// 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.ir.conversion;

import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.DexEncodedMethod;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.ir.conversion.CallGraph.Node;
import com.android.tools.r8.shaking.AppInfoWithLiveness;
import com.google.common.collect.Sets;
import java.util.Set;

public abstract class CallSiteInformation {

  /**
   * Check if the <code>method</code> is guaranteed to only have a single call site.
   * <p>
   * For pinned methods (methods kept through Proguard keep rules) this will always answer
   * <code>false</code>.
   */
  public abstract boolean hasSingleCallSite(DexMethod method);

  public abstract boolean hasDoubleCallSite(DexMethod method);

  public static CallSiteInformation empty() {
    return EmptyCallSiteInformation.EMPTY_INFO;
  }

  private static class EmptyCallSiteInformation extends CallSiteInformation {

    private static final EmptyCallSiteInformation EMPTY_INFO = new EmptyCallSiteInformation();

    @Override
    public boolean hasSingleCallSite(DexMethod method) {
      return false;
    }

    @Override
    public boolean hasDoubleCallSite(DexMethod method) {
      return false;
    }
  }

  static class CallGraphBasedCallSiteInformation extends CallSiteInformation {

    private final Set<DexMethod> singleCallSite = Sets.newIdentityHashSet();
    private final Set<DexMethod> doubleCallSite = Sets.newIdentityHashSet();

    CallGraphBasedCallSiteInformation(AppView<AppInfoWithLiveness> appView, CallGraph graph) {
      for (Node node : graph.nodes) {
        DexEncodedMethod encodedMethod = node.method;
        DexMethod method = encodedMethod.method;

        // For non-pinned methods and methods that override library methods we do not know the exact
        // number of call sites.
        if (appView.appInfo().isPinned(method)
            || encodedMethod.isLibraryMethodOverride().isTrue()) {
          continue;
        }

        int numberOfCallSites = node.getNumberOfCallSites();
        if (numberOfCallSites == 1) {
          singleCallSite.add(method);
        } else if (numberOfCallSites == 2) {
          doubleCallSite.add(method);
        }
      }
    }

    /**
     * Checks if the given method only has a single call site.
     *
     * <p>For pinned methods (methods kept through Proguard keep rules) and methods that override a
     * library method this always returns false.
     */
    @Override
    public boolean hasSingleCallSite(DexMethod method) {
      return singleCallSite.contains(method);
    }

    /**
     * Checks if the given method only has two call sites.
     *
     * <p>For pinned methods (methods kept through Proguard keep rules) and methods that override a
     * library method this always returns false.
     */
    @Override
    public boolean hasDoubleCallSite(DexMethod method) {
      return doubleCallSite.contains(method);
    }
  }
}