/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.activemq.broker.region;

import org.apache.activemq.broker.region.policy.SimpleDispatchSelector;
import org.apache.activemq.command.ActiveMQDestination;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Queue dispatch policy that determines if a message can be sent to a subscription
 *
 * @org.apache.xbean.XBean
 *
 */
public class QueueDispatchSelector extends SimpleDispatchSelector {
    private static final Logger LOG = LoggerFactory.getLogger(QueueDispatchSelector.class);
    private Subscription exclusiveConsumer;
    private volatile boolean paused;

    /**
     * @param destination
     */
    public QueueDispatchSelector(ActiveMQDestination destination) {
        super(destination);
    }

    public Subscription getExclusiveConsumer() {
        return exclusiveConsumer;
    }
    public void setExclusiveConsumer(Subscription exclusiveConsumer) {
        this.exclusiveConsumer = exclusiveConsumer;
    }

    public boolean isExclusiveConsumer(Subscription s) {
        return s == this.exclusiveConsumer;
    }

    public boolean canSelect(Subscription subscription,
            MessageReference m) throws Exception {

        boolean result = !paused && super.canDispatch(subscription, m);
        if (result && !subscription.isBrowser()) {
            result = exclusiveConsumer == null || exclusiveConsumer == subscription;
        }
        return result;
    }

    public void pause() {
        paused = true;
    }

    public void resume() {
        paused = false;
    }

    public boolean isPaused() {
        return paused;
    }
}
