/*

 * Copyright (c) 2008, 2019, 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 sun.nio.ch;

import java.net.InetAddress;

import java.net.NetworkInterface;

import java.nio.channels.MembershipKey;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

/**

 * Simple registry of membership keys for a MulticastChannel.

 *

 * Instances of this object are not safe by multiple concurrent threads.

 */

class MembershipRegistry {

    // map multicast group to list of keys

    private Map<InetAddress, List<MembershipKeyImpl>> groups;

    MembershipRegistry() {

    }

    /**

     * Checks registry for membership of the group on the given

     * network interface.

     */

    MembershipKey checkMembership(InetAddress group, NetworkInterface interf,

                                  InetAddress source)

    {

        if (groups != null) {

            List<MembershipKeyImpl> keys = groups.get(group);

            if (keys != null) {

                for (MembershipKeyImpl key: keys) {

                    if (key.networkInterface().equals(interf)) {

                        // already a member to receive all packets so return

                        // existing key or detect conflict

                        if (source == null) {

                            if (key.sourceAddress() == null)

                                return key;

                            throw new IllegalStateException("Already a member to receive all packets");

                        }

                        // already have source-specific membership so return key

                        // or detect conflict

                        if (key.sourceAddress() == null)

                            throw new IllegalStateException("Already have source-specific membership");

                        if (source.equals(key.sourceAddress()))

                            return key;

                    }

                }

            }

        }

        return null;

    }

    /**

     * Add membership to the registry, returning a new membership key.

     */

    void add(MembershipKeyImpl key) {

        InetAddress group = key.group();

        List<MembershipKeyImpl> keys;

        if (groups == null) {

            groups = new HashMap<>();

            keys = null;

        } else {

            keys = groups.get(group);

        }

        if (keys == null) {

            keys = new LinkedList<>();

            groups.put(group, keys);

        }

        keys.add(key);

    }

    /**

     * Remove a key from the registry

     */

    void remove(MembershipKeyImpl key) {

        InetAddress group = key.group();

        List<MembershipKeyImpl> keys = groups.get(group);

        if (keys != null) {

            Iterator<MembershipKeyImpl> i = keys.iterator();

            while (i.hasNext()) {

                if (i.next() == key) {

                    i.remove();

                    break;

                }

            }

            if (keys.isEmpty()) {

                groups.remove(group);

            }

        }

    }

    @FunctionalInterface

    interface ThrowingConsumer<T, X extends Throwable> {

        void accept(T action) throws X;

    }

    /**

     * Invoke an action for each key in the registry

     */

     <X extends Throwable>

     void forEach(ThrowingConsumer<MembershipKeyImpl, X> action) throws X {

        if (groups != null) {

            for (List<MembershipKeyImpl> keys : groups.values()) {

                for (MembershipKeyImpl key : keys) {

                    action.accept(key);

                }

            }

        }

    }

    /**

     * Invalidate all keys in the registry

     */

    void invalidateAll() {

        forEach(MembershipKeyImpl::invalidate);

    }

}