// Copyright (c) 2018, 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.optimize;

import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.DexClass;
import com.android.tools.r8.graph.DexEncodedMethod;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.graph.GraphLens;
import com.android.tools.r8.graph.GraphLens.NestedGraphLens;
import com.android.tools.r8.ir.code.Invoke.Type;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import java.util.Set;

final class PublicizerLens extends NestedGraphLens {

  private final AppView appView;
  private final Set<DexMethod> publicizedMethods;

  private PublicizerLens(AppView appView, Set<DexMethod> publicizedMethods) {
    super(
        ImmutableMap.of(),
        ImmutableMap.of(),
        ImmutableMap.of(),
        null,
        null,
        appView.graphLens(),
        appView.dexItemFactory());
    this.appView = appView;
    this.publicizedMethods = publicizedMethods;
  }

  @Override
  protected boolean isLegitimateToHaveEmptyMappings() {
    // This lens does not map any DexItem's at all.
    // It will just tweak invoke type for publicized methods from invoke-direct to invoke-virtual.
    return true;
  }

  @Override
  public GraphLensLookupResult lookupMethod(DexMethod method, DexMethod context, Type type) {
    GraphLensLookupResult previous = previousLens.lookupMethod(method, context, type);
    method = previous.getMethod();
    type = previous.getType();
    if (type == Type.DIRECT && publicizedMethods.contains(method)) {
      assert publicizedMethodIsPresentOnHolder(method, context);
      return new GraphLensLookupResult(method, Type.VIRTUAL);
    }
    return super.lookupMethod(method, context, type);
  }

  private boolean publicizedMethodIsPresentOnHolder(DexMethod method, DexMethod context) {
    GraphLensLookupResult lookup = appView.graphLens().lookupMethod(method, context, Type.VIRTUAL);
    DexMethod signatureInCurrentWorld = lookup.getMethod();
    DexClass clazz = appView.definitionFor(signatureInCurrentWorld.holder);
    assert clazz != null;
    DexEncodedMethod actualEncodedTarget = clazz.lookupVirtualMethod(signatureInCurrentWorld);
    assert actualEncodedTarget != null;
    assert actualEncodedTarget.isPublicized();
    return true;
  }

  static PublicizedLensBuilder createBuilder() {
    return new PublicizedLensBuilder();
  }

  static class PublicizedLensBuilder {
    private final Set<DexMethod> publicizedMethods = Sets.newIdentityHashSet();

    private PublicizedLensBuilder() {}

    public GraphLens build(AppView appView) {
      if (publicizedMethods.isEmpty()) {
        return appView.graphLens();
      }
      return new PublicizerLens(appView, publicizedMethods);
    }

    public void add(DexMethod publicizedMethod) {
      publicizedMethods.add(publicizedMethod);
    }
  }
}