// 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.buildtool;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.base.Stopwatch;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.actions.BuildFailedException;
import com.google.devtools.build.lib.actions.TestExecException;
import com.google.devtools.build.lib.analysis.AnalysisPhaseCompleteEvent;
import com.google.devtools.build.lib.analysis.BuildInfoEvent;
import com.google.devtools.build.lib.analysis.BuildView;
import com.google.devtools.build.lib.analysis.BuildView.AnalysisResult;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.LicensesProvider;
import com.google.devtools.build.lib.analysis.LicensesProvider.TargetLicense;
import com.google.devtools.build.lib.analysis.MakeEnvironmentEvent;
import com.google.devtools.build.lib.analysis.StaticallyLinkedMarkerProvider;
import com.google.devtools.build.lib.analysis.ViewCreationFailedException;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollection;
import com.google.devtools.build.lib.analysis.config.BuildOptions;
import com.google.devtools.build.lib.analysis.config.DefaultsPackage;
import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
import com.google.devtools.build.lib.buildeventstream.AbortedEvent;
import com.google.devtools.build.lib.buildeventstream.BuildEventId;
import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos.Aborted.AbortReason;
import com.google.devtools.build.lib.buildtool.CqueryBuildTool.ConfiguredTargetQueryCommandLineException;
import com.google.devtools.build.lib.buildtool.buildevent.BuildCompleteEvent;
import com.google.devtools.build.lib.buildtool.buildevent.BuildInterruptedEvent;
import com.google.devtools.build.lib.buildtool.buildevent.BuildStartingEvent;
import com.google.devtools.build.lib.buildtool.buildevent.NoAnalyzeEvent;
import com.google.devtools.build.lib.buildtool.buildevent.NoExecutionEvent;
import com.google.devtools.build.lib.buildtool.buildevent.TestFilteringCompleteEvent;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.cmdline.TargetParsingException;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.OutputFilter;
import com.google.devtools.build.lib.events.Reporter;
import com.google.devtools.build.lib.packages.InputFile;
import com.google.devtools.build.lib.packages.License;
import com.google.devtools.build.lib.packages.License.DistributionType;
import com.google.devtools.build.lib.packages.NoSuchPackageException;
import com.google.devtools.build.lib.packages.NoSuchTargetException;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.packages.TargetUtils;
import com.google.devtools.build.lib.pkgcache.LoadingCallback;
import com.google.devtools.build.lib.pkgcache.LoadingFailedException;
import com.google.devtools.build.lib.pkgcache.LoadingPhaseRunner;
import com.google.devtools.build.lib.pkgcache.LoadingResult;
import com.google.devtools.build.lib.profiler.ProfilePhase;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.runtime.BlazeRuntime;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.build.lib.skyframe.BuildConfigurationValue;
import com.google.devtools.build.lib.util.AbruptExitException;
import com.google.devtools.build.lib.util.ExitCode;
import com.google.devtools.build.lib.util.RegexFilter;
import com.google.devtools.common.options.OptionsParsingException;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Pattern;
import java.util.stream.Stream;

/**
 * Provides the bulk of the implementation of the 'blaze build' command.
 *
 * <p>The various concrete build command classes handle the command options and request
 * setup, then delegate the handling of the request (the building of targets) to this class.
 *
 * <p>The main entry point is {@link #buildTargets}.
 *
 * <p>Most of analysis is handled in {@link BuildView}, and execution in {@link ExecutionTool}.
 */
public class BuildTool {

  private static Logger logger = Logger.getLogger(BuildTool.class.getName());

  protected CommandEnvironment env;
  protected BlazeRuntime runtime;

  /**
   * Constructs a BuildTool.
   *
   * @param env a reference to the command environment of the currently executing command
   */
  public BuildTool(CommandEnvironment env) {
    this.env = env;
    this.runtime = env.getRuntime();
  }

  /**
   * The crux of the build system. Builds the targets specified in the request using the specified
   * Executor.
   *
   * <p>Performs loading, analysis and execution for the specified set of targets, honoring the
   * configuration options in the BuildRequest. Returns normally iff successful, throws an exception
   * otherwise.
   *
   * <p>Callers must ensure that {@link #stopRequest} is called after this method, even if it
   * throws.
   *
   * <p>The caller is responsible for setting up and syncing the package cache.
   *
   * <p>During this function's execution, the actualTargets and successfulTargets fields of the
   * request object are set.
   *
   * @param request the build request that this build tool is servicing, which specifies various
   *     options; during this method's execution, the actualTargets and successfulTargets fields of
   *     the request object are populated
   * @param result the build result that is the mutable result of this build
   * @param validator target validator
   */
  public void buildTargets(
      BuildRequest request,
      BuildResult result,
      TargetValidator validator)
      throws BuildFailedException, InterruptedException, ViewCreationFailedException,
          TargetParsingException, LoadingFailedException, AbruptExitException,
          InvalidConfigurationException, TestExecException,
          ConfiguredTargetQueryCommandLineException {
    validateOptions(request);
    BuildOptions buildOptions = runtime.createBuildOptions(request);
    // Sync the package manager before sending the BuildStartingEvent in runLoadingPhase()
    env.setupPackageCache(request, DefaultsPackage.getDefaultsPackageContent(buildOptions));

    ExecutionTool executionTool = null;
    boolean catastrophe = false;
    try {
      env.getEventBus().post(new BuildStartingEvent(env, request));
      logger.info("Build identifier: " + request.getId());

      // Error out early if multi_cpus is set, but we're not in build or test command.
      if (!request.getMultiCpus().isEmpty()) {
        getReporter().handle(Event.warn(
            "The --experimental_multi_cpu option is _very_ experimental and only intended for "
            + "internal testing at this time. If you do not work on the build tool, then you "
            + "should stop now!"));
        if (!"build".equals(request.getCommandName()) && !"test".equals(request.getCommandName())) {
          throw new InvalidConfigurationException(
              "The experimental setting to select multiple CPUs is only supported for 'build' and "
              + "'test' right now!");
        }
      }

      // Exit if there are any pending exceptions from modules.
      env.throwPendingException();

      // Target pattern evaluation.
      LoadingResult loadingResult = evaluateTargetPatterns(request, validator);
      env.setWorkspaceName(loadingResult.getWorkspaceName());
      executionTool = new ExecutionTool(env, request);
      if (needsExecutionPhase(request.getBuildOptions())) {
        executionTool.init();
      }

      // Compute the heuristic instrumentation filter if needed.
      if (request.needsInstrumentationFilter()) {
        String instrumentationFilter =
            InstrumentationFilterSupport.computeInstrumentationFilter(
                env.getReporter(), loadingResult.getTestsToRun());
        try {
          // We're modifying the buildOptions in place, which is not ideal, but we also don't want
          // to pay the price for making a copy. Maybe reconsider later if this turns out to be a
          // problem (and the performance loss may not be a big deal).
          buildOptions.get(BuildConfiguration.Options.class).instrumentationFilter =
              new RegexFilter.RegexFilterConverter().convert(instrumentationFilter);
        } catch (OptionsParsingException e) {
          throw new InvalidConfigurationException(e);
        }
      }

      // Exit if there are any pending exceptions from modules.
      env.throwPendingException();

      // Configuration creation.
      // TODO(gregce): Consider dropping this phase and passing on-the-fly target / host configs as
      // needed. This requires cleaning up the invalidation in SkyframeBuildView.setConfigurations.
      BuildConfigurationCollection configurations =
          env.getSkyframeExecutor()
              .createConfigurations(
                  env.getReporter(),
                  runtime.getConfigurationFragmentFactories(),
                  buildOptions,
                  request.getMultiCpus(),
                  request.getKeepGoing());

      env.throwPendingException();
      if (configurations.getTargetConfigurations().size() == 1) {
        // TODO(bazel-team): This is not optimal - we retain backwards compatibility in the case
        // where there's only a single configuration, but we don't send an event in the multi-config
        // case. Can we do better? [multi-config]
        env.getEventBus().post(new MakeEnvironmentEvent(
            configurations.getTargetConfigurations().get(0).getMakeEnvironment()));
      }
      logger.info("Configurations created");

      if (request.getBuildOptions().performAnalysisPhase) {
        AnalysisResult analysisResult = runAnalysisPhase(request, loadingResult, configurations);
        result.setBuildConfigurationCollection(configurations);
        result.setActualTargets(analysisResult.getTargetsToBuild());
        result.setTestTargets(analysisResult.getTargetsToTest());

        reportTargets(analysisResult);

        for (ConfiguredTarget target : analysisResult.getTargetsToSkip()) {
          BuildConfiguration config =
              env.getSkyframeExecutor()
                  .getConfiguration(env.getReporter(), target.getConfigurationKey());
          Label label = target.getLabel();
          env.getEventBus().post(
              new AbortedEvent(
                  BuildEventId.targetCompleted(label, config.getEventId()),
                  AbortReason.SKIPPED,
                  String.format("Target %s build was skipped.", label), label));
        }
        postProcessAnalysisResult(request, analysisResult, configurations);
        // Execution phase.
        if (needsExecutionPhase(request.getBuildOptions())) {
          executionTool.executeBuild(
              request.getId(),
              analysisResult,
              result,
              configurations,
              analysisResult.getPackageRoots(),
              request.getTopLevelArtifactContext());
        } else {
          getReporter().post(new NoExecutionEvent());
        }
        String delayedErrorMsg = analysisResult.getError();
        if (delayedErrorMsg != null) {
          throw new BuildFailedException(delayedErrorMsg);
        }
      } else {
        getReporter().handle(Event.progress("Loading complete."));
        getReporter().post(new NoAnalyzeEvent());
        logger.info("No analysis requested, so finished");
        String errorMessage = BuildView.createErrorMessage(loadingResult, null);
        if (errorMessage != null) {
          throw new BuildFailedException(errorMessage);
        }
        // Will return after profiler line below.
      }
      Profiler.instance().markPhase(ProfilePhase.FINISH);
    } catch (RuntimeException e) {
      // Print an error message for unchecked runtime exceptions. This does not concern Error
      // subclasses such as OutOfMemoryError.
      request.getOutErr().printErrLn(
          "Unhandled exception thrown during build; message: " + e.getMessage());
      catastrophe = true;
      throw e;
    } catch (Error e) {
      catastrophe = true;
      throw e;
    } catch (InvalidConfigurationException e) {
      // TODO(gregce): With "global configurations" we cannot tie a configuration creation failure
      // to a single target and have to halt the entire build. Once configurations are genuinely
      // created as part of the analysis phase they should report their error on the level of the
      // target(s) that triggered them.
      catastrophe = true;
      throw e;
    } finally {
      if (executionTool != null) {
        executionTool.shutdown();
      }
      if (!catastrophe) {
        // Delete dirty nodes to ensure that they do not accumulate indefinitely.
        long versionWindow = request.getViewOptions().versionWindowForDirtyNodeGc;
        if (versionWindow != -1) {
          env.getSkyframeExecutor().deleteOldNodes(versionWindow);
        }
        // The workspace status actions will not run with certain flags, or if an error
        // occurs early in the build. Tell a lie so that the event is not missing.
        // If multiple build_info events are sent, only the first is kept, so this does not harm
        // successful runs (which use the workspace status action).
        env.getEventBus()
            .post(
                new BuildInfoEvent(
                    env.getBlazeWorkspace().getWorkspaceStatusActionFactory()
                        .createDummyWorkspaceStatus()));
      }
    }
  }

  /**
   * This class is meant to be overridden by classes that want to perform the Analysis phase and
   * then process the results in some interesting way. See {@link CqueryBuildTool} as an example.
   */
  protected void postProcessAnalysisResult(
      BuildRequest request,
      AnalysisResult analysisResult,
      BuildConfigurationCollection configurations)
      throws InterruptedException, ViewCreationFailedException,
          ConfiguredTargetQueryCommandLineException {
  }

  private void reportExceptionError(Exception e) {
    if (e.getMessage() != null) {
      getReporter().handle(Event.error(e.getMessage()));
    }
  }

  /**
   * The crux of the build system. Builds the targets specified in the request using the specified
   * Executor.
   *
   * <p>Performs loading, analysis and execution for the specified set of targets, honoring the
   * configuration options in the BuildRequest. Returns normally iff successful, throws an exception
   * otherwise.
   *
   * <p>The caller is responsible for setting up and syncing the package cache.
   *
   * <p>During this function's execution, the actualTargets and successfulTargets
   * fields of the request object are set.
   *
   * @param request the build request that this build tool is servicing, which specifies various
   *        options; during this method's execution, the actualTargets and successfulTargets fields
   *        of the request object are populated
   * @param validator target validator
   * @return the result as a {@link BuildResult} object
   */
  public BuildResult processRequest(
      BuildRequest request, TargetValidator validator) {
    BuildResult result = new BuildResult(request.getStartTime());
    env.getEventBus().register(result);
    maybeSetStopOnFirstFailure(request, result);
    Throwable catastrophe = null;
    ExitCode exitCode = ExitCode.BLAZE_INTERNAL_ERROR;
    try {
      buildTargets(request, result, validator);
      exitCode = ExitCode.SUCCESS;
    } catch (BuildFailedException e) {
      if (e.isErrorAlreadyShown()) {
        // The actual error has already been reported by the Builder.
      } else {
        reportExceptionError(e);
      }
      if (e.isCatastrophic()) {
        result.setCatastrophe();
      }
      exitCode = e.getExitCode() != null ? e.getExitCode() : ExitCode.BUILD_FAILURE;
    } catch (InterruptedException e) {
      // We may have been interrupted by an error, or the user's interruption may have raced with
      // an error, so check to see if we should report that error code instead.
      exitCode = env.getPendingExitCode();
      if (exitCode == null) {
        exitCode = ExitCode.INTERRUPTED;
        env.getReporter().handle(Event.error("build interrupted"));
        env.getEventBus().post(new BuildInterruptedEvent());
      } else {
        // Report the exception from the environment - the exception we're handling here is just an
        // interruption.
        reportExceptionError(env.getPendingException());
        result.setCatastrophe();
      }
    } catch (TargetParsingException | LoadingFailedException | ViewCreationFailedException e) {
      exitCode = ExitCode.PARSING_FAILURE;
      reportExceptionError(e);
    } catch (ConfiguredTargetQueryCommandLineException e) {
      exitCode = ExitCode.COMMAND_LINE_ERROR;
      reportExceptionError(e);
    } catch (TestExecException e) {
      // ExitCode.SUCCESS means that build was successful. Real return code of program
      // is going to be calculated in TestCommand.doTest().
      exitCode = ExitCode.SUCCESS;
      reportExceptionError(e);
    } catch (InvalidConfigurationException e) {
      exitCode = ExitCode.COMMAND_LINE_ERROR;
      reportExceptionError(e);
      // TODO(gregce): With "global configurations" we cannot tie a configuration creation failure
      // to a single target and have to halt the entire build. Once configurations are genuinely
      // created as part of the analysis phase they should report their error on the level of the
      // target(s) that triggered them.
      result.setCatastrophe();
    } catch (AbruptExitException e) {
      exitCode = e.getExitCode();
      reportExceptionError(e);
      result.setCatastrophe();
    } catch (Throwable throwable) {
      catastrophe = throwable;
      Throwables.propagate(throwable);
    } finally {
      stopRequest(result, catastrophe, exitCode);
    }

    return result;
  }

  private void maybeSetStopOnFirstFailure(BuildRequest request, BuildResult result) {
    if (shouldStopOnFailure(request)) {
      result.setStopOnFirstFailure(true);
    }
  }

  private boolean shouldStopOnFailure(BuildRequest request) {
    return !(request.getKeepGoing() && request.getExecutionOptions().testKeepGoing);
  }

  private final LoadingResult evaluateTargetPatterns(
      final BuildRequest request, final TargetValidator validator)
      throws LoadingFailedException, TargetParsingException, InterruptedException {
    Profiler.instance().markPhase(ProfilePhase.LOAD);
    initializeOutputFilter(request);

    final boolean keepGoing = request.getKeepGoing();

    LoadingCallback callback = new LoadingCallback() {
      @Override
      public void notifyTargets(Collection<Target> targets) throws LoadingFailedException {
        if (validator != null) {
          validator.validateTargets(targets, keepGoing);
        }
      }
    };

    LoadingPhaseRunner loadingPhaseRunner = env.getSkyframeExecutor().getLoadingPhaseRunner(
        runtime.getPackageFactory().getRuleClassNames(),
        request.getLoadingOptions().useSkyframeTargetPatternEvaluator);
    LoadingResult result =
        loadingPhaseRunner.execute(
            getReporter(),
            request.getTargets(),
            env.getRelativeWorkingDirectory(),
            request.getLoadingOptions(),
            keepGoing,
            request.shouldRunTests(),
            callback);
    return result;
  }

  /**
   * Initializes the output filter to the value given with {@code --output_filter}.
   */
  private void initializeOutputFilter(BuildRequest request) {
    Pattern outputFilter = request.getBuildOptions().outputFilter;
    if (outputFilter != null) {
      getReporter().setOutputFilter(OutputFilter.RegexOutputFilter.forPattern(outputFilter));
    }
  }

  /**
   * Performs the initial phases 0-2 of the build: Setup, Loading and Analysis.
   * <p>
   * Postcondition: On success, populates the BuildRequest's set of targets to
   * build.
   *
   * @return null if loading / analysis phases were successful; a useful error
   *         message if loading or analysis phase errors were encountered and
   *         request.keepGoing.
   * @throws InterruptedException if the current thread was interrupted.
   * @throws ViewCreationFailedException if analysis failed for any reason.
   */
  private AnalysisResult runAnalysisPhase(BuildRequest request, LoadingResult loadingResult,
      BuildConfigurationCollection configurations)
      throws InterruptedException, ViewCreationFailedException {
    Stopwatch timer = Stopwatch.createStarted();
    getReporter().handle(Event.progress("Loading complete.  Analyzing..."));
    Profiler.instance().markPhase(ProfilePhase.ANALYZE);

    BuildView view = new BuildView(env.getDirectories(), runtime.getRuleClassProvider(),
        env.getSkyframeExecutor(), runtime.getCoverageReportActionFactory(request));
    AnalysisResult analysisResult =
        view.update(
            loadingResult,
            configurations,
            request.getAspects(),
            request.getViewOptions(),
            request.getKeepGoing(),
            request.getLoadingPhaseThreadCount(),
            request.getTopLevelArtifactContext(),
            env.getReporter(),
            env.getEventBus());

    // TODO(bazel-team): Merge these into one event.
    env.getEventBus().post(new AnalysisPhaseCompleteEvent(analysisResult.getTargetsToBuild(),
        view.getTargetsVisited(), timer.stop().elapsed(TimeUnit.MILLISECONDS),
        view.getAndClearPkgManagerStatistics()));
    ImmutableSet<BuildConfigurationValue.Key> configurationKeys =
        Stream.concat(
                analysisResult
                    .getTargetsToBuild()
                    .stream()
                    .map(ConfiguredTarget::getConfigurationKey)
                    .distinct(),
                analysisResult.getTargetsToTest() == null
                    ? Stream.empty()
                    : analysisResult
                        .getTargetsToTest()
                        .stream()
                        .map(ConfiguredTarget::getConfigurationKey)
                        .distinct())
            .filter(Objects::nonNull)
            .distinct()
            .collect(ImmutableSet.toImmutableSet());
    Map<BuildConfigurationValue.Key, BuildConfiguration> configurationMap =
        env.getSkyframeExecutor().getConfigurations(env.getReporter(), configurationKeys);
    env.getEventBus()
        .post(
            new TestFilteringCompleteEvent(
                analysisResult.getTargetsToBuild(),
                analysisResult.getTargetsToTest(),
                configurationMap));

    // Check licenses.
    // We check licenses if the first target configuration has license checking enabled. Right now,
    // it is not possible to have multiple target configurations with different settings for this
    // flag, which allows us to take this short cut.
    boolean checkLicenses = configurations.getTargetConfigurations().get(0).checkLicenses();
    if (checkLicenses) {
      Profiler.instance().markPhase(ProfilePhase.LICENSE);
      validateLicensingForTargets(analysisResult.getTargetsToBuild(), request.getKeepGoing());
    }

    return analysisResult;
  }

  private static boolean needsExecutionPhase(BuildRequestOptions options) {
    return options.performAnalysisPhase && options.performExecutionPhase;
  }

  /**
   * Stops processing the specified request.
   *
   * <p>This logs the build result, cleans up and stops the clock.
   *
   * @param crash Any unexpected RuntimeException or Error. May be null
   * @param exitCondition A suggested exit condition from either the build logic or
   *        a thrown exception somewhere along the way.
   */
  public void stopRequest(BuildResult result, Throwable crash, ExitCode exitCondition) {
    Preconditions.checkState((crash == null) || !exitCondition.equals(ExitCode.SUCCESS));
    result.setUnhandledThrowable(crash);
    result.setExitCondition(exitCondition);
    InterruptedException ie = null;
    try {
      env.getSkyframeExecutor().notifyCommandComplete();
    } catch (InterruptedException e) {
      env.getReporter().handle(Event.error("Build interrupted during command completion"));
      ie = e;
    }
    // The stop time has to be captured before we send the BuildCompleteEvent.
    result.setStopTime(runtime.getClock().currentTimeMillis());
    env.getEventBus()
        .post(new BuildCompleteEvent(result, ImmutableList.of(BuildEventId.buildToolLogs())));
    if (ie != null) {
      if (exitCondition.equals(ExitCode.SUCCESS)) {
        result.setExitCondition(ExitCode.INTERRUPTED);
      } else if (!exitCondition.equals(ExitCode.INTERRUPTED)) {
        logger.log(
            Level.WARNING,
            "Suppressed interrupted exception during stop request because already failing with exit"
                + " code "
                + exitCondition,
            ie);
      }
    }
  }

  private void reportTargets(AnalysisResult analysisResult) {
    Collection<ConfiguredTarget> targetsToBuild = analysisResult.getTargetsToBuild();
    Collection<ConfiguredTarget> targetsToTest = analysisResult.getTargetsToTest();
    if (targetsToTest != null) {
      int testCount = targetsToTest.size();
      int targetCount = targetsToBuild.size() - testCount;
      if (targetCount == 0) {
        getReporter().handle(Event.info("Found "
            + testCount + (testCount == 1 ? " test target..." : " test targets...")));
      } else {
        getReporter().handle(Event.info("Found "
            + targetCount + (targetCount == 1 ? " target and " : " targets and ")
            + testCount + (testCount == 1 ? " test target..." : " test targets...")));
      }
    } else {
      int targetCount = targetsToBuild.size();
      getReporter().handle(Event.info("Found "
          + targetCount + (targetCount == 1 ? " target..." : " targets...")));
    }
  }

  /**
   * Validates the options for this BuildRequest.
   *
   * <p>Issues warnings for the use of deprecated options, and warnings or errors for any option
   * settings that conflict.
   */
  @VisibleForTesting
  public void validateOptions(BuildRequest request) throws InvalidConfigurationException {
    for (String issue : request.validateOptions()) {
      getReporter().handle(Event.warn(issue));
    }
  }

  /**
   * Takes a set of configured targets, and checks if the distribution methods
   * declared for the targets are compatible with the constraints imposed by
   * their prerequisites' licenses.
   *
   * @param configuredTargets the targets to check
   * @param keepGoing if false, and a licensing error is encountered, both
   *        generates an error message on the reporter, <em>and</em> throws an
   *        exception. If true, then just generates a message on the reporter.
   * @throws ViewCreationFailedException if the license checking failed (and not
   *         --keep_going)
   */
  private void validateLicensingForTargets(Iterable<ConfiguredTarget> configuredTargets,
      boolean keepGoing) throws ViewCreationFailedException {
    for (ConfiguredTarget configuredTarget : configuredTargets) {
      Target target = null;
      try {
        target = env.getPackageManager().getTarget(env.getReporter(), configuredTarget.getLabel());
      } catch (NoSuchPackageException | NoSuchTargetException | InterruptedException e) {
        env.getReporter().handle(Event.error("Failed to get target to validate license"));
        throw new ViewCreationFailedException(
            "Build aborted due to issue getting targets to validate licenses", e);
      }

      if (TargetUtils.isTestRule(target)) {
        continue;  // Tests are exempt from license checking
      }

      final Set<DistributionType> distribs = target.getDistributions();
      StaticallyLinkedMarkerProvider markerProvider =
          configuredTarget.getProvider(StaticallyLinkedMarkerProvider.class);
      boolean staticallyLinked = markerProvider != null && markerProvider.isLinkedStatically();

      LicensesProvider provider = configuredTarget.getProvider(LicensesProvider.class);
      if (provider != null) {
        NestedSet<TargetLicense> licenses = provider.getTransitiveLicenses();
        for (TargetLicense targetLicense : licenses) {
          if (!targetLicense.getLicense().checkCompatibility(
              distribs, target, targetLicense.getLabel(), getReporter(), staticallyLinked)) {
            if (!keepGoing) {
              throw new ViewCreationFailedException("Build aborted due to licensing error");
            }
          }
        }
      } else if (target instanceof InputFile) {
        // Input file targets do not provide licenses because they do not
        // depend on the rule where their license is taken from. This is usually
        // not a problem, because the transitive collection of licenses always
        // hits the rule they come from, except when the input file is a
        // top-level target. Thus, we need to handle that case specially here.
        //
        // See FileTarget#getLicense for more information about the handling of
        // license issues with File targets.
        License license = target.getLicense();
        if (!license.checkCompatibility(distribs, target, configuredTarget.getLabel(),
            getReporter(), staticallyLinked)) {
          if (!keepGoing) {
            throw new ViewCreationFailedException("Build aborted due to licensing error");
          }
        }
      }
    }
  }

  private Reporter getReporter() {
    return env.getReporter();
  }
}