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.abstracts;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.asterix.external.input.filter.embedder.IExternalFilterValueEmbedder;
  import org.apache.asterix.external.input.stream.AbstractMultipleInputStream;
  import org.apache.hyracks.api.util.CleanupUtils;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  public abstract class AbstractExternalInputStream extends AbstractMultipleInputStream {
  
      protected static final Logger LOGGER = LogManager.getLogger();
  
      // Configuration
      protected final Map<String, String> configuration;
  
      // File fields
      protected final List<String> filePaths;
      private final IExternalFilterValueEmbedder valueEmbedder;
      protected int nextFileIndex = 0;
  
      public AbstractExternalInputStream(Map<String, String> configuration, List<String> filePaths,
              IExternalFilterValueEmbedder valueEmbedder) {
          this.configuration = configuration;
          this.filePaths = filePaths;
          this.valueEmbedder = valueEmbedder;
      }
  
      @Override
      protected boolean advance() throws IOException {
          // No files to read for this partition
          if (filePaths == null || filePaths.isEmpty()) {
              return false;
          }
  
          // Finished reading all the files
          if (nextFileIndex >= filePaths.size()) {
              return false;
          }
  
          // Close the current stream before going to the next one
          if (in != null) {
              CleanupUtils.close(in, null);
          }
  
          String path = filePaths.get(nextFileIndex);
          boolean isAvailableStream = getInputStream();
          nextFileIndex++; // Always point to next file after getting the current stream
          if (!isAvailableStream) {
              return advance();
          } else {
              valueEmbedder.setPath(path);
          }
  
          if (notificationHandler != null) {
              notificationHandler.notifyNewSource();
          }
          return true;
      }
  
      protected abstract boolean getInputStream() throws IOException;
  
      @Override
      public boolean stop() {
          return false;
      }
  
      @Override
      public boolean handleException(Throwable th) {
          return false;
      }
  
      @Override
      public void close() throws IOException {
          if (in != null) {
              CleanupUtils.close(in, null);
          }
      }
  
      @Override
      public String getStreamName() {
          return getStreamNameAt(nextFileIndex - 1);
      }
  
      @Override
      public String getPreviousStreamName() {
          return getStreamNameAt(nextFileIndex - 2);
      }
  
      private String getStreamNameAt(int fileIndex) {
          return fileIndex < 0 || filePaths == null || filePaths.isEmpty() ? "" : filePaths.get(fileIndex);
      }
  }
  