/*
    * 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.giraph.io.formats;
  
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataOutputStream;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.io.Text;
  import org.apache.hadoop.io.compress.CompressionCodec;
  import org.apache.hadoop.io.compress.GzipCodec;
  import org.apache.hadoop.mapreduce.RecordWriter;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
  import org.apache.hadoop.util.ReflectionUtils;
  
  /**
   * The text output format used for Giraph text writing.
   */
  public abstract class GiraphTextOutputFormat
    extends TextOutputFormat<Text, Text> {
  
    @Override
    public RecordWriter<Text, Text> getRecordWriter(TaskAttemptContext job)
      throws IOException, InterruptedException {
      String extension = "";
      CompressionCodec codec = null;
      Configuration conf = job.getConfiguration();
      boolean isCompressed = getCompressOutput(job);
  
      if (isCompressed) {
        Class<? extends CompressionCodec> codecClass =
          getOutputCompressorClass(job, GzipCodec.class);
        codec =
          (CompressionCodec) ReflectionUtils.newInstance(codecClass, conf);
        extension = codec.getDefaultExtension();
      }
      Path file = getDefaultWorkFile(job, extension);
  
      /* adjust the path */
      FSDataOutputStream fileOut;
      FileSystem fs = file.getFileSystem(conf);
      String subdir = getSubdir();
      if (!subdir.isEmpty()) {
        Path subdirPath = new Path(subdir);
        Path subdirAbsPath = new Path(file.getParent(), subdirPath);
        Path vertexFile = new Path(subdirAbsPath, file.getName());
        fileOut = fs.create(vertexFile, false);
      } else {
        fileOut = fs.create(file, false);
      }
  
      String separator = "\t";
  
      if (!isCompressed) {
        return new LineRecordWriter<Text, Text>(fileOut, separator);
      } else {
        DataOutputStream out =
          new DataOutputStream(codec.createOutputStream(fileOut));
        return new LineRecordWriter<Text, Text>(out, separator);
      }
    }
  
    /**
     * This function is used to provide an additional path level to keep
     * different text outputs into different directories.
     *
     * @return  the subdirectory to be created under the output path
     */
    protected abstract String getSubdir();
  }