// Copyright 2017 The Bazel Authors. 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.lib.buildeventstream;

import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos.BuildEventId;
import java.util.Collection;

/**
 * {@link BuildEvent} presenting the configuration in the build event protocol that internally is
 * just a null pointer.
 */
public final class NullConfiguration implements BuildEvent {
  public static final NullConfiguration INSTANCE = new NullConfiguration();

  @Override
  public BuildEventId getEventId() {
    return BuildEventIdUtil.nullConfigurationId();
  }

  @Override
  public Collection<BuildEventId> getChildrenEvents() {
    return ImmutableList.of();
  }

  @Override
  public BuildEventStreamProtos.BuildEvent asStreamProto(BuildEventContext converters) {
    return GenericBuildEvent.protoChaining(this)
        .setConfiguration(BuildEventStreamProtos.Configuration.getDefaultInstance())
        .build();
  }

  private NullConfiguration() {}
}