/***********************************************************************************************************************
 * Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
 *
 * Licensed 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 eu.stratosphere.test.iterative;

import java.io.Serializable;
import java.util.Iterator;

import eu.stratosphere.test.util.RecordAPITestBase;
import org.junit.Assert;

import eu.stratosphere.api.common.Plan;
import eu.stratosphere.api.java.record.operators.BulkIteration;
import eu.stratosphere.api.java.record.operators.FileDataSink;
import eu.stratosphere.api.java.record.operators.FileDataSource;
import eu.stratosphere.api.java.record.functions.MapFunction;
import eu.stratosphere.api.java.record.functions.ReduceFunction;
import eu.stratosphere.api.java.record.io.CsvOutputFormat;
import eu.stratosphere.api.java.record.io.TextInputFormat;
import eu.stratosphere.api.java.record.operators.MapOperator;
import eu.stratosphere.api.java.record.operators.ReduceOperator;
import eu.stratosphere.types.Record;
import eu.stratosphere.types.StringValue;
import eu.stratosphere.util.Collector;

public class IterationTerminationWithTerminationTail extends RecordAPITestBase {

	private static final String INPUT = "1\n" + "2\n" + "3\n" + "4\n" + "5\n";
	private static final String EXPECTED = "22\n";

	protected String dataPath;
	protected String resultPath;
	
	@Override
	protected void preSubmit() throws Exception {
		dataPath = createTempFile("datapoints.txt", INPUT);
		resultPath = getTempFilePath("result");
	}
	
	@Override
	protected void postSubmit() throws Exception {
		compareResultsByLinesInMemory(EXPECTED, resultPath);
	}

	@Override
	protected Plan getTestJob() {
		return getTestPlanPlan(4, dataPath, resultPath);
	}
	
	private static Plan getTestPlanPlan(int numSubTasks, String input, String output) {

		FileDataSource initialInput = new FileDataSource(TextInputFormat.class, input, "input");
		
		BulkIteration iteration = new BulkIteration("Loop");
		iteration.setInput(initialInput);
		iteration.setMaximumNumberOfIterations(5);
		Assert.assertTrue(iteration.getMaximumNumberOfIterations() > 1);

		ReduceOperator sumReduce = ReduceOperator.builder(new SumReducer())
				.input(iteration.getPartialSolution())
				.name("Compute sum (Reduce)")
				.build();
		
		iteration.setNextPartialSolution(sumReduce);
		
		MapOperator terminationMapper = MapOperator.builder(new TerminationMapper())
				.input(sumReduce)
				.name("Compute termination criterion (Map)")
				.build();
		
		iteration.setTerminationCriterion(terminationMapper);

		FileDataSink finalResult = new FileDataSink(CsvOutputFormat.class, output, iteration, "Output");
		CsvOutputFormat.configureRecordFormat(finalResult)
			.recordDelimiter('\n')
			.fieldDelimiter(' ')
			.field(StringValue.class, 0);

		Plan plan = new Plan(finalResult, "Iteration with AllReducer (keyless Reducer)");
		plan.setDefaultParallelism(numSubTasks);
		Assert.assertTrue(plan.getDefaultParallelism() > 1);
		return plan;
	}
	
	public static final class SumReducer extends ReduceFunction implements Serializable {
		
		private static final long serialVersionUID = 1L;
		
		@Override
		public void reduce(Iterator<Record> it, Collector<Record> out) {
			// Compute the sum
			int sum = 0;
			while (it.hasNext()) {
				sum += Integer.parseInt(it.next().getField(0, StringValue.class).getValue()) + 1;
			}
			
			out.collect(new Record(new StringValue(Integer.toString(sum))));
		}
	}
	
	public static class TerminationMapper extends MapFunction implements Serializable {
		private static final long serialVersionUID = 1L;
		
		@Override
		public void map(Record record, Collector<Record> collector) {
			
			int currentSum = Integer.parseInt(record.getField(0, StringValue.class).getValue());

			if(currentSum < 22)
				collector.collect(record);
		}
	}

}