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.server.common.KRaftVersion;
  import org.apache.kafka.server.common.MetadataVersion;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Optional;
  
  
  /**
   * Represents changes to the cluster in the metadata image.
   */
  public final class FeaturesDelta {
      private final FeaturesImage image;
  
      private final Map<String, Optional<Short>> changes = new HashMap<>();
  
      private MetadataVersion metadataVersionChange = null;
  
      public FeaturesDelta(FeaturesImage image) {
          this.image = image;
      }
  
      public Map<String, Optional<Short>> changes() {
          return changes;
      }
  
      public Optional<MetadataVersion> metadataVersionChange() {
          return Optional.ofNullable(metadataVersionChange);
      }
  
      public void finishSnapshot() {
          for (String featureName : image.finalizedVersions().keySet()) {
              if (!changes.containsKey(featureName)) {
                  changes.put(featureName, Optional.empty());
              }
          }
      }
  
      public void replay(FeatureLevelRecord record) {
          if (record.name().equals(MetadataVersion.FEATURE_NAME)) {
              try {
                  metadataVersionChange = MetadataVersion.fromFeatureLevel(record.featureLevel());
              } catch (IllegalArgumentException e) {
                  throw new IllegalArgumentException("Unsupported metadata version - if you are currently upgrading your cluster, "
                          + "please ensure the metadata version is set to " + MetadataVersion.MINIMUM_VERSION + " (or higher) before "
                          + "updating the software version. The metadata version can be updated via the `kafka-features` command-line tool.", e);
              }
          } else if (record.name().equals(KRaftVersion.FEATURE_NAME)) {
              // KAFKA-18979 - Skip any feature level record for kraft.version. This has two benefits:
              // 1. It removes from snapshots any FeatureLevelRecord for kraft.version that was incorrectly written to the log
              // 2. Allows ApiVersions to report the correct finalized kraft.version
          } else {
              if (record.featureLevel() == 0) {
                  changes.put(record.name(), Optional.empty());
              } else {
                  changes.put(record.name(), Optional.of(record.featureLevel()));
              }
          }
      }
  
      public FeaturesImage apply() {
          Map<String, Short> newFinalizedVersions =
              new HashMap<>(image.finalizedVersions().size());
          for (Entry<String, Short> entry : image.finalizedVersions().entrySet()) {
              String name = entry.getKey();
              Optional<Short> change = changes.get(name);
              if (change == null) {
                  newFinalizedVersions.put(name, entry.getValue());
              } else if (change.isPresent()) {
                  newFinalizedVersions.put(name, change.get());
              }
          }
          for (Entry<String, Optional<Short>> entry : changes.entrySet()) {
              String name = entry.getKey();
              Optional<Short> change = entry.getValue();
              if (!newFinalizedVersions.containsKey(name)) {
                  if (change.isPresent()) {
                      newFinalizedVersions.put(name, change.get());
                  }
              }
          }
  
          final Optional<MetadataVersion> metadataVersion;
          if (metadataVersionChange == null) {
              metadataVersion = image.metadataVersion();
          } else {
              metadataVersion = Optional.of(metadataVersionChange);
          }
  
          return new FeaturesImage(newFinalizedVersions, metadataVersion);
      }
  
      @Override
      public String toString() {
          return "FeaturesDelta(" +
              "changes=" + changes +
              ", metadataVersionChange=" + metadataVersionChange +
              ')';
      }
  }
  