/*
 * 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.io;


import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.io.RichOutputFormat;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.java.typeutils.InputTypeConfigurable;
import org.apache.flink.configuration.Configuration;

/**
 *  An output format that writes record into collection
 */
@PublicEvolving
public class LocalCollectionOutputFormat<T> extends RichOutputFormat<T> implements InputTypeConfigurable {

	private static final long serialVersionUID = 1L;

	private static Map<Integer,Collection<?>> RESULT_HOLDER = new HashMap<Integer, Collection<?>>();

	private transient ArrayList<T> taskResult;

	private TypeSerializer<T> typeSerializer;

	private int id;

	public LocalCollectionOutputFormat(Collection<T> out) {
		synchronized (RESULT_HOLDER) {
			this.id = generateRandomId();
			RESULT_HOLDER.put(this.id, out);
		}
	}

	private int generateRandomId() {
		int num = (int) (Math.random() * Integer.MAX_VALUE);
		while (RESULT_HOLDER.containsKey(num)) {
			num = (int) (Math.random() * Integer.MAX_VALUE);
		}
		return num;
	}

	@Override
	public void configure(Configuration parameters) {}


	@Override
	public void open(int taskNumber, int numTasks) throws IOException {
		this.taskResult = new ArrayList<T>();
	}

	@Override
	public void writeRecord(T record) throws IOException {
		T recordCopy = this.typeSerializer.createInstance();
		recordCopy = this.typeSerializer.copy(record, recordCopy);
		this.taskResult.add(recordCopy);
	}


	@Override
	public void close() throws IOException {
		synchronized (RESULT_HOLDER) {
			@SuppressWarnings("unchecked")
			Collection<T> result = (Collection<T>) RESULT_HOLDER.get(this.id);
			result.addAll(this.taskResult);
		}
	}

	@Override
	@SuppressWarnings("unchecked")
	public void setInputType(TypeInformation<?> type, ExecutionConfig executionConfig) {
		this.typeSerializer = (TypeSerializer<T>)type.createSerializer(executionConfig);
	}
}