// Copyright (c) 2019, 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 com.android.tools.r8.kotlin;

import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
import static org.hamcrest.CoreMatchers.not;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import com.android.tools.r8.ToolHelper.KotlinTargetVersion;
import com.android.tools.r8.utils.codeinspector.ClassSubject;
import com.android.tools.r8.utils.codeinspector.CodeInspector;
import com.android.tools.r8.utils.codeinspector.FieldSubject;
import com.android.tools.r8.utils.codeinspector.InstructionSubject;
import com.android.tools.r8.utils.codeinspector.InstructionSubject.JumboStringMode;
import com.android.tools.r8.utils.codeinspector.MethodSubject;
import com.google.common.collect.ImmutableList;
import org.junit.Test;

public class KotlinUnusedSingletonTest extends AbstractR8KotlinTestBase {

  private static final String printlnSignature =
      "void java.io.PrintStream.println(java.lang.Object)";

  public KotlinUnusedSingletonTest(
      KotlinTargetVersion targetVersion, boolean allowAccessModification) {
    super(targetVersion, allowAccessModification);
  }

  @Test
  public void b110196118() throws Exception {
    final String mainClassName = "unused_singleton.MainKt";
    final String moduleName = "unused_singleton.TestModule";
    runTest(
        "unused_singleton",
        mainClassName,
        "-dontobfuscate",
        app -> {
          CodeInspector inspector = new CodeInspector(app);
          ClassSubject main = inspector.clazz(mainClassName);
          assertThat(main, isPresent());

          MethodSubject mainMethod = main.mainMethod();
          assertThat(mainMethod, isPresent());

          // The const-string from provideGreeting() has been propagated.
          assertTrue(
              mainMethod
                  .iterateInstructions(i -> i.isConstString("Hello", JumboStringMode.ALLOW))
                  .hasNext());

          // The method provideGreeting() is no longer being invoked -- i.e., we have been able to
          // determine that the class initialization of the enclosing class is trivial.
          ClassSubject module = inspector.clazz(moduleName);
          assertThat(main, isPresent());
          assertEquals(
              0,
              mainMethod
                  .streamInstructions()
                  .filter(InstructionSubject::isInvoke)
                  .map(i -> i.getMethod().toSourceString())
                  .filter(
                      invokedMethod ->
                          !invokedMethod.equals(checkParameterIsNotNullSignature)
                              && !invokedMethod.equals(printlnSignature)
                              && !invokedMethod.equals(throwParameterIsNotNullExceptionSignature))
                  .count());

          // The field `INSTANCE` has been removed entirely.
          FieldSubject instance = module.uniqueFieldWithName("INSTANCE");
          assertThat(instance, not(isPresent()));

          // The class initializer is no longer there.
          MethodSubject clinit = module.clinit();
          assertThat(clinit, not(isPresent()));

          // Also, the instance initializer is no longer there, since it is only reachable from the
          // class initializer.
          MethodSubject init = module.init(ImmutableList.of());
          assertThat(init, not(isPresent()));
        });
  }
}