/*
    * Copyright 2012 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.sctp.oio;
  
  import com.sun.nio.sctp.SctpChannel;
  import com.sun.nio.sctp.SctpServerChannel;
  import io.netty.channel.ChannelException;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelMetadata;
  import io.netty.channel.ChannelOutboundBuffer;
  import io.netty.channel.ChannelPromise;
  import io.netty.channel.oio.AbstractOioMessageChannel;
  import io.netty.channel.sctp.DefaultSctpServerChannelConfig;
  import io.netty.channel.sctp.SctpServerChannelConfig;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import java.io.IOException;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.Selector;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Set;
  
  /**
   * {@link io.netty.channel.sctp.SctpServerChannel} implementation which use blocking mode to accept new
   * connections and create the {@link OioSctpChannel} for them.
   *
   * Be aware that not all operations systems support SCTP. Please refer to the documentation of your operation system,
   * to understand what you need to do to use it. Also this feature is only supported on Java 7+.
   */
  public class OioSctpServerChannel extends AbstractOioMessageChannel
          implements io.netty.channel.sctp.SctpServerChannel {
  
      private static final InternalLogger logger =
              InternalLoggerFactory.getInstance(OioSctpServerChannel.class);
  
      private static final ChannelMetadata METADATA = new ChannelMetadata(false);
  
      private static SctpServerChannel newServerSocket() {
          try {
              return SctpServerChannel.open();
          } catch (IOException e) {
              throw new ChannelException("failed to create a sctp server channel", e);
          }
      }
  
      private final SctpServerChannel sch;
      private final SctpServerChannelConfig config;
      private final Selector selector;
  
      /**
       * Create a new instance with an new {@link SctpServerChannel}
       */
      public OioSctpServerChannel() {
          this(newServerSocket());
      }
  
      /**
       * Create a new instance from the given {@link SctpServerChannel}
       *
       * @param sch    the {@link SctpServerChannel} which is used by this instance
       */
      public OioSctpServerChannel(SctpServerChannel sch) {
          super(null);
          if (sch == null) {
              throw new NullPointerException("sctp server channel");
          }
  
          this.sch = sch;
          boolean success = false;
          try {
              sch.configureBlocking(false);
              selector = Selector.open();
              sch.register(selector, SelectionKey.OP_ACCEPT);
              config = new OioSctpServerChannelConfig(this, sch);
              success = true;
          } catch (Exception e) {
              throw new ChannelException("failed to initialize a sctp server channel", e);
          } finally {
              if (!success) {
                 try {
                     sch.close();
                 } catch (IOException e) {
                     logger.warn("Failed to close a sctp server channel.", e);
                 }
             }
         }
     }
 
     @Override
     public ChannelMetadata metadata() {
         return METADATA;
     }
 
     @Override
     public SctpServerChannelConfig config() {
         return config;
     }
 
     @Override
     public InetSocketAddress remoteAddress() {
         return null;
     }
 
     @Override
     public InetSocketAddress localAddress() {
         return (InetSocketAddress) super.localAddress();
     }
 
     @Override
     public boolean isOpen() {
         return sch.isOpen();
     }
 
     @Override
     protected SocketAddress localAddress0() {
         try {
             Iterator<SocketAddress> i = sch.getAllLocalAddresses().iterator();
             if (i.hasNext()) {
                 return i.next();
             }
         } catch (IOException e) {
             // ignore
         }
         return null;
     }
 
     @Override
     public Set<InetSocketAddress> allLocalAddresses() {
         try {
             final Set<SocketAddress> allLocalAddresses = sch.getAllLocalAddresses();
             final Set<InetSocketAddress> addresses = new LinkedHashSet<InetSocketAddress>(allLocalAddresses.size());
             for (SocketAddress socketAddress : allLocalAddresses) {
                 addresses.add((InetSocketAddress) socketAddress);
             }
             return addresses;
         } catch (Throwable ignored) {
             return Collections.emptySet();
         }
     }
 
     @Override
     public boolean isActive() {
         return isOpen() && localAddress0() != null;
     }
 
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
         sch.bind(localAddress, config.getBacklog());
     }
 
     @Override
     protected void doClose() throws Exception {
         try {
             selector.close();
         } catch (IOException e) {
             logger.warn("Failed to close a selector.", e);
         }
         sch.close();
     }
 
     @Override
     protected int doReadMessages(List<Object> buf) throws Exception {
         if (!isActive()) {
             return -1;
         }
 
         SctpChannel s = null;
         int acceptedChannels = 0;
         try {
             final int selectedKeys = selector.select(SO_TIMEOUT);
             if (selectedKeys > 0) {
                 final Iterator<SelectionKey> selectionKeys = selector.selectedKeys().iterator();
                 for (;;) {
                     SelectionKey key = selectionKeys.next();
                     selectionKeys.remove();
                     if (key.isAcceptable()) {
                         s = sch.accept();
                         if (s != null) {
                             buf.add(new OioSctpChannel(this, s));
                             acceptedChannels ++;
                         }
                     }
                     if (!selectionKeys.hasNext()) {
                         return acceptedChannels;
                     }
                 }
             }
         } catch (Throwable t) {
             logger.warn("Failed to create a new channel from an accepted sctp channel.", t);
             if (s != null) {
                 try {
                     s.close();
                 } catch (Throwable t2) {
                     logger.warn("Failed to close a sctp channel.", t2);
                 }
             }
         }
 
         return acceptedChannels;
     }
 
     @Override
     public ChannelFuture bindAddress(InetAddress localAddress) {
         return bindAddress(localAddress, newPromise());
     }
 
     @Override
     public ChannelFuture bindAddress(final InetAddress localAddress, final ChannelPromise promise) {
         if (eventLoop().inEventLoop()) {
             try {
                 sch.bindAddress(localAddress);
                 promise.setSuccess();
             } catch (Throwable t) {
                 promise.setFailure(t);
             }
         } else {
             eventLoop().execute(new Runnable() {
                 @Override
                 public void run() {
                     bindAddress(localAddress, promise);
                 }
             });
         }
         return promise;
     }
 
     @Override
     public ChannelFuture unbindAddress(InetAddress localAddress) {
         return unbindAddress(localAddress, newPromise());
     }
 
     @Override
     public ChannelFuture unbindAddress(final InetAddress localAddress, final ChannelPromise promise) {
         if (eventLoop().inEventLoop()) {
             try {
                 sch.unbindAddress(localAddress);
                 promise.setSuccess();
             } catch (Throwable t) {
                 promise.setFailure(t);
             }
         } else {
             eventLoop().execute(new Runnable() {
                 @Override
                 public void run() {
                     unbindAddress(localAddress, promise);
                 }
             });
         }
         return promise;
     }
 
     @Override
     protected void doConnect(
             SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
         throw new UnsupportedOperationException();
     }
 
     @Override
     protected SocketAddress remoteAddress0() {
         return null;
     }
 
     @Override
     protected void doDisconnect() throws Exception {
         throw new UnsupportedOperationException();
     }
 
     @Override
     protected void doWrite(ChannelOutboundBuffer in) throws Exception {
         throw new UnsupportedOperationException();
     }
 
     @Override
     protected Object filterOutboundMessage(Object msg) throws Exception {
         throw new UnsupportedOperationException();
     }
 
     private final class OioSctpServerChannelConfig extends DefaultSctpServerChannelConfig {
         private OioSctpServerChannelConfig(OioSctpServerChannel channel, SctpServerChannel javaChannel) {
             super(channel, javaChannel);
         }
 
         @Override
         protected void autoReadCleared() {
             setReadPending(false);
         }
     }
 }