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.naming.core;
  
  import com.alibaba.nacos.naming.core.v2.pojo.Service;
  import com.alibaba.nacos.naming.pojo.Subscriber;
  import com.alibaba.nacos.naming.push.NamingSubscriberServiceAggregationImpl;
  import com.alibaba.nacos.naming.push.NamingSubscriberServiceLocalImpl;
  import org.apache.commons.collections.CollectionUtils;
  import org.springframework.beans.factory.annotation.Autowired;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.function.Function;
  import java.util.function.Predicate;
  import java.util.stream.Collectors;
  
  /**
   * Subscribe manager.
   *
   * @author Nicholas
   * @author xiweng.yy
   * @since 1.0.1
   */
  @org.springframework.stereotype.Service
  public class SubscribeManager {
      
      @Autowired
      private NamingSubscriberServiceLocalImpl localService;
      
      @Autowired
      private NamingSubscriberServiceAggregationImpl aggregationService;
      
      /**
       * Get subscribers.
       *
       * @param serviceName service name
       * @param namespaceId namespace id
       * @param aggregation aggregation
       * @return list of subscriber
       */
      public List<Subscriber> getSubscribers(String serviceName, String namespaceId, boolean aggregation) {
          if (aggregation) {
              Collection<Subscriber> result = aggregationService.getFuzzySubscribers(namespaceId, serviceName);
              return CollectionUtils.isNotEmpty(result) ? result.stream().filter(distinctByKey(Subscriber::toString))
                      .collect(Collectors.toList()) : Collections.emptyList();
          } else {
              return new LinkedList<>(localService.getFuzzySubscribers(namespaceId, serviceName));
          }
      }
      
      /**
       * Get subscribers.
       *
       * @param service service info
       * @param aggregation aggregation
       * @return list of subscriber
       */
      public List<Subscriber> getSubscribers(Service service, boolean aggregation) {
          if (aggregation) {
              Collection<Subscriber> result = aggregationService.getSubscribers(service);
              return CollectionUtils.isNotEmpty(result) ? result.stream().filter(distinctByKey(Subscriber::toString))
                      .collect(Collectors.toList()) : Collections.emptyList();
          } else {
              return new LinkedList<>(localService.getSubscribers(service));
          }
      }
      
      public static <T> Predicate<T> distinctByKey(Function<? super T, Object> keyExtractor) {
          Map<Object, Boolean> seen = new ConcurrentHashMap<>(128);
          return object -> seen.putIfAbsent(keyExtractor.apply(object), Boolean.TRUE) == null;
      }
  }
  