/***********************************************************************************************************************
 *
 * Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
 *
 * Licensed 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 eu.stratosphere.api.java.operators.translation;

import java.util.Iterator;

import eu.stratosphere.api.common.functions.GenericCoGrouper;
import eu.stratosphere.api.common.operators.BinaryOperatorInformation;
import eu.stratosphere.api.common.operators.base.CoGroupOperatorBase;
import eu.stratosphere.api.java.functions.CoGroupFunction;
import eu.stratosphere.api.java.operators.Keys;
import eu.stratosphere.api.java.tuple.Tuple2;
import eu.stratosphere.types.TypeInformation;
import eu.stratosphere.util.Collector;

public class PlanUnwrappingCoGroupOperator<I1, I2, OUT, K> 
	extends CoGroupOperatorBase<Tuple2<K, I1>, Tuple2<K, I2>, OUT, GenericCoGrouper<Tuple2<K, I1>, Tuple2<K, I2>, OUT>>
{

	public PlanUnwrappingCoGroupOperator(CoGroupFunction<I1, I2, OUT> udf, 
			Keys.SelectorFunctionKeys<I1, K> key1, Keys.SelectorFunctionKeys<I2, K> key2, String name,
			TypeInformation<OUT> type, TypeInformation<Tuple2<K, I1>> typeInfoWithKey1, TypeInformation<Tuple2<K, I2>> typeInfoWithKey2)
	{
		super(new TupleUnwrappingCoGrouper<I1, I2, OUT, K>(udf),
				new BinaryOperatorInformation<Tuple2<K, I1>, Tuple2<K, I2>, OUT>(typeInfoWithKey1, typeInfoWithKey2, type),
				key1.computeLogicalKeyPositions(), key2.computeLogicalKeyPositions(), name);
	}
	
	public PlanUnwrappingCoGroupOperator(CoGroupFunction<I1, I2, OUT> udf, 
			int[] key1, Keys.SelectorFunctionKeys<I2, K> key2, String name,
			TypeInformation<OUT> type, TypeInformation<Tuple2<K, I1>> typeInfoWithKey1, TypeInformation<Tuple2<K, I2>> typeInfoWithKey2)
	{
		super(new TupleUnwrappingCoGrouper<I1, I2, OUT, K>(udf),
				new BinaryOperatorInformation<Tuple2<K, I1>, Tuple2<K, I2>, OUT>(typeInfoWithKey1,typeInfoWithKey2, type),
				new int[]{0}, key2.computeLogicalKeyPositions(), name);
	}
	
	public PlanUnwrappingCoGroupOperator(CoGroupFunction<I1, I2, OUT> udf, 
			Keys.SelectorFunctionKeys<I1, K> key1, int[] key2, String name,
			TypeInformation<OUT> type, TypeInformation<Tuple2<K, I1>> typeInfoWithKey1, TypeInformation<Tuple2<K, I2>> typeInfoWithKey2)
	{
		super(new TupleUnwrappingCoGrouper<I1, I2, OUT, K>(udf),
				new BinaryOperatorInformation<Tuple2<K, I1>, Tuple2<K, I2>, OUT>(typeInfoWithKey1,typeInfoWithKey2, type),
				key1.computeLogicalKeyPositions(), new int[]{0}, name);
	}

	// --------------------------------------------------------------------------------------------
	
	public static final class TupleUnwrappingCoGrouper<I1, I2, OUT, K> extends WrappingFunction<CoGroupFunction<I1, I2, OUT>>
		implements GenericCoGrouper<Tuple2<K, I1>, Tuple2<K, I2>, OUT>
	{
		private static final long serialVersionUID = 1L;
		
		private final TupleUnwrappingIterator<I1, K> iter1;
		private final TupleUnwrappingIterator<I2, K> iter2;
		
		private TupleUnwrappingCoGrouper(CoGroupFunction<I1, I2, OUT> wrapped) {
			super(wrapped);
			
			this.iter1 = new TupleUnwrappingIterator<I1, K>();
			this.iter2 = new TupleUnwrappingIterator<I2, K>();
		}


		@Override
		public void coGroup(Iterator<Tuple2<K, I1>> records1, Iterator<Tuple2<K, I2>> records2, Collector<OUT> out) throws Exception {
			iter1.set(records1);
			iter2.set(records2);
			this.wrappedFunction.coGroup(iter1, iter2, out);
		}
		
	}
	
	public static class UnwrappingKeyIterator<K, I1> implements Iterator<I1> {

		private Iterator<Tuple2<K, I1>> outerIterator;
		I1 firstValue;
		
		public UnwrappingKeyIterator(Iterator<Tuple2<K, I1>> records1) {
			this.outerIterator = records1;
			this.firstValue = null;
		}
		
		public UnwrappingKeyIterator(Iterator<Tuple2<K, I1>> records1, I1 firstValue ) {
			this.outerIterator = records1;
			this.firstValue = firstValue;
		}
		
		@Override
		public boolean hasNext() {
			return firstValue != null || outerIterator.hasNext();
		}

		@Override
		public I1 next() {
			if(firstValue != null) {
				firstValue = null;
				return firstValue;
			}
			return outerIterator.next().getField(1);
		}

		@Override
		public void remove() {
			throw new UnsupportedOperationException();
		}
		
	}
}