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.selector;
  
  import com.alibaba.nacos.api.naming.pojo.Instance;
  import com.alibaba.nacos.api.naming.selector.NamingSelector;
  import com.alibaba.nacos.common.utils.CollectionUtils;
  import com.alibaba.nacos.common.utils.StringUtils;
  
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import java.util.TreeSet;
  import java.util.function.Predicate;
  import java.util.regex.Pattern;
  
  /**
   * Selectors factory.
   *
   * @author lideyou
   */
  public final class NamingSelectorFactory {
      
      public static final NamingSelector EMPTY_SELECTOR = context -> context::getInstances;
      
      public static final NamingSelector HEALTHY_SELECTOR = new DefaultNamingSelector(Instance::isHealthy);
      
      /**
       * Cluster selector.
       */
      private static class ClusterSelector extends DefaultNamingSelector {
          
          private final String clusterString;
          
          public ClusterSelector(Predicate<Instance> filter, String clusterString) {
              super(filter);
              this.clusterString = clusterString;
          }
          
          @Override
          public boolean equals(Object o) {
              if (this == o) {
                  return true;
              }
              if (o == null || getClass() != o.getClass()) {
                  return false;
              }
              ClusterSelector that = (ClusterSelector) o;
              return Objects.equals(this.clusterString, that.clusterString);
          }
          
          @Override
          public int hashCode() {
              return Objects.hashCode(this.clusterString);
          }
      }
      
      private NamingSelectorFactory() {
      }
      
      /**
       * Create a cluster selector.
       *
       * @param clusters target cluster
       * @return cluster selector
       */
      public static NamingSelector newClusterSelector(Collection<String> clusters) {
          if (CollectionUtils.isNotEmpty(clusters)) {
              final Set<String> set = new HashSet<>(clusters);
              Predicate<Instance> filter = instance -> set.contains(instance.getClusterName());
              String clusterString = getUniqueClusterString(clusters);
              return new ClusterSelector(filter, clusterString);
          } else {
              return EMPTY_SELECTOR;
          }
      }
      
      /**
       * Create a IP selector.
       *
       * @param regex regular expression of IP
       * @return IP selector
       */
      public static NamingSelector newIpSelector(String regex) {
          if (regex == null) {
              throw new IllegalArgumentException("The parameter 'regex' cannot be null.");
          }
          return new DefaultNamingSelector(instance -> Pattern.matches(regex, instance.getIp()));
      }
      
      /**
       * Create a metadata selector.
       *
       * @param metadata metadata that needs to be matched
       * @return metadata selector
       */
      public static NamingSelector newMetadataSelector(Map<String, String> metadata) {
          return newMetadataSelector(metadata, false);
      }
      
      /**
       * Create a metadata selector.
       *
       * @param metadata target metadata
       * @param isAny    true if any of the metadata needs to be matched, false if all the metadata need to be matched.
       * @return metadata selector
       */
      public static NamingSelector newMetadataSelector(Map<String, String> metadata, boolean isAny) {
          if (metadata == null) {
              throw new IllegalArgumentException("The parameter 'metadata' cannot be null.");
          }
          
          Predicate<Instance> filter = instance -> instance.getMetadata().size() >= metadata.size();
          
          for (Map.Entry<String, String> entry : metadata.entrySet()) {
              Predicate<Instance> nextFilter = instance -> {
                  Map<String, String> map = instance.getMetadata();
                  return Objects.equals(map.get(entry.getKey()), entry.getValue());
              };
              if (isAny) {
                  filter = filter.or(nextFilter);
              } else {
                  filter = filter.and(nextFilter);
              }
          }
          return new DefaultNamingSelector(filter);
      }
      
      public static String getUniqueClusterString(Collection<String> cluster) {
          TreeSet<String> treeSet = new TreeSet<>(cluster);
          return StringUtils.join(treeSet, ",");
      }
      
  }
  