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.client.naming.cache;
  
  import com.alibaba.nacos.api.naming.pojo.Instance;
  import com.alibaba.nacos.api.naming.pojo.ServiceInfo;
  import com.alibaba.nacos.client.naming.event.InstancesDiff;
  import com.alibaba.nacos.common.utils.JacksonUtils;
  import com.alibaba.nacos.common.utils.StringUtils;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import static com.alibaba.nacos.client.utils.LogUtils.NAMING_LOGGER;
  
  /**
   * The instance list differ for nacos naming.
   *
   * @author xiweng.yy
   */
  public final class InstancesDiffer {
      
      /**
       * Do instance different for input service info.
       *
       * @param oldService old service info
       * @param newService new service info
       * @return {@link InstancesDiff} of the differences between old and new service info.
       */
      public InstancesDiff doDiff(ServiceInfo oldService, ServiceInfo newService) {
          InstancesDiff instancesDiff = new InstancesDiff();
          if (null == oldService) {
              NAMING_LOGGER.info("init new ips({}) service: {} -> {}", newService.ipCount(), newService.getKey(),
                      JacksonUtils.toJson(newService.getHosts()));
              instancesDiff.setAddedInstances(newService.getHosts());
              return instancesDiff;
          }
          if (oldService.getLastRefTime() > newService.getLastRefTime()) {
              NAMING_LOGGER.warn("out of date data received, old-t: {}, new-t: {}", oldService.getLastRefTime(),
                      newService.getLastRefTime());
              return instancesDiff;
          }
          
          Map<String, Instance> oldHostMap = new HashMap<>(oldService.getHosts().size());
          for (Instance host : oldService.getHosts()) {
              oldHostMap.put(host.toInetAddr(), host);
          }
          Map<String, Instance> newHostMap = new HashMap<>(newService.getHosts().size());
          for (Instance host : newService.getHosts()) {
              newHostMap.put(host.toInetAddr(), host);
          }
          
          Set<Instance> modHosts = new HashSet<>();
          Set<Instance> newHosts = new HashSet<>();
          Set<Instance> remvHosts = new HashSet<>();
          
          List<Map.Entry<String, Instance>> newServiceHosts = new ArrayList<>(newHostMap.entrySet());
          for (Map.Entry<String, Instance> entry : newServiceHosts) {
              Instance host = entry.getValue();
              String key = entry.getKey();
              if (oldHostMap.containsKey(key) && !StringUtils.equals(host.toString(), oldHostMap.get(key).toString())) {
                  modHosts.add(host);
                  continue;
              }
              
              if (!oldHostMap.containsKey(key)) {
                  newHosts.add(host);
              }
          }
          
          for (Map.Entry<String, Instance> entry : oldHostMap.entrySet()) {
              Instance host = entry.getValue();
              String key = entry.getKey();
              if (newHostMap.containsKey(key)) {
                  continue;
              }
              
              //add to remove hosts
              remvHosts.add(host);
          }
          
          if (newHosts.size() > 0) {
              NAMING_LOGGER.info("new ips({}) service: {} -> {}", newHosts.size(), newService.getKey(),
                      JacksonUtils.toJson(newHosts));
              instancesDiff.setAddedInstances(newHosts);
          }
          
          if (remvHosts.size() > 0) {
              NAMING_LOGGER.info("removed ips({}) service: {} -> {}", remvHosts.size(), newService.getKey(),
                      JacksonUtils.toJson(remvHosts));
              instancesDiff.setRemovedInstances(remvHosts);
          }
          
          if (modHosts.size() > 0) {
              NAMING_LOGGER.info("modified ips({}) service: {} -> {}", modHosts.size(), newService.getKey(),
                      JacksonUtils.toJson(modHosts));
              instancesDiff.setModifiedInstances(modHosts);
          }
          return instancesDiff;
      }
  }
  