content: /**
   * 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.apex.malhar.contrib.kinesis;
  
  import java.util.List;
  import com.amazonaws.AmazonClientException;
  import com.amazonaws.auth.BasicAWSCredentials;
  import com.amazonaws.services.kinesis.AmazonKinesisClient;
  import com.amazonaws.services.kinesis.model.DescribeStreamRequest;
  import com.amazonaws.services.kinesis.model.DescribeStreamResult;
  import com.amazonaws.services.kinesis.model.GetRecordsRequest;
  import com.amazonaws.services.kinesis.model.GetRecordsResult;
  import com.amazonaws.services.kinesis.model.GetShardIteratorRequest;
  import com.amazonaws.services.kinesis.model.GetShardIteratorResult;
  import com.amazonaws.services.kinesis.model.Record;
  import com.amazonaws.services.kinesis.model.Shard;
  import com.amazonaws.services.kinesis.model.ShardIteratorType;
  
  /**
   * A util class for Amazon Kinesis. Contains the wrappers for creating client, get the shard list and records from shard.
   *
   * @since 2.0.0
   */
  public class KinesisUtil
  {
  
    private transient AmazonKinesisClient client = null;
  
    private static KinesisUtil instance = null;
  
    private KinesisUtil()
    {
    }
  
    public static KinesisUtil getInstance()
    {
      if (instance == null) {
        instance = new KinesisUtil();
      }
      return instance;
    }
  
    /**
     * Create the AmazonKinesisClient with the given credentials
     * @param accessKey AWS accessKeyId
     * @param secretKey AWS secretAccessKey
     * @throws Exception
     */
    public void createKinesisClient(String accessKey, String secretKey, String endPoint) throws Exception
    {
      if (client == null) {
        try {
          client = new AmazonKinesisClient(new BasicAWSCredentials(accessKey, secretKey));
          if (endPoint != null) {
            client.setEndpoint(endPoint);
          }
        } catch (Exception e) {
          throw new AmazonClientException("Unable to load credentials", e);
        }
      }
    }
  
    /**
     * Get the available shards from the kinesis
     * @param streamName Name of the stream from where the shards to be accessed
     * @return the list of shards from the given stream
     */
    public List<Shard> getShardList(String streamName)
    {
      assert client != null : "Illegal client";
      DescribeStreamRequest describeRequest = new DescribeStreamRequest();
      describeRequest.setStreamName(streamName);
  
      DescribeStreamResult describeResponse = client.describeStream(describeRequest);
      return describeResponse.getStreamDescription().getShards();
    }
  
    /**
     * Get the records from the particular shard
     * @param streamName Name of the stream from where the records to be accessed
     * @param recordsLimit Number of records to return from shard
     * @param shId Shard Id of the shard
     * @param iteratorType Shard iterator type
     * @param seqNo Record sequence number
     * @return the list of records from the given shard
     * @throws AmazonClientException
     */
    public List<Record> getRecords(String streamName, Integer recordsLimit, String shId, ShardIteratorType iteratorType, String seqNo)
      throws AmazonClientException
    {
      assert client != null : "Illegal client";
      try {
        // Create the GetShardIteratorRequest instance and sets streamName, shardId and iteratorType to it
        GetShardIteratorRequest iteratorRequest = new GetShardIteratorRequest();
        iteratorRequest.setStreamName(streamName);
        iteratorRequest.setShardId(shId);
        iteratorRequest.setShardIteratorType(iteratorType);
  
        // If the iteratorType is AFTER_SEQUENCE_NUMBER, set the sequence No to the iteratorRequest
        if (ShardIteratorType.AFTER_SEQUENCE_NUMBER.equals(iteratorType) ||
            ShardIteratorType.AT_SEQUENCE_NUMBER.equals(iteratorType)) {
          iteratorRequest.setStartingSequenceNumber(seqNo);
        }
        // Get the Response from the getShardIterator service method & get the shardIterator from that response
        GetShardIteratorResult iteratorResponse = client.getShardIterator(iteratorRequest);
        // getShardIterator() specifies the position in the shard
        String iterator = iteratorResponse.getShardIterator();
  
        // Create the GetRecordsRequest instance and set the recordsLimit and iterator
        GetRecordsRequest getRequest = new GetRecordsRequest();
        getRequest.setLimit(recordsLimit);
        getRequest.setShardIterator(iterator);
  
        // Get the Response from the getRecords service method and get the data records from that response.
        GetRecordsResult getResponse = client.getRecords(getRequest);
        return getResponse.getRecords();
      } catch (AmazonClientException e) {
        throw new RuntimeException(e);
      }
    }
  
    public AmazonKinesisClient getClient()
    {
      return client;
    }
  
    public void setClient(AmazonKinesisClient client)
    {
      this.client = client;
    }
  }
  