/*
    * Copyright 2013 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.channel.group;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufHolder;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ServerChannel;
  import io.netty.util.ReferenceCountUtil;
  import io.netty.util.concurrent.EventExecutor;
  import io.netty.util.internal.ConcurrentSet;
  import io.netty.util.internal.StringUtil;
  
  import java.util.AbstractSet;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.concurrent.atomic.AtomicInteger;
  
  /**
   * The default {@link ChannelGroup} implementation.
   */
  public class DefaultChannelGroup extends AbstractSet<Channel> implements ChannelGroup {
  
      private static final AtomicInteger nextId = new AtomicInteger();
      private final String name;
      private final EventExecutor executor;
      private final ConcurrentSet<Channel> serverChannels = new ConcurrentSet<Channel>();
      private final ConcurrentSet<Channel> nonServerChannels = new ConcurrentSet<Channel>();
      private final ChannelFutureListener remover = new ChannelFutureListener() {
          @Override
          public void operationComplete(ChannelFuture future) throws Exception {
              remove(future.channel());
          }
      };
      private final boolean stayClosed;
      private volatile boolean closed;
  
      /**
       * Creates a new group with a generated name and the provided {@link EventExecutor} to notify the
       * {@link ChannelGroupFuture}s.
       */
      public DefaultChannelGroup(EventExecutor executor) {
          this(executor, false);
      }
  
      /**
       * Creates a new group with the specified {@code name} and {@link EventExecutor} to notify the
       * {@link ChannelGroupFuture}s.  Please note that different groups can have the same name, which means no
       * duplicate check is done against group names.
       */
      public DefaultChannelGroup(String name, EventExecutor executor) {
          this(name, executor, false);
      }
  
      /**
       * Creates a new group with a generated name and the provided {@link EventExecutor} to notify the
       * {@link ChannelGroupFuture}s. {@code stayClosed} defines whether or not, this group can be closed
       * more than once. Adding channels to a closed group will immediately close them, too. This makes it
       * easy, to shutdown server and child channels at once.
       */
      public DefaultChannelGroup(EventExecutor executor, boolean stayClosed) {
          this("group-0x" + Integer.toHexString(nextId.incrementAndGet()), executor, stayClosed);
      }
  
      /**
       * Creates a new group with the specified {@code name} and {@link EventExecutor} to notify the
       * {@link ChannelGroupFuture}s. {@code stayClosed} defines whether or not, this group can be closed
       * more than once. Adding channels to a closed group will immediately close them, too. This makes it
       * easy, to shutdown server and child channels at once. Please note that different groups can have
       * the same name, which means no duplicate check is done against group names.
       */
      public DefaultChannelGroup(String name, EventExecutor executor, boolean stayClosed) {
          if (name == null) {
              throw new NullPointerException("name");
          }
          this.name = name;
          this.executor = executor;
          this.stayClosed = stayClosed;
      }
  
      @Override
     public String name() {
         return name;
     }
 
     @Override
     public boolean isEmpty() {
         return nonServerChannels.isEmpty() && serverChannels.isEmpty();
     }
 
     @Override
     public int size() {
         return nonServerChannels.size() + serverChannels.size();
     }
 
     @Override
     public boolean contains(Object o) {
         if (o instanceof Channel) {
             Channel c = (Channel) o;
             if (o instanceof ServerChannel) {
                 return serverChannels.contains(c);
             } else {
                 return nonServerChannels.contains(c);
             }
         } else {
             return false;
         }
     }
 
     @Override
     public boolean add(Channel channel) {
         ConcurrentSet<Channel> set =
             channel instanceof ServerChannel? serverChannels : nonServerChannels;
 
         boolean added = set.add(channel);
         if (added) {
             channel.closeFuture().addListener(remover);
         }
 
         if (stayClosed && closed) {
 
             // First add channel, than check if closed.
             // Seems inefficient at first, but this way a volatile
             // gives us enough synchronization to be thread-safe.
             //
             // If true: Close right away.
             // (Might be closed a second time by ChannelGroup.close(), but this is ok)
             //
             // If false: Channel will definitely be closed by the ChannelGroup.
             // (Because closed=true always happens-before ChannelGroup.close())
             //
             // See https://github.com/netty/netty/issues/4020
             channel.close();
         }
 
         return added;
     }
 
     @Override
     public boolean remove(Object o) {
         if (!(o instanceof Channel)) {
             return false;
         }
         boolean removed;
         Channel c = (Channel) o;
         if (c instanceof ServerChannel) {
             removed = serverChannels.remove(c);
         } else {
             removed = nonServerChannels.remove(c);
         }
         if (!removed) {
             return false;
         }
 
         c.closeFuture().removeListener(remover);
         return true;
     }
 
     @Override
     public void clear() {
         nonServerChannels.clear();
         serverChannels.clear();
     }
 
     @Override
     public Iterator<Channel> iterator() {
         return new CombinedIterator<Channel>(
                 serverChannels.iterator(),
                 nonServerChannels.iterator());
     }
 
     @Override
     public Object[] toArray() {
         Collection<Channel> channels = new ArrayList<Channel>(size());
         channels.addAll(serverChannels);
         channels.addAll(nonServerChannels);
         return channels.toArray();
     }
 
     @Override
     public <T> T[] toArray(T[] a) {
         Collection<Channel> channels = new ArrayList<Channel>(size());
         channels.addAll(serverChannels);
         channels.addAll(nonServerChannels);
         return channels.toArray(a);
     }
 
     @Override
     public ChannelGroupFuture close() {
         return close(ChannelMatchers.all());
     }
 
     @Override
     public ChannelGroupFuture disconnect() {
         return disconnect(ChannelMatchers.all());
     }
 
     @Override
     public ChannelGroupFuture deregister() {
         return deregister(ChannelMatchers.all());
     }
 
     @Override
     public ChannelGroupFuture write(Object message) {
         return write(message, ChannelMatchers.all());
     }
 
     // Create a safe duplicate of the message to write it to a channel but not affect other writes.
     // See https://github.com/netty/netty/issues/1461
     private static Object safeDuplicate(Object message) {
         if (message instanceof ByteBuf) {
             return ((ByteBuf) message).duplicate().retain();
         } else if (message instanceof ByteBufHolder) {
             return ((ByteBufHolder) message).duplicate().retain();
         } else {
             return ReferenceCountUtil.retain(message);
         }
     }
 
     @Override
     public ChannelGroupFuture write(Object message, ChannelMatcher matcher) {
         if (message == null) {
             throw new NullPointerException("message");
         }
         if (matcher == null) {
             throw new NullPointerException("matcher");
         }
 
         Map<Channel, ChannelFuture> futures = new LinkedHashMap<Channel, ChannelFuture>(size());
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.write(safeDuplicate(message)));
             }
         }
 
         ReferenceCountUtil.release(message);
         return new DefaultChannelGroupFuture(this, futures, executor);
     }
 
     @Override
     public ChannelGroup flush() {
         return flush(ChannelMatchers.all());
     }
 
     @Override
     public ChannelGroupFuture flushAndWrite(Object message) {
         return writeAndFlush(message);
     }
 
     @Override
     public ChannelGroupFuture writeAndFlush(Object message) {
         return writeAndFlush(message, ChannelMatchers.all());
     }
 
     @Override
     public ChannelGroupFuture disconnect(ChannelMatcher matcher) {
         if (matcher == null) {
             throw new NullPointerException("matcher");
         }
 
         Map<Channel, ChannelFuture> futures =
                 new LinkedHashMap<Channel, ChannelFuture>(size());
 
         for (Channel c: serverChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.disconnect());
             }
         }
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.disconnect());
             }
         }
 
         return new DefaultChannelGroupFuture(this, futures, executor);
     }
 
     @Override
     public ChannelGroupFuture close(ChannelMatcher matcher) {
         if (matcher == null) {
             throw new NullPointerException("matcher");
         }
 
         Map<Channel, ChannelFuture> futures =
                 new LinkedHashMap<Channel, ChannelFuture>(size());
 
         if (stayClosed) {
             // It is important to set the closed to true, before closing channels.
             // Our invariants are:
             // closed=true happens-before ChannelGroup.close()
             // ChannelGroup.add() happens-before checking closed==true
             //
             // See https://github.com/netty/netty/issues/4020
             closed = true;
         }
 
         for (Channel c: serverChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.close());
             }
         }
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.close());
             }
         }
 
         return new DefaultChannelGroupFuture(this, futures, executor);
     }
 
     @Override
     public ChannelGroupFuture deregister(ChannelMatcher matcher) {
         if (matcher == null) {
             throw new NullPointerException("matcher");
         }
 
         Map<Channel, ChannelFuture> futures =
                 new LinkedHashMap<Channel, ChannelFuture>(size());
 
         for (Channel c: serverChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.deregister());
             }
         }
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.deregister());
             }
         }
 
         return new DefaultChannelGroupFuture(this, futures, executor);
     }
 
     @Override
     public ChannelGroup flush(ChannelMatcher matcher) {
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 c.flush();
             }
         }
         return this;
     }
 
     @Override
     public ChannelGroupFuture flushAndWrite(Object message, ChannelMatcher matcher) {
         return writeAndFlush(message, matcher);
     }
 
     @Override
     public ChannelGroupFuture writeAndFlush(Object message, ChannelMatcher matcher) {
         if (message == null) {
             throw new NullPointerException("message");
         }
 
         Map<Channel, ChannelFuture> futures = new LinkedHashMap<Channel, ChannelFuture>(size());
 
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.writeAndFlush(safeDuplicate(message)));
             }
         }
 
         ReferenceCountUtil.release(message);
 
         return new DefaultChannelGroupFuture(this, futures, executor);
     }
 
     /**
      * Returns the {@link ChannelGroupFuture} which will be notified when all {@link Channel}s that are part of this
      * {@link ChannelGroup}, at the time of calling, are closed.
      */
     public ChannelGroupFuture newCloseFuture() {
         return newCloseFuture(ChannelMatchers.all());
     }
 
     /**
      * Returns the {@link ChannelGroupFuture} which will be notified when all {@link Channel}s that are part of this
      * {@link ChannelGroup}, at the time of calling, are closed.
      */
     public ChannelGroupFuture newCloseFuture(ChannelMatcher matcher) {
         Map<Channel, ChannelFuture> futures =
                 new LinkedHashMap<Channel, ChannelFuture>(size());
 
         for (Channel c: serverChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.closeFuture());
             }
         }
         for (Channel c: nonServerChannels) {
             if (matcher.matches(c)) {
                 futures.put(c, c.closeFuture());
             }
         }
 
         return new DefaultChannelGroupFuture(this, futures, executor);
     }
 
     @Override
     public int hashCode() {
         return System.identityHashCode(this);
     }
 
     @Override
     public boolean equals(Object o) {
         return this == o;
     }
 
     @Override
     public int compareTo(ChannelGroup o) {
         int v = name().compareTo(o.name());
         if (v != 0) {
             return v;
         }
 
         return System.identityHashCode(this) - System.identityHashCode(o);
     }
 
     @Override
     public String toString() {
         return StringUtil.simpleClassName(this) + "(name: " + name() + ", size: " + size() + ')';
     }
 }