/*
 * 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.graph.pregel;

import org.apache.flink.api.common.Plan;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.operators.util.FieldList;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.io.DiscardingOutputFormat;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.graph.Edge;
import org.apache.flink.graph.Graph;
import org.apache.flink.graph.Vertex;
import org.apache.flink.graph.utils.Tuple2ToVertexMap;
import org.apache.flink.optimizer.plan.DualInputPlanNode;
import org.apache.flink.optimizer.plan.OptimizedPlan;
import org.apache.flink.optimizer.plan.PlanNode;
import org.apache.flink.optimizer.plan.SingleInputPlanNode;
import org.apache.flink.optimizer.plan.SinkPlanNode;
import org.apache.flink.optimizer.plan.WorksetIterationPlanNode;
import org.apache.flink.optimizer.util.CompilerTestBase;
import org.apache.flink.runtime.operators.shipping.ShipStrategyType;
import org.apache.flink.types.NullValue;

import org.junit.Test;

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

/**
 * Validate compiled {@link VertexCentricIteration} programs.
 */
public class PregelCompilerTest extends CompilerTestBase {

	private static final long serialVersionUID = 1L;

	@SuppressWarnings("serial")
	@Test
	public void testPregelCompiler() {
		ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
		env.setParallelism(DEFAULT_PARALLELISM);
		// compose test program
		{

			DataSet<Vertex<Long, Long>> initialVertices = env.fromElements(
				new Tuple2<>(1L, 1L), new Tuple2<>(2L, 2L))
				.map(new Tuple2ToVertexMap<>());

			DataSet<Edge<Long, NullValue>> edges = env.fromElements(new Tuple2<>(1L, 2L))
				.map(new MapFunction<Tuple2<Long, Long>, Edge<Long, NullValue>>() {

					public Edge<Long, NullValue> map(Tuple2<Long, Long> edge) {
						return new Edge<>(edge.f0, edge.f1, NullValue.getInstance());
					}
				});

			Graph<Long, Long, NullValue> graph = Graph.fromDataSet(initialVertices, edges, env);

			DataSet<Vertex<Long, Long>> result = graph.runVertexCentricIteration(
				new CCCompute(), null, 100).getVertices();

			result.output(new DiscardingOutputFormat<>());
		}

		Plan p = env.createProgramPlan("Pregel Connected Components");
		OptimizedPlan op = compileNoStats(p);

		// check the sink
		SinkPlanNode sink = op.getDataSinks().iterator().next();
		assertEquals(ShipStrategyType.FORWARD, sink.getInput().getShipStrategy());
		assertEquals(DEFAULT_PARALLELISM, sink.getParallelism());

		// check the iteration
		WorksetIterationPlanNode iteration = (WorksetIterationPlanNode) sink.getInput().getSource();
		assertEquals(DEFAULT_PARALLELISM, iteration.getParallelism());

		// check the solution set delta
		PlanNode ssDelta = iteration.getSolutionSetDeltaPlanNode();
		assertTrue(ssDelta instanceof SingleInputPlanNode);

		SingleInputPlanNode ssFlatMap = (SingleInputPlanNode) ((SingleInputPlanNode) (ssDelta)).getInput().getSource();
		assertEquals(DEFAULT_PARALLELISM, ssFlatMap.getParallelism());
		assertEquals(ShipStrategyType.FORWARD, ssFlatMap.getInput().getShipStrategy());

		// check the computation coGroup
		DualInputPlanNode computationCoGroup = (DualInputPlanNode) (ssFlatMap.getInput().getSource());
		assertEquals(DEFAULT_PARALLELISM, computationCoGroup.getParallelism());
		assertEquals(ShipStrategyType.FORWARD, computationCoGroup.getInput1().getShipStrategy());
		assertEquals(ShipStrategyType.PARTITION_HASH, computationCoGroup.getInput2().getShipStrategy());
		assertTrue(computationCoGroup.getInput2().getTempMode().isCached());

		assertEquals(new FieldList(0), computationCoGroup.getInput2().getShipStrategyKeys());

		// check that the initial partitioning is pushed out of the loop
		assertEquals(ShipStrategyType.PARTITION_HASH, iteration.getInput1().getShipStrategy());
		assertEquals(new FieldList(0), iteration.getInput1().getShipStrategyKeys());
	}

	@SuppressWarnings("serial")
	@Test
	public void testPregelCompilerWithBroadcastVariable() {
		final String broadcastSetName = "broadcast";

		ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
		env.setParallelism(DEFAULT_PARALLELISM);
		// compose test program
		{
			DataSet<Long> bcVar = env.fromElements(1L);

			DataSet<Vertex<Long, Long>> initialVertices = env.fromElements(
				new Tuple2<>(1L, 1L), new Tuple2<>(2L, 2L))
				.map(new Tuple2ToVertexMap<>());

			DataSet<Edge<Long, NullValue>> edges = env.fromElements(new Tuple2<>(1L, 2L))
				.map(new MapFunction<Tuple2<Long, Long>, Edge<Long, NullValue>>() {

					public Edge<Long, NullValue> map(Tuple2<Long, Long> edge) {
						return new Edge<>(edge.f0, edge.f1, NullValue.getInstance());
					}
				});

			Graph<Long, Long, NullValue> graph = Graph.fromDataSet(initialVertices, edges, env);

			VertexCentricConfiguration parameters = new VertexCentricConfiguration();
			parameters.addBroadcastSet(broadcastSetName, bcVar);

			DataSet<Vertex<Long, Long>> result = graph.runVertexCentricIteration(
				new CCCompute(), null, 100, parameters)
				.getVertices();

			result.output(new DiscardingOutputFormat<>());
		}

		Plan p = env.createProgramPlan("Pregel Connected Components");
		OptimizedPlan op = compileNoStats(p);

		// check the sink
		SinkPlanNode sink = op.getDataSinks().iterator().next();
		assertEquals(ShipStrategyType.FORWARD, sink.getInput().getShipStrategy());
		assertEquals(DEFAULT_PARALLELISM, sink.getParallelism());

		// check the iteration
		WorksetIterationPlanNode iteration = (WorksetIterationPlanNode) sink.getInput().getSource();
		assertEquals(DEFAULT_PARALLELISM, iteration.getParallelism());

		// check the solution set delta
		PlanNode ssDelta = iteration.getSolutionSetDeltaPlanNode();
		assertTrue(ssDelta instanceof SingleInputPlanNode);

		SingleInputPlanNode ssFlatMap = (SingleInputPlanNode) ((SingleInputPlanNode) (ssDelta)).getInput().getSource();
		assertEquals(DEFAULT_PARALLELISM, ssFlatMap.getParallelism());
		assertEquals(ShipStrategyType.FORWARD, ssFlatMap.getInput().getShipStrategy());

		// check the computation coGroup
		DualInputPlanNode computationCoGroup = (DualInputPlanNode) (ssFlatMap.getInput().getSource());
		assertEquals(DEFAULT_PARALLELISM, computationCoGroup.getParallelism());
		assertEquals(ShipStrategyType.FORWARD, computationCoGroup.getInput1().getShipStrategy());
		assertEquals(ShipStrategyType.PARTITION_HASH, computationCoGroup.getInput2().getShipStrategy());
		assertTrue(computationCoGroup.getInput2().getTempMode().isCached());

		assertEquals(new FieldList(0), computationCoGroup.getInput2().getShipStrategyKeys());

		// check that the initial partitioning is pushed out of the loop
		assertEquals(ShipStrategyType.PARTITION_HASH, iteration.getInput1().getShipStrategy());
		assertEquals(new FieldList(0), iteration.getInput1().getShipStrategyKeys());
	}

	@SuppressWarnings("serial")
	@Test
	public void testPregelWithCombiner() {
		ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
		env.setParallelism(DEFAULT_PARALLELISM);
		// compose test program
		{

			DataSet<Vertex<Long, Long>> initialVertices = env.fromElements(
				new Tuple2<>(1L, 1L), new Tuple2<>(2L, 2L))
				.map(new Tuple2ToVertexMap<>());

			DataSet<Edge<Long, NullValue>> edges = env.fromElements(new Tuple2<>(1L, 2L))
				.map(new MapFunction<Tuple2<Long, Long>, Edge<Long, NullValue>>() {

					public Edge<Long, NullValue> map(Tuple2<Long, Long> edge) {
						return new Edge<>(edge.f0, edge.f1, NullValue.getInstance());
					}
				});

			Graph<Long, Long, NullValue> graph = Graph.fromDataSet(initialVertices, edges, env);

			DataSet<Vertex<Long, Long>> result = graph.runVertexCentricIteration(
				new CCCompute(), new CCCombiner(), 100).getVertices();

			result.output(new DiscardingOutputFormat<>());
		}

		Plan p = env.createProgramPlan("Pregel Connected Components");
		OptimizedPlan op = compileNoStats(p);

		// check the sink
		SinkPlanNode sink = op.getDataSinks().iterator().next();
		assertEquals(ShipStrategyType.FORWARD, sink.getInput().getShipStrategy());
		assertEquals(DEFAULT_PARALLELISM, sink.getParallelism());

		// check the iteration
		WorksetIterationPlanNode iteration = (WorksetIterationPlanNode) sink.getInput().getSource();
		assertEquals(DEFAULT_PARALLELISM, iteration.getParallelism());

		// check the combiner
		SingleInputPlanNode combiner = (SingleInputPlanNode) iteration.getInput2().getSource();
		assertEquals(ShipStrategyType.FORWARD, combiner.getInput().getShipStrategy());

		// check the solution set delta
		PlanNode ssDelta = iteration.getSolutionSetDeltaPlanNode();
		assertTrue(ssDelta instanceof SingleInputPlanNode);

		SingleInputPlanNode ssFlatMap = (SingleInputPlanNode) ((SingleInputPlanNode) (ssDelta)).getInput().getSource();
		assertEquals(DEFAULT_PARALLELISM, ssFlatMap.getParallelism());
		assertEquals(ShipStrategyType.FORWARD, ssFlatMap.getInput().getShipStrategy());

		// check the computation coGroup
		DualInputPlanNode computationCoGroup = (DualInputPlanNode) (ssFlatMap.getInput().getSource());
		assertEquals(DEFAULT_PARALLELISM, computationCoGroup.getParallelism());
		assertEquals(ShipStrategyType.FORWARD, computationCoGroup.getInput1().getShipStrategy());
		assertEquals(ShipStrategyType.PARTITION_HASH, computationCoGroup.getInput2().getShipStrategy());
		assertTrue(computationCoGroup.getInput2().getTempMode().isCached());

		assertEquals(new FieldList(0), computationCoGroup.getInput2().getShipStrategyKeys());

		// check that the initial partitioning is pushed out of the loop
		assertEquals(ShipStrategyType.PARTITION_HASH, iteration.getInput1().getShipStrategy());
		assertEquals(new FieldList(0), iteration.getInput1().getShipStrategyKeys());
	}

	@SuppressWarnings("serial")
	private static final class CCCompute extends ComputeFunction<Long, Long, NullValue, Long> {

		@Override
		public void compute(Vertex<Long, Long> vertex, MessageIterator<Long> messages) throws Exception {
			long currentComponent = vertex.getValue();

			for (Long msg : messages) {
				currentComponent = Math.min(currentComponent, msg);
			}

			if ((getSuperstepNumber() == 1) || (currentComponent < vertex.getValue())) {
				setNewVertexValue(currentComponent);
				for (Edge<Long, NullValue> edge : getEdges()) {
					sendMessageTo(edge.getTarget(), currentComponent);
				}
			}
		}
	}

	@SuppressWarnings("serial")
	private static final class CCCombiner extends MessageCombiner<Long, Long> {

		public void combineMessages(MessageIterator<Long> messages) {

			long minMessage = Long.MAX_VALUE;
			for (Long msg : messages) {
				minMessage = Math.min(minMessage, msg);
			}
			sendCombinedMessage(minMessage);
		}
	}
}