public function save() {
        if (!tao_helpers_Request::isAjax()) {
            throw new common_exception_IsAjaxAction(__METHOD__);
        }
        if (!$this->hasRequestParameter('uri')) {
            throw new common_exception_MissingParameter('uri', __METHOD__);
        }
        if (!$this->hasRequestParameter('stylesheetUri')) {
            throw new common_exception_MissingParameter('stylesheetUri', __METHOD__);
        }
        if (!$this->hasRequestParameter('lang')) {
            throw new common_exception_MissingParameter('lang', __METHOD__);
        }
        
        $item = new \core_kernel_classes_Resource($this->getRequestParameter('uri'));
        $lang = $this->getRequestParameter('lang');
        $styleSheet = $this->getRequestParameter('stylesheetUri');
        if (!\tao_helpers_File::securityCheck($styleSheet, true)) {
            throw new \common_exception_Error('invalid stylesheet path "'.$styleSheet.'"');
        }

        $css = $this->getCssArray();
        CssHelper::saveCssFile($item, $lang, $styleSheet, $css);
    }