/*
    * Copyright 2022 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:
    *
    *   https://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.socket.InternetProtocolFamily;
  import io.netty.util.internal.PlatformDependent;
  import io.netty.util.internal.SuppressJava6Requirement;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import java.io.IOException;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.net.StandardProtocolFamily;
  import java.nio.channels.Channel;
  import java.nio.channels.SocketChannel;
  import java.nio.channels.spi.SelectorProvider;
  
  final class SelectorProviderUtil {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(SelectorProviderUtil.class);
  
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      static Method findOpenMethod(String methodName) {
          if (PlatformDependent.javaVersion() >= 15) {
              try {
                  return SelectorProvider.class.getMethod(methodName, java.net.ProtocolFamily.class);
              } catch (Throwable e) {
                  logger.debug("SelectorProvider.{}(ProtocolFamily) not available, will use default", methodName, e);
              }
          }
          return null;
      }
  
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      private static <C extends Channel> C newChannel(Method method, SelectorProvider provider,
                                              Object family) throws IOException {
          /**
           *  Use the {@link SelectorProvider} to open {@link SocketChannel} and so remove condition in
           *  {@link SelectorProvider#provider()} which is called by each SocketChannel.open() otherwise.
           *
           *  See <a href="https://github.com/netty/netty/issues/2308">#2308</a>.
           */
          if (family != null && method != null) {
              try {
                  @SuppressWarnings("unchecked")
                  C channel = (C) method.invoke(provider, family);
                  return channel;
              } catch (InvocationTargetException e) {
                  throw new IOException(e);
              } catch (IllegalAccessException e) {
                  throw new IOException(e);
              }
          }
          return null;
      }
  
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      static <C extends Channel> C newChannel(Method method, SelectorProvider provider,
                                                      InternetProtocolFamily family) throws IOException {
          if (family != null) {
              return newChannel(method, provider, ProtocolFamilyConverter.convert(family));
          }
          return null;
      }
  
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      static <C extends Channel> C newDomainSocketChannel(Method method, SelectorProvider provider) throws IOException {
          return newChannel(method, provider, StandardProtocolFamily.valueOf("UNIX"));
      }
  
      private SelectorProviderUtil() { }
  }