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.common.requests;
  
  import org.apache.kafka.common.errors.UnsupportedVersionException;
  import org.apache.kafka.common.message.OffsetFetchResponseData;
  import org.apache.kafka.common.message.OffsetFetchResponseData.OffsetFetchResponseGroup;
  import org.apache.kafka.common.message.OffsetFetchResponseData.OffsetFetchResponsePartition;
  import org.apache.kafka.common.message.OffsetFetchResponseData.OffsetFetchResponseTopic;
  import org.apache.kafka.common.protocol.ApiKeys;
  import org.apache.kafka.common.protocol.Errors;
  import org.apache.kafka.common.protocol.Readable;
  
  import java.util.Arrays;
  import java.util.EnumMap;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  
  import static org.apache.kafka.common.record.RecordBatch.NO_PARTITION_LEADER_EPOCH;
  import static org.apache.kafka.common.requests.OffsetFetchRequest.BATCH_MIN_VERSION;
  import static org.apache.kafka.common.requests.OffsetFetchRequest.TOP_LEVEL_ERROR_AND_NULL_TOPICS_MIN_VERSION;
  
  /**
   * Possible error codes:
   *
   * - Partition errors:
   *   - {@link Errors#UNKNOWN_TOPIC_OR_PARTITION}
   *   - {@link Errors#TOPIC_AUTHORIZATION_FAILED}
   *   - {@link Errors#UNSTABLE_OFFSET_COMMIT}
   *
   * - Group or coordinator errors:
   *   - {@link Errors#COORDINATOR_LOAD_IN_PROGRESS}
   *   - {@link Errors#COORDINATOR_NOT_AVAILABLE}
   *   - {@link Errors#NOT_COORDINATOR}
   *   - {@link Errors#GROUP_AUTHORIZATION_FAILED}
   *   - {@link Errors#UNKNOWN_MEMBER_ID}
   *   - {@link Errors#STALE_MEMBER_EPOCH}
   */
  public class OffsetFetchResponse extends AbstractResponse {
      public static final long INVALID_OFFSET = -1L;
      public static final String NO_METADATA = "";
  
      // We only need to track the partition errors returned in version 1. This
      // is used to identify group level errors when the response is normalized.
      private static final List<Errors> PARTITION_ERRORS = Arrays.asList(
          Errors.UNKNOWN_TOPIC_OR_PARTITION,
          Errors.TOPIC_AUTHORIZATION_FAILED
      );
  
      private final short version;
      private final OffsetFetchResponseData data;
      // Lazily initialized when OffsetFetchResponse#group is called.
      private Map<String, OffsetFetchResponseData.OffsetFetchResponseGroup> groups = null;
  
      public static class Builder {
          private final List<OffsetFetchResponseGroup> groups;
  
          public Builder(OffsetFetchResponseGroup group) {
              this(List.of(group));
          }
  
          public Builder(List<OffsetFetchResponseGroup> groups) {
              this.groups = groups;
          }
  
          public OffsetFetchResponse build(short version) {
              var data = new OffsetFetchResponseData();
  
              if (version >= BATCH_MIN_VERSION) {
                  data.setGroups(groups);
              } else {
                  if (groups.size() != 1) {
                      throw new UnsupportedVersionException(
                          "Version " + version + " of OffsetFetchResponse only supports one group."
                      );
                  }
  
                  OffsetFetchResponseGroup group = groups.get(0);
                  data.setErrorCode(group.errorCode());
  
                  group.topics().forEach(topic -> {
                      OffsetFetchResponseTopic newTopic = new OffsetFetchResponseTopic().setName(topic.name());
                      data.topics().add(newTopic);
  
                      topic.partitions().forEach(partition -> {
                          OffsetFetchResponsePartition newPartition;
  
                          if (version < TOP_LEVEL_ERROR_AND_NULL_TOPICS_MIN_VERSION && group.errorCode() != Errors.NONE.code()) {
                              // Versions prior to version 2 do not support a top level error. Therefore,
                              // we put it at the partition level.
                              newPartition = new OffsetFetchResponsePartition()
                                  .setPartitionIndex(partition.partitionIndex())
                                  .setErrorCode(group.errorCode())
                                  .setCommittedOffset(INVALID_OFFSET)
                                  .setMetadata(NO_METADATA)
                                  .setCommittedLeaderEpoch(NO_PARTITION_LEADER_EPOCH);
                          } else {
                              newPartition = new OffsetFetchResponsePartition()
                                  .setPartitionIndex(partition.partitionIndex())
                                  .setErrorCode(partition.errorCode())
                                  .setCommittedOffset(partition.committedOffset())
                                  .setMetadata(partition.metadata())
                                  .setCommittedLeaderEpoch(partition.committedLeaderEpoch());
                          }
  
                          newTopic.partitions().add(newPartition);
                      });
                  });
              }
  
              return new OffsetFetchResponse(data, version);
          }
      }
  
      public OffsetFetchResponse(OffsetFetchResponseData data, short version) {
          super(ApiKeys.OFFSET_FETCH);
          this.data = data;
          this.version = version;
      }
  
      public OffsetFetchResponseData.OffsetFetchResponseGroup group(String groupId) {
          if (version < BATCH_MIN_VERSION) {
              // for version 2 and later use the top-level error code from the response.
              // for older versions there is no top-level error in the response and all errors are partition errors,
              // so if there is a group or coordinator error at the partition level use that as the top-level error.
              // this way clients can depend on the top-level error regardless of the offset fetch version.
              // we return the error differently starting with version 8, so we will only populate the
              // error field if we are between version 2 and 7. if we are in version 8 or greater, then
              // we will populate the map of group id to error codes.
              short topLevelError = version < TOP_LEVEL_ERROR_AND_NULL_TOPICS_MIN_VERSION ? topLevelError(data).code() : data.errorCode();
              if (topLevelError != Errors.NONE.code()) {
                  return new OffsetFetchResponseGroup()
                      .setGroupId(groupId)
                      .setErrorCode(topLevelError);
              } else {
                  return new OffsetFetchResponseGroup()
                      .setGroupId(groupId)
                      .setTopics(data.topics().stream().map(topic ->
                          new OffsetFetchResponseData.OffsetFetchResponseTopics()
                              .setName(topic.name())
                              .setPartitions(topic.partitions().stream().map(partition ->
                                  new OffsetFetchResponseData.OffsetFetchResponsePartitions()
                                      .setPartitionIndex(partition.partitionIndex())
                                      .setErrorCode(partition.errorCode())
                                      .setCommittedOffset(partition.committedOffset())
                                      .setMetadata(partition.metadata())
                                      .setCommittedLeaderEpoch(partition.committedLeaderEpoch())
                              ).collect(Collectors.toList()))
                      ).collect(Collectors.toList()));
              }
          } else {
              if (groups == null) {
                  groups = data.groups().stream().collect(Collectors.toMap(
                      OffsetFetchResponseData.OffsetFetchResponseGroup::groupId,
                      Function.identity()
                  ));
              }
              var group = groups.get(groupId);
              if (group == null) {
                  throw new IllegalArgumentException("Group " + groupId + " not found in the response");
              }
              return group;
          }
      }
  
      private static Errors topLevelError(OffsetFetchResponseData data) {
          for (OffsetFetchResponseTopic topic : data.topics()) {
              for (OffsetFetchResponsePartition partition : topic.partitions()) {
                  Errors partitionError = Errors.forCode(partition.errorCode());
                  if (partitionError != Errors.NONE && !PARTITION_ERRORS.contains(partitionError)) {
                      return partitionError;
                  }
              }
          }
          return Errors.NONE;
      }
  
      @Override
      public int throttleTimeMs() {
          return data.throttleTimeMs();
      }
  
      @Override
      public void maybeSetThrottleTimeMs(int throttleTimeMs) {
          data.setThrottleTimeMs(throttleTimeMs);
      }
  
      @Override
      public Map<Errors, Integer> errorCounts() {
          Map<Errors, Integer> counts = new EnumMap<>(Errors.class);
          if (version < BATCH_MIN_VERSION) {
              if (version >= TOP_LEVEL_ERROR_AND_NULL_TOPICS_MIN_VERSION) {
                  updateErrorCounts(counts, Errors.forCode(data.errorCode()));
              }
              data.topics().forEach(topic ->
                  topic.partitions().forEach(partition ->
                      updateErrorCounts(counts, Errors.forCode(partition.errorCode()))
                  )
              );
          } else {
              data.groups().forEach(group -> {
                  updateErrorCounts(counts, Errors.forCode(group.errorCode()));
                  group.topics().forEach(topic ->
                      topic.partitions().forEach(partition ->
                          updateErrorCounts(counts, Errors.forCode(partition.errorCode()))
                      )
                  );
              });
          }
          return counts;
      }
  
      public static OffsetFetchResponse parse(Readable readable, short version) {
          return new OffsetFetchResponse(new OffsetFetchResponseData(readable, version), version);
      }
  
      @Override
      public OffsetFetchResponseData data() {
          return data;
      }
  
      @Override
      public boolean shouldClientThrottle(short version) {
          return version >= 4;
      }
  }
  