/*
 * 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.test.iterative;

import java.io.BufferedReader;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.aggregation.Aggregations;
import org.apache.flink.api.java.operators.DeltaIteration;
import org.apache.flink.api.java.tuple.Tuple1;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.examples.java.graph.ConnectedComponents;
import org.apache.flink.test.testdata.ConnectedComponentsData;
import org.apache.flink.test.util.JavaProgramTestBase;


public class ConnectedComponentsITCase extends JavaProgramTestBase {
	
	private static final long SEED = 0xBADC0FFEEBEEFL;
	
	private static final int NUM_VERTICES = 1000;
	
	private static final int NUM_EDGES = 10000;

	
	protected String verticesPath;
	protected String edgesPath;
	protected String resultPath;

	@Override
	protected void preSubmit() throws Exception {
		verticesPath = createTempFile("vertices.txt", ConnectedComponentsData.getEnumeratingVertices(NUM_VERTICES));
		edgesPath = createTempFile("edges.txt", ConnectedComponentsData.getRandomOddEvenEdges(NUM_EDGES, NUM_VERTICES, SEED));
		resultPath = getTempFilePath("results");
	}

	@Override
	protected void testProgram() throws Exception {
		// set up execution environment
		ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

		// read vertex and edge data
		DataSet<Tuple1<Long>> vertices = env.readCsvFile(verticesPath).types(Long.class);

		DataSet<Tuple2<Long, Long>> edges = env.readCsvFile(edgesPath).fieldDelimiter(" ").types(Long.class, Long.class)
				.flatMap(new ConnectedComponents.UndirectEdge());

		// assign the initial components (equal to the vertex id)
		DataSet<Tuple2<Long, Long>> verticesWithInitialId = vertices.map(new DuplicateValue<Long>());

		// open a delta iteration
		DeltaIteration<Tuple2<Long, Long>, Tuple2<Long, Long>> iteration =
				verticesWithInitialId.iterateDelta(verticesWithInitialId, 100, 0);

		// apply the step logic: join with the edges, select the minimum neighbor, update if the component of the candidate is smaller
		DataSet<Tuple2<Long, Long>> changes = iteration.getWorkset().join(edges).where(0).equalTo(0).with(new ConnectedComponents.NeighborWithComponentIDJoin())
				.groupBy(0).aggregate(Aggregations.MIN, 1)
				.join(iteration.getSolutionSet()).where(0).equalTo(0)
				.with(new ConnectedComponents.ComponentIdFilter());

		// close the delta iteration (delta and new workset are identical)
		DataSet<Tuple2<Long, Long>> result = iteration.closeWith(changes, changes);

		result.writeAsCsv(resultPath, "\n", " ");

		// execute program
		env.execute("Connected Components Example");
	}

	@Override
	protected void postSubmit() throws Exception {
		for (BufferedReader reader : getResultReader(resultPath)) {
			ConnectedComponentsData.checkOddEvenResult(reader);
		}
	}

	public static final class DuplicateValue<T> implements MapFunction<Tuple1<T>, Tuple2<T, T>> {

		@Override
		public Tuple2<T, T> map(Tuple1<T> vertex) {
			return new Tuple2<>(vertex.f0, vertex.f0);
		}
	}
}