/**
   * Check validity of and populates defaults in a job configuration. This will return a deep copy
   * of the provided job configuration with default configuration values applied, and configuration
   * map values sanitized and applied to their respective struct fields.
   *
   * @param job Job to validate and populate.
   * @return A deep copy of {@code job} that has been populated.
   * @throws TaskDescriptionException If the job configuration is invalid.
   */
  public IJobConfiguration validateAndPopulate(IJobConfiguration job)
      throws TaskDescriptionException {

    requireNonNull(job);

    if (!job.isSetTaskConfig()) {
      throw new TaskDescriptionException("Job configuration must have taskConfig set.");
    }

    if (job.getInstanceCount() <= 0) {
      throw new TaskDescriptionException("Instance count must be positive.");
    }

    JobConfiguration builder = job.newBuilder();

    if (!JobKeys.isValid(job.getKey())) {
      throw new TaskDescriptionException("Job key " + job.getKey() + " is invalid.");
    }

    if (job.isSetOwner() && !UserProvidedStrings.isGoodIdentifier(job.getOwner().getUser())) {
      throw new TaskDescriptionException(
          "Job user contains illegal characters: " + job.getOwner().getUser());
    }

    builder.setTaskConfig(
        validateAndPopulate(ITaskConfig.build(builder.getTaskConfig())).newBuilder());

    // Only one of [service=true, cron_schedule] may be set.
    if (!Strings.isNullOrEmpty(job.getCronSchedule()) && builder.getTaskConfig().isIsService()) {
      throw new TaskDescriptionException(
          "A service task may not be run on a cron schedule: " + builder);
    }

    return IJobConfiguration.build(builder);
  }
  /**
   * Check validity of and populates defaults in a task configuration. This will return a deep copy
   * of the provided task configuration with default configuration values applied, and configuration
   * map values sanitized and applied to their respective struct fields.
   *
   * @param config Task config to validate and populate.
   * @return A reference to the modified {@code config} (for chaining).
   * @throws TaskDescriptionException If the task is invalid.
   */
  public ITaskConfig validateAndPopulate(ITaskConfig config) throws TaskDescriptionException {
    TaskConfig builder = config.newBuilder();

    if (!builder.isSetRequestedPorts()) {
      builder.setRequestedPorts(ImmutableSet.of());
    }

    if (config.isSetTier() && !UserProvidedStrings.isGoodIdentifier(config.getTier())) {
      throw new TaskDescriptionException("Tier contains illegal characters: " + config.getTier());
    }

    try {
      tierManager.getTier(config);
    } catch (IllegalArgumentException e) {
      throw new TaskDescriptionException(e.getMessage(), e);
    }

    if (!JobKeys.isValid(config.getJob())) {
      // Job key is set but invalid
      throw new TaskDescriptionException("Job key " + config.getJob() + " is invalid.");
    }

    // A task must either have an executor configuration or specify a Docker container.
    if (!builder.isSetExecutorConfig()
        && !(builder.isSetContainer() && builder.getContainer().isSetDocker())) {

      throw new TaskDescriptionException(NO_EXECUTOR_OR_CONTAINER);
    }

    // Docker containers don't require executors, validate the rest
    if (builder.isSetExecutorConfig()) {

      if (!builder.getExecutorConfig().isSetName()) {
        throw new TaskDescriptionException(INVALID_EXECUTOR_CONFIG);
      }

      executorSettings
          .getExecutorConfig(builder.getExecutorConfig().getName())
          .orElseThrow(
              () ->
                  new TaskDescriptionException(
                      "Configuration for executor '"
                          + builder.getExecutorConfig().getName()
                          + "' doesn't exist."));
    }

    // Maximize the usefulness of any thrown error message by checking required fields first.
    for (RequiredFieldValidator<?> validator : REQUIRED_FIELDS_VALIDATORS) {
      validator.validate(builder);
    }

    IConstraint constraint = getDedicatedConstraint(config);
    if (constraint != null) {
      if (!isValueConstraint(constraint.getConstraint())) {
        throw new TaskDescriptionException("A dedicated constraint must be of value type.");
      }

      IValueConstraint valueConstraint = constraint.getConstraint().getValue();

      if (valueConstraint.getValues().size() != 1) {
        throw new TaskDescriptionException("A dedicated constraint must have exactly one value");
      }

      String dedicatedRole = getRole(valueConstraint);
      if (!("*".equals(dedicatedRole) || config.getJob().getRole().equals(dedicatedRole))) {
        throw new TaskDescriptionException(
            "Only " + dedicatedRole + " may use hosts dedicated for that role.");
      }
    }

    Optional<Container._Fields> containerType;
    if (config.isSetContainer()) {
      IContainer containerConfig = config.getContainer();
      containerType = Optional.of(containerConfig.getSetField());
      if (containerConfig.isSetDocker()) {
        if (!containerConfig.getDocker().isSetImage()) {
          throw new TaskDescriptionException("A container must specify an image.");
        }
        if (containerConfig.getDocker().getParameters().isEmpty()) {
          for (Map.Entry<String, String> e : settings.defaultDockerParameters.entries()) {
            builder
                .getContainer()
                .getDocker()
                .addToParameters(new DockerParameter(e.getKey(), e.getValue()));
          }
        } else {
          if (!settings.allowDockerParameters) {
            throw new TaskDescriptionException(NO_DOCKER_PARAMETERS);
          }
        }

        if (settings.requireDockerUseExecutor && !config.isSetExecutorConfig()) {
          throw new TaskDescriptionException(EXECUTOR_REQUIRED_WITH_DOCKER);
        }
      }
    } else {
      // Default to mesos container type if unset.
      containerType = Optional.of(Container._Fields.MESOS);
    }

    if (!containerType.isPresent()) {
      throw new TaskDescriptionException("A job must have a container type.");
    }
    if (!settings.allowedContainerTypes.contains(containerType.get())) {
      throw new TaskDescriptionException(
          "This scheduler is not configured to allow the container type "
              + containerType.get().toString());
    }

    thriftBackfill.backfillTask(builder);

    String types =
        config
            .getResources()
            .stream()
            .collect(Collectors.groupingBy(e -> ResourceType.fromResource(e)))
            .entrySet()
            .stream()
            .filter(e -> !e.getKey().isMultipleAllowed() && e.getValue().size() > 1)
            .map(r -> r.getKey().getAuroraName())
            .sorted()
            .collect(Collectors.joining(", "));

    if (!Strings.isNullOrEmpty(types)) {
      throw new TaskDescriptionException("Multiple resource values are not supported for " + types);
    }

    if (!settings.allowGpuResource
        && config
            .getResources()
            .stream()
            .filter(r -> ResourceType.fromResource(r).equals(GPUS))
            .findAny()
            .isPresent()) {

      throw new TaskDescriptionException("GPU resource support is disabled in this cluster.");
    }

    if (!settings.enableMesosFetcher && !config.getMesosFetcherUris().isEmpty()) {
      throw new TaskDescriptionException(MESOS_FETCHER_DISABLED);
    }

    if (config.getContainer().isSetMesos()) {
      IMesosContainer container = config.getContainer().getMesos();
      if (!settings.allowContainerVolumes && !container.getVolumes().isEmpty()) {
        throw new TaskDescriptionException(NO_CONTAINER_VOLUMES);
      }
    }

    maybeFillLinks(builder);

    return ITaskConfig.build(builder);
  }