/*

 * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * This source code is provided to illustrate the usage of a given feature

 * or technique and has been deliberately simplified. Additional steps

 * required for a production-quality application, such as security checks,

 * input validation and proper error handling, might not be present in

 * this sample code.

 */

import java.nio.channels.*;

import java.nio.charset.*;

import java.nio.ByteBuffer;

import java.net.*;

import java.io.IOException;

import java.util.*;

public class Reader {

    static void usage() {

        System.err.println("usage: java Reader group:port@interf [-only source...] [-block source...]");

        System.exit(-1);

    }

    static void printDatagram(SocketAddress sa, ByteBuffer buf) {

        System.out.format("-- datagram from %s --\n",

            ((InetSocketAddress)sa).getAddress().getHostAddress());

        System.out.println(Charset.defaultCharset().decode(buf));

    }

    static void parseAddessList(String s, List<InetAddress> list)

        throws UnknownHostException

    {

        String[] sources = s.split(",");

        for (int i=0; i<sources.length; i++) {

            list.add(InetAddress.getByName(sources[i]));

        }

    }

    public static void main(String[] args) throws IOException {

        if (args.length == 0)

            usage();

        // first parameter is the multicast address (interface required)

        MulticastAddress target = MulticastAddress.parse(args[0]);

        if (target.interf() == null)

            usage();

        // addition arguments are source addresses to include or exclude

        List<InetAddress> includeList = new ArrayList<InetAddress>();

        List<InetAddress> excludeList = new ArrayList<InetAddress>();

        int argc = 1;

        while (argc < args.length) {

            String option = args[argc++];

            if (argc >= args.length)

                usage();

            String value = args[argc++];

            if (option.equals("-only")) {

                 parseAddessList(value, includeList);

                continue;

            }

            if (option.equals("-block")) {

                parseAddessList(value, excludeList);

                continue;

            }

            usage();

        }

        if (!includeList.isEmpty() && !excludeList.isEmpty()) {

            usage();

        }

        // create and bind socket

        ProtocolFamily family = StandardProtocolFamily.INET;

        if (target.group() instanceof Inet6Address) {

            family = StandardProtocolFamily.INET6;

        }

        DatagramChannel dc = DatagramChannel.open(family)

            .setOption(StandardSocketOptions.SO_REUSEADDR, true)

            .bind(new InetSocketAddress(target.port()));

        if (includeList.isEmpty()) {

            // join group and block addresses on the exclude list

            MembershipKey key = dc.join(target.group(), target.interf());

            for (InetAddress source: excludeList) {

                key.block(source);

            }

        } else {

            // join with source-specific membership for each source

            for (InetAddress source: includeList) {

                dc.join(target.group(), target.interf(), source);

            }

        }

        // register socket with Selector

        Selector sel = Selector.open();

        dc.configureBlocking(false);

        dc.register(sel, SelectionKey.OP_READ);

        // print out each datagram that we receive

        ByteBuffer buf = ByteBuffer.allocateDirect(4096);

        for (;;) {

            int updated = sel.select();

            if (updated > 0) {

                Iterator<SelectionKey> iter = sel.selectedKeys().iterator();

                while (iter.hasNext()) {

                    SelectionKey sk = iter.next();

                    iter.remove();

                    DatagramChannel ch = (DatagramChannel)sk.channel();

                    SocketAddress sa = ch.receive(buf);

                    if (sa != null) {

                        buf.flip();

                        printDatagram(sa, buf);

                        buf.rewind();

                        buf.limit(buf.capacity());

                    }

                }

            }

        }

    }

}