/*
    * 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.socket.nio;
  
  import io.netty.channel.ChannelException;
  import io.netty.channel.socket.DatagramChannelConfig;
  import io.netty.channel.socket.DefaultDatagramChannelConfig;
  import io.netty.util.internal.PlatformDependent;
  import io.netty.util.internal.SocketUtils;
  
  import java.lang.reflect.Method;
  import java.net.InetAddress;
  import java.net.NetworkInterface;
  import java.net.SocketException;
  import java.nio.channels.DatagramChannel;
  import java.util.Enumeration;
  
  /**
   * The default {@link NioDatagramChannelConfig} implementation.
   */
  class NioDatagramChannelConfig extends DefaultDatagramChannelConfig {
  
      private static final Object IP_MULTICAST_TTL;
      private static final Object IP_MULTICAST_IF;
      private static final Object IP_MULTICAST_LOOP;
      private static final Method GET_OPTION;
      private static final Method SET_OPTION;
  
      static {
          ClassLoader classLoader = PlatformDependent.getClassLoader(DatagramChannel.class);
          Class<?> socketOptionType = null;
          try {
              socketOptionType = Class.forName("java.net.SocketOption", true, classLoader);
          } catch (Exception e) {
              // Not Java 7+
          }
          Class<?> stdSocketOptionType = null;
          try {
              stdSocketOptionType = Class.forName("java.net.StandardSocketOptions", true, classLoader);
          } catch (Exception e) {
              // Not Java 7+
          }
  
          Object ipMulticastTtl = null;
          Object ipMulticastIf = null;
          Object ipMulticastLoop = null;
          Method getOption = null;
          Method setOption = null;
          if (socketOptionType != null) {
              try {
                  ipMulticastTtl = stdSocketOptionType.getDeclaredField("IP_MULTICAST_TTL").get(null);
              } catch (Exception e) {
                  throw new Error("cannot locate the IP_MULTICAST_TTL field", e);
              }
  
              try {
                  ipMulticastIf = stdSocketOptionType.getDeclaredField("IP_MULTICAST_IF").get(null);
              } catch (Exception e) {
                  throw new Error("cannot locate the IP_MULTICAST_IF field", e);
              }
  
              try {
                  ipMulticastLoop = stdSocketOptionType.getDeclaredField("IP_MULTICAST_LOOP").get(null);
              } catch (Exception e) {
                  throw new Error("cannot locate the IP_MULTICAST_LOOP field", e);
              }
  
              Class<?> networkChannelClass = null;
              try {
                  networkChannelClass = Class.forName("java.nio.channels.NetworkChannel", true, classLoader);
              } catch (Throwable ignore) {
                  // Not Java 7+
              }
  
              if (networkChannelClass == null) {
                  getOption = null;
                  setOption = null;
              } else {
                  try {
                      getOption = networkChannelClass.getDeclaredMethod("getOption", socketOptionType);
                  } catch (Exception e) {
                      throw new Error("cannot locate the getOption() method", e);
                  }
  
                  try {
                      setOption = networkChannelClass.getDeclaredMethod("setOption", socketOptionType, Object.class);
                 } catch (Exception e) {
                     throw new Error("cannot locate the setOption() method", e);
                 }
             }
         }
         IP_MULTICAST_TTL = ipMulticastTtl;
         IP_MULTICAST_IF = ipMulticastIf;
         IP_MULTICAST_LOOP = ipMulticastLoop;
         GET_OPTION = getOption;
         SET_OPTION = setOption;
     }
 
     private final DatagramChannel javaChannel;
 
     NioDatagramChannelConfig(NioDatagramChannel channel, DatagramChannel javaChannel) {
         super(channel, javaChannel.socket());
         this.javaChannel = javaChannel;
     }
 
     @Override
     public int getTimeToLive() {
         return (Integer) getOption0(IP_MULTICAST_TTL);
     }
 
     @Override
     public DatagramChannelConfig setTimeToLive(int ttl) {
         setOption0(IP_MULTICAST_TTL, ttl);
         return this;
     }
 
     @Override
     public InetAddress getInterface() {
         NetworkInterface inf = getNetworkInterface();
         if (inf == null) {
             return null;
         } else {
             Enumeration<InetAddress> addresses = SocketUtils.addressesFromNetworkInterface(inf);
             if (addresses.hasMoreElements()) {
                 return addresses.nextElement();
             }
             return null;
         }
     }
 
     @Override
     public DatagramChannelConfig setInterface(InetAddress interfaceAddress) {
         try {
             setNetworkInterface(NetworkInterface.getByInetAddress(interfaceAddress));
         } catch (SocketException e) {
             throw new ChannelException(e);
         }
         return this;
     }
 
     @Override
     public NetworkInterface getNetworkInterface() {
         return (NetworkInterface) getOption0(IP_MULTICAST_IF);
     }
 
     @Override
     public DatagramChannelConfig setNetworkInterface(NetworkInterface networkInterface) {
         setOption0(IP_MULTICAST_IF, networkInterface);
         return this;
     }
 
     @Override
     public boolean isLoopbackModeDisabled() {
         return (Boolean) getOption0(IP_MULTICAST_LOOP);
     }
 
     @Override
     public DatagramChannelConfig setLoopbackModeDisabled(boolean loopbackModeDisabled) {
         setOption0(IP_MULTICAST_LOOP, loopbackModeDisabled);
         return this;
     }
 
     @Override
     public DatagramChannelConfig setAutoRead(boolean autoRead) {
         super.setAutoRead(autoRead);
         return this;
     }
 
     @Override
     protected void autoReadCleared() {
         ((NioDatagramChannel) channel).setReadPending(false);
     }
 
     private Object getOption0(Object option) {
         if (GET_OPTION == null) {
             throw new UnsupportedOperationException();
         } else {
             try {
                 return GET_OPTION.invoke(javaChannel, option);
             } catch (Exception e) {
                 throw new ChannelException(e);
             }
         }
     }
 
     private void setOption0(Object option, Object value) {
         if (SET_OPTION == null) {
             throw new UnsupportedOperationException();
         } else {
             try {
                 SET_OPTION.invoke(javaChannel, option, value);
             } catch (Exception e) {
                 throw new ChannelException(e);
             }
         }
     }
 }