/*
 * 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.common.accumulators;

import org.junit.Test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

public class AverageAccumulatorTest {

	@Test
	public void testGet() {
		AverageAccumulator average = new AverageAccumulator();
		assertEquals(0.0, average.getLocalValue(), 0.0);
	}

	@Test
	public void testAdd() {
		AverageAccumulator average = new AverageAccumulator();
		int i1;
		for (i1 = 0; i1 < 10; i1++) {
			average.add(i1);
		}
		assertEquals(4.5, average.getLocalValue(), 0.0);
		average.resetLocal();

		Integer i2;
		for (i2 = 0; i2 < 10; i2++) {
			average.add(i2);
		}
		assertEquals(4.5, average.getLocalValue(), 0.0);
		average.resetLocal();

		long i3;
		for (i3 = 0; i3 < 10; i3++) {
			average.add(i3);
		}
		assertEquals(4.5, average.getLocalValue(), 0.0);
		average.resetLocal();

		Long i4;
		for (i4 = 0L; i4 < 10; i4++) {
			average.add(i4);
		}
		assertEquals(4.5, average.getLocalValue(), 0.0);
		average.resetLocal();

		double i5;
		for (i5 = 0; i5 < 10; i5++) {
			average.add(i5);
		}
		assertEquals(4.5, average.getLocalValue(), 0.0);
		average.resetLocal();

		Double i6;
		for (i6 = 0.0; i6 < 10; i6++) {
			average.add(i6);
		}
		assertEquals(4.5, average.getLocalValue(), 0.0);
		average.resetLocal();

		assertEquals(0.0, average.getLocalValue(), 0.0);
	}

	@Test
	public void testMergeSuccess() {
		AverageAccumulator avg1 = new AverageAccumulator();
		for (int i = 0; i < 5; i++) {
			avg1.add(i);
		}

		AverageAccumulator avg2 = new AverageAccumulator();
		for (int i = 5; i < 10; i++) {
			avg2.add(i);
		}

		avg1.merge(avg2);
		assertEquals(4.5, avg1.getLocalValue(), 0.0);
	}

	@Test
	public void testMergeFailed() {
		AverageAccumulator average = new AverageAccumulator();
		Accumulator<Double, Double> averageNew = null;
		average.add(1);
		try {
			average.merge(averageNew);
			fail("should fail with an exception");
		}
		catch (IllegalArgumentException e) {
			assertNotNull(e.getMessage());
			assertTrue(e.getMessage().contains("The merged accumulator must be AverageAccumulator."));
		}
		catch (Throwable t) {
			fail("wrong exception; expected IllegalArgumentException but found " + t.getClass().getName());
		}
	}

	@Test
	public void testClone() {
		AverageAccumulator average = new AverageAccumulator();
		average.add(1);
		AverageAccumulator averageNew = average.clone();
		assertEquals(1, averageNew.getLocalValue(), 0.0);
	}
}