/*
 * 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.sysml.runtime.transform;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.ByteWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.wink.json4j.JSONException;
import org.apache.sysml.runtime.io.IOUtilFunctions;
import org.apache.sysml.runtime.matrix.CSVReblockMR.OffsetCount;
import org.apache.sysml.runtime.matrix.mapred.MRJobConfiguration;


public class GTFMTDReducer implements Reducer<IntWritable, DistinctValue, Text, LongWritable> {
	
	private JobConf _rJob = null;
	TfUtils _agents = null;
	
	@Override
	public void configure(JobConf job) {
		_rJob = job;
		
		try {
			String outputDir = MRJobConfiguration.getOutputs(job)[0];
			_agents = new TfUtils(job, outputDir);
		} 
		catch(IOException e)  { throw new RuntimeException(e); }
		catch(JSONException e)  { throw new RuntimeException(e); }
	}

	@Override
	public void close() throws IOException {
	}
	
	@Override
	public void reduce(IntWritable key, Iterator<DistinctValue> values,
			OutputCollector<Text, LongWritable> output, Reporter reporter)
			throws IOException {
		
		FileSystem fs = FileSystem.get(_rJob);
		
		int colID = key.get();
		
		if(colID < 0) 
		{
			// process mapper output for MV and Bin agents
			colID = colID*-1;
			_agents.getMVImputeAgent().mergeAndOutputTransformationMetadata(values, _agents.getTfMtdDir(), colID, fs, _agents);
		}
		else if ( colID == _agents.getNumCols() + 1)
		{
			// process mapper output for OFFSET_FILE
			ArrayList<OffsetCount> list = new ArrayList<OffsetCount>();
			while(values.hasNext())
				list.add(new OffsetCount(values.next().getOffsetCount()));
			
			long numTfRows = generateOffsetsFile(list);
			reporter.incrCounter(MRJobConfiguration.DataTransformCounters.TRANSFORMED_NUM_ROWS, numTfRows);

		}
		else 
		{
			// process mapper output for Recode agent
			_agents.getRecodeAgent().mergeAndOutputTransformationMetadata(values, _agents.getTfMtdDir(), colID, fs, _agents);
		}
		
	}
	
	@SuppressWarnings({"unchecked","deprecation"})
	private long generateOffsetsFile(ArrayList<OffsetCount> list) throws IllegalArgumentException, IOException 
	{
		Collections.sort(list);
		
		SequenceFile.Writer writer = null;
		long lineOffset=0;
		try {
			writer = new SequenceFile.Writer(
				FileSystem.get(_rJob), _rJob, 
				new Path(_agents.getOffsetFile()+"/part-00000"), 
				ByteWritable.class, OffsetCount.class);
		
			for(OffsetCount oc: list)
			{
				long count=oc.count;
				oc.count=lineOffset;
				writer.append(new ByteWritable((byte)0), oc);
				lineOffset+=count;
			}
		}
		finally {
			IOUtilFunctions.closeSilently(writer);
		}
		list.clear();
		return lineOffset;
	}
	
}