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.streams.processor.internals;
  
  import org.apache.kafka.streams.processor.TaskId;
  
  import java.util.Objects;
  import java.util.concurrent.CompletableFuture;
  
  public class TaskAndAction {
  
      public enum Action {
          ADD,
          REMOVE
      }
  
      private final Task task;
      private final TaskId taskId;
      private final Action action;
      private final CompletableFuture<StateUpdater.RemovedTaskResult> futureForRemove;
  
      private TaskAndAction(final Task task,
                            final TaskId taskId,
                            final Action action,
                            final CompletableFuture<StateUpdater.RemovedTaskResult> futureForRemove) {
          this.task = task;
          this.taskId = taskId;
          this.action = action;
          this.futureForRemove = futureForRemove;
      }
  
      public static TaskAndAction createAddTask(final Task task) {
          Objects.requireNonNull(task, "Task to add is null!");
          return new TaskAndAction(task, null, Action.ADD, null);
      }
  
      public static TaskAndAction createRemoveTask(final TaskId taskId,
                                                   final CompletableFuture<StateUpdater.RemovedTaskResult> future) {
          Objects.requireNonNull(taskId, "Task ID of task to remove is null!");
          Objects.requireNonNull(future, "Future for task to remove is null!");
          return new TaskAndAction(null, taskId, Action.REMOVE, future);
      }
  
      public static TaskAndAction createRemoveTask(final TaskId taskId) {
          Objects.requireNonNull(taskId, "Task ID of task to remove is null!");
          return new TaskAndAction(null, taskId, Action.REMOVE, null);
      }
  
      public Task task() {
          if (action != Action.ADD) {
              throw new IllegalStateException("Action type " + action + " cannot have a task!");
          }
          return task;
      }
  
      public TaskId taskId() {
          if (action != Action.REMOVE) {
              throw new IllegalStateException("Action type " + action + " cannot have a task ID!");
          }
          return taskId;
      }
  
      public CompletableFuture<StateUpdater.RemovedTaskResult> futureForRemove() {
          if (action != Action.REMOVE) {
              throw new IllegalStateException("Action type " + action + " cannot have a future with a single result!");
          }
          return futureForRemove;
      }
  
      public Action action() {
          return action;
      }
  }