Create plugin to add more field to restriction section of product

$cart->messages[] = array('msg' => 'product not purchasable yet', 'product_id' => $product_id, 'type' => 'notice');

$cartClass = hikashop_get('class.cart');
$cartClass->addMessage($cart, array('msg' => 'product not purchasable yet', 'product_id' => $product_id, 'type' => 'error'));

			$nameboxType = hikashop_get('type.namebox');
			if(!is_array($value))
				$value = explode(',', trim($value));
			echo $nameboxType->display(
				$map,
				$value,
				hikashopNameboxType::NAMEBOX_MULTIPLE,
				'rawlist',
				array(
					'delete' => true,
					'sort' => true,
					'default_text' => '<em>'.JText::_('HIKA_NONE').'</em>',
					'rawdata' => $values
				)
			);

data[product][xxx]

	function onNameboxTypesLoad(&$loaded_types)
	{
		$loaded_types['client_selector'] = array(
			'class' => 'class.user',
			'name' => 'user_id',
			'mode' => 'list',
			'displayFormat' => '{user_id} - {name}',
			'url' => 'xxx&task=getValues',
			'options' => array(
				'olist' => array(
					'table' => array('user_id' => 'ID', 'name' => 'HIKA_NAME', 'user_email' => 'HIKA_EMAIL'),
					'displayFormat' => '{user_id} - {name}',
				)
			)
		);
	}

	public function onHikashopPluginController($ctrl)
	{
		if (!in_array($ctrl, array('xxx')))
			return;
		$prefix = 'ctrl';

		if (!hikashop_isClient('administrator'))
			return;

		// register the controller for the client selector
		return array(
			'type' => 'hikashop',
			'name' => 'xxx',
			'prefix' => $prefix,
		);
	}

<?php


/**
 *
 */
class  xxxController extends hikashopController {
	public $display = array('getValues');
	public $modify_views = array();
	public $add = array();
	public $modify = array();
	public $delete = array();

	public $pluginCtrl = array('hikashop', 'xxx');
	public $type = 'plg_xxx';

	/**
	 *
	 * @param array $config
	 * @param boolean $skip
	 */
	public function __construct($config = array(), $skip = false) {
		parent::__construct($config, $skip);
		if(!$skip)
			$this->registerDefaultTask('listing');
	}

	/**
	 *
	 */
	protected function getACLName($task) {
		return '';
	}
	/**
	 * user data feeder for the client selector
	 */
	public function getValues() {
		$displayFormat = hikaInput::get()->getVar('displayFormat', '');
		$search = hikaInput::get()->getVar('search', null);
		$start = hikaInput::get()->getInt('start', 0);

		$nameboxType = hikashop_get('type.namebox');
		$options = array(
			'start' => $start,
			'displayFormat' => $displayFormat
		);
		$ret = $nameboxType->getValues($search, 'user', $options);
		if(!empty($ret)) {
			echo json_encode($ret);
			exit;
		}
		echo '[]';
		exit;
	}
}

$ret = $nameboxType->getValues($search, 'user', $options);