# -*- coding: utf-8 -*-
# Copyright 2017 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Module to manage builder statuses."""

from __future__ import print_function

import collections
import cPickle

from chromite.lib import buildbucket_lib
from chromite.lib import build_failure_message
from chromite.lib import config_lib
from chromite.lib import constants
from chromite.lib import cros_collections
from chromite.lib import cros_logging as logging
from chromite.lib import failure_message_lib
from chromite.lib import metrics


BUILD_STATUS_URL = (
    '%s/builder-status' % config_lib.GetSiteParams().MANIFEST_VERSIONS_GS_URL)
NUM_RETRIES = 20

# Namedtupe to store CIDB status info.
CIDBStatusInfo = collections.namedtuple(
    'CIDBStatusInfo',
    ['buildbucket_id', 'status'])


def CancelBuilds(buildbucket_ids, buildbucket_client,
                 debug=True, config=None):
  """Cancel Buildbucket builds in a set.

  Args:
    buildbucket_ids: A list of build_ids (strings).
    buildbucket_client: Instance of buildbucket_lib.buildbucket_client.
    debug: Boolean indicating whether it's a dry run. Default to True.
    config: Instance of config_lib.BuildConfig. Config dict for the master
      build initiating the cancel. Optional.
  """
  if buildbucket_ids:
    logging.info("Canceling buildbucket_ids: %s", buildbucket_ids)
    if (not debug) and config:
      fields = {'build_type': config.build_type,
                'build_name': config.name}
      metrics.Counter(constants.MON_BB_CANCEL_BATCH_BUILDS_COUNT).increment(
          fields=fields)
    cancel_results = buildbucket_client.CancelBatchBuildsRequest(
        buildbucket_ids,
        dryrun=debug)
    result_map = buildbucket_lib.GetResultMap(cancel_results)
    for buildbucket_id, result in result_map.iteritems():
      #Check for error messages
      if buildbucket_lib.GetNestedAttr(result, ['error']):
        # TODO(nxia): Get build url and log url in the warnings.
        logging.warning("Error cancelling build %s with reason: %s. "
                        "Please check the status of the build.",
                        buildbucket_id,
                        buildbucket_lib.GetErrorReason(result))


def GetFailedMessages(statuses, failing):
  """Gathers the BuildFailureMessages from the |failing| builders.

  Args:
    statuses: A dict mapping build config names to their BuilderStatus.
    failing: Names of the builders that failed.

  Returns:
    A list of build_failure_message.BuildFailureMessage or NoneType objects.
  """
  return [statuses[x].message for x in failing]


def GetBuildersWithNoneMessages(statuses, failing):
  """Returns a list of failed builders with NoneType failure message.

  Args:
    statuses: A dict mapping build config names to their BuilderStatus.
    failing: Names of the builders that failed.

  Returns:
    A list of builder names.
  """
  return [x for x in failing if statuses[x].message is None]


def GetSlavesAbortedBySelfDestructedMaster(master_build_identifier, buildstore):
  """Get the build configs of the slaves aborted by self-destruction.

  Args:
    master_build_identifier: The BuildIdentifier instance of the master build.
    buildstore: A BuildStore instance to make DB calls.

  Returns:
    A set of build configs of the slaves recorded in CIDB. An empty set if no
    db connection created.
  """
  if not buildstore.AreClientsReady():
    return set()

  slave_buildbucket_ids = buildstore.GetKilledChildBuilds(
      master_build_identifier)
  # tentative fix for crbug.com/890651
  if not slave_buildbucket_ids:
    logging.warning('No build message retrieved for master_build_id=%s',
                    master_build_identifier.cidb_id)
    return set()
  build_statuses = buildstore.GetBuildStatuses(
      buildbucket_ids=slave_buildbucket_ids)
  return set(b['build_config'] for b in build_statuses)


class BuilderStatus(object):
  """Object representing the status of a build."""

  def __init__(self, status, message, dashboard_url=None):
    """Constructor for BuilderStatus.

    Args:
      status: Status string (should be one of BUILDER_STATUS_FAILED,
              BUILDER_STATUS_PASSED, BUILDER_STATUS_INFLIGHT, or
              BUILDER_STATUS_MISSING).
      message: A build_failure_message.BuildFailureMessage object with details
               of builder failure. Or, None.
      dashboard_url: Optional url linking to builder dashboard for this build.
    """
    self.status = status
    self.message = message
    self.dashboard_url = dashboard_url

  # Helper methods to make checking the status object easy.

  def Failed(self):
    """Returns True if the Builder failed."""
    return self.status == constants.BUILDER_STATUS_FAILED

  def Passed(self):
    """Returns True if the Builder passed."""
    return self.status == constants.BUILDER_STATUS_PASSED

  def Inflight(self):
    """Returns True if the Builder is still inflight."""
    return self.status == constants.BUILDER_STATUS_INFLIGHT

  def Missing(self):
    """Returns True if the Builder is missing any status."""
    return self.status == constants.BUILDER_STATUS_MISSING

  def Completed(self):
    """Returns True if the Builder has completed."""
    return self.status in constants.BUILDER_COMPLETED_STATUSES

  @classmethod
  def GetCompletedStatus(cls, success):
    """Return the appropriate status constant for a completed build.

    Args:
      success: Whether the build was successful or not.
    """
    if success:
      return constants.BUILDER_STATUS_PASSED
    else:
      return constants.BUILDER_STATUS_FAILED

  def AsFlatDict(self):
    """Returns a flat json-able representation of this builder status.

    Returns:
      A dictionary of the form {'status' : status, 'message' : message,
      'dashboard_url' : dashboard_url} where all values are guaranteed
      to be strings. If dashboard_url is None, the key will be excluded.
    """
    flat_dict = {'status' : str(self.status),
                 'message' : str(self.message),
                 'reason' : str(None if self.message is None
                                else self.message.reason)}
    if self.dashboard_url is not None:
      flat_dict['dashboard_url'] = str(self.dashboard_url)
    return flat_dict

  def AsPickledDict(self):
    """Returns a pickled dictionary representation of this builder status."""
    return cPickle.dumps(dict(status=self.status, message=self.message,
                              dashboard_url=self.dashboard_url))


class BuilderStatusManager(object):
  """Operations to manage BuilderStatus."""

  @classmethod
  def CreateBuildFailureMessage(cls, build_config, overlays,
                                dashboard_url, failure_messages,
                                aborted_by_self_destruction=False):
    """Creates a message summarizing the failures.

    Args:
      build_config: Build config name (string) of a slave build.
      overlays: The overlays used for the build.
      dashboard_url: The URL of the build.
      failure_messages: A list of stage failure messages (instances of
        StageFailureMessage or its sub-classes) of the given build.
      aborted_by_self_destruction: Whether the build was canceled by master.

    Returns:
      A build_failure_message.BuildFailureMessage object.
    """
    internal = overlays in [constants.PRIVATE_OVERLAYS,
                            constants.BOTH_OVERLAYS]
    details = []

    if failure_messages:
      for x in failure_messages:
        details.append('The %s stage failed: %s' % (
            x.stage_name, x.exception_message))

    if not details:
      details = ['cbuildbot failed']
      if aborted_by_self_destruction:
        details = ['aborted by self-destruction']

    # reason does not include builder name or URL. This is mainly for
    # populating the "failure message" column in the stats sheet.
    reason = ' '.join(details)
    details.append('in %s' % dashboard_url)
    msg_summary = '%s: %s' % (build_config, ' '.join(details))

    return build_failure_message.BuildFailureMessage(
        msg_summary, failure_messages, internal, reason, build_config)

  @classmethod
  def AbortedBySelfDestruction(cls, buildstore, buildbucket_id,
                               master_build_identifier):
    """Check BuildStore for whether a specified build was aborted by master.

    Args:
      buildstore: A BuildStore instance to make DB calls.
      buildbucket_id: The buildbucket ID (int) of the build to get status of
      master_build_identifier: The build ID (int) of the master build which may
        have aborted it.

    Retuns:
      A boolean for whether the build was canceled by master during
      self-destruction.
    """
    if (master_build_identifier is None
        or master_build_identifier.cidb_id is None
        or master_build_identifier.buildbucket_id is None):
      # Builds without master_build_id can't be aborted by self-destruction.
      return False

    buildbucket_ids = buildstore.GetKilledChildBuilds(master_build_identifier)
    # Both child_id and buildbucket_id can be str or int. Convert them both
    # into int before comparison.
    if buildbucket_ids is None:
      return False
    return any(child_id for child_id in buildbucket_ids
               if int(child_id) == int(buildbucket_id))


class SlaveBuilderStatus(object):
  """Operations to manage slave BuilderStatus.

  This class fetches slave statuses and slave failures from Buildbucket and
  CIDB, generates BuilderStatus instances for slave builds. This class only
  fetches BuilderStatus information for important slaves.
  """

  def __init__(self, master_build_identifier, buildstore, config, metadata,
               buildbucket_client, builders_array, dry_run,
               exclude_experimental=True):
    """Create an instance of SlaveBuilderStatus for a given master build.

    Args:
      master_build_identifier: The build_identifier of the master build.
      buildstore: A BuildStore instance to make DB calls with.
      config: Instance of config_lib.BuildConfig. Config dict of this build.
      metadata: Instance of metadata_lib.CBuildbotMetadata. Metadata of this
                build.
      buildbucket_client: Instance of buildbucket_lib.buildbucket_client.
      builders_array: List of the expected and important slave builds.
      dry_run: Boolean indicating whether it's a dry run. Default to True.
      exclude_experimental: Whether to exclude the builds which are important in
        the config but are marked as experimental in the tree status. Default to
        True.
    """
    self.master_build_identifier = master_build_identifier
    self.master_build_id = master_build_identifier.cidb_id
    self.buildstore = buildstore
    self.db = buildstore.GetCIDBHandle()
    self.config = config
    self.metadata = metadata
    self.buildbucket_client = buildbucket_client
    self.builders_array = builders_array
    self.dry_run = dry_run
    self.exclude_experimental = exclude_experimental

    self.buildbucket_info_dict = None
    self.cidb_info_dict = None
    self.slave_failures_dict = None
    self.aborted_slaves = None
    self._InitSlaveInfo()

  def _GetSlaveFailures(self, buildbucket_info_dict):
    """Get a dict mapping slave builds to their build failures.

    Args:
      buildbucket_info_dict: A dict mapping slave build config names
        (strings) to their BuildbucketInfos.

    Returns:
      A dict mapping the slave build config names (strings) to stage failure
      messages (See return type of
      FailureMessageManager.ConstructStageFailureMessages)
    """
    slave_failures_dict = {}

    child_buildbucket_ids = (
        None if buildbucket_info_dict is None else
        [bb_info.buildbucket_id for bb_info in buildbucket_info_dict.values()])

    stage_failures = self.buildstore.GetBuildsFailures(child_buildbucket_ids)
    stage_failures_by_build = cros_collections.GroupNamedtuplesByKey(
        stage_failures, 'build_config')

    failure_msg_manager = failure_message_lib.FailureMessageManager()
    for build_config, stage_failures in stage_failures_by_build.items():
      slave_failures_dict[build_config] = (
          failure_msg_manager.ConstructStageFailureMessages(stage_failures))

    return slave_failures_dict

  def _GetSlavesAbortedBySelfDestruction(self, cidb_info_dict):
    """Get slaves aborted by self-destruction of the master.

    Args:
      cidb_info_dict: A dict mapping slave build config names (strings) to their
        cidb infos (in the format of CIDBStatusInfo).

    Returns:
      A set of build config names (strings) of slaves aborted by
      self-destruction.
    """
    return set(build_config
               for build_config, cidb_info in cidb_info_dict.iteritems()
               if BuilderStatusManager.AbortedBySelfDestruction(
                   self.buildstore, cidb_info.buildbucket_id,
                   self.master_build_identifier))

  def _InitSlaveInfo(self):
    """Init slave info including buildbucket info, cidb info and failures."""
    scheduled_buildbucket_info_dict = buildbucket_lib.GetBuildInfoDict(
        self.metadata, exclude_experimental=self.exclude_experimental)
    self.buildbucket_info_dict = self.GetAllSlaveBuildbucketInfo(
        self.buildbucket_client, scheduled_buildbucket_info_dict,
        dry_run=self.dry_run)
    self.builders_array = self.buildbucket_info_dict.keys()

    self.cidb_info_dict = self.GetAllSlaveCIDBStatusInfo(
        self.buildstore, self.master_build_identifier,
        self.buildbucket_info_dict)

    self.slave_failures_dict = self._GetSlaveFailures(
        self.buildbucket_info_dict)

    self.aborted_slaves = self._GetSlavesAbortedBySelfDestruction(
        self.cidb_info_dict)

  def _GetStatus(self, build_config, cidb_info_dict, buildbucket_info_dict):
    """Get status of a given build.

    Args:
      build_config: Build config name (string) of a slave build.
      cidb_info_dict: A dict mapping slave build config names (strings) to their
        cidb infos (in the format of CIDBStatusInfo).
      buildbucket_info_dict: A dict mapping slave build config names (strings)
        to their Buildbucket infos (in the format of BuildbucketInfo).

    Returns:
      Builder status of the given build.
    """
    cidb_info = cidb_info_dict.get(build_config)
    if cidb_info is None:
      return constants.BUILDER_STATUS_MISSING
    elif (cidb_info.status in (constants.BUILDER_STATUS_PASSED,
                               constants.BUILDER_STATUS_FAILED)):
      return cidb_info.status
    else:
      if buildbucket_info_dict is not None:
        if (buildbucket_info_dict[build_config].status ==
            constants.BUILDBUCKET_BUILDER_STATUS_STARTED):
          return constants.BUILDER_STATUS_INFLIGHT
        else:
          return constants.BUILDER_STATUS_FAILED
      else:
        return constants.BUILDER_STATUS_INFLIGHT

  # TODO(nxia): Buildbucket response returns luci-milo instead buildbot urls.
  def _GetDashboardUrl(self, build_config, _cidb_info_dict,
                       buildbucket_info_dict):
    """Get dashboard url of a given build.

    Args:
      build_config: Build config name (string) of a slave build.
      cidb_info_dict: A dict mapping slave build config names (strings) to their
        cidb infos (in the format of CIDBStatusInfo).
      buildbucket_info_dict: A dict mapping slave build config names (strings)
        to their Buildbucket infos (in the format of BuildbucketInfo).

    Returns:
      Dashboard url of the given build. None if no entry found for this given
      build in CIDB and buildbucket_info_dict is None.
    """
    if buildbucket_info_dict is not None:
      # If no entry found in CIDB, get the buildbot url from Buildbucket.
      return buildbucket_info_dict[build_config].url

  def _GetMessage(self, build_config, status, dashboard_url,
                  slave_failures_dict, aborted_slaves):
    """Get build_failure_message.BuildFailureMessage of a given build.

    Args:
      build_config: Build config name (string) of a slave build.
      status: The status of the build (See return type of self._GetStatus())
      dashboard_url: The URL of the build.
      slave_failures_dict: A dict mapping the slave build config names (strings)
        to stage failure messages (See return type of _GetSlaveFailures)
      aborted_slaves: A set of build config names (strings) of slaves aborted by
        self-destruction.

    Returns:
      A build_failure_message.BuildFailureMessage object if the status is
      constants.BUILDER_STATUS_FAILED; else, None.
    """
    site_config = config_lib.GetConfig()
    if status == constants.BUILDER_STATUS_FAILED:
      failure_messages = slave_failures_dict.get(build_config)
      overlays = site_config[build_config].overlays
      aborted = build_config in aborted_slaves
      return BuilderStatusManager.CreateBuildFailureMessage(
          build_config, overlays, dashboard_url, failure_messages,
          aborted_by_self_destruction=aborted)

  def GetBuilderStatusForBuild(self, build_config):
    """Get BuilderStatus for a given build.

    Args:
      build_config: Build config name (string) of a slave build.

    Returns:
      An instance of BuilderStatus of the given build.
    """
    status = self._GetStatus(
        build_config, self.cidb_info_dict, self.buildbucket_info_dict)
    dashboard_url = self._GetDashboardUrl(
        build_config, self.cidb_info_dict, self.buildbucket_info_dict)
    message = self._GetMessage(
        build_config, status, dashboard_url, self.slave_failures_dict,
        self.aborted_slaves)

    return BuilderStatus(status, message, dashboard_url=dashboard_url)

  @staticmethod
  def GetAllSlaveBuildbucketInfo(buildbucket_client,
                                 scheduled_buildbucket_info_dict,
                                 dry_run=True):
    """Get buildbucket info from Buildbucket for all scheduled slave builds.

    For each build in the scheduled builds dict, get build status and build
    result from Buildbucket and return a updated buildbucket_info_dict.

    Args:
      buildbucket_client: Instance of buildbucket_lib.buildbucket_client.
      scheduled_buildbucket_info_dict: A dict mapping scheduled slave build
        config name to its buildbucket information in the format of
        BuildbucketInfo (see buildbucket.GetBuildInfoDict for details).
      dry_run: Boolean indicating whether it's a dry run. Default to True.

    Returns:
      A dict mapping all scheduled slave build config names to their
      BuildbucketInfos (The BuildbucketInfo of the most recently retried one of
      there're multiple retries for a slave build config).
    """
    #TODO(nxia): consider replacing this with a more elaborate fix
    if buildbucket_client is None:
      return {}

    all_buildbucket_info_dict = {}
    for build_config, build_info in scheduled_buildbucket_info_dict.iteritems():
      buildbucket_id = build_info.buildbucket_id
      retry = build_info.retry
      created_ts = build_info.created_ts
      status = None
      result = None
      url = None

      try:
        content = buildbucket_client.GetBuildRequest(buildbucket_id, dry_run)
        status = buildbucket_lib.GetBuildStatus(content)
        result = buildbucket_lib.GetBuildResult(content)
        url = buildbucket_lib.GetBuildURL(content)
      except buildbucket_lib.BuildbucketResponseException as e:
        # If we have a temporary issue accessing the build status from the
        # Buildbucket, log the error and continue with other builds.
        # SlaveStatus will handle the missing builds in ShouldWait().
        logging.error('Failed to get status for build %s id %s: %s',
                      build_config, buildbucket_id, e)

      all_buildbucket_info_dict[build_config] = buildbucket_lib.BuildbucketInfo(
          buildbucket_id, retry, created_ts, status, result, url)

    return all_buildbucket_info_dict

  @staticmethod
  def GetAllSlaveCIDBStatusInfo(buildstore, master_build_identifier,
                                all_buildbucket_info_dict):
    """Get build status information from CIDB for all slaves.

    Args:
      buildstore: An instance of buildstore.BuildStore.
      master_build_identifier: The BuildIdentifier of the master build.
      all_buildbucket_info_dict: A dict mapping all build config names to their
        information fetched from Buildbucket server (in the format of
        BuildbucketInfo).

    Returns:
      A dict mapping build config names to their cidb infos (in the format of
      CIDBStatusInfo). If all_buildbucket_info_dict is not None, the returned
      map only contains slave builds which are associated with buildbucket_ids
      recorded in all_buildbucket_info_dict.
    """
    # TODO(buildstore): make sure buildstore is BuildStore, not CIDBConnection.
    all_cidb_status_dict = {}
    if buildstore is not None:
      buildbucket_ids = None if all_buildbucket_info_dict is None else [
          info.buildbucket_id for info in all_buildbucket_info_dict.values()]

      if buildbucket_ids:
        slave_statuses = buildstore.GetBuildStatuses(
            buildbucket_ids=buildbucket_ids)
      else:
        slave_statuses = buildstore.GetSlaveStatuses(master_build_identifier)

      all_cidb_status_dict = {s['build_config']: CIDBStatusInfo(
          s['buildbucket_id'], s['status']) for s in slave_statuses}

    return all_cidb_status_dict


class BuilderStatusesFetcher(object):
  """Class to fetch BuilderStatus of a build and its slave builds(if any)."""

  def __init__(self, build_identifier, buildstore, success, message, config,
               metadata, buildbucket_client, builders_array=None,
               exclude_experimental=True, dry_run=True):
    """Initialize BuilderStatusesFetcher.

    Args:
      build_identifier: Build id of the build.
      buildstore: A BuildStore instance to make DB calls.
      success: Whether the build succeeded so far.
      message: The failure message (see return type of
        generic_stages.GetBuildFailureMessage) of the build.
      config: Instance of config_lib.BuildConfig. Config dict of this build.
      metadata: Instance of metadata_lib.CBuildbotMetadata. Metadata of this
        build.
      buildbucket_client: Instance of buildbucket_lib.buildbucket_client.
      builders_array: List of the expected and slave builds, it also contains
        the builds marked as experimental in the tree status. Default to None.
      exclude_experimental: Whether to exclude the builds which are important in
        the config but are marked as experimental in the tree status. Default to
        True.
      dry_run: Boolean indicating whether it's a dry run. Default to True.
    """
    self.build_identifier = build_identifier
    self.build_id = build_identifier.cidb_id
    self.buildstore = buildstore
    self.db = buildstore.GetCIDBHandle()
    self.success = success
    self.message = message
    self.config = config
    self.metadata = metadata
    self.buildbucket_client = buildbucket_client
    self.dry_run = dry_run
    self.exclude_experimental = exclude_experimental

    self.builders_array = buildbucket_lib.FetchCurrentSlaveBuilders(
        self.config, self.metadata, builders_array,
        exclude_experimental=self.exclude_experimental)

  def _FetchLocalBuilderStatus(self):
    """Fetch the BuilderStatus of the local build.

    Returns:
      A dict mapping the bot_id of the build to its builder_status.
    """
    status = BuilderStatus.GetCompletedStatus(self.success)
    status_obj = BuilderStatus(status, self.message)
    return {self.config.name: status_obj}

  def _FetchSlaveBuilderStatuses(self):
    """Fetch the BuilderStatus of the slaves if the local build.

    Returns:
      A dict mapping build configs (strings) to their BuilderStatus instances.
      It contains the statuses for builders marked as experimental in the tree
      status.
    """
    if not self.builders_array:
      return {}

    slave_builder_statuses = SlaveBuilderStatus(
        self.build_identifier, self.buildstore, self.config, self.metadata,
        self.buildbucket_client, self.builders_array, self.dry_run,
        exclude_experimental=self.exclude_experimental)

    slave_builder_status_dict = {}
    for builder in self.builders_array:
      logging.info('Creating BuilderStatus for builder %s', builder)
      builder_status = slave_builder_statuses.GetBuilderStatusForBuild(builder)
      slave_builder_status_dict[builder] = builder_status
      message = (builder_status.message.BuildFailureMessageToStr()
                 if builder_status.message is not None else None)
      logging.info(
          'Builder %s BuilderStatus.status %s BuilderStatus.message %s'
          ' BuilderStatus.dashboard_url %s ',
          builder, builder_status.status, message,
          builder_status.dashboard_url)
    return slave_builder_status_dict

  def GetBuilderStatuses(self):
    """Get BuilderStatus of a given build and its slave builds (if any).

    Returns:
      A pair of dict mapping build names (strings) to their BuilderStatus
      instances. important_statuses only contains builds which are important and
      not marked experimental in the tree status. experimental_statuses contains
      builds marked as experimental in the tree status.
    """
    statuses = self._FetchLocalBuilderStatus()

    if not self.config.master:
      # The build returns its own status.
      logging.info('The build is not a master.')

      return statuses, {}

    logging.info('Fetching BuilderStatus of slaves.')

    statuses.update(self._FetchSlaveBuilderStatuses())

    # Get builders marked as experimental in the tree status from metadata.
    experimental_builders = self.metadata.GetValueWithDefault(
        constants.METADATA_EXPERIMENTAL_BUILDERS, [])

    if not experimental_builders:
      return statuses, {}

    important_statuses = {}
    experimental_statuses = {}
    for k, v in statuses.iteritems():
      if k in experimental_builders:
        experimental_statuses[k] = v
      else:
        important_statuses[k] = v

    return important_statuses, experimental_statuses

  @staticmethod
  def GetFailingBuilds(statuses):
    """Get the names of builds which are failed.

    Args:
      statuses: A dict mapping build config names to their BuilderStatus.

    Returns:
      A set of failed build config names.
    """
    return set(builder for builder, status in statuses.iteritems()
               if status.Failed())

  @staticmethod
  def GetInflightBuilds(statuses):
    """Get the names of builds which are inflight.

    Args:
      statuses: A dict mapping build config names to their BuilderStatus.

    Returns:
      A set of inflight build config names.
    """
    return set(builder for builder, status in statuses.iteritems()
               if status.Inflight())

  @staticmethod
  def GetNostatBuilds(statuses):
    """Get the names of builds which are missing.

    Args:
      statuses: A dict mapping build config names to their BuilderStatus.

    Returns:
      A set of missing build config names.
    """
    return set(builder for builder, status in statuses.iteritems()
               if status.Missing())