/**
 * 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.mahout.utils.vectors;

import com.google.common.io.Closeables;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.util.ToolRunner;
import org.apache.mahout.common.AbstractJob;
import org.apache.mahout.common.Pair;
import org.apache.mahout.common.iterator.sequencefile.PathType;
import org.apache.mahout.common.iterator.sequencefile.SequenceFileDirIterable;
import org.apache.mahout.math.VectorWritable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Map;

public class RowIdJob extends AbstractJob {
  private static final Logger log = LoggerFactory.getLogger(RowIdJob.class);

  @Override
  public int run(String[] args) throws Exception {

    addInputOption();
    addOutputOption();

    Map<String,String> parsedArgs = parseArguments(args);
    if (parsedArgs == null) {
      return -1;
    }

    Configuration conf = getConf();
    FileSystem fs = FileSystem.get(conf);

    Path outputPath = getOutputPath();
    Path indexPath = new Path(outputPath, "docIndex");
    Path matrixPath = new Path(outputPath, "matrix");
    SequenceFile.Writer indexWriter = SequenceFile.createWriter(fs,
                                                                conf,
                                                                indexPath,
                                                                IntWritable.class,
                                                                Text.class);
    SequenceFile.Writer matrixWriter = SequenceFile.createWriter(fs,
                                                                 conf,
                                                                 matrixPath,
                                                                 IntWritable.class,
                                                                 VectorWritable.class);
    try {
      IntWritable docId = new IntWritable();
      int i = 0;
      int numCols = 0;
      for (Pair<Text,VectorWritable> record :
           new SequenceFileDirIterable<Text,VectorWritable>(getInputPath(),
                                                            PathType.LIST,
                                                            null,
                                                            null,
                                                            true,
                                                            conf)) {
        VectorWritable value = record.getSecond();
        docId.set(i);
        indexWriter.append(docId, record.getFirst());
        matrixWriter.append(docId, value);
        i++;
        numCols = value.get().size();
      }

      log.info("Wrote out matrix with {} rows and {} columns to {}", new Object[] { i, numCols, matrixPath });
      return 0;
    } finally {
      Closeables.closeQuietly(indexWriter);
      Closeables.closeQuietly(matrixWriter);
    }
  }

  public static void main(String[] args) throws Exception {
    ToolRunner.run(new RowIdJob(), args);
  }

}