// Copyright 2014 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.skyframe;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.Action;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.packages.Package;
import com.google.devtools.build.skyframe.SkyKey;

import java.util.Map;

import javax.annotation.Nullable;

/**
 * A configured target in the context of a Skyframe graph.
 */
@Immutable
@ThreadSafe
@VisibleForTesting
public final class ConfiguredTargetValue extends ActionLookupValue {

  // These variables are only non-final because they may be clear()ed to save memory. They are null
  // only after they are cleared.
  @Nullable private ConfiguredTarget configuredTarget;

  // We overload this variable to check whether the value has been clear()ed. We don't use a
  // separate variable in order to save memory.
  @Nullable private volatile Iterable<Action> actions;

  private final NestedSet<Package> transitivePackages;

  ConfiguredTargetValue(ConfiguredTarget configuredTarget,
      Map<Artifact, Action> generatingActionMap, NestedSet<Package> transitivePackages) {
    super(generatingActionMap);
    this.configuredTarget = configuredTarget;
    this.actions = generatingActionMap.values();
    this.transitivePackages = transitivePackages;
  }

  @VisibleForTesting
  public ConfiguredTarget getConfiguredTarget() {
    Preconditions.checkNotNull(actions, configuredTarget);
    return configuredTarget;
  }

  @VisibleForTesting
  public Iterable<Action> getActions() {
    return Preconditions.checkNotNull(actions, configuredTarget);
  }

  public NestedSet<Package> getTransitivePackages() {
    return transitivePackages;
  }
  /**
   * Clears configured target data from this value, leaving only the artifact->generating action
   * map.
   *
   * <p>Should only be used when user specifies --discard_analysis_cache. Must be called at most
   * once per value, after which {@link #getConfiguredTarget} and {@link #getActions} cannot be
   * called.
   */
  public void clear() {
    Preconditions.checkNotNull(actions, configuredTarget);
    configuredTarget = null;
    actions = null;
  }

  @VisibleForTesting
  public static SkyKey key(Label label, BuildConfiguration configuration) {
    return key(new ConfiguredTargetKey(label, configuration));
  }

  static ImmutableList<SkyKey> keys(Iterable<ConfiguredTargetKey> lacs) {
    ImmutableList.Builder<SkyKey> keys = ImmutableList.builder();
    for (ConfiguredTargetKey lac : lacs) {
      keys.add(key(lac));
    }
    return keys.build();
  }

  /**
   * Returns a label of ConfiguredTargetValue.
   */
  @ThreadSafe
  static Label extractLabel(SkyKey value) {
    Object valueName = value.argument();
    Preconditions.checkState(valueName instanceof ConfiguredTargetKey, valueName);
    return ((ConfiguredTargetKey) valueName).getLabel();
  }

  @Override
  public String toString() {
    return "ConfiguredTargetValue: "
        + configuredTarget + ", actions: " + (actions == null ? null : Iterables.toString(actions));
  }
}