/*
 * 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.wayang.java.operators;

import org.apache.wayang.basic.data.Tuple2;
import org.apache.wayang.basic.function.ProjectionDescriptor;
import org.apache.wayang.core.function.ReduceDescriptor;
import org.apache.wayang.core.types.DataSetType;
import org.apache.wayang.core.types.DataUnitType;
import org.apache.wayang.java.channels.JavaChannelInstance;
import org.junit.jupiter.api.Test;

import java.util.Arrays;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

/**
 * Test suite for {@link JavaReduceByOperator}.
 */
class JavaReduceByOperatorTest extends JavaExecutionOperatorTestBase {

    @Test
    void testExecution() {
        // Prepare test data.
        Stream<Tuple2<String, Integer>> inputStream = Arrays.stream("aaabbccccdeefff".split(""))
                .map(string -> new Tuple2<>(string, 1));

        // Build the reduce operator.
        JavaReduceByOperator<Tuple2<String, Integer>, String> reduceByOperator =
                new JavaReduceByOperator<>(
                        DataSetType.createDefaultUnchecked(Tuple2.class),
                        new ProjectionDescriptor<>(
                                DataUnitType.createBasicUnchecked(Tuple2.class),
                                DataUnitType.createBasic(String.class),
                                "field0"),
                        new ReduceDescriptor<>(
                                (a, b) -> {
                                    a.field1 += b.field1;
                                    return a;
                                }, DataUnitType.createGroupedUnchecked(Tuple2.class),
                                DataUnitType.createBasicUnchecked(Tuple2.class)
                        ));

        JavaChannelInstance[] inputs = new JavaChannelInstance[]{createStreamChannelInstance(inputStream)};
        JavaChannelInstance[] outputs = new JavaChannelInstance[]{createCollectionChannelInstance()};

        // Execute the reduce operator.
        evaluate(reduceByOperator, inputs, outputs);

        // Verify the outcome.
        final Set<Tuple2<String, Integer>> result =
                outputs[0].<Tuple2<String, Integer>>provideStream().collect(Collectors.toSet());
        final Tuple2[] expectedResults = {
                new Tuple2<>("a", 3),
                new Tuple2<>("b", 2),
                new Tuple2<>("c", 4),
                new Tuple2<>("d", 1),
                new Tuple2<>("e", 2),
                new Tuple2<>("f", 3)
        };
        Arrays.stream(expectedResults)
                .forEach(expected -> assertTrue(result.contains(expected), "Not contained: " + expected));
        assertEquals(expectedResults.length, result.size());

    }
}
