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.image;
  
  import org.apache.kafka.common.metadata.FeatureLevelRecord;
  import org.apache.kafka.image.node.FeaturesImageNode;
  import org.apache.kafka.image.writer.ImageWriter;
  import org.apache.kafka.image.writer.ImageWriterOptions;
  import org.apache.kafka.server.common.EligibleLeaderReplicasVersion;
  import org.apache.kafka.server.common.MetadataVersion;
  
  import java.util.Collections;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Objects;
  import java.util.Optional;
  
  
  /**
   * Represents the feature levels in the metadata image.
   *
   * This class is thread-safe.
   */
  public final class FeaturesImage {
      public static final FeaturesImage EMPTY = new FeaturesImage(
          Map.of(),
          Optional.empty()
      );
  
      private final Map<String, Short> finalizedVersions;
  
      private final Optional<MetadataVersion> metadataVersion;
  
      public FeaturesImage(
              Map<String, Short> finalizedVersions,
              MetadataVersion metadataVersion) {
          this(finalizedVersions, Optional.of(metadataVersion));
      }
  
      FeaturesImage(
              Map<String, Short> finalizedVersions,
              Optional<MetadataVersion> metadataVersion) {
          this.finalizedVersions = Collections.unmodifiableMap(finalizedVersions);
          this.metadataVersion = metadataVersion;
      }
  
      public boolean isEmpty() {
          return finalizedVersions.isEmpty() && metadataVersion.isEmpty();
      }
  
      public Optional<MetadataVersion> metadataVersion() {
          return metadataVersion;
      }
  
  
      public MetadataVersion metadataVersionOrThrow() {
          return metadataVersion.orElseThrow(() ->
                  new IllegalStateException("Unknown metadata version for FeaturesImage: " + this));
      }
  
      public Map<String, Short> finalizedVersions() {
          return finalizedVersions;
      }
  
      public boolean isElrEnabled() {
          return finalizedVersions.getOrDefault(EligibleLeaderReplicasVersion.FEATURE_NAME, EligibleLeaderReplicasVersion.ELRV_0.featureLevel())
              >= EligibleLeaderReplicasVersion.ELRV_1.featureLevel();
      }
  
      public void write(ImageWriter writer, ImageWriterOptions options) {
          writeFeatureLevels(writer, options);
      }
  
      private void writeFeatureLevels(ImageWriter writer, ImageWriterOptions options) {
          // It is important to write out the metadata.version record first, because it may have an
          // impact on how we decode records that come after it.
          //
          // Note: it's important that this initial FeatureLevelRecord be written with version 0 and
          // not any later version, so that any modern reader can process it.
          writer.write(0, new FeatureLevelRecord().
                  setName(MetadataVersion.FEATURE_NAME).
                  setFeatureLevel(options.metadataVersion().featureLevel()));
  
          // Write out the metadata versions for other features.
          for (Entry<String, Short> entry : finalizedVersions.entrySet()) {
              if (!entry.getKey().equals(MetadataVersion.FEATURE_NAME)) {
                  writer.write(0, new FeatureLevelRecord().
                          setName(entry.getKey()).
                          setFeatureLevel(entry.getValue()));
              }
          }
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(finalizedVersions, metadataVersion);
      }
  
      @Override
      public boolean equals(Object o) {
          if (!(o instanceof FeaturesImage other)) return false;
          return finalizedVersions.equals(other.finalizedVersions) &&
              metadataVersion.equals(other.metadataVersion);
      }
  
      @Override
      public String toString() {
          return new FeaturesImageNode(this).stringify();
      }
  }
  