/*
 * 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.streaming.api.operators;

import java.util.concurrent.ConcurrentLinkedQueue;

import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.functions.RichReduceFunction;
import org.apache.flink.api.common.typeinfo.BasicTypeInfo;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.common.typeutils.base.IntSerializer;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.watermark.Watermark;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
import org.apache.flink.streaming.util.KeyedOneInputStreamOperatorTestHarness;
import org.apache.flink.streaming.util.OneInputStreamOperatorTestHarness;
import org.apache.flink.streaming.util.TestHarnessUtil;
import org.junit.Assert;
import org.junit.Test;

/**
 * Tests for {@link StreamGroupedReduce}. These test that:
 *
 * <ul>
 *     <li>RichFunction methods are called correctly</li>
 *     <li>Timestamps of processed elements match the input timestamp</li>
 *     <li>Watermarks are correctly forwarded</li>
 * </ul>
 */

public class StreamGroupedReduceTest {

	@Test
	public void testGroupedReduce() throws Exception {

		KeySelector<Integer, Integer> keySelector = new IntegerKeySelector();

		StreamGroupedReduce<Integer> operator = new StreamGroupedReduce<>(new MyReducer(), IntSerializer.INSTANCE);

		OneInputStreamOperatorTestHarness<Integer, Integer> testHarness =
				new KeyedOneInputStreamOperatorTestHarness<>(operator, keySelector, BasicTypeInfo.INT_TYPE_INFO);

		long initialTime = 0L;
		ConcurrentLinkedQueue<Object> expectedOutput = new ConcurrentLinkedQueue<>();

		testHarness.open();

		testHarness.processElement(new StreamRecord<>(1, initialTime + 1));
		testHarness.processElement(new StreamRecord<>(1, initialTime + 2));
		testHarness.processWatermark(new Watermark(initialTime + 2));
		testHarness.processElement(new StreamRecord<>(2, initialTime + 3));
		testHarness.processElement(new StreamRecord<>(2, initialTime + 4));
		testHarness.processElement(new StreamRecord<>(3, initialTime + 5));

		expectedOutput.add(new StreamRecord<>(1, initialTime + 1));
		expectedOutput.add(new StreamRecord<>(2, initialTime + 2));
		expectedOutput.add(new Watermark(initialTime + 2));
		expectedOutput.add(new StreamRecord<>(2, initialTime + 3));
		expectedOutput.add(new StreamRecord<>(4, initialTime + 4));
		expectedOutput.add(new StreamRecord<>(3, initialTime + 5));

		TestHarnessUtil.assertOutputEquals("Output was not correct.", expectedOutput, testHarness.getOutput());
	}

	@Test
	public void testOpenClose() throws Exception {

		KeySelector<Integer, Integer> keySelector = new IntegerKeySelector();

		StreamGroupedReduce<Integer> operator =
				new StreamGroupedReduce<>(new TestOpenCloseReduceFunction(), IntSerializer.INSTANCE);
		OneInputStreamOperatorTestHarness<Integer, Integer> testHarness =
				new KeyedOneInputStreamOperatorTestHarness<>(operator, keySelector, BasicTypeInfo.INT_TYPE_INFO);

		long initialTime = 0L;

		testHarness.open();

		testHarness.processElement(new StreamRecord<>(1, initialTime));
		testHarness.processElement(new StreamRecord<>(2, initialTime));

		testHarness.close();

		Assert.assertTrue("RichFunction methods where not called.", TestOpenCloseReduceFunction.closeCalled);
		Assert.assertTrue("Output contains no elements.", testHarness.getOutput().size() > 0);
	}

	// This must only be used in one test, otherwise the static fields will be changed
	// by several tests concurrently
	private static class TestOpenCloseReduceFunction extends RichReduceFunction<Integer> {
		private static final long serialVersionUID = 1L;

		public static boolean openCalled = false;
		public static boolean closeCalled = false;

		@Override
		public void open(Configuration parameters) throws Exception {
			super.open(parameters);
			if (closeCalled) {
				Assert.fail("Close called before open.");
			}
			openCalled = true;
		}

		@Override
		public void close() throws Exception {
			super.close();
			if (!openCalled) {
				Assert.fail("Open was not called before close.");
			}
			closeCalled = true;
		}

		@Override
		public Integer reduce(Integer in1, Integer in2) throws Exception {
			if (!openCalled) {
				Assert.fail("Open was not called before run.");
			}
			return in1 + in2;
		}
	}

	// Utilities

	private static class MyReducer implements ReduceFunction<Integer> {

		private static final long serialVersionUID = 1L;

		@Override
		public Integer reduce(Integer value1, Integer value2) throws Exception {
			return value1 + value2;
		}

	}

	private static class IntegerKeySelector implements KeySelector<Integer, Integer> {
		private static final long serialVersionUID = 1L;

		@Override
		public Integer getKey(Integer value) throws Exception {
			return value;
		}
	}

	private static TypeInformation<Integer> typeInfo = BasicTypeInfo.INT_TYPE_INFO;
}