/*
 * 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.matrix.data;

import org.apache.sysml.api.DMLException;
import org.apache.sysml.runtime.util.UtilFunctions;

public class BinaryBlockToRowBlockConverter implements Converter<MatrixIndexes, MatrixBlock, MatrixIndexes, MatrixBlock>
{
	
	private MatrixBlock _srcBlock = null;	
	private int _srcRlen = -1;
	private int _srcBrlen = -1;
	private int _pos = -1;
	
	private long _startRowID = -1;
	private long _colID = -1;
	
	//output blocks for reuse
	private MatrixIndexes _destIx = null;
	private MatrixBlock _destBlock = null;
	private Pair<MatrixIndexes, MatrixBlock> _pair = null;
	
	public BinaryBlockToRowBlockConverter()
	{
		_destIx = new MatrixIndexes();
		_destBlock = new MatrixBlock();
		_pair=new Pair<MatrixIndexes, MatrixBlock>(_destIx, _destBlock);
	}
	
	private void reset()
	{
		_srcBlock = null;
		_pos = -1;
		
		_startRowID =-1;
		_colID = -1;
	}
	
	@Override
	public void convert(MatrixIndexes k1, MatrixBlock v1) {
		reset();
		_startRowID = UtilFunctions.computeCellIndex(k1.getRowIndex(), _srcBrlen, 0);
		_colID = k1.getColumnIndex();
		_destBlock.reset(1, v1.getNumColumns());
		_srcRlen = v1.getNumRows();
		
		_srcBlock = v1;
		_pos = 0;
	}

	@Override
	public boolean hasNext() 
	{
		//reached end of block
		if( _pos >= _srcRlen )
			return false;
		
		return true;
	}

	@Override
	public Pair<MatrixIndexes, MatrixBlock> next() 
	{
		//check for valid next call
		if( _pos >= _srcRlen )
			return null;
		
		//prepare partial rowblock key
		_destIx.setIndexes(_startRowID+_pos, _colID);
		
		//slice next row
		try {
			//rowlow, rowup, collow, colup (1-based specification)
			_srcBlock.sliceOperations( _pos, _pos, 0, _srcBlock.getNumColumns()-1, _destBlock );
		}
		catch(DMLException ex)
		{
			throw new RuntimeException("Failed to slice matrix block into row blocks.", ex);
		}
			
		//increment current pos
		_pos++;
		
		return _pair;
	}

	@Override
	public void setBlockSize(int nr, int nc) {
		_srcBrlen = nr;
	}
}