/*
 * 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.beam.sdk.io.gcp.pubsub;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.Map;
import javax.annotation.Nullable;

/**
 * Class representing a Pub/Sub message. Each message contains a single message payload and
 * a map of attached attributes.
 */
public class PubsubMessage {

  private byte[] message;
  private Map<String, String> attributes;

  public PubsubMessage(byte[] payload, Map<String, String> attributes) {
    this.message = payload;
    this.attributes = attributes;
  }

  /**
   * Returns the main PubSub message.
   */
  public byte[] getPayload() {
    return message;
  }

  /**
   * Returns the given attribute value. If not such attribute exists, returns null.
   */
  @Nullable
  public String getAttribute(String attribute) {
    checkNotNull(attribute, "attribute");
    return attributes.get(attribute);
  }

  /**
   * Returns the full map of attributes. This is an unmodifiable map.
   */
  public Map<String, String> getAttributeMap() {
    return attributes;
  }
}