $project->get_item_holder_value("folder_id", null, $value['status_id']);
                                         $parent_data_entity_id = Folder::get_data_entity_id_by_folder_id($folder_id);
                                         $child_data_entity = new DataEntity($data_entity_id);
                                         if ($child_data_entity->set_as_child_of($parent_data_entity_id, true, $parent_item_id) == false) {
                                             return false;
                                         }
                                     }
                                 }
                             }
                         }
                     }
                 }
             }
             if (self::create($get_array['project_id'], $event_object->get_item_id(), $get_array['key'], $post_array['keywords'], $post_array['description']) == false) {
                 if ($transaction_id != null) {
                     $transaction->rollback($transaction_id);
                 }
                 return false;
             } else {
                 if ($transaction_id != null) {
                     $transaction->commit($transaction_id);
                 }
             }
         }
     }
     if ($event_object instanceof ItemHolderAddEvent) {
         $id_array = $event_object->get_id_array();
         $item_id = $event_object->get_item_id();
         $parent_item_id = $event_object->get_parent_item_id();
         $pos_id = $event_object->get_pos_id();
         if (is_array($id_array) and count($id_array) >= 1) {
             if (is_array($id_array['project']) and count($id_array['project']) >= 1) {
                 foreach ($id_array['project'] as $key => $value) {
                     if (self::$project_instance_array[$value['id']]) {
                         $project = self::$project_instance_array[$value['id']];
                     } else {
                         $project = new Project($value['id']);
                         self::$project_instance_array[$value['id']] = $project;
                     }
                     if (($item_status_id = $project->is_sub_item_required($value['pos_id'], $value['status_id'], $pos_id)) == true) {
                         if (self::create($value['id'], $item_id, null, null, null, $parent_item_id, $item_status_id) == false) {
                             return false;
                         }
                         if (DataEntity::is_kind_of("file", $item_id) or DataEntity::is_kind_of("value", $item_id) or DataEntity::is_kind_of("parameter", $sub_item_value)) {
                             $data_entity_id = DataEntity::get_entry_by_item_id($item_id);
                             $folder_id = $project->get_item_holder_value("folder_id", null, $item_status_id);
                             $parent_data_entity_id = Folder::get_data_entity_id_by_folder_id($folder_id);
                             $child_data_entity = new DataEntity($data_entity_id);
                             if ($child_data_entity->set_as_child_of($parent_data_entity_id, true, $parent_item_id) == false) {
                                 return false;
                             }
                         }
                     }
                 }
             }
         }
     }
     return true;
 }