public function renderList()
    {
        $this->addRowAction('view');
        $this->addRowAction('delete');
        $this->_select = '
 			CONCAT(c.`firstname`," ",c.`lastname`) as customer, cl.`name` as contact, l.`name` as language, group_concat(message) as messages,
 			(
				SELECT IFNULL(CONCAT(LEFT(e.`firstname`, 1),". ",e.`lastname`), "--")
				FROM `' . _DB_PREFIX_ . 'customer_message` cm2
				INNER JOIN ' . _DB_PREFIX_ . 'employee e
					ON e.`id_employee` = cm2.`id_employee`
				WHERE cm2.id_employee > 0
					AND cm2.`id_customer_thread` = a.`id_customer_thread`
				ORDER BY cm2.`date_add` DESC LIMIT 1
			) as employee';
        $this->_join = '
			LEFT JOIN `' . _DB_PREFIX_ . 'customer` c
				ON c.`id_customer` = a.`id_customer`
			LEFT JOIN `' . _DB_PREFIX_ . 'customer_message` cm
				ON cm.`id_customer_thread` = a.`id_customer_thread`
			LEFT JOIN `' . _DB_PREFIX_ . 'lang` l
				ON l.`id_lang` = a.`id_lang`
			LEFT JOIN `' . _DB_PREFIX_ . 'contact_lang` cl
				ON (cl.`id_contact` = a.`id_contact` AND cl.`id_lang` = ' . (int) $this->context->language->id . ')';
        $this->_group = 'GROUP BY cm.id_customer_thread';
        $this->_orderBy = 'id_customer_thread';
        $this->_orderWay = 'DESC';
        $contacts = CustomerThread::getContacts();
        $categories = Contact::getCategoriesContacts();
        $params = array($this->l('Total threads') => $all = CustomerThread::getTotalCustomerThreads(), $this->l('Threads pending') => $pending = CustomerThread::getTotalCustomerThreads('status LIKE "%pending%"'), $this->l('Total number of customer messages') => CustomerMessage::getTotalCustomerMessages('id_employee = 0'), $this->l('Total number of employee messages') => CustomerMessage::getTotalCustomerMessages('id_employee != 0'), $this->l('Unread threads') => $unread = CustomerThread::getTotalCustomerThreads('status = "open"'), $this->l('Closed threads') => $all - ($unread + $pending));
        $this->tpl_list_vars = array('contacts' => $contacts, 'categories' => $categories, 'params' => $params);
        return parent::renderList();
    }