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"""Logical units for queries."""

from ganeti import constants

from ganeti import errors

from ganeti import query

from ganeti.cmdlib.base import NoHooksLU

from ganeti.cmdlib.cluster import ClusterQuery

from ganeti.cmdlib.misc import ExtStorageQuery

from ganeti.cmdlib.operating_system import OsQuery

#: Query type implementations

_QUERY_IMPL = {

  constants.QR_CLUSTER: ClusterQuery,

  constants.QR_OS: OsQuery,

  constants.QR_EXTSTORAGE: ExtStorageQuery,

  }

assert set(_QUERY_IMPL.keys()) == constants.QR_VIA_OP

def _GetQueryImplementation(name):

  """Returns the implementation for a query type.

  @param name: Query type, must be one of L{constants.QR_VIA_OP}

  """

  try:

    return _QUERY_IMPL[name]

  except KeyError:

    raise errors.OpPrereqError("Unknown query resource '%s'" % name,

                               errors.ECODE_INVAL)

class LUQuery(NoHooksLU):

  """Query for resources/items of a certain kind.

  """

  # pylint: disable=W0142

  REQ_BGL = False

  def CheckArguments(self):

    qcls = _GetQueryImplementation(self.op.what)

    self.impl = qcls(self.op.qfilter, self.op.fields, self.op.use_locking)

  def ExpandNames(self):

    self.impl.ExpandNames(self)

  def DeclareLocks(self, level):

    self.impl.DeclareLocks(self, level)

  def Exec(self, feedback_fn):

    return self.impl.NewStyleQuery(self)

class LUQueryFields(NoHooksLU):

  """Query for resources/items of a certain kind.

  """

  # pylint: disable=W0142

  REQ_BGL = False

  def CheckArguments(self):

    self.qcls = _GetQueryImplementation(self.op.what)

  def ExpandNames(self):

    self.needed_locks = {}

  def Exec(self, feedback_fn):

    return query.QueryFields(self.qcls.FIELDS, self.op.fields)