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.asterix.external.input.record.reader.twitter;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.apache.asterix.external.api.IRawRecord;
  import org.apache.asterix.external.api.IRecordReader;
  import org.apache.asterix.external.dataflow.AbstractFeedDataFlowController;
  import org.apache.asterix.external.input.record.CharArrayRecord;
  import org.apache.asterix.external.util.IFeedLogManager;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  
  import twitter4j.Query;
  import twitter4j.QueryResult;
  import twitter4j.Status;
  import twitter4j.Twitter;
  import twitter4j.TwitterException;
  import twitter4j.TwitterObjectFactory;
  
  public class TwitterPullRecordReader implements IRecordReader<char[]> {
  
      private Query query;
      private Twitter twitter;
      private int requestInterval = 5; // seconds
      private QueryResult result;
      private int nextTweetIndex = 0;
      private long lastTweetIdReceived = 0;
      private CharArrayRecord record;
      private boolean stopped = false;
  
      public TwitterPullRecordReader(Twitter twitter, String keywords, int requestInterval) {
          this.twitter = twitter;
          this.requestInterval = requestInterval;
          this.query = new Query(keywords);
          this.query.setCount(100);
          this.record = new CharArrayRecord();
      }
  
      @Override
      public void close() throws IOException {
          // do nothing
      }
  
      @Override
      public boolean hasNext() throws Exception {
          return !stopped;
      }
  
      @Override
      public IRawRecord<char[]> next() throws IOException, InterruptedException {
          if (result == null || nextTweetIndex >= result.getTweets().size()) {
              Thread.sleep(1000 * requestInterval);
              query.setSinceId(lastTweetIdReceived);
              try {
                  result = twitter.search(query);
              } catch (TwitterException e) {
                  throw HyracksDataException.create(e);
              }
              nextTweetIndex = 0;
          }
          if (result != null && !result.getTweets().isEmpty()) {
              List<Status> tw = result.getTweets();
              Status tweet = tw.get(nextTweetIndex++);
              if (lastTweetIdReceived < tweet.getId()) {
                  lastTweetIdReceived = tweet.getId();
              }
              String jsonTweet = TwitterObjectFactory.getRawJSON(tweet); // transform tweet obj to json
              record.set(jsonTweet);
              return record;
          } else {
              return null;
          }
      }
  
      @Override
      public boolean stop() {
          stopped = true;
          return true;
      }
  
      @Override
      public void setFeedLogManager(IFeedLogManager feedLogManager) {
          // do nothing
      }
  
      @Override
      public void setController(AbstractFeedDataFlowController controller) {
          // do nothing
      }
  
      @Override
      public boolean handleException(Throwable th) {
          return false;
      }
  }
  