public static function get_css_path($files)
 {
     if (!empty($files)) {
         if (is_array($files)) {
             $cache_file_location = '/cache/css/css-cache-' . md5(implode(';', $files)) . '.css';
         } else {
             $files = str_replace('{THEME}', AppContext::get_current_user()->get_theme(), $files);
             $cache_file_location = '/cache/css/css-cache-' . md5($files) . '.css';
             $files = explode(';', $files);
         }
         $css_cache = new CSSCacheManager();
         $css_cache->set_files($files);
         $css_cache->set_cache_file_location(PATH_TO_ROOT . $cache_file_location);
         $css_cache->execute(CSSCacheConfig::load()->get_optimization_level());
         return TPL_PATH_TO_ROOT . $cache_file_location;
     }
 }
 protected function get_modules_css_files_html_code()
 {
     $css_cache_config = CSSCacheConfig::load();
     $css_files = array_merge(ModulesCssFilesService::get_css_files_always_displayed(), ModulesCssFilesService::get_css_files_running_module_displayed());
     if ($css_cache_config->is_enabled()) {
         $html_code = '<link rel="stylesheet" href="' . CSSCacheManager::get_css_path($css_files) . '" type="text/css" media="screen, print" />';
     } else {
         $html_code = '';
         foreach ($css_files as $file) {
             $html_code .= '<link rel="stylesheet" href="' . Url::to_rel($file) . '" type="text/css" media="screen, print" />';
         }
     }
     return $html_code;
 }