Printer::canUnrecurs PHP Method

    function canUnrecurs()
    {
        global $DB, $CFG_GLPI;
        $ID = $this->fields['id'];
        if ($ID < 0 || !$this->fields['is_recursive']) {
            return true;
        }
        if (!parent::canUnrecurs()) {
            return false;
        }
        $entities = getAncestorsOf("glpi_entities", $this->fields['entities_id']);
        $entities[] = $this->fields['entities_id'];
        // RELATION : printers -> _port -> _wire -> _port -> device
        // Evaluate connection in the 2 ways
        for ($tabend = array("networkports_id_1" => "networkports_id_2", "networkports_id_2" => "networkports_id_1"); list($enda, $endb) = each($tabend);) {
            $sql = "SELECT `itemtype`,\n                        GROUP_CONCAT(DISTINCT `items_id`) AS ids\n                 FROM `glpi_networkports_networkports`,\n                      `glpi_networkports`\n                 WHERE `glpi_networkports_networkports`.`{$endb}` = `glpi_networkports`.`id`\n                       AND `glpi_networkports_networkports`.`{$enda}`\n                            IN (SELECT `id`\n                                FROM `glpi_networkports`\n                                WHERE `itemtype` = '" . $this->getType() . "'\n                                      AND `items_id` = '{$ID}')\n                 GROUP BY `itemtype`";
            $res = $DB->query($sql);
            if ($res) {
                while ($data = $DB->fetch_assoc($res)) {
                    $itemtable = getTableForItemType($data["itemtype"]);
                    if ($item = getItemForItemtype($data["itemtype"])) {
                        // For each itemtype which are entity dependant
                        if ($item->isEntityAssign()) {
                            if (countElementsInTable($itemtable, ['id' => $data["ids"], 'NOT' => ['entities_id' => $entities]]) > 0) {
                                return false;
                            }
                        }
                    }
                }
            }
        }
        return true;
    }