content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.kafka.metadata;
  
  import org.apache.kafka.common.Cluster;
  import org.apache.kafka.common.Node;
  import org.apache.kafka.common.PartitionInfo;
  import org.apache.kafka.common.TopicPartition;
  import org.apache.kafka.common.Uuid;
  import org.apache.kafka.common.internals.Topic;
  import org.apache.kafka.common.message.DescribeClientQuotasRequestData;
  import org.apache.kafka.common.message.DescribeClientQuotasResponseData;
  import org.apache.kafka.common.message.DescribeTopicPartitionsResponseData;
  import org.apache.kafka.common.message.DescribeUserScramCredentialsRequestData;
  import org.apache.kafka.common.message.DescribeUserScramCredentialsResponseData;
  import org.apache.kafka.common.message.MetadataResponseData;
  import org.apache.kafka.common.network.ListenerName;
  import org.apache.kafka.image.MetadataImage;
  import org.apache.kafka.server.common.FinalizedFeatures;
  import org.apache.kafka.server.common.MetadataVersion;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Set;
  import java.util.concurrent.ThreadLocalRandom;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  
  public interface MetadataCache extends ConfigRepository {
  
      /**
       * Return topic metadata for a given set of topics and listener. See KafkaApis#handleTopicMetadataRequest for details
       * on the use of the two boolean flags.
       *
       * @param topics                      The set of topics.
       * @param listenerName                The listener name.
       * @param errorUnavailableEndpoints   If true, we return an error on unavailable brokers. This is used to support
       *                                    MetadataResponse version 0.
       * @param errorUnavailableListeners   If true, return LEADER_NOT_AVAILABLE if the listener is not found on the leader.
       *                                    This is used for MetadataResponse versions 0-5.
       * @return                            A collection of topic metadata.
       */
      List<MetadataResponseData.MetadataResponseTopic> getTopicMetadata(
          Set<String> topics,
          ListenerName listenerName,
          boolean errorUnavailableEndpoints,
          boolean errorUnavailableListeners);
  
      Set<String> getAllTopics();
  
      boolean hasAliveBroker(int brokerId);
  
      Optional<Long> getAliveBrokerEpoch(int brokerId);
  
      boolean isBrokerFenced(int brokerId);
  
      boolean isBrokerShuttingDown(int brokerId);
  
      Uuid getTopicId(String topicName);
  
      Optional<String> getTopicName(Uuid topicId);
  
      Optional<Node> getAliveBrokerNode(int brokerId, ListenerName listenerName);
  
      List<Node> getAliveBrokerNodes(ListenerName listenerName);
  
      List<Node> getBrokerNodes(ListenerName listenerName);
  
      Optional<LeaderAndIsr> getLeaderAndIsr(String topic, int partitionId);
  
      /**
       * Return the number of partitions in the given topic, or None if the given topic does not exist.
       */
      Optional<Integer> numPartitions(String topic);
  
      Map<Uuid, String> topicIdsToNames();
  
      Map<String, Uuid> topicNamesToIds();
  
      /**
       * Get a partition leader's endpoint
       *
       * @return  If the leader is known, and the listener name is available, return Some(node). If the leader is known,
       *          but the listener is unavailable, return Some(Node.NO_NODE). Otherwise, if the leader is not known,
       *          return None
       */
      Optional<Node> getPartitionLeaderEndpoint(String topic, int partitionId, ListenerName listenerName);
  
      Map<Integer, Node> getPartitionReplicaEndpoints(TopicPartition tp, ListenerName listenerName);
  
      boolean contains(String topic);
  
      boolean contains(TopicPartition tp);
  
      MetadataVersion metadataVersion();
  
      Optional<Integer> getRandomAliveBrokerId();
  
      FinalizedFeatures features();
  
      DescribeClientQuotasResponseData describeClientQuotas(DescribeClientQuotasRequestData request);
  
      DescribeUserScramCredentialsResponseData describeScramCredentials(DescribeUserScramCredentialsRequestData request);
  
      /**
       * Get the topic metadata for the given topics.
       *
       * The quota is used to limit the number of partitions to return. The NextTopicPartition field points to the first
       * partition can't be returned due the limit.
       * If a topic can't return any partition due to quota limit reached, this topic will not be included in the response.
       *
       * Note, the topics should be sorted in alphabetical order. The topics in the DescribeTopicPartitionsResponseData
       * will also be sorted in alphabetical order.
       *
       * @param topics                        The iterator of topics and their corresponding first partition id to fetch.
       * @param listenerName                  The listener name.
       * @param topicPartitionStartIndex      The start partition index for the first topic
       * @param maximumNumberOfPartitions     The max number of partitions to return.
       * @param ignoreTopicsWithExceptions    Whether ignore the topics with exception.
       */
      DescribeTopicPartitionsResponseData describeTopicResponse(
          Iterator<String> topics,
          ListenerName listenerName,
          Function<String, Integer> topicPartitionStartIndex,
          int maximumNumberOfPartitions,
          boolean ignoreTopicsWithExceptions);
  
      static Cluster toCluster(String clusterId, MetadataImage image) {
          Map<Integer, List<Node>> brokerToNodes = new HashMap<>();
          image.cluster().brokers().values().stream()
              .filter(broker -> !broker.fenced())
              .forEach(broker -> brokerToNodes.put(broker.id(), broker.nodes()));
  
          List<PartitionInfo> partitionInfos = new ArrayList<>();
          Set<String> internalTopics = new HashSet<>();
  
          image.topics().topicsByName().values().forEach(topic -> {
              topic.partitions().forEach((partitionId, partition) -> {
                  List<Node> nodes = brokerToNodes.get(partition.leader);
                  if (nodes != null) {
                      nodes.forEach(node -> {
                          partitionInfos.add(new PartitionInfo(
                              topic.name(),
                              partitionId,
                              node,
                              toArray(partition.replicas, brokerToNodes),
                              toArray(partition.isr, brokerToNodes),
                              getOfflineReplicas(image, partition).stream()
                                  .map(brokerToNodes::get)
                                  .flatMap(Collection::stream)
                                  .toArray(Node[]::new)
                          ));
                      });
                      if (Topic.isInternal(topic.name())) {
                          internalTopics.add(topic.name());
                      }
                  }
              });
          });
  
          Node controllerNode = Optional.ofNullable(brokerToNodes.get(getRandomAliveBroker(image).orElse(-1)))
              .map(nodes -> nodes.get(0))
              .orElse(Node.noNode());
  
          return new Cluster(
              clusterId,
              brokerToNodes.values().stream().flatMap(Collection::stream).collect(Collectors.toList()),
              partitionInfos,
              Collections.emptySet(),
              internalTopics,
              controllerNode
          );
      }
  
      private static Node[] toArray(int[] replicas, Map<Integer, List<Node>> brokerToNodes) {
          return Arrays.stream(replicas)
              .mapToObj(brokerToNodes::get)
              .flatMap(Collection::stream)
              .toArray(Node[]::new);
      }
  
      private static List<Integer> getOfflineReplicas(MetadataImage image, PartitionRegistration partition) {
          List<Integer> offlineReplicas = new ArrayList<>();
          for (int brokerId : partition.replicas) {
              BrokerRegistration broker = image.cluster().broker(brokerId);
              if (broker == null || isReplicaOffline(partition, broker)) {
                  offlineReplicas.add(brokerId);
              }
          }
          return offlineReplicas;
      }
  
      private static boolean isReplicaOffline(PartitionRegistration partition, BrokerRegistration broker) {
          return broker.fenced() || !broker.hasOnlineDir(partition.directory(broker.id()));
      }
  
      private static Optional<Integer> getRandomAliveBroker(MetadataImage image) {
          List<Integer> aliveBrokers = image.cluster().brokers().values().stream()
              .filter(broker -> !broker.fenced())
              .map(BrokerRegistration::id)
              .toList();
          if (aliveBrokers.isEmpty()) return Optional.empty();
          return Optional.of(aliveBrokers.get(ThreadLocalRandom.current().nextInt(aliveBrokers.size())));
      }
  }