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.provider;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.lang.reflect.InvocationTargetException;
  import java.net.URL;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.asterix.common.exceptions.AsterixException;
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.external.input.record.reader.aws.delta.DeltaFileRecordReader;
  import org.apache.asterix.external.input.record.reader.stream.AvroRecordReader;
  import org.apache.asterix.external.input.record.reader.stream.StreamRecordReader;
  import org.apache.asterix.external.util.ExternalDataConstants;
  import org.apache.avro.generic.GenericRecord;
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.lang3.tuple.Pair;
  
  public class StreamRecordReaderProvider {
  
      private static final String RESOURCE =
              "META-INF/services/org.apache.asterix.external.input.record." + "reader.stream.StreamRecordReader";
      private static Map<String, List<Pair<String[], Class>>> recordReaders = null;
  
      protected static StreamRecordReader getInstance(Class clazz) throws AsterixException {
          try {
              return (StreamRecordReader) clazz.newInstance();
          } catch (InstantiationException | IllegalAccessException e) {
              throw new AsterixException("Cannot create RecordReader: " + clazz.getSimpleName(), e);
          }
      }
  
      private StreamRecordReaderProvider() {
          // do nothing
      }
  
      public static Class<?> getRecordClass(Map<String, String> configuration) throws AsterixException {
          String format = configuration.get(ExternalDataConstants.KEY_FORMAT);
          if (format == null) {
              throw new AsterixException("Unspecified parameter: " + ExternalDataConstants.KEY_FORMAT);
          }
          if (format.equalsIgnoreCase(ExternalDataConstants.FORMAT_AVRO)) {
              return GenericRecord.class;
          }
          // By default, return char[]
          return char[].class;
      }
  
      public static Class findRecordReaderClazzWithConfig(Map<String, String> configuration, String format)
              throws AsterixException {
          List<Pair<String[], Class>> requiredConfigs = recordReaders.get(format);
          Class clazz = null;
          int maxOptNum = 0;
          for (Pair<String[], Class> configPair : requiredConfigs) {
              Boolean matchFlag = true;
              int matchOptNum = 0;
              // Here StreamRecordReaderProvider will try its best to find the most suitable
              // record reader by matching options. However, if there is a option key error,
              // it will be ignored and a potential wrong record reader with less required options
              // will be returned.
              for (String configKey : configPair.getLeft()) {
                  if (configKey.length() > 0 && !configuration.containsKey(configKey)) {
                      matchFlag = false;
                      break;
                  }
                  if (configKey.length() > 0) {
                      matchOptNum++;
                  }
              }
              if (matchFlag && matchOptNum >= maxOptNum) {
                  clazz = configPair.getRight();
                  maxOptNum = matchOptNum;
              }
          }
          if (clazz != null) {
              return clazz;
          } else {
              throw new AsterixException(ErrorCode.PROVIDER_STREAM_RECORD_READER_WRONG_CONFIGURATION, format);
          }
      }
  
      public static Class getRecordReaderClazz(Map<String, String> configuration) throws AsterixException {
          String format = configuration.get(ExternalDataConstants.KEY_FORMAT);
          if (recordReaders == null) {
              recordReaders = initRecordReaders();
          }
  
          if (format != null) {
              if (format.equalsIgnoreCase(ExternalDataConstants.FORMAT_AVRO)) {
                  return AvroRecordReader.class;
              } else if (format.equalsIgnoreCase(ExternalDataConstants.FORMAT_DELTA)) {
                  return DeltaFileRecordReader.class;
              } else if (recordReaders.containsKey(format)) {
                  return findRecordReaderClazzWithConfig(configuration, format);
              }
              throw new AsterixException(ErrorCode.PROVIDER_STREAM_RECORD_READER_UNKNOWN_FORMAT, format);
          }
          throw new AsterixException("Unspecified parameter: " + ExternalDataConstants.KEY_FORMAT);
      }
  
      protected static Map<String, List<Pair<String[], Class>>> initRecordReaders() throws AsterixException {
          Map<String, List<Pair<String[], Class>>> recordReaders = new HashMap<>();
          ClassLoader cl = StreamRecordReaderProvider.class.getClassLoader();
          final Charset encoding = Charset.forName("UTF-8");
          try {
              Enumeration<URL> urls = cl.getResources(RESOURCE);
              for (URL url : Collections.list(urls)) {
                  InputStream is = url.openStream();
                  String config = IOUtils.toString(is, encoding);
                  is.close();
                  String[] classNames = config.split("\n");
                  for (String className : classNames) {
                      if (className.startsWith("#")) {
                          continue;
                      }
                      final Class<?> clazz = Class.forName(className);
                      StreamRecordReader newInstance = (StreamRecordReader) clazz.getConstructor().newInstance();
                      List<String> formats = newInstance.getRecordReaderFormats();
                      String[] configs = newInstance.getRequiredConfigs().split(":");
                      for (String format : formats) {
                          if (!recordReaders.containsKey(format)) {
                              recordReaders.put(format, new ArrayList<>());
                          }
                          recordReaders.get(format).add(Pair.of(configs, clazz));
                      }
                  }
              }
          } catch (IOException | ClassNotFoundException | InvocationTargetException | IllegalAccessException
                  | NoSuchMethodException | InstantiationException e) {
              throw new AsterixException(e);
          }
          return recordReaders;
      }
  }
  