// 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.analysis;

import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.rules.test.TestProvider;
import com.google.devtools.build.lib.skyframe.AspectValue;

/**
 * A small static class containing utility methods for handling the inclusion of
 * extra top-level artifacts into the build.
 */
public final class TopLevelArtifactHelper {

  /***
   * The set of artifacts to build.
   *
   * <p>There are two kinds: the ones that the user cares about (e.g. files to build) and the ones
   * she doesn't (e.g. baseline coverage artifacts). The latter type doesn't get reported on various
   * outputs, e.g. on the console  output listing the output artifacts of targets on the command
   * line.
   */
  @Immutable
  public static final class ArtifactsToBuild {
    private final NestedSet<Artifact> important;
    private final NestedSet<Artifact> all;

    private ArtifactsToBuild(NestedSet<Artifact> important, NestedSet<Artifact> all) {
      this.important = important;
      this.all = all;
    }

    /**
     * Returns the artifacts that the user should know about.
     */
    public NestedSet<Artifact> getImportantArtifacts() {
      return important;
    }

    /**
     * Returns the actual set of artifacts that need to be built.
     */
    public NestedSet<Artifact> getAllArtifacts() {
      return all;
    }
  }

  private TopLevelArtifactHelper() {
    // Prevent instantiation.
  }

  /**
   * Utility function to form a list of all test output Artifacts of the given targets to test.
   */
  public static ImmutableCollection<Artifact> getAllArtifactsToTest(
      Iterable<? extends TransitiveInfoCollection> targets) {
    if (targets == null) {
      return ImmutableList.of();
    }
    ImmutableList.Builder<Artifact> allTestArtifacts = ImmutableList.builder();
    for (TransitiveInfoCollection target : targets) {
      allTestArtifacts.addAll(TestProvider.getTestStatusArtifacts(target));
    }
    return allTestArtifacts.build();
  }

  /**
   * Utility function to form a NestedSet of all top-level Artifacts of the given targets.
   */
  public static ArtifactsToBuild getAllArtifactsToBuild(
      Iterable<? extends TransitiveInfoCollection> targets, TopLevelArtifactContext context) {
    NestedSetBuilder<Artifact> allArtifacts = NestedSetBuilder.stableOrder();
    NestedSetBuilder<Artifact> importantArtifacts = NestedSetBuilder.stableOrder();
    for (TransitiveInfoCollection target : targets) {
      ArtifactsToBuild targetArtifacts = getAllArtifactsToBuild(target, context);
      allArtifacts.addTransitive(targetArtifacts.getAllArtifacts());
      importantArtifacts.addTransitive(targetArtifacts.getImportantArtifacts());
    }
    return new ArtifactsToBuild(importantArtifacts.build(), allArtifacts.build());
  }

  /**
   * Utility function to form a NestedSet of all top-level Artifacts of the given targets.
   */
  public static ArtifactsToBuild getAllArtifactsToBuildFromAspects(
      Iterable<AspectValue> aspects, TopLevelArtifactContext context) {
    NestedSetBuilder<Artifact> allArtifacts = NestedSetBuilder.stableOrder();
    NestedSetBuilder<Artifact> importantArtifacts = NestedSetBuilder.stableOrder();
    for (AspectValue aspect : aspects) {
      ArtifactsToBuild aspectArtifacts = getAllArtifactsToBuild(aspect, context);
      allArtifacts.addTransitive(aspectArtifacts.getAllArtifacts());
      importantArtifacts.addTransitive(aspectArtifacts.getImportantArtifacts());
    }
    return new ArtifactsToBuild(importantArtifacts.build(), allArtifacts.build());
  }


  /**
   * Returns all artifacts to build if this target is requested as a top-level target. The resulting
   * set includes the temps and either the files to compile, if
   * {@code context.compileOnly() == true}, or the files to run.
   *
   * <p>Calls to this method should generally return quickly; however, the runfiles computation can
   * be lazy, in which case it can be expensive on the first call. Subsequent calls may or may not
   * return the same {@code Iterable} instance.
   */
  public static ArtifactsToBuild getAllArtifactsToBuild(TransitiveInfoCollection target,
      TopLevelArtifactContext context) {
    NestedSetBuilder<Artifact> importantBuilder = NestedSetBuilder.stableOrder();
    NestedSetBuilder<Artifact> allBuilder = NestedSetBuilder.stableOrder();

    OutputGroupProvider outputGroupProvider =
        target.getProvider(OutputGroupProvider.class);

    for (String outputGroup : context.outputGroups()) {
      NestedSetBuilder<Artifact> results = NestedSetBuilder.stableOrder();

      if (outputGroup.equals(OutputGroupProvider.DEFAULT)) {
        // For the default group, we also throw in filesToBuild
        FileProvider fileProvider = target.getProvider(FileProvider.class);
        if (fileProvider != null) {
          results.addTransitive(fileProvider.getFilesToBuild());
        }
      }

      if (outputGroupProvider != null) {
        results.addTransitive(outputGroupProvider.getOutputGroup(outputGroup));
      }

      if (outputGroup.startsWith(OutputGroupProvider.HIDDEN_OUTPUT_GROUP_PREFIX)) {
        allBuilder.addTransitive(results.build());
      } else {
        importantBuilder.addTransitive(results.build());
      }
    }

    NestedSet<Artifact> importantArtifacts = importantBuilder.build();
    allBuilder.addTransitive(importantArtifacts);
    return new ArtifactsToBuild(importantArtifacts, allBuilder.build());
  }

  public static ArtifactsToBuild getAllArtifactsToBuild(
      AspectValue aspectValue, TopLevelArtifactContext context) {
    NestedSetBuilder<Artifact> importantBuilder = NestedSetBuilder.stableOrder();
    NestedSetBuilder<Artifact> allBuilder = NestedSetBuilder.stableOrder();

    OutputGroupProvider outputGroupProvider =
        aspectValue.getAspect().getProvider(OutputGroupProvider.class);

    for (String outputGroup : context.outputGroups()) {
      NestedSetBuilder<Artifact> results = NestedSetBuilder.stableOrder();

      if (outputGroup.equals(OutputGroupProvider.DEFAULT)) {
        // For the default group, we also throw in filesToBuild
        FileProvider fileProvider = aspectValue.getAspect().getProvider(FileProvider.class);
        if (fileProvider != null) {
          results.addTransitive(fileProvider.getFilesToBuild());
        }
      }

      if (outputGroupProvider != null) {
        results.addTransitive(outputGroupProvider.getOutputGroup(outputGroup));
      }

      if (outputGroup.startsWith(OutputGroupProvider.HIDDEN_OUTPUT_GROUP_PREFIX)) {
        allBuilder.addTransitive(results.build());
      } else {
        importantBuilder.addTransitive(results.build());
      }
    }

    NestedSet<Artifact> importantArtifacts = importantBuilder.build();
    allBuilder.addTransitive(importantArtifacts);
    return new ArtifactsToBuild(importantArtifacts, allBuilder.build());
  }
}