/*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project 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 io.netty.util.concurrent;
  
  import io.netty.util.internal.ObjectUtil;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  public final class UnaryPromiseNotifier<T> implements FutureListener<T> {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(UnaryPromiseNotifier.class);
      private final Promise<? super T> promise;
  
      public UnaryPromiseNotifier(Promise<? super T> promise) {
          this.promise = ObjectUtil.checkNotNull(promise, "promise");
      }
  
      @Override
      public void operationComplete(Future<T> future) throws Exception {
          cascadeTo(future, promise);
      }
  
      public static <X> void cascadeTo(Future<X> completedFuture, Promise<? super X> promise) {
          if (completedFuture.isSuccess()) {
              if (!promise.trySuccess(completedFuture.getNow())) {
                  logger.warn("Failed to mark a promise as success because it is done already: {}", promise);
              }
          } else if (completedFuture.isCancelled()) {
              if (!promise.cancel(false)) {
                  logger.warn("Failed to cancel a promise because it is done already: {}", promise);
              }
          } else {
              if (!promise.tryFailure(completedFuture.cause())) {
                  logger.warn("Failed to mark a promise as failure because it's done already: {}", promise,
                              completedFuture.cause());
              }
          }
      }
  }