/*
    * junixsocket
    *
    * Copyright 2009-2024 Christian Kohlschütter
    *
    * Licensed 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 org.newsclub.net.unix.darwin.system;
  
  import java.io.FileDescriptor;
  import java.io.IOException;
  import java.net.Socket;
  import java.net.SocketException;
  
  import org.newsclub.net.unix.AFSYSTEMSocketAddress;
  import org.newsclub.net.unix.AFSYSTEMSocketImplExtensions;
  import org.newsclub.net.unix.AFSocket;
  import org.newsclub.net.unix.AFSocketCapability;
  import org.newsclub.net.unix.AFSocketFactory;
  
  /**
   * Implementation of an {@code AF_SYSTEM} socket.
   *
   * @author Christian Kohlschütter
   */
  public final class AFSYSTEMSocket extends AFSocket<AFSYSTEMSocketAddress> implements
      AFSYSTEMSocketExtensions {
    private static AFSYSTEMSocketImplExtensions staticExtensions = null;
  
    AFSYSTEMSocket(FileDescriptor fdObj, AFSocketFactory<AFSYSTEMSocketAddress> factory)
        throws SocketException {
      super(new AFSYSTEMSocketImpl(fdObj), factory);
    }
  
    @SuppressWarnings("unused")
    private static synchronized AFSYSTEMSocketImplExtensions getStaticImplExtensions()
        throws IOException {
      if (staticExtensions == null) {
        try (AFSYSTEMSocket socket = new AFSYSTEMSocket(null, null)) {
          staticExtensions = (AFSYSTEMSocketImplExtensions) socket.getImplExtensions();
        }
      }
      return staticExtensions;
    }
  
    /**
     * Returns <code>true</code> iff {@link AFSYSTEMSocket}s (sockets of type "AF_SYSTEM") are
     * supported by the current Java VM and the kernel.
     *
     * To support {@link AFSYSTEMSocket}s, a custom JNI library must be loaded that is supplied with
     * <em>junixsocket</em>, and the system must support AF_SYSTEM sockets.
     *
     * This call is equivalent to checking {@link AFSocket#isSupported()} and
     * {@link AFSocket#supports(AFSocketCapability)} with
     * {@link AFSocketCapability#CAPABILITY_DARWIN}.
     *
     * @return {@code true} iff supported.
     */
    public static boolean isSupported() {
      return AFSocket.isSupported() && AFSocket.supports(AFSocketCapability.CAPABILITY_DARWIN);
    }
  
    @Override
    protected AFSYSTEMSocketChannel newChannel() {
      return new AFSYSTEMSocketChannel(this);
    }
  
    /**
     * Creates a new, unbound {@link AFSocket}.
     *
     * This "default" implementation is a bit "lenient" with respect to the specification.
     *
     * In particular, we ignore calls to {@link Socket#getTcpNoDelay()} and
     * {@link Socket#setTcpNoDelay(boolean)}.
     *
     * @return A new, unbound socket.
     * @throws IOException if the operation fails.
     */
    public static AFSYSTEMSocket newInstance() throws IOException {
      return (AFSYSTEMSocket) AFSocket.newInstance(AFSYSTEMSocket::new, (AFSYSTEMSocketFactory) null);
    }
  
    static AFSYSTEMSocket newInstance(AFSYSTEMSocketFactory factory) throws SocketException {
      return (AFSYSTEMSocket) AFSocket.newInstance(AFSYSTEMSocket::new, factory);
    }
  
    /**
     * Creates a new, unbound, "strict" {@link AFSocket}.
     *
    * This call uses an implementation that tries to be closer to the specification than
    * {@link #newInstance()}, at least for some cases.
    *
    * @return A new, unbound socket.
    * @throws IOException if the operation fails.
    */
   public static AFSYSTEMSocket newStrictInstance() throws IOException {
     return (AFSYSTEMSocket) AFSocket.newInstance(AFSYSTEMSocket::new, (AFSYSTEMSocketFactory) null);
   }
 
   /**
    * Creates a new {@link AFSocket} and connects it to the given {@link AFSYSTEMSocketAddress}.
    *
    * @param addr The address to connect to.
    * @return A new, connected socket.
    * @throws IOException if the operation fails.
    */
   public static AFSYSTEMSocket connectTo(AFSYSTEMSocketAddress addr) throws IOException {
     return (AFSYSTEMSocket) AFSocket.connectTo(AFSYSTEMSocket::new, addr);
   }
 
   @Override
   public AFSYSTEMSocketChannel getChannel() {
     return (AFSYSTEMSocketChannel) super.getChannel();
   }
 
   /**
    * Very basic self-test function.
    *
    * Prints "supported" and "capabilities" status to System.out.
    *
    * @param args ignored.
    */
   public static void main(String[] args) {
     System.out.print(AFSYSTEMSocket.class.getName() + ".isSupported(): ");
     System.out.flush();
     System.out.println(AFSYSTEMSocket.isSupported());
   }
 }