content: /*
   * Copyright 1999-2023 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.nacos.core.remote.tls;
  
  import com.alibaba.nacos.common.spi.NacosServiceLoader;
  import com.alibaba.nacos.common.utils.StringUtils;
  import com.alibaba.nacos.core.utils.Loggers;
  import com.alibaba.nacos.sys.env.EnvUtil;
  
  import java.util.Collection;
  import java.util.Properties;
  
  /**
   * Holder for managing instances of {@link RpcServerSslContextRefresher}. This class is responsible for initializing and
   * providing instances of the SSL context refresher based on the communication type (SDK or Cluster).
   *
   * @author liuzunfei
   * @version $Id: RpcServerSslContextRefresherHolder.java, v 0.1 2023年03月17日 12:00 PM liuzunfei Exp $
   */
  public class RpcServerSslContextRefresherHolder {
  
      /**
       * The instance of {@link RpcServerSslContextRefresher} for SDK communication.
       */
      private static RpcServerSslContextRefresher sdkInstance;
  
      /**
       * The instance of {@link RpcServerSslContextRefresher} for Cluster communication.
       */
      private static RpcServerSslContextRefresher clusterInstance;
  
      static {
          init();
      }
  
      /**
       * Gets the instance of {@link RpcServerSslContextRefresher} for SDK communication.
       *
       * @return The instance of {@link RpcServerSslContextRefresher} for SDK communication.
       */
      public static RpcServerSslContextRefresher getSdkInstance() {
          return sdkInstance;
      }
  
      /**
       * Gets the instance of {@link RpcServerSslContextRefresher} for Cluster communication.
       *
       * @return The instance of {@link RpcServerSslContextRefresher} for Cluster communication.
       */
      public static RpcServerSslContextRefresher getClusterInstance() {
          return clusterInstance;
      }
  
      /**
       * Initializes the holder by loading SSL context refreshers and matching them with the configured types (SDK and
       * Cluster).
       */
      private static void init() {
          synchronized (RpcServerSslContextRefresherHolder.class) {
              Properties properties = EnvUtil.getProperties();
              RpcServerTlsConfig clusterServerTlsConfig = RpcServerTlsConfigFactory.getInstance().createClusterConfig(properties);
              RpcServerTlsConfig sdkServerTlsConfig = RpcServerTlsConfigFactory.getInstance().createSdkConfig(properties);
              Collection<RpcServerSslContextRefresher> refreshers = NacosServiceLoader.load(
                      RpcServerSslContextRefresher.class);
              sdkInstance = getSslContextRefresher(refreshers, sdkServerTlsConfig);
              clusterInstance = getSslContextRefresher(refreshers, clusterServerTlsConfig);
              Loggers.REMOTE.info("RpcServerSslContextRefresher initialization completed.");
          }
      }
  
      /**
       * Initializes the SSL context refresher instance based on the specified configuration.
       *
       * @param refreshers        Collection of SSL context refreshers to choose from.
       * @param serverTlsConfig   Configuration instance for the SSL context refresher.
       * @return The instance of {@link RpcServerSslContextRefresher}.
       */
      private static RpcServerSslContextRefresher getSslContextRefresher(
              Collection<RpcServerSslContextRefresher> refreshers, RpcServerTlsConfig serverTlsConfig) {
          String refresherName = serverTlsConfig.getSslContextRefresher();
          RpcServerSslContextRefresher instance = null;
          if (StringUtils.isNotBlank(refresherName)) {
              for (RpcServerSslContextRefresher contextRefresher : refreshers) {
                  if (refresherName.equals(contextRefresher.getName())) {
                      instance = contextRefresher;
                      Loggers.REMOTE.info("RpcServerSslContextRefresher initialized using {}.",
                              contextRefresher.getClass().getSimpleName());
                      break;
                  }
              }
              if (instance == null) {
                  Loggers.REMOTE.warn("Failed to find RpcServerSslContextRefresher with name {}.", refresherName);
              }
          } else {
              Loggers.REMOTE.info("Ssl Context auto refresh is not supported.");
          }
          return instance;
      }
  }
  