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.controller;
  
  import org.apache.kafka.metadata.PartitionRegistration;
  import org.apache.kafka.metadata.Replicas;
  import org.apache.kafka.metadata.placement.PartitionAssignment;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.Set;
  import java.util.TreeSet;
  
  
  class PartitionReassignmentReplicas {
      private final List<Integer> removing;
      private final List<Integer> adding;
      private final List<Integer> replicas;
  
      public PartitionReassignmentReplicas(
          List<Integer> removing,
          List<Integer> adding,
          List<Integer> replicas
      ) {
          this.removing = removing;
          this.adding = adding;
          this.replicas = replicas;
      }
  
      private static Set<Integer> calculateDifference(List<Integer> a, List<Integer> b) {
          Set<Integer> result = new TreeSet<>(a);
          result.removeAll(b);
          return result;
      }
  
      PartitionReassignmentReplicas(
          PartitionAssignment currentAssignment,
          PartitionAssignment targetAssignment
      ) {
          Set<Integer> removing = calculateDifference(currentAssignment.replicas(), targetAssignment.replicas());
          this.removing = new ArrayList<>(removing);
          Set<Integer> adding = calculateDifference(targetAssignment.replicas(), currentAssignment.replicas());
          this.adding = new ArrayList<>(adding);
          this.replicas = new ArrayList<>(targetAssignment.replicas());
          this.replicas.addAll(removing);
      }
  
      List<Integer> removing() {
          return removing;
      }
  
      List<Integer> adding() {
          return adding;
      }
  
      List<Integer> replicas() {
          return replicas;
      }
  
      boolean isReassignmentInProgress() {
          return isReassignmentInProgress(
              removing,
              adding);
      }
  
      static boolean isReassignmentInProgress(PartitionRegistration part) {
          return isReassignmentInProgress(
              Replicas.toList(part.removingReplicas),
              Replicas.toList(part.addingReplicas));
      }
  
      private static boolean isReassignmentInProgress(
          List<Integer> removingReplicas,
          List<Integer> addingReplicas
      ) {
          return !removingReplicas.isEmpty() || !addingReplicas.isEmpty();
      }
  
  
      Optional<CompletedReassignment> maybeCompleteReassignment(List<Integer> targetIsr) {
          // Check if there is a reassignment to complete.
          if (!isReassignmentInProgress()) {
              return Optional.empty();
          }
  
          List<Integer> newTargetIsr = new ArrayList<>(targetIsr);
          List<Integer> newTargetReplicas = replicas;
          if (!removing.isEmpty()) {
              newTargetIsr = new ArrayList<>(targetIsr.size());
              for (int replica : targetIsr) {
                  if (!removing.contains(replica)) {
                      newTargetIsr.add(replica);
                  }
              }
              if (newTargetIsr.isEmpty()) return Optional.empty();
  
              newTargetReplicas = new ArrayList<>(replicas.size());
              for (int replica : replicas) {
                  if (!removing.contains(replica)) {
                      newTargetReplicas.add(replica);
                  }
              }
              if (newTargetReplicas.isEmpty()) return Optional.empty();
          }
          if (!newTargetIsr.containsAll(newTargetReplicas)) return Optional.empty();
  
          return Optional.of(
              new CompletedReassignment(
                  newTargetReplicas,
                  newTargetIsr
              )
          );
      }
  
      static class CompletedReassignment {
          final List<Integer> replicas;
          final List<Integer> isr;
  
          public CompletedReassignment(List<Integer> replicas, List<Integer> isr) {
              this.replicas = replicas;
              this.isr = isr;
          }
      }
  
      List<Integer> originalReplicas() {
          List<Integer> replicas = new ArrayList<>(this.replicas);
          replicas.removeAll(adding);
          return replicas;
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(removing, adding, replicas);
      }
  
      @Override
      public boolean equals(Object o) {
          if (!(o instanceof PartitionReassignmentReplicas other)) return false;
          return removing.equals(other.removing) &&
              adding.equals(other.adding) &&
              replicas.equals(other.replicas);
      }
  
      @Override
      public String toString() {
          return "PartitionReassignmentReplicas(" +
              "removing=" + removing + ", " +
              "adding=" + adding + ", " +
              "replicas=" + replicas + ")";
      }
  }
  