package org.apache.blur.utils;

/**
 * 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.
 */
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.blur.thrift.BException;
import org.apache.blur.thrift.generated.BlurException;


public class BlurExecutorCompletionService<T> extends ExecutorCompletionService<T> {

  private AtomicInteger count = new AtomicInteger(0);
  private Collection<Future<T>> _bag;
  private Cancel _cancel;

  public interface Cancel {
    void cancel();
  }

  public BlurExecutorCompletionService(Executor executor, Cancel cancel) {
    super(executor);
    _bag = Collections.synchronizedCollection(new HashSet<Future<T>>());
    _cancel = cancel;
  }

  public void cancelAll() {
    for (Future<T> future : _bag) {
      future.cancel(true);
    }
    _cancel.cancel();
  }

  private Future<T> remember(Future<T> future) {
    _bag.add(future);
    return future;
  }

  private Future<T> forget(Future<T> future) {
    _bag.remove(future);
    return future;
  }

  public int getRemainingCount() {
    return count.get();
  }

  @Override
  public Future<T> poll() {
    Future<T> poll = super.poll();
    if (poll != null) {
      count.decrementAndGet();
    }
    return forget(poll);
  }

  @Override
  public Future<T> poll(long timeout, TimeUnit unit) throws InterruptedException {
    Future<T> poll = super.poll(timeout, unit);
    if (poll != null) {
      count.decrementAndGet();
    }
    return forget(poll);
  }

  @Override
  public Future<T> submit(Callable<T> task) {
    Future<T> future = super.submit(task);
    count.incrementAndGet();
    return remember(future);
  }

  @Override
  public Future<T> submit(Runnable task, T result) {
    Future<T> future = super.submit(task, result);
    count.incrementAndGet();
    return remember(future);
  }

  @Override
  public Future<T> take() throws InterruptedException {
    Future<T> take = super.take();
    if (take != null) {
      count.decrementAndGet();
    }
    return forget(take);
  }

  public Future<T> poll(long timeout, TimeUnit unit, boolean throwExceptionIfTimeout, Object... parameters) throws BlurException {
    try {
      Future<T> future = poll(timeout, unit);
      if (future == null) {
        throw new BException("Call timeout [{0}]", Arrays.asList(parameters));
      }
      return future;
    } catch (InterruptedException e) {
      throw new BException("Call interrupted [{0}]", e, Arrays.asList(parameters));
    }
  }

  public T getResultThrowException(Future<T> future, Object... parameters) throws BlurException {
    try {
      return future.get();
    } catch (InterruptedException e) {
      throw new BException("Call interrupted [{0}]", e, Arrays.asList(parameters));
    } catch (ExecutionException e) {
      Throwable cause = e.getCause();
      if (cause instanceof BlurException) {
        throw (BlurException) cause;
      }
      throw new BException("Call execution exception [{0}]", cause, Arrays.asList(parameters));
    }
  }

}