/*
 * Copyright 2012 LinkedIn, Inc
 *
 * Licensed 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 com.linkedin.parseq.promise;

import java.util.concurrent.atomic.AtomicInteger;


/**
 * Sets a value on a {@link SettablePromise} after this listener has been
 * notified of a specified number of promise resolutions.
 * If one of promises has been resolved with failure then {@code SettablePromise}
 * will be resolved immediately with that failure.
 *
 * @author Jaroslaw Odzga (jodzga@linkedin.com)
 */
public class FastFailCountDownPromiseListener<T> implements PromiseListener<T> {
  private final AtomicInteger _counter;
  private final SettablePromise<T> _promise;
  private final T _value;

  public FastFailCountDownPromiseListener(final int count, final SettablePromise<T> promise, final T value) {
    _counter = new AtomicInteger(count);
    _promise = promise;
    _value = value;
  }

  @Override
  public void onResolved(Promise<T> resolvedPromise) {
    if (resolvedPromise.isFailed()) {
      if (!_promise.isDone()) {
        try {
          _promise.fail(resolvedPromise.getError());
        } catch (PromiseResolvedException e) {
          //ignore cases when there are multiple failures
        }
      }
    }
    if (_counter.decrementAndGet() == 0) {
      if (!_promise.isDone()) {
        try {
          _promise.done(_value);
        } catch (PromiseResolvedException e) {
          //ignore cases when there are multiple failures
        }
      }
    }
  }
}