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/**
 * Copyright 2018 Nikita Koksharov
 *
 * 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.redisson;

import java.io.IOException;
import java.util.Collections;
import java.util.List;

import org.redisson.api.RFuture;
import org.redisson.api.RTopic;
import org.redisson.api.listener.MessageListener;
import org.redisson.api.listener.StatusListener;
import org.redisson.client.ChannelName;
import org.redisson.client.RedisPubSubListener;
import org.redisson.client.RedisTimeoutException;
import org.redisson.client.codec.Codec;
import org.redisson.client.codec.LongCodec;
import org.redisson.client.codec.StringCodec;
import org.redisson.client.protocol.RedisCommands;
import org.redisson.command.CommandAsyncExecutor;
import org.redisson.config.MasterSlaveServersConfig;
import org.redisson.misc.RPromise;
import org.redisson.misc.RedissonObjectFactory;
import org.redisson.misc.RedissonPromise;
import org.redisson.misc.TransferListener;
import org.redisson.pubsub.AsyncSemaphore;
import org.redisson.pubsub.PubSubConnectionEntry;
import org.redisson.pubsub.PublishSubscribeService;

import io.netty.buffer.ByteBuf;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;

/**
 * Distributed topic implementation. Messages are delivered to all message listeners across Redis cluster.
 *
 * @author Nikita Koksharov
 *
 */
public class RedissonTopic implements RTopic {

    final PublishSubscribeService subscribeService;
    final CommandAsyncExecutor commandExecutor;
    private final String name;
    private final ChannelName channelName;
    private final Codec codec;

    public RedissonTopic(CommandAsyncExecutor commandExecutor, String name) {
        this(commandExecutor.getConnectionManager().getCodec(), commandExecutor, name);
    }

    public RedissonTopic(Codec codec, CommandAsyncExecutor commandExecutor, String name) {
        this.commandExecutor = commandExecutor;
        this.name = name;
        this.channelName = new ChannelName(name);
        this.codec = codec;
        this.subscribeService = commandExecutor.getConnectionManager().getSubscribeService();
    }
    
    @Override
    public List getChannelNames() {
        return Collections.singletonList(name);
    }

    @Override
    public long publish(Object message) {
        return commandExecutor.get(publishAsync(message));
    }

    @Override
    public RFuture publishAsync(Object message) {
        return commandExecutor.writeAsync(name, StringCodec.INSTANCE, RedisCommands.PUBLISH, name, encode(message));
    }

    protected ByteBuf encode(Object value) {
        if (commandExecutor.isRedissonReferenceSupportEnabled()) {
            RedissonReference reference = RedissonObjectFactory.toReference(commandExecutor.getConnectionManager().getCfg(), value);
            if (reference != null) {
                value = reference;
            }
        }
        
        try {
            return codec.getValueEncoder().encode(value);
        } catch (IOException e) {
            throw new IllegalArgumentException(e);
        }
    }
    
    @Override
    public int addListener(StatusListener listener) {
        return addListener(new PubSubStatusListener(listener, name));
    };

    @Override
    public  int addListener(Class type, MessageListener listener) {
        PubSubMessageListener pubSubListener = new PubSubMessageListener(type, (MessageListener)listener, name);
        return addListener(pubSubListener);
    }
    
    @Override
    public RFuture addListenerAsync(StatusListener listener) {
        PubSubStatusListener pubSubListener = new PubSubStatusListener(listener, name);
        return addListenerAsync((RedisPubSubListener)pubSubListener);
    }
    
    @Override
    public  RFuture addListenerAsync(Class type, MessageListener listener) {
        PubSubMessageListener pubSubListener = new PubSubMessageListener(type, listener, name);
        return addListenerAsync(pubSubListener);
    }

    private int addListener(RedisPubSubListener pubSubListener) {
        RFuture future = subscribeService.subscribe(codec, channelName, pubSubListener);
        commandExecutor.syncSubscription(future);
        return System.identityHashCode(pubSubListener);
    }
    
    private RFuture addListenerAsync(final RedisPubSubListener pubSubListener) {
        RFuture future = subscribeService.subscribe(codec, channelName, pubSubListener);
        final RPromise result = new RedissonPromise();
        future.addListener(new FutureListener() {
            @Override
            public void operationComplete(Future future) throws Exception {
                if (!future.isSuccess()) {
                    result.tryFailure(future.cause());
                    return;
                }
                
                result.trySuccess(System.identityHashCode(pubSubListener));
            }
        });
        return result;
    }

    @Override
    public void removeAllListeners() {
        AsyncSemaphore semaphore = subscribeService.getSemaphore(channelName);
        acquire(semaphore);
        
        PubSubConnectionEntry entry = subscribeService.getPubSubEntry(channelName);
        if (entry == null) {
            semaphore.release();
            return;
        }

        if (entry.removeAllListeners(channelName)) {
            subscribeService.unsubscribe(channelName, semaphore).syncUninterruptibly();
        } else {
            semaphore.release();
        }
    }

    protected void acquire(AsyncSemaphore semaphore) {
        MasterSlaveServersConfig config = commandExecutor.getConnectionManager().getConfig();
        int timeout = config.getTimeout() + config.getRetryInterval() * config.getRetryAttempts();
        if (!semaphore.tryAcquire(timeout)) {
            throw new RedisTimeoutException("Remove listeners operation timeout: (" + timeout + "ms) for " + name + " topic");
        }
    }
    
    @Override
    public void removeListener(MessageListener listener) {
        AsyncSemaphore semaphore = subscribeService.getSemaphore(channelName);
        acquire(semaphore);
        
        PubSubConnectionEntry entry = subscribeService.getPubSubEntry(channelName);
        if (entry == null) {
            semaphore.release();
            return;
        }

        entry.removeListener(channelName, listener);
        if (!entry.hasListeners(channelName)) {
            subscribeService.unsubscribe(channelName, semaphore);
        } else {
            semaphore.release();
        }

    }
    
    @Override
    public RFuture removeListenerAsync(final MessageListener listener) {
        final RPromise promise = new RedissonPromise();
        final AsyncSemaphore semaphore = subscribeService.getSemaphore(channelName);
        semaphore.acquire(new Runnable() {
            @Override
            public void run() {
                PubSubConnectionEntry entry = subscribeService.getPubSubEntry(channelName);
                if (entry == null) {
                    semaphore.release();
                    promise.trySuccess(null);
                    return;
                }
                
                entry.removeListener(channelName, listener);
                if (!entry.hasListeners(channelName)) {
                    subscribeService.unsubscribe(channelName, semaphore)
                        .addListener(new TransferListener(promise));
                } else {
                    semaphore.release();
                    promise.trySuccess(null);
                }
                
            }
        });
        return promise;
    }

    @Override
    public RFuture removeListenerAsync(final int listenerId) {
        final RPromise promise = new RedissonPromise();
        final AsyncSemaphore semaphore = subscribeService.getSemaphore(channelName);
        semaphore.acquire(new Runnable() {
            @Override
            public void run() {
                PubSubConnectionEntry entry = subscribeService.getPubSubEntry(channelName);
                if (entry == null) {
                    semaphore.release();
                    promise.trySuccess(null);
                    return;
                }

                entry.removeListener(channelName, listenerId);
                if (!entry.hasListeners(channelName)) {
                    subscribeService.unsubscribe(channelName, semaphore)
                        .addListener(new TransferListener(promise));
                } else {
                    semaphore.release();
                    promise.trySuccess(null);
                }
            }
        });
        return promise;
    }
    
    @Override
    public void removeListener(int listenerId) {
        AsyncSemaphore semaphore = subscribeService.getSemaphore(channelName);
        acquire(semaphore);
        
        PubSubConnectionEntry entry = subscribeService.getPubSubEntry(channelName);
        if (entry == null) {
            semaphore.release();
            return;
        }

        entry.removeListener(channelName, listenerId);
        if (!entry.hasListeners(channelName)) {
            subscribeService.unsubscribe(channelName, semaphore).syncUninterruptibly();
        } else {
            semaphore.release();
        }
    }

    @Override
    public int countListeners() {
        PubSubConnectionEntry entry = subscribeService.getPubSubEntry(channelName);
        if (entry != null) {
            return entry.countListeners();
        }
        return 0;
    }

    @Override
    public RFuture countSubscribersAsync() {
        return commandExecutor.writeAsync(name, LongCodec.INSTANCE, RedisCommands.PUBSUB_NUMSUB, name);
    }

    @Override
    public long countSubscribers() {
        return commandExecutor.get(countSubscribersAsync());
    }

}