/**
 *
 * Copyright the original author or authors
 *
 * 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.jivesoftware.smackx.pubsub;

import java.util.Collections;
import java.util.List;

/**
 * Base class to represents events that are associated to subscriptions.
 * 
 * @author Robin Collier
 */
public abstract class SubscriptionEvent extends NodeEvent
{
    private List<String> subIds = Collections.emptyList();

    /**
     * Construct an event with no subscription id's.  This can 
     * occur when there is only one subscription to a node.  The
     * event may or may not report the subscription id along 
     * with the event.
     * 
     * @param nodeId The id of the node the event came from
     */
    protected SubscriptionEvent(String nodeId)
    {
        super(nodeId);
    }

    /**
     * Construct an event with multiple subscriptions.
     * 
     * @param nodeId The id of the node the event came from
     * @param subscriptionIds The list of subscription id's
     */
    protected SubscriptionEvent(String nodeId, List<String> subscriptionIds)
    {
        super(nodeId);

        if (subscriptionIds != null)
            subIds = subscriptionIds;
    }

    /** 
     * Get the subscriptions this event is associated with.
     * 
     * @return List of subscription id's
     */
    public List<String> getSubscriptions()
    {
        return Collections.unmodifiableList(subIds);
    }

    /**
     * Set the list of subscription id's for this event.
     * 
     * @param subscriptionIds The list of subscription id's
     */
    protected void setSubscriptions(List<String> subscriptionIds)
    {
        if (subscriptionIds != null)
            subIds = subscriptionIds;
    }
}