content: /*
   * Copyright 2015, 2024 StreamEx contributors
   *
   * 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 one.util.streamex;
  
  import org.junit.Test;
  
  import java.util.*;
  import java.util.Map.Entry;
  import java.util.function.BiConsumer;
  import java.util.function.Function;
  import java.util.function.Supplier;
  import java.util.stream.Stream;
  
  import static one.util.streamex.TestHelpers.*;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotNull;
  
  /**
   * @author Tagir Valeev
   *
   */
  public class CollapseSpliteratorTest {
      private static <T> void splitEquals(Spliterator<T> source, BiConsumer<Spliterator<T>, Spliterator<T>> consumer) {
          Spliterator<T> right = new CollapseSpliterator<>(Objects::equals, Function.identity(), Internals
                  .selectFirst(), Internals.selectFirst(), source);
          Spliterator<T> left = right.trySplit();
          assertNotNull(left);
          consumer.accept(left, right);
      }
  
      @Test
      public void testSimpleSplit() {
          List<Integer> input = Arrays.asList(1, 1, 1, 2, 2, 2, 2, 2);
          splitEquals(input.spliterator(), (left, right) -> {
              List<Integer> result = new ArrayList<>();
              left.forEachRemaining(result::add);
              right.forEachRemaining(result::add);
              assertEquals(Arrays.asList(1, 2), result);
          });
          splitEquals(input.spliterator(), (left, right) -> {
              List<Integer> result = new ArrayList<>();
              List<Integer> resultRight = new ArrayList<>();
              right.forEachRemaining(resultRight::add);
              left.forEachRemaining(result::add);
              result.addAll(resultRight);
              assertEquals(Arrays.asList(1, 2), result);
          });
          input = IntStreamEx.of(new Random(1), 100, 1, 10).sorted().boxed().toList();
          splitEquals(input.spliterator(), (left, right) -> {
              List<Integer> result = new ArrayList<>();
              List<Integer> resultRight = new ArrayList<>();
              for (int i = 0; i < 10; i++) {
                  left.tryAdvance(result::add);
                  right.tryAdvance(resultRight::add);
              }
              result.addAll(resultRight);
              assertEquals(IntStreamEx.range(1, 10).boxed().toList(), result);
          });
          input = IntStreamEx.constant(100, 100).append(2).prepend(1).boxed().toList();
          splitEquals(StreamEx.of(input).without(100).parallel().spliterator(), (left, right) -> {
              List<Integer> result = new ArrayList<>();
              left.forEachRemaining(result::add);
              right.forEachRemaining(result::add);
              assertEquals(Arrays.asList(1, 2), result);
          });
          input = Arrays.asList(0, 0, 1, 1, 1, 1, 4, 6, 6, 3, 3, 10);
          splitEquals(Stream.concat(Stream.empty(), input.parallelStream()).spliterator(), (left, right) -> {
              List<Integer> result = new ArrayList<>();
              left.forEachRemaining(result::add);
              right.forEachRemaining(result::add);
              assertEquals(Arrays.asList(0, 1, 4, 6, 3, 10), result);
          });
      }
  
      @Test
      public void testNonIdentity() {
          checkNonIdentity(Arrays.asList(1, 2, 5, 6, 7, 8, 10, 11, 15));
          checkNonIdentity(IntStreamEx.range(3, 100).prepend(1).boxed().toList());
      }
  
      private static void checkNonIdentity(List<Integer> input) {
          checkSpliterator("collpase", () -> new CollapseSpliterator<Integer, Entry<Integer, Integer>>(
                  (a, b) -> (b - a == 1), a -> new AbstractMap.SimpleEntry<>(a, a),
                  (acc, a) -> new AbstractMap.SimpleEntry<>(acc.getKey(), a), (a, b) -> new AbstractMap.SimpleEntry<>(a
                          .getKey(), b.getValue()), input.spliterator()));
      }
  
      @Test
      public void testMultiSplit() {
          List<Integer> input = Arrays.asList(0, 0, 1, 1, 1, 1, 4, 6, 6, 3, 3, 10);
          multiSplit(input::spliterator);
          multiSplit(() -> Stream.concat(Stream.empty(), input.parallelStream()).spliterator());
      }
  
      private static void multiSplit(Supplier<Spliterator<Integer>> inputSpliterator) throws AssertionError {
          withRandom(r -> repeat(100, n -> {
              Spliterator<Integer> spliterator = new CollapseSpliterator<>(Objects::equals, Function.identity(),
                      Internals.selectFirst(), Internals.selectFirst(), inputSpliterator.get());
              List<Integer> result = new ArrayList<>();
              List<Spliterator<Integer>> spliterators = new ArrayList<>();
              spliterators.add(spliterator);
              for (int i = 0; i < 8; i++) {
                  Spliterator<Integer> split = spliterators.get(r.nextInt(spliterators.size())).trySplit();
                  if (split != null)
                      spliterators.add(split);
              }
              Collections.shuffle(spliterators, r);
              repeat(spliterators.size(), i -> spliterators.get(i - 1).forEachRemaining(result::add));
              assertEquals(6, result.size());
          }));
      }
  }
  