/**
 * 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.metron.dataloads.extractor.inputformat;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

import java.io.IOException;
import java.util.List;
import java.util.Map;

public class WholeFileFormat implements InputFormatHandler {

  public static class WholeFileRecordReader extends RecordReader<NullWritable, Text> {
    private FileSplit fileSplit;
    private Configuration conf;
    private Text value = new Text();
    private boolean processed = false;

    @Override
    public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
      this.fileSplit = (FileSplit) split;
      this.conf = context.getConfiguration();
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
      if (!processed) {
        byte[] contents = new byte[(int) fileSplit.getLength()];
        Path file = fileSplit.getPath();
        FileSystem fs = file.getFileSystem(conf);
        FSDataInputStream in = null;
        try {
          in = fs.open(file);
          IOUtils.readFully(in, contents, 0, contents.length);
          value.set(contents, 0, contents.length);
        } finally {
          IOUtils.closeStream(in);
        }
        processed = true;
        return true;
      }
      return false;
    }

    @Override
    public NullWritable getCurrentKey() throws IOException, InterruptedException {
      return NullWritable.get();
    }
    @Override
    public Text getCurrentValue() throws IOException, InterruptedException{
      return value;
    }

    @Override
    public float getProgress() throws IOException {
      return processed ? 1.0f : 0.0f;
    }

    @Override
    public void close() throws IOException{
      //do nothing :)
    }
  }

  public static class WholeFileInputFormat extends FileInputFormat<NullWritable, Text> {

    @Override
    protected boolean isSplitable(JobContext context, Path file) {
      return false;
    }

    @Override
    public RecordReader<NullWritable, Text> createRecordReader(
            InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
      WholeFileRecordReader reader = new WholeFileRecordReader();
      reader.initialize(split, context);
      return reader;
    }
  }
  @Override
  public void set(Job job, List<Path> inputs, Map<String, Object> config) throws IOException {
    for(Path input : inputs) {
      WholeFileInputFormat.addInputPath(job, input);
    }
    job.setInputFormatClass(WholeFileInputFormat.class);
  }
}
