/*
 * Copyright (C) 2011 Google Inc.
 *
 * 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.ros.android.view.visualization.layer;

import com.google.common.base.Preconditions;

import org.ros.android.view.visualization.VisualizationView;
import org.ros.namespace.GraphName;
import org.ros.node.ConnectedNode;
import org.ros.node.Node;
import org.ros.node.topic.Subscriber;

/**
 * @author damonkohler@google.com (Damon Kohler)
 */
public class SubscriberLayer<T> extends DefaultLayer {

  private final GraphName topicName;
  private final String messageType;

  private Subscriber<T> subscriber;

  public SubscriberLayer(GraphName topicName, String messageType) {
    this.topicName = topicName;
    this.messageType = messageType;
  }

  @Override
  public void onStart(VisualizationView view, ConnectedNode connectedNode) {
    super.onStart(view, connectedNode);
    subscriber = connectedNode.newSubscriber(topicName, messageType);
  }

  @Override
  public void onShutdown(VisualizationView view, Node node) {
    subscriber.shutdown();
    super.onShutdown(view, node);
  }

  public Subscriber<T> getSubscriber() {
    Preconditions.checkNotNull(subscriber);
    return subscriber;
  }
}
