/*
 * 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.runtime.iterative.event;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.flink.api.common.aggregators.Aggregator;
import org.apache.flink.core.memory.DataInputViewStreamWrapper;
import org.apache.flink.core.memory.DataOutputViewStreamWrapper;
import org.apache.flink.types.LongValue;
import org.apache.flink.types.StringValue;
import org.apache.flink.types.Value;

import org.junit.Assert;
import org.junit.Test;


public class EventWithAggregatorsTest {
	
	private ClassLoader cl = ClassLoader.getSystemClassLoader();
	
	@Test
	public void testSerializationOfEmptyEvent() {
		AllWorkersDoneEvent e = new AllWorkersDoneEvent();
		IterationEventWithAggregators deserialized = pipeThroughSerialization(e);
		
		Assert.assertEquals(0, deserialized.getAggregatorNames().length);
		Assert.assertEquals(0, deserialized.getAggregates(cl).length);
	}
	
	@Test
	public void testSerializationOfEventWithAggregateValues() {
		StringValue stringValue = new StringValue("test string");
		LongValue longValue = new LongValue(68743254);
		
		String stringValueName = "stringValue";
		String longValueName = "longValue";
		
		Aggregator<StringValue> stringAgg = new TestAggregator<StringValue>(stringValue);
		Aggregator<LongValue> longAgg = new TestAggregator<LongValue>(longValue);
		
		Map<String, Aggregator<?>> aggMap = new HashMap<String,  Aggregator<?>>();
		aggMap.put(stringValueName, stringAgg);
		aggMap.put(longValueName, longAgg);
		
		Set<String> allNames = new HashSet<String>();
		allNames.add(stringValueName);
		allNames.add(longValueName);
		
		Set<Value> allVals = new HashSet<Value>();
		allVals.add(stringValue);
		allVals.add(longValue);
		
		// run the serialization
		AllWorkersDoneEvent e = new AllWorkersDoneEvent(aggMap);
		IterationEventWithAggregators deserialized = pipeThroughSerialization(e);
		
		// verify the result
		String[] names = deserialized.getAggregatorNames();
		Value[] aggregates = deserialized.getAggregates(cl);
		
		Assert.assertEquals(allNames.size(), names.length);
		Assert.assertEquals(allVals.size(), aggregates.length);
		
		// check that all the correct names and values are returned
		for (String s : names) {
			allNames.remove(s);
		}
		for (Value v : aggregates) {
			allVals.remove(v);
		}
		
		Assert.assertTrue(allNames.isEmpty());
		Assert.assertTrue(allVals.isEmpty());
	}
	
	private IterationEventWithAggregators pipeThroughSerialization(IterationEventWithAggregators event) {
		try {
			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			event.write(new DataOutputViewStreamWrapper(baos));
			
			byte[] data = baos.toByteArray();
			baos.close();
			
			DataInputViewStreamWrapper in = new DataInputViewStreamWrapper(new ByteArrayInputStream(data));
			IterationEventWithAggregators newEvent = event.getClass().newInstance();
			newEvent.read(in);
			in.close();
			
			return newEvent;
		}
		catch (Exception e) {
			System.err.println(e.getMessage());
			e.printStackTrace();
			Assert.fail("Test threw an exception: " + e.getMessage());
			return null;
		}
	}
	
	private static class TestAggregator<T extends Value> implements Aggregator<T> {

		private static final long serialVersionUID = 1L;
		
		private final T val;
		
		
		public TestAggregator(T val) {
			this.val = val;
		}

		@Override
		public T getAggregate() {
			return val;
		}

		@Override
		public void aggregate(T element) {
			throw new UnsupportedOperationException();
		}

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

}