/*
 * 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.operators;

import org.apache.flink.api.common.functions.GroupReduceFunction;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.functions.RichReduceFunction;
import org.apache.flink.api.common.operators.base.ReduceOperatorBase.CombineHint;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.tuple.Tuple3;
import org.apache.flink.api.java.tuple.Tuple5;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.test.operators.util.CollectionDataSets;
import org.apache.flink.test.operators.util.CollectionDataSets.CustomType;
import org.apache.flink.test.operators.util.CollectionDataSets.PojoWithDateAndEnum;
import org.apache.flink.test.util.MultipleProgramsTestBase;
import org.apache.flink.util.Collector;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;

import java.util.Collection;
import java.util.Date;
import java.util.List;

/** Integration tests for {@link ReduceFunction} and {@link RichReduceFunction}. */
@SuppressWarnings("serial")
@RunWith(Parameterized.class)
public class ReduceITCase extends MultipleProgramsTestBase {

    public ReduceITCase(TestExecutionMode mode) {
        super(mode);
    }

    @Test
    public void testReduceOnTuplesWithKeyFieldSelector() throws Exception {
        /*
         * Reduce on tuples with key field selector
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
        DataSet<Tuple3<Integer, Long, String>> reduceDs =
                ds.groupBy(1).reduce(new Tuple3Reduce("B-)"));

        List<Tuple3<Integer, Long, String>> result = reduceDs.collect();

        String expected =
                "1,1,Hi\n"
                        + "5,2,B-)\n"
                        + "15,3,B-)\n"
                        + "34,4,B-)\n"
                        + "65,5,B-)\n"
                        + "111,6,B-)\n";

        compareResultAsTuples(result, expected);
    }

    @Test
    public void testReduceOnTupleWithMultipleKeyFieldSelectors() throws Exception {
        /*
         * Reduce on tuples with multiple key field selectors
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple5<Integer, Long, Integer, String, Long>> ds =
                CollectionDataSets.get5TupleDataSet(env);
        DataSet<Tuple5<Integer, Long, Integer, String, Long>> reduceDs =
                ds.groupBy(4, 0)
                        .reduce(
                                (in1, in2) -> {
                                    Tuple5<Integer, Long, Integer, String, Long> out =
                                            new Tuple5<>();
                                    out.setFields(in1.f0, in1.f1 + in2.f1, 0, "P-)", in1.f4);
                                    return out;
                                });

        List<Tuple5<Integer, Long, Integer, String, Long>> result = reduceDs.collect();

        String expected =
                "1,1,0,Hallo,1\n"
                        + "2,3,2,Hallo Welt wie,1\n"
                        + "2,2,1,Hallo Welt,2\n"
                        + "3,9,0,P-),2\n"
                        + "3,6,5,BCD,3\n"
                        + "4,17,0,P-),1\n"
                        + "4,17,0,P-),2\n"
                        + "5,11,10,GHI,1\n"
                        + "5,29,0,P-),2\n"
                        + "5,25,0,P-),3\n";

        compareResultAsTuples(result, expected);
    }

    @Test
    public void testReduceOnTuplesWithKeyExtractor() throws Exception {
        /*
         * Reduce on tuples with key extractor
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
        DataSet<Tuple3<Integer, Long, String>> reduceDs =
                ds.groupBy(new KeySelector1()).reduce(new Tuple3Reduce("B-)"));

        List<Tuple3<Integer, Long, String>> result = reduceDs.collect();

        String expected =
                "1,1,Hi\n"
                        + "5,2,B-)\n"
                        + "15,3,B-)\n"
                        + "34,4,B-)\n"
                        + "65,5,B-)\n"
                        + "111,6,B-)\n";

        compareResultAsTuples(result, expected);
    }

    private static class KeySelector1 implements KeySelector<Tuple3<Integer, Long, String>, Long> {
        private static final long serialVersionUID = 1L;

        @Override
        public Long getKey(Tuple3<Integer, Long, String> in) {
            return in.f1;
        }
    }

    @Test
    public void testReduceOnCustomTypeWithKeyExtractor() throws Exception {
        /*
         * Reduce on custom type with key extractor
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<CustomType> ds = CollectionDataSets.getCustomTypeDataSet(env);
        DataSet<CustomType> reduceDs =
                ds.groupBy(new KeySelector2()).reduce(new CustomTypeReduce());

        List<CustomType> result = reduceDs.collect();

        String expected =
                "1,0,Hi\n"
                        + "2,3,Hello!\n"
                        + "3,12,Hello!\n"
                        + "4,30,Hello!\n"
                        + "5,60,Hello!\n"
                        + "6,105,Hello!\n";

        compareResultAsText(result, expected);
    }

    private static class KeySelector2 implements KeySelector<CustomType, Integer> {
        private static final long serialVersionUID = 1L;

        @Override
        public Integer getKey(CustomType in) {
            return in.myInt;
        }
    }

    @Test
    public void testAllReduceForTuple() throws Exception {
        /*
         * All-reduce for tuple
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
        DataSet<Tuple3<Integer, Long, String>> reduceDs = ds.reduce(new AllAddingTuple3Reduce());

        List<Tuple3<Integer, Long, String>> result = reduceDs.collect();

        String expected = "231,91,Hello World\n";

        compareResultAsTuples(result, expected);
    }

    @Test
    public void testAllReduceForCustomTypes() throws Exception {
        /*
         * All-reduce for custom types
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<CustomType> ds = CollectionDataSets.getCustomTypeDataSet(env);
        DataSet<CustomType> reduceDs = ds.reduce(new AllAddingCustomTypeReduce());

        List<CustomType> result = reduceDs.collect();

        String expected = "91,210,Hello!";

        compareResultAsText(result, expected);
    }

    @Test
    public void testReduceWithBroadcastSet() throws Exception {
        /*
         * Reduce with broadcast set
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Integer> intDs = CollectionDataSets.getIntegerDataSet(env);

        DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
        DataSet<Tuple3<Integer, Long, String>> reduceDs =
                ds.groupBy(1).reduce(new BCTuple3Reduce()).withBroadcastSet(intDs, "ints");

        List<Tuple3<Integer, Long, String>> result = reduceDs.collect();

        String expected =
                "1,1,Hi\n" + "5,2,55\n" + "15,3,55\n" + "34,4,55\n" + "65,5,55\n" + "111,6,55\n";

        compareResultAsTuples(result, expected);
    }

    @Test
    public void testReduceATupleReturningKeySelector() throws Exception {
        /*
         * Reduce with a Tuple-returning KeySelector
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple5<Integer, Long, Integer, String, Long>> ds =
                CollectionDataSets.get5TupleDataSet(env);
        DataSet<Tuple5<Integer, Long, Integer, String, Long>> reduceDs =
                ds.groupBy(new KeySelector3()).reduce(new Tuple5Reduce());

        List<Tuple5<Integer, Long, Integer, String, Long>> result = reduceDs.collect();

        String expected =
                "1,1,0,Hallo,1\n"
                        + "2,3,2,Hallo Welt wie,1\n"
                        + "2,2,1,Hallo Welt,2\n"
                        + "3,9,0,P-),2\n"
                        + "3,6,5,BCD,3\n"
                        + "4,17,0,P-),1\n"
                        + "4,17,0,P-),2\n"
                        + "5,11,10,GHI,1\n"
                        + "5,29,0,P-),2\n"
                        + "5,25,0,P-),3\n";

        compareResultAsTuples(result, expected);
    }

    private static class KeySelector3
            implements KeySelector<
                    Tuple5<Integer, Long, Integer, String, Long>, Tuple2<Integer, Long>> {
        private static final long serialVersionUID = 1L;

        @Override
        public Tuple2<Integer, Long> getKey(Tuple5<Integer, Long, Integer, String, Long> t) {
            return new Tuple2<Integer, Long>(t.f0, t.f4);
        }
    }

    @Test
    public void testReduceOnTupleWithMultipleKeyExpressions() throws Exception {
        /*
         * Case 2 with String-based field expression
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple5<Integer, Long, Integer, String, Long>> ds =
                CollectionDataSets.get5TupleDataSet(env);
        DataSet<Tuple5<Integer, Long, Integer, String, Long>> reduceDs =
                ds.groupBy("f4", "f0").reduce(new Tuple5Reduce());

        List<Tuple5<Integer, Long, Integer, String, Long>> result = reduceDs.collect();

        String expected =
                "1,1,0,Hallo,1\n"
                        + "2,3,2,Hallo Welt wie,1\n"
                        + "2,2,1,Hallo Welt,2\n"
                        + "3,9,0,P-),2\n"
                        + "3,6,5,BCD,3\n"
                        + "4,17,0,P-),1\n"
                        + "4,17,0,P-),2\n"
                        + "5,11,10,GHI,1\n"
                        + "5,29,0,P-),2\n"
                        + "5,25,0,P-),3\n";

        compareResultAsTuples(result, expected);
    }

    @Test
    public void testReduceOnTupleWithMultipleKeyExpressionsWithHashHint() throws Exception {
        /*
         * Case 2 with String-based field expression
         */

        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        DataSet<Tuple5<Integer, Long, Integer, String, Long>> ds =
                CollectionDataSets.get5TupleDataSet(env);
        DataSet<Tuple5<Integer, Long, Integer, String, Long>> reduceDs =
                ds.groupBy("f4", "f0").reduce(new Tuple5Reduce()).setCombineHint(CombineHint.HASH);

        List<Tuple5<Integer, Long, Integer, String, Long>> result = reduceDs.collect();

        String expected =
                "1,1,0,Hallo,1\n"
                        + "2,3,2,Hallo Welt wie,1\n"
                        + "2,2,1,Hallo Welt,2\n"
                        + "3,9,0,P-),2\n"
                        + "3,6,5,BCD,3\n"
                        + "4,17,0,P-),1\n"
                        + "4,17,0,P-),2\n"
                        + "5,11,10,GHI,1\n"
                        + "5,29,0,P-),2\n"
                        + "5,25,0,P-),3\n";

        compareResultAsTuples(result, expected);
    }

    @Test
    public void testSupportForDataAndEnumSerialization() throws Exception {
        /** Test support for Date and enum serialization */
        final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        DataSet<PojoWithDateAndEnum> ds = env.generateSequence(0, 2).map(new Mapper1());
        ds = ds.union(CollectionDataSets.getPojoWithDateAndEnum(env));

        DataSet<String> res = ds.groupBy("group").reduceGroup(new GroupReducer1());

        List<String> result = res.collect();

        String expected = "ok\nok";

        compareResultAsText(result, expected);
    }

    private static class Mapper1 implements MapFunction<Long, PojoWithDateAndEnum> {
        @Override
        public PojoWithDateAndEnum map(Long value) throws Exception {
            int l = value.intValue();
            switch (l) {
                case 0:
                    PojoWithDateAndEnum one = new PojoWithDateAndEnum();
                    one.group = "a";
                    one.date = new Date(666);
                    one.cat = CollectionDataSets.Category.CAT_A;
                    return one;
                case 1:
                    PojoWithDateAndEnum two = new PojoWithDateAndEnum();
                    two.group = "a";
                    two.date = new Date(666);
                    two.cat = CollectionDataSets.Category.CAT_A;
                    return two;
                case 2:
                    PojoWithDateAndEnum three = new PojoWithDateAndEnum();
                    three.group = "b";
                    three.date = new Date(666);
                    three.cat = CollectionDataSets.Category.CAT_B;
                    return three;
            }
            throw new RuntimeException("Unexpected value for l=" + l);
        }
    }

    private static class GroupReducer1
            implements GroupReduceFunction<CollectionDataSets.PojoWithDateAndEnum, String> {
        private static final long serialVersionUID = 1L;

        @Override
        public void reduce(Iterable<PojoWithDateAndEnum> values, Collector<String> out)
                throws Exception {
            for (PojoWithDateAndEnum val : values) {
                if (val.cat == CollectionDataSets.Category.CAT_A) {
                    Assert.assertEquals("a", val.group);
                } else if (val.cat == CollectionDataSets.Category.CAT_B) {
                    Assert.assertEquals("b", val.group);
                } else {
                    Assert.fail("error. Cat = " + val.cat);
                }
                Assert.assertEquals(666, val.date.getTime());
            }
            out.collect("ok");
        }
    }

    private static class Tuple3Reduce implements ReduceFunction<Tuple3<Integer, Long, String>> {
        private static final long serialVersionUID = 1L;
        private final Tuple3<Integer, Long, String> out = new Tuple3<Integer, Long, String>();
        private final String f2Replace;

        public Tuple3Reduce() {
            this.f2Replace = null;
        }

        public Tuple3Reduce(String f2Replace) {
            this.f2Replace = f2Replace;
        }

        @Override
        public Tuple3<Integer, Long, String> reduce(
                Tuple3<Integer, Long, String> in1, Tuple3<Integer, Long, String> in2)
                throws Exception {

            if (f2Replace == null) {
                out.setFields(in1.f0 + in2.f0, in1.f1, in1.f2);
            } else {
                out.setFields(in1.f0 + in2.f0, in1.f1, this.f2Replace);
            }
            return out;
        }
    }

    private static class Tuple5Reduce
            implements ReduceFunction<Tuple5<Integer, Long, Integer, String, Long>> {
        private static final long serialVersionUID = 1L;
        private final Tuple5<Integer, Long, Integer, String, Long> out =
                new Tuple5<Integer, Long, Integer, String, Long>();

        @Override
        public Tuple5<Integer, Long, Integer, String, Long> reduce(
                Tuple5<Integer, Long, Integer, String, Long> in1,
                Tuple5<Integer, Long, Integer, String, Long> in2)
                throws Exception {

            out.setFields(in1.f0, in1.f1 + in2.f1, 0, "P-)", in1.f4);
            return out;
        }
    }

    private static class CustomTypeReduce implements ReduceFunction<CustomType> {
        private static final long serialVersionUID = 1L;
        private final CustomType out = new CustomType();

        @Override
        public CustomType reduce(CustomType in1, CustomType in2) throws Exception {

            out.myInt = in1.myInt;
            out.myLong = in1.myLong + in2.myLong;
            out.myString = "Hello!";
            return out;
        }
    }

    private static class AllAddingTuple3Reduce
            implements ReduceFunction<Tuple3<Integer, Long, String>> {
        private static final long serialVersionUID = 1L;
        private final Tuple3<Integer, Long, String> out = new Tuple3<Integer, Long, String>();

        @Override
        public Tuple3<Integer, Long, String> reduce(
                Tuple3<Integer, Long, String> in1, Tuple3<Integer, Long, String> in2)
                throws Exception {

            out.setFields(in1.f0 + in2.f0, in1.f1 + in2.f1, "Hello World");
            return out;
        }
    }

    private static class AllAddingCustomTypeReduce implements ReduceFunction<CustomType> {
        private static final long serialVersionUID = 1L;
        private final CustomType out = new CustomType();

        @Override
        public CustomType reduce(CustomType in1, CustomType in2) throws Exception {

            out.myInt = in1.myInt + in2.myInt;
            out.myLong = in1.myLong + in2.myLong;
            out.myString = "Hello!";
            return out;
        }
    }

    private static class BCTuple3Reduce extends RichReduceFunction<Tuple3<Integer, Long, String>> {
        private static final long serialVersionUID = 1L;
        private final Tuple3<Integer, Long, String> out = new Tuple3<Integer, Long, String>();
        private String f2Replace = "";

        @Override
        public void open(Configuration config) {

            Collection<Integer> ints = this.getRuntimeContext().getBroadcastVariable("ints");
            int sum = 0;
            for (Integer i : ints) {
                sum += i;
            }
            f2Replace = sum + "";
        }

        @Override
        public Tuple3<Integer, Long, String> reduce(
                Tuple3<Integer, Long, String> in1, Tuple3<Integer, Long, String> in2)
                throws Exception {

            out.setFields(in1.f0 + in2.f0, in1.f1, this.f2Replace);
            return out;
        }
    }
}