/*
 * 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.flink.api.java.hadoop.mapred;

import java.io.IOException;

import org.apache.flink.annotation.Public;
import org.apache.flink.api.java.typeutils.TypeExtractor;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
import org.apache.flink.api.java.typeutils.TupleTypeInfo;
import org.apache.hadoop.mapred.JobConf;

/**
 * Wrapper for using HadoopInputFormats (mapred-variant) with Flink.
 *
 * The IF is returning a {@code Tuple2<K,V>}.
 *
 * @param <K> Type of the key
 * @param <V> Type of the value.
 */
@Public
public class HadoopInputFormat<K, V> extends HadoopInputFormatBase<K, V, Tuple2<K,V>> implements ResultTypeQueryable<Tuple2<K,V>> {
	
	private static final long serialVersionUID = 1L;

	public HadoopInputFormat(org.apache.hadoop.mapred.InputFormat<K,V> mapredInputFormat, Class<K> key, Class<V> value, JobConf job) {
		super(mapredInputFormat, key, value, job);
	}

	public HadoopInputFormat(org.apache.hadoop.mapred.InputFormat<K,V> mapredInputFormat, Class<K> key, Class<V> value) {
		super(mapredInputFormat, key, value, new JobConf());
	}
	
	@Override
	public Tuple2<K, V> nextRecord(Tuple2<K, V> record) throws IOException {
		if(!fetched) {
			fetchNext();
		}
		if(!hasNext) {
			return null;
		}
		record.f0 = key;
		record.f1 = value;
		fetched = false;
		return record;
	}
	
	@Override
	public TypeInformation<Tuple2<K,V>> getProducedType() {
		return new TupleTypeInfo<>(TypeExtractor.createTypeInfo(keyClass), TypeExtractor.createTypeInfo(valueClass));
	}
}