/*
 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.internal.net.rdma;

import java.io.IOException;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.AbstractSelector;
import java.nio.channels.spi.SelectorProvider;
import sun.nio.ch.SelectorProviderImpl;
import java.security.AccessController;
import java.security.PrivilegedAction;

public class RdmaPollSelectorProvider
    extends SelectorProviderImpl
{
    private static final Object lock = new Object();
    private static SelectorProvider provider = null;

    private static PlatformRdmaPollSelectorProvider pPollSelectorProvider =
            PlatformRdmaPollSelectorProvider.get();

    public static SelectorProvider provider() {
        synchronized (lock) {
            if (provider != null)
                return provider;
            return AccessController.doPrivileged(
                new PrivilegedAction<>() {
                    public SelectorProvider run() {
                            provider = new RdmaPollSelectorProvider();
                            return provider;
                        }
                    });
        }
    }

    public AbstractSelector openSelector() throws IOException {
        return pPollSelectorProvider.openSelector(this);
    }

    public SocketChannel openSocketChannel() throws IOException {
        return pPollSelectorProvider.openSocketChannel(this);
    }

    public ServerSocketChannel openServerSocketChannel() throws IOException {
        return pPollSelectorProvider.openServerSocketChannel(this);
    }

    static class PlatformRdmaPollSelectorProvider {

        @SuppressWarnings("unchecked")
        private static PlatformRdmaPollSelectorProvider newInstance(String cn) {
            Class<PlatformRdmaPollSelectorProvider> c;
            try {
                c = (Class<PlatformRdmaPollSelectorProvider>)Class.forName(cn);
                return c.getConstructor(new Class<?>[] {}).newInstance();
            } catch (ReflectiveOperationException x) {
                throw new AssertionError(x);
            }
        }

        private static PlatformRdmaPollSelectorProvider create() {
            String osname = AccessController.doPrivileged(
                    new PrivilegedAction<String>() {
                        public String run() {
                            return System.getProperty("os.name");
                        }
                    });
            if ("Linux".equals(osname))
                return newInstance("jdk.internal.net.rdma.LinuxRdmaPollSelectorProvider");
            return new PlatformRdmaPollSelectorProvider();
        }

        private static final PlatformRdmaPollSelectorProvider instance = create();

        static PlatformRdmaPollSelectorProvider get() {
            return instance;
        }
   
        public AbstractSelector openSelector(RdmaPollSelectorProvider sp) 
                throws IOException {
            throw new UnsupportedOperationException("unsupported socket operation");
        }

        public SocketChannel openSocketChannel(RdmaPollSelectorProvider sp)
                throws IOException {
            throw new UnsupportedOperationException("unsupported socket operation");
        }

        public ServerSocketChannel openServerSocketChannel(RdmaPollSelectorProvider sp)
                throws IOException {
            throw new UnsupportedOperationException("unsupported socket operation");
        }
    }
}