// Copyright (c) 2017, 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.shaking;

import com.android.tools.r8.graph.DexEncodedMethod;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.utils.MethodSignatureEquivalence;
import com.google.common.base.Equivalence;
import com.google.common.base.Equivalence.Wrapper;
import java.util.HashMap;
import java.util.Map;

class ScopedDexMethodSet {

  public enum AddMethodIfMoreVisibleResult {
    NOT_ADDED,
    ADDED_NOT_EXISTING,
    ADDED_MORE_VISIBLE
  }

  private static final Equivalence<DexMethod> METHOD_EQUIVALENCE = MethodSignatureEquivalence.get();

  private ScopedDexMethodSet parent;
  private final Map<Wrapper<DexMethod>, DexEncodedMethod> items = new HashMap<>();

  public ScopedDexMethodSet() {
    this(null);
  }

  private ScopedDexMethodSet(ScopedDexMethodSet parent) {
    this.parent = parent;
  }

  public ScopedDexMethodSet newNestedScope() {
    return new ScopedDexMethodSet(this);
  }

  private DexEncodedMethod lookup(Wrapper<DexMethod> item) {
    DexEncodedMethod ownMethod = items.get(item);
    return ownMethod != null ? ownMethod : (parent != null ? parent.lookup(item) : null);
  }

  private boolean contains(Wrapper<DexMethod> item) {
    return lookup(item) != null;
  }

  public boolean addMethod(DexEncodedMethod method) {
    Wrapper<DexMethod> wrapped = METHOD_EQUIVALENCE.wrap(method.getReference());
    if (contains(wrapped)) {
      return false;
    }
    items.put(wrapped, method);
    return true;
  }

  public AddMethodIfMoreVisibleResult addMethodIfMoreVisible(DexEncodedMethod method) {
    Wrapper<DexMethod> wrapped = METHOD_EQUIVALENCE.wrap(method.getReference());
    DexEncodedMethod existing = lookup(wrapped);
    if (existing == null) {
      items.put(wrapped, method);
      return AddMethodIfMoreVisibleResult.ADDED_NOT_EXISTING;
    }
    if (method.accessFlags.isMoreVisibleThan(
        existing.accessFlags,
        method.getHolderType().getPackageName(),
        existing.getHolderType().getPackageName())) {
      items.put(wrapped, method);
      return AddMethodIfMoreVisibleResult.ADDED_MORE_VISIBLE;
    }
    return AddMethodIfMoreVisibleResult.NOT_ADDED;
  }

  public ScopedDexMethodSet getParent() {
    return parent;
  }

  public void setParent(ScopedDexMethodSet parent) {
    this.parent = parent;
  }
}