Method getCartDiscountsById

/*
 * ID ... id of cart
 */
public static function getCartDiscountsById($id = 0, $returnArray = 0)
{
    if (is_null($id)) {
        throw new Exception('Function Error: No id added', 500);
        return false;
    }
    $id = (int) $id;
    //- if( !array_key_exists( $id, self::$cart ) ) {
    $db = Factory::getDBO();
    $user = PhocacartUser::getUser();
    $userLevels = implode(',', $user->getAuthorisedViewLevels());
    $userGroups = implode(',', PhocacartGroup::getGroupsById($user->id, 1, 1));
    $wheres = array();
    $wheres[] = "a.access IN (" . $userLevels . ")";
    $wheres[] = " (ga.group_id IN (" . $userGroups . ") OR ga.group_id IS NULL)";
    $wheres[] = 'a.published = 1';
    $where = count($wheres) ? ' WHERE ' . implode(' AND ', $wheres) : '';
    $columns = 'a.id, a.title, a.alias, a.discount, a.access, a.discount, a.total_amount, a.free_shipping, a.free_payment, a.calculation_type, a.quantity_from, a.quantity_to, a.valid_from, a.valid_to, a.category_filter, a.product_filter,' . ' GROUP_CONCAT(DISTINCT dp.product_id) AS product,' . ' GROUP_CONCAT(DISTINCT dc.category_id) AS category';
    // line of selected categories
    $groupsFull = 'a.id, a.title, a.alias, a.discount, a.access, a.discount, a.total_amount, a.free_shipping, a.free_payment, a.calculation_type, a.quantity_from, a.quantity_to, a.valid_from, a.valid_to, a.category_filter, a.product_filter';
    $groupsFast = 'a.id';
    $groups = PhocacartUtilsSettings::isFullGroupBy() ? $groupsFull : $groupsFast;
    $query = 'SELECT ' . $columns . ' FROM #__phocacart_discounts AS a' . ' LEFT JOIN #__phocacart_discount_products AS dp ON dp.discount_id = a.id' . ' LEFT JOIN #__phocacart_discount_categories AS dc ON dc.discount_id = a.id' . ' LEFT JOIN #__phocacart_item_groups AS ga ON a.id = ga.item_id AND ga.type = 5' . $where . ' GROUP BY ' . $groups;
    $query .= ' ORDER BY a.id';
    PhocacartUtils::setConcatCharCount();
    $db->setQuery($query);
    if ($returnArray) {
        $discounts = $db->loadAssocList();
    } else {
        $discounts = $db->loadObjectList();
    }
    self::$cart[$id] = $discounts;
    //- }
    return self::$cart[$id];
}