/*
 * 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.typeutils.runtime.tuple.base;

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

import org.apache.flink.api.common.typeutils.TypePairComparator;
import org.apache.flink.api.java.tuple.Tuple;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.TestLogger;
import org.junit.Test;

/**
 * Abstract test base for TuplePairComparators.
 *
 * @param <T>
 * @param <R>
 */
public abstract class TuplePairComparatorTestBase<T extends Tuple, R extends Tuple> extends TestLogger {

	protected abstract TypePairComparator<T, R> createComparator(boolean ascending);

	protected abstract Tuple2<T[], R[]> getSortedTestData();

	@Test
	public void testEqualityWithReference() {
		try {
			TypePairComparator<T, R> comparator = getComparator(true);
			Tuple2<T[], R[]> data = getSortedData();
			for (int x = 0; x < data.f0.length; x++) {
				comparator.setReference(data.f0[x]);

				assertTrue(comparator.equalToReference(data.f1[x]));
			}
		} catch (Exception e) {
			System.err.println(e.getMessage());
			e.printStackTrace();
			fail("Exception in test: " + e.getMessage());
		}
	}

	@Test
	public void testInequalityWithReference() {
		testGreatSmallAscDescWithReference(true);
		testGreatSmallAscDescWithReference(false);
	}

	protected void testGreatSmallAscDescWithReference(boolean ascending) {
		try {
			Tuple2<T[], R[]> data = getSortedData();

			TypePairComparator<T, R> comparator = getComparator(ascending);

			//compares every element in high with every element in low
			for (int x = 0; x < data.f0.length - 1; x++) {
				for (int y = x + 1; y < data.f1.length; y++) {
					comparator.setReference(data.f0[x]);
					if (ascending) {
						assertTrue(comparator.compareToReference(data.f1[y]) > 0);
					} else {
						assertTrue(comparator.compareToReference(data.f1[y]) < 0);
					}
				}
			}
		} catch (Exception e) {
			System.err.println(e.getMessage());
			e.printStackTrace();
			fail("Exception in test: " + e.getMessage());
		}
	}

	// --------------------------------------------------------------------------------------------
	protected TypePairComparator<T, R> getComparator(boolean ascending) {
		TypePairComparator<T, R> comparator = createComparator(ascending);
		if (comparator == null) {
			throw new RuntimeException("Test case corrupt. Returns null as comparator.");
		}
		return comparator;
	}

	protected Tuple2<T[], R[]> getSortedData() {
		Tuple2<T[], R[]> data = getSortedTestData();
		if (data == null || data.f0 == null || data.f1 == null) {
			throw new RuntimeException("Test case corrupt. Returns null as test data.");
		}
		if (data.f0.length < 2 || data.f1.length < 2) {
			throw new RuntimeException("Test case does not provide enough sorted test data.");
		}

		return data;
	}
}