/*
 * 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.formats.avro;

import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.java.typeutils.runtime.kryo.KryoSerializer;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.Registration;
import org.junit.Test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;

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

/**
 * Tests that the set of Kryo registrations is the same across compatible
 * Flink versions.
 *
 * <p>Special version of {@code KryoSerializerRegistrationsTest} that sits in the Avro module
 * and verifies that we correctly register Avro types at the {@link KryoSerializer} when
 * Avro is present.
 */
public class AvroKryoSerializerRegistrationsTest {

	/**
	 * Tests that the registered classes in Kryo did not change.
	 *
	 * <p>Once we have proper serializer versioning this test will become obsolete.
	 * But currently a change in the serializers can break savepoint backwards
	 * compatibility between Flink versions.
	 */
	@Test
	public void testDefaultKryoRegisteredClassesDidNotChange() throws Exception {
		final Kryo kryo = new KryoSerializer<>(Integer.class, new ExecutionConfig()).getKryo();

		try (BufferedReader reader = new BufferedReader(new InputStreamReader(
				getClass().getClassLoader().getResourceAsStream("flink_11-kryo_registrations")))) {

			String line;
			while ((line = reader.readLine()) != null) {
				String[] split = line.split(",");
				final int tag = Integer.parseInt(split[0]);
				final String registeredClass = split[1];

				Registration registration = kryo.getRegistration(tag);

				if (registration == null) {
					fail(String.format("Registration for %d = %s got lost", tag, registeredClass));
				}
				else if (!registeredClass.equals(registration.getType().getName())) {
					fail(String.format("Registration for %d = %s changed to %s",
							tag, registeredClass, registration.getType().getName()));
				}
			}
		}
	}

	/**
	 * Creates a Kryo serializer and writes the default registrations out to a
	 * comma separated file with one entry per line:
	 *
	 * <pre>
	 * id,class
	 * </pre>
	 *
	 * <p>The produced file is used to check that the registered IDs don't change
	 * in future Flink versions.
	 *
	 * <p>This method is not used in the tests, but documents how the test file
	 * has been created and can be used to re-create it if needed.
	 *
	 * @param filePath File path to write registrations to
	 */
	private void writeDefaultKryoRegistrations(String filePath) throws IOException {
		final File file = new File(filePath);
		if (file.exists()) {
			assertTrue(file.delete());
		}

		final Kryo kryo = new KryoSerializer<>(Integer.class, new ExecutionConfig()).getKryo();
		final int nextId = kryo.getNextRegistrationId();

		try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
			for (int i = 0; i < nextId; i++) {
				Registration registration = kryo.getRegistration(i);
				String str = registration.getId() + "," + registration.getType().getName();
				writer.write(str, 0, str.length());
				writer.newLine();
			}

			System.out.println("Created file with registrations at " + file.getAbsolutePath());
		}
	}
}