// Copyright 2014 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.skyframe;

import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.devtools.build.lib.util.GroupedList;
import com.google.devtools.build.lib.util.GroupedList.GroupedListHelper;

import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

/** {@link NotifyingInMemoryGraph} that returns reverse deps ordered alphabetically. */
public class DeterministicInMemoryGraph extends NotifyingInMemoryGraph {
  private static final Comparator<SkyKey> ALPHABETICAL_SKYKEY_COMPARATOR =
      new Comparator<SkyKey>() {
    @Override
    public int compare(SkyKey o1, SkyKey o2) {
      return o1.toString().compareTo(o2.toString());
    }
  };

  public DeterministicInMemoryGraph(Listener listener) {
    super(listener);
  }

  public DeterministicInMemoryGraph() {
    super(Listener.NULL_LISTENER);
  }

  @Override
  protected DeterministicValueEntry getEntry(SkyKey key) {
    return new DeterministicValueEntry(key);
  }

  @Override
  public Map<SkyKey, NodeEntry> getBatch(Iterable<SkyKey> keys) {
    Map<SkyKey, NodeEntry> result = new TreeMap<>(ALPHABETICAL_SKYKEY_COMPARATOR);
    result.putAll(super.getBatch(keys));
    return result;
  }

  /**
   * This class uses TreeSet to store reverse dependencies of NodeEntry. As a result all values are
   * lexicographically sorted.
   */
  private class DeterministicValueEntry extends NotifyingNodeEntry {
    private DeterministicValueEntry(SkyKey myKey) {
      super(myKey);
    }

    @SuppressWarnings("unchecked")
    @Override
    public synchronized Collection<SkyKey> getReverseDeps() {
      TreeSet<SkyKey> result = new TreeSet<>(ALPHABETICAL_SKYKEY_COMPARATOR);
      Iterables.addAll(result, super.getReverseDeps());
      return result;
    }

    @Override
    public synchronized Set<SkyKey> getInProgressReverseDeps() {
      TreeSet<SkyKey> result = new TreeSet<>(ALPHABETICAL_SKYKEY_COMPARATOR);
      result.addAll(buildingState.getReverseDepsToSignal());
      return result;
    }

    @Override
    public synchronized void addTemporaryDirectDeps(GroupedListHelper<SkyKey> helper) {
      GroupedList<SkyKey> groupedList = new GroupedList<>();
      groupedList.append(helper);
      GroupedListHelper<SkyKey> orderedHelper = new GroupedListHelper<>();
      for (Iterable<SkyKey> group : groupedList) {
        orderedHelper.startGroup();
        List<SkyKey> orderedGroup = Lists.newArrayList(group);
        Collections.sort(orderedGroup, ALPHABETICAL_SKYKEY_COMPARATOR);
        for (SkyKey dep : orderedGroup) {
          orderedHelper.add(dep);
        }
        orderedHelper.endGroup();
      }
      super.addTemporaryDirectDeps(orderedHelper);
    }
  }
}