/*
    * 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.hadoop.chukwa.extraction.demux.processor.mapper;
  
  
  import java.util.HashMap;
  import org.apache.log4j.Logger;
  
  public class ProcessorFactory {
    static Logger log = Logger.getLogger(ProcessorFactory.class);
  
    // TODO
    // add new mapper package at the end.
    // We should have a more generic way to do this.
    // Ex: read from config
    // list of alias
    // and
    // alias -> processor class
  
    private static HashMap<String, ChunkProcessor> processors = new HashMap<String, ChunkProcessor>(); // registry
  
    private ProcessorFactory() {
    }
  
    public static ChunkProcessor getProcessor(String recordType)
        throws UnknownRecordTypeException {
      String path = "org.apache.hadoop.chukwa.extraction.demux.processor.mapper"
          + recordType;
      if (processors.containsKey(recordType)) {
        return processors.get(recordType);
      } else {
        ChunkProcessor processor = null;
        try {
          processor = (ChunkProcessor) Class.forName(path).getConstructor()
              .newInstance();
        } catch (ClassNotFoundException e) {
          throw new UnknownRecordTypeException(
              "Unknown recordType:" + recordType, e);
        } catch (Exception e) {
          throw new UnknownRecordTypeException("error constructing processor", e);
        }
  
        // TODO using a ThreadSafe/reuse flag to actually decide if we want
        // to reuse the same processor again and again
        register(recordType, processor);
        return processor;
      }
    }
  
    /**
     * Register a specific parser for a {@link ChunkProcessor} implementation.
     */
    public static synchronized void register(String recordType,
        ChunkProcessor processor) {
      log.info("register " + processor.getClass().getName()
          + " for this recordType :" + recordType);
      if (processors.containsKey(recordType)) {
        throw new DuplicateProcessorException(
            "Duplicate processor for recordType:" + recordType);
      }
      ProcessorFactory.processors.put(recordType, processor);
    }
  
  }