// Copyright (c) 2022, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package desugaredlibrary;

import static com.android.tools.r8.desugar.desugaredlibrary.test.CompilationSpecification.DEFAULT_SPECIFICATIONS;
import static com.android.tools.r8.desugar.desugaredlibrary.test.LibraryDesugaringSpecification.JDK11;
import static com.android.tools.r8.desugar.desugaredlibrary.test.LibraryDesugaringSpecification.JDK11_LEGACY;
import static com.android.tools.r8.desugar.desugaredlibrary.test.LibraryDesugaringSpecification.JDK11_PATH;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import com.android.tools.r8.TestParameters;
import com.android.tools.r8.desugar.desugaredlibrary.DesugaredLibraryTestBase;
import com.android.tools.r8.desugar.desugaredlibrary.test.CompilationSpecification;
import com.android.tools.r8.desugar.desugaredlibrary.test.LibraryDesugaringSpecification;
import com.android.tools.r8.utils.AndroidApiLevel;
import com.android.tools.r8.utils.StringUtils;
import com.android.tools.r8.utils.codeinspector.CodeInspector;
import com.android.tools.r8.utils.codeinspector.MethodSubject;
import com.google.common.collect.ImmutableList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

@RunWith(Parameterized.class)
public class NewCollectorsTest extends DesugaredLibraryTestBase {

  private static final AndroidApiLevel NEW_COLLECTORS_LEVEL = AndroidApiLevel.T;

  private final TestParameters parameters;
  private final LibraryDesugaringSpecification libraryDesugaringSpecification;
  private final CompilationSpecification compilationSpecification;

  private static final String EXPECTED_OUTPUT = StringUtils.lines("1", "1", "1", "1", "1", "1");

  @Parameters(name = "{0}, spec: {1}, {2}")
  public static List<Object[]> data() {
    return buildParameters(
        getTestParameters().withDexRuntimes().withAllApiLevels().build(),
        ImmutableList.of(JDK11, JDK11_PATH, JDK11_LEGACY),
        DEFAULT_SPECIFICATIONS);
  }

  public NewCollectorsTest(
      TestParameters parameters,
      LibraryDesugaringSpecification libraryDesugaringSpecification,
      CompilationSpecification compilationSpecification) {
    this.parameters = parameters;
    this.libraryDesugaringSpecification = libraryDesugaringSpecification;
    this.compilationSpecification = compilationSpecification;
  }

  @Test
  public void test() throws Throwable {
    testForDesugaredLibrary(parameters, libraryDesugaringSpecification, compilationSpecification)
        .addInnerClassesAndStrippedOuter(getClass())
        .addKeepMainRule(Main.class)
        .compile()
        .inspect(this::assertCollectors)
        .run(parameters.getRuntime(), Main.class)
        .assertSuccessWithOutput(EXPECTED_OUTPUT);
  }

  private void assertCollectors(CodeInspector inspector) {
    MethodSubject methodSubject = inspector.clazz(Main.class).mainMethod();
    assertTrue(methodSubject.isPresent());
    if (libraryDesugaringSpecification.hasEmulatedInterfaceDesugaring(parameters)) {
      // Collectors is not present, all calls to the j$ version.
      assertTrue(anyStaticInvokeToHolder(methodSubject, "j$.util.stream.Collectors"));
      // In JDK11_LEGACY DesugarCollectors is used whenever possible, in other specifications,
      // it is used only when needed.
      assertEquals(
          libraryDesugaringSpecification == JDK11_LEGACY,
          anyStaticInvokeToHolder(methodSubject, "j$.util.stream.DesugarCollectors"));
      assertFalse(anyStaticInvokeToHolder(methodSubject, "java.util.stream.Collectors"));
      return;
    }
    if (parameters.getApiLevel().isLessThan(NEW_COLLECTORS_LEVEL)) {
      // Collectors is present, but partially, calls to java Collectors and DesugarCollectors.
      assertFalse(anyStaticInvokeToHolder(methodSubject, "j$.util.stream.Collectors"));
      assertTrue(anyStaticInvokeToHolder(methodSubject, "j$.util.stream.DesugarCollectors"));
      assertTrue(anyStaticInvokeToHolder(methodSubject, "java.util.stream.Collectors"));
      return;
    }
    // Collectors is fully present, all calls to java Collectors.
    assertFalse(anyStaticInvokeToHolder(methodSubject, "j$.util.stream.Collectors"));
    assertFalse(anyStaticInvokeToHolder(methodSubject, "j$.util.stream.DesugarCollectors"));
    assertTrue(anyStaticInvokeToHolder(methodSubject, "java.util.stream.Collectors"));
  }

  private boolean anyStaticInvokeToHolder(MethodSubject methodSubject, String holder) {
    return methodSubject
        .streamInstructions()
        .anyMatch(
            i -> i.isInvokeStatic() && i.getMethod().getHolderType().toString().equals(holder));
  }

  public static class Main {

    public static void main(String[] args) {
      Collector<Object, ?, List<Object>> filtering =
          Collectors.filtering(Objects::nonNull, Collectors.toList());
      System.out.println(Stream.of(null, 1).collect(filtering).get(0));

      Collector<List<?>, ?, List<Object>> collector =
          Collectors.flatMapping(Collection::stream, Collectors.toList());
      System.out.println(Stream.of(List.of(1)).collect(collector).get(0));

      Collector<Object, ?, List<Object>> toList = Collectors.toUnmodifiableList();
      System.out.println(Stream.of(1).collect(toList).get(0));
      Collector<Object, ?, Set<Object>> toSet = Collectors.toUnmodifiableSet();
      System.out.println(Stream.of(1).collect(toSet).iterator().next());
      Collector<Object, ?, Map<String, Integer>> toMap1 =
          Collectors.toUnmodifiableMap(Object::toString, Object::hashCode);
      System.out.println(Stream.of(1).collect(toMap1).keySet().iterator().next());
      Collector<Object, ?, Map<String, Integer>> toMap2 =
          Collectors.toUnmodifiableMap(Object::toString, Object::hashCode, (x, y) -> x);
      System.out.println(Stream.of(1).collect(toMap2).keySet().iterator().next());
    }
  }
}