/*
 * 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.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.List;
import java.util.concurrent.atomic.AtomicInteger;
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 JavaMaterializedGroupByOperatorTest extends JavaExecutionOperatorTestBase {

    @Test
    void testExecution() {
        // Prepare test data.
        AtomicInteger counter = new AtomicInteger(0);
        Stream<Tuple2<String, Integer>> inputStream = Arrays.stream("abcaba".split(""))
                .map(string -> new Tuple2<>(string, counter.getAndIncrement()));

        // Build the reduce operator.
        JavaMaterializedGroupByOperator<Tuple2<String, Integer>, String> collocateByOperator =
                new JavaMaterializedGroupByOperator<>(
                        new ProjectionDescriptor<>(
                                DataUnitType.createBasicUnchecked(Tuple2.class),
                                DataUnitType.createBasicUnchecked(Tuple2.class),
                                "field0"),
                        DataSetType.createDefaultUnchecked(Tuple2.class),
                        DataSetType.createGroupedUnchecked(Tuple2.class)
                );

        // Execute.
        JavaChannelInstance[] inputs = new JavaChannelInstance[]{createStreamChannelInstance(inputStream)};
        JavaChannelInstance[] outputs = new JavaChannelInstance[]{createCollectionChannelInstance()};
        evaluate(collocateByOperator, inputs, outputs);

        // Verify the outcome.
        final List<Tuple2<String, Integer>> result = outputs[0].<Tuple2<String, Integer>>provideStream()
                .collect(Collectors.toList());
        final List[] expectedResults = {
                Arrays.asList(new Tuple2<>("a", 0), new Tuple2<>("a", 3), new Tuple2<>("a", 5)),
                Arrays.asList(new Tuple2<>("b", 1), new Tuple2<>("b", 4)),
                Arrays.asList(new Tuple2<>("c", 2))
        };
        Arrays.stream(expectedResults)
                .forEach(expected -> assertTrue(result.contains(expected), "Not contained: " + expected));
        assertEquals(expectedResults.length, result.size());

    }
}
