/*
 * 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.graph;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.core.io.SimpleVersionedSerializer;
import org.apache.flink.runtime.checkpoint.MasterTriggerRestoreHook;
import org.apache.flink.runtime.checkpoint.MasterTriggerRestoreHook.Factory;
import org.apache.flink.runtime.concurrent.Future;
import org.apache.flink.runtime.jobgraph.JobGraph;
import org.apache.flink.streaming.api.checkpoint.WithMasterCheckpointHook;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.sink.DiscardingSink;
import org.apache.flink.streaming.api.functions.source.SourceFunction;

import org.apache.flink.util.SerializedValue;
import org.junit.Test;

import javax.annotation.Nullable;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.Executor;

import static java.util.Arrays.asList;
import static org.junit.Assert.*;

/**
 * Tests that when sources implement {@link WithMasterCheckpointHook} the hooks are properly
 * configured in the job's checkpoint settings.
 */
@SuppressWarnings("serial")
public class WithMasterCheckpointHookConfigTest {

	/**
	 * This test creates a program with 4 sources (2 with master hooks, 2 without).
	 * The resulting job graph must have 2 configured master hooks.
	 */
	@Test
	public void testHookConfiguration() throws Exception {
		// create some sources some of which configure master hooks
		final TestSource source1 = new TestSource();
		final TestSourceWithHook source2 = new TestSourceWithHook("foo");
		final TestSource source3 = new TestSource();
		final TestSourceWithHook source4 = new TestSourceWithHook("bar");

		final MapFunction<String, String> identity = new Identity<>();
		final IdentityWithHook<String> identityWithHook1 = new IdentityWithHook<>("apple");
		final IdentityWithHook<String> identityWithHook2 = new IdentityWithHook<>("orange");

		final Set<MasterTriggerRestoreHook<?>> hooks = new HashSet<MasterTriggerRestoreHook<?>>(asList(
				source2.createMasterTriggerRestoreHook(),
				source4.createMasterTriggerRestoreHook(),
				identityWithHook1.createMasterTriggerRestoreHook(),
				identityWithHook2.createMasterTriggerRestoreHook()));

		// we can instantiate a local environment here, because we never actually execute something
		final StreamExecutionEnvironment env = StreamExecutionEnvironment.createLocalEnvironment();
		env.enableCheckpointing(500);

		env
			.addSource(source1).map(identity)
			.union(env.addSource(source2).map(identity))
			.union(env.addSource(source3).map(identityWithHook1))
			.union(env.addSource(source4).map(identityWithHook2))
			.addSink(new DiscardingSink<String>());

		final JobGraph jg = env.getStreamGraph().getJobGraph();

		SerializedValue<Factory[]> serializedConfiguredHooks = jg.getCheckpointingSettings().getMasterHooks();
		assertNotNull(serializedConfiguredHooks);

		Factory[] configuredHooks = serializedConfiguredHooks.deserializeValue(getClass().getClassLoader());
		assertEquals(hooks.size(), configuredHooks.length);

		// check that all hooks are contained and exist exactly once
		for (Factory f : configuredHooks) {
			MasterTriggerRestoreHook<?> hook = f.create();
			assertTrue(hooks.remove(hook));
		}
		assertTrue(hooks.isEmpty());
	}

	// -----------------------------------------------------------------------

	private static class TestHook implements MasterTriggerRestoreHook<String> {

		private final String id;

		TestHook(String id) {
			this.id = id;
		}

		@Override
		public String getIdentifier() {
			return id;
		}

		@Override
		public Future<String> triggerCheckpoint(long checkpointId, long timestamp, Executor executor) {
			throw new UnsupportedOperationException();
		}

		@Override
		public void restoreCheckpoint(long checkpointId, @Nullable String checkpointData) throws Exception {
			throw new UnsupportedOperationException();
		}

		@Nullable
		@Override
		public SimpleVersionedSerializer<String> createCheckpointDataSerializer() {
			throw new UnsupportedOperationException();
		}

		@Override
		public boolean equals(Object obj) {
			return obj == this || (obj != null && obj.getClass() == getClass() && ((TestHook) obj).id.equals(id));
		}

		@Override
		public int hashCode() {
			return id.hashCode();
		}
	}

	// -----------------------------------------------------------------------

	private static class TestSource implements SourceFunction<String> {

		@Override
		public void run(SourceContext<String> ctx) {
			throw new UnsupportedOperationException();
		}

		@Override
		public void cancel() {}
	}

	// -----------------------------------------------------------------------

	private static class TestSourceWithHook extends TestSource implements WithMasterCheckpointHook<String> {

		private final String id;

		TestSourceWithHook(String id) {
			this.id = id;
		}

		@Override
		public TestHook createMasterTriggerRestoreHook() {
			return new TestHook(id);
		}
	}

	// -----------------------------------------------------------------------

	private static class Identity<T> implements MapFunction<T, T> {

		@Override
		public T map(T value) {
			return value;
		}
	}

	// -----------------------------------------------------------------------

	private static class IdentityWithHook<T> extends Identity<T> implements WithMasterCheckpointHook<String> {

		private final String id;

		IdentityWithHook(String id) {
			this.id = id;
		}

		@Override
		public TestHook createMasterTriggerRestoreHook() {
			return new TestHook(id);
		}
	}
}