content: /*
   * Copyright 1999-2018 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.client.naming.event;
  
  import com.alibaba.nacos.api.naming.pojo.ServiceInfo;
  import com.alibaba.nacos.api.naming.utils.NamingUtils;
  import com.alibaba.nacos.client.naming.selector.NamingSelectorWrapper;
  import com.alibaba.nacos.client.selector.SelectorManager;
  import com.alibaba.nacos.common.JustForTest;
  import com.alibaba.nacos.common.notify.Event;
  import com.alibaba.nacos.common.notify.listener.Subscriber;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.UUID;
  
  /**
   * A subscriber to notify eventListener callback.
   *
   * @author horizonzy
   * @since 1.4.1
   */
  public class InstancesChangeNotifier extends Subscriber<InstancesChangeEvent> {
      
      private final String eventScope;
      
      private final SelectorManager<NamingSelectorWrapper> selectorManager = new SelectorManager<>();
      
      @JustForTest
      public InstancesChangeNotifier() {
          this.eventScope = UUID.randomUUID().toString();
      }
      
      public InstancesChangeNotifier(String eventScope) {
          this.eventScope = eventScope;
      }
      
      /**
       * register listener.
       *
       * @param groupName   group name
       * @param serviceName serviceName
       * @param wrapper     selectorWrapper
       */
      public void registerListener(String groupName, String serviceName, NamingSelectorWrapper wrapper) {
          if (wrapper == null) {
              return;
          }
          String subId = NamingUtils.getGroupedName(serviceName, groupName);
          selectorManager.addSelectorWrapper(subId, wrapper);
      }
      
      /**
       * deregister listener.
       *
       * @param groupName   group name
       * @param serviceName serviceName
       * @param wrapper     selectorWrapper
       */
      public void deregisterListener(String groupName, String serviceName, NamingSelectorWrapper wrapper) {
          if (wrapper == null) {
              return;
          }
          String subId = NamingUtils.getGroupedName(serviceName, groupName);
          selectorManager.removeSelectorWrapper(subId, wrapper);
      }
      
      /**
       * check serviceName,groupName is subscribed.
       *
       * @param groupName   group name
       * @param serviceName serviceName
       * @return is serviceName,clusters subscribed
       */
      public boolean isSubscribed(String groupName, String serviceName) {
          String subId = NamingUtils.getGroupedName(serviceName, groupName);
          return selectorManager.isSubscribed(subId);
      }
      
      public List<ServiceInfo> getSubscribeServices() {
          List<ServiceInfo> serviceInfos = new ArrayList<>();
          for (String key : selectorManager.getSubscriptions()) {
              serviceInfos.add(ServiceInfo.fromKey(key));
          }
          return serviceInfos;
      }
      
      @Override
      public void onEvent(InstancesChangeEvent event) {
          String subId = NamingUtils.getGroupedName(event.getServiceName(), event.getGroupName());
          Collection<NamingSelectorWrapper> selectorWrappers = selectorManager.getSelectorWrappers(subId);
          for (NamingSelectorWrapper selectorWrapper : selectorWrappers) {
              selectorWrapper.notifyListener(event);
          }
      }
      
      @Override
      public Class<? extends Event> subscribeType() {
          return InstancesChangeEvent.class;
      }
      
      @Override
      public boolean scopeMatches(InstancesChangeEvent event) {
          return this.eventScope.equals(event.scope());
      }
  }
  