app/summerofcode/logic/slot_transfer.py

# Copyright 2014 the Melange authors.
#
# 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.

"""Logic for slot transfer requests."""

from google.appengine.ext import ndb

from melange.utils import rich_bool

from summerofcode.models import slot_transfer as slot_transfer_model


PENDING_SLOT_TRANSFER_EXISTS = 'pending_slot_transfer_exists'
NOT_ENOUGH_SLOTS_ALLOCATED = 'not_enough_slots_allocated'
NOT_ENOUGH_SLOTS_TRANSFERRED = 'not_enough_slots_transferred'
SLOT_TRANSFER_NOT_EXISTING = 'slot_transfer_not_existing'
SLOT_TRANSFER_NOT_PENDING = 'slot_transfer_not_pending'
ORG_NOT_EXISTING = 'org_not_existing'


@ndb.transactional
def createSlotTransfer(org_key, quantity, org_message=None):
  """Creates a new slot transfer entity for the specified quantity and
  organization.

  Args:
    org_key: ndb.Key of organization entity.
    quantity: An integer telling how many slots is requested to be given back.
    org_message: Optional string with a message from the organization.

  Returns:
    rich_bool.RichBool whose value is set to True, if a new slot transfer
    request has been created properly. In that case, the extra part points to
    the newly created entity. Otherwise, rich_bool.RichBool whose value is set
    to False and extra part is a string that represents the reason why it is
    not possible to create a new slot transfer request.
  """
  if hasPendingSlotTransfer(org_key):
      # a pending slot transfer request exists for the organization
    return rich_bool.RichBool(False, PENDING_SLOT_TRANSFER_EXISTS)
  else:
    organization = org_key.get()
    if organization.slot_allocation < quantity:
      return rich_bool.RichBool(False, NOT_ENOUGH_SLOTS_ALLOCATED)
    elif quantity <= 0:
      return rich_bool.RichBool(False, NOT_ENOUGH_SLOTS_TRANSFERRED)
    else:
      slot_transfer = slot_transfer_model.SlotTransfer(
          parent=org_key, quantity=quantity, program=organization.program,
          org_message=org_message)
      slot_transfer.put()
      return rich_bool.RichBool(True, slot_transfer)


@ndb.transactional
def acceptSlotTransfer(slot_transfer_key):
  """Accepts the specified slot transfer.

  Args:
    slot_trasnfer_key: ndb.Key of slot transfer entity.

  Returns:
    rich_bool.RichBool whose value is set to True, if the slot transfer is
    properly accepted. Otherwise, rich_bool.RichBool whose value is set
    to False and extra part is a string that represents the reason why the
    action is not possible at this time.
  """
  slot_transfer = slot_transfer_key.get()
  if not slot_transfer:
    return rich_bool.RichBool(False, SLOT_TRANSFER_NOT_EXISTING)
  elif slot_transfer.status != slot_transfer_model.Status.PENDING:
    return rich_bool.RichBool(False, SLOT_TRANSFER_NOT_PENDING)
  elif slot_transfer.quantity <= 0:
    return rich_bool.RichBool(False, NOT_ENOUGH_SLOTS_TRANSFERRED)
  else:
    org = slot_transfer.key.parent().get()
    if not org:
      return rich_bool.RichBool(False, ORG_NOT_EXISTING)
    else:
      slot_transfer.status = slot_transfer_model.Status.ACCEPTED
      org.slot_allocation = max(org.slot_allocation - slot_transfer.quantity, 0)
      ndb.put_multi([slot_transfer, org])
      return rich_bool.TRUE


@ndb.transactional
def rejectSlotTransfer(slot_transfer_key):
  """Rejects the specified slot transfer request.

  Args:
    slot_trasnfer_key: ndb.Key of slot transfer entity.

  Returns:
    rich_bool.RichBool whose value is set to True, if the slot transfer is
    properly rejected. Otherwise, rich_bool.RichBool whose value is set
    to False and extra part is a string that represents the reason why the
    action is not possible at this time.
  """
  slot_transfer = slot_transfer_key.get()
  if not slot_transfer:
    return rich_bool.RichBool(False, SLOT_TRANSFER_NOT_EXISTING)
  elif slot_transfer.status != slot_transfer_model.Status.PENDING:
    return rich_bool.RichBool(False, SLOT_TRANSFER_NOT_PENDING)
  else:
    slot_transfer.status = slot_transfer_model.Status.REJECTED
    slot_transfer.put()
    return rich_bool.TRUE


def getSlotTransfersForOrg(org_key):
  """Returns all slot transfer requests for the specified organization.

  Args:
    org_key: ndb.Key of organization entity.

  Returns:
    A list of slot_transfer.SlotTransfer entities.
  """
  return slot_transfer_model.SlotTransfer.query(
      ancestor=org_key).fetch(1000)


def hasPendingSlotTransfer(org_key):
  """Tells whether the specified organization has a pending slot transfer
  request at this time.

  Args:
    org_key: ndb.Key of organization entity.

  Returns:
    True, if the organization has a pending slot transfer request. Otherwise,
    False is returned.
  """
  query = slot_transfer_model.SlotTransfer.query(
      slot_transfer_model.SlotTransfer.status
          == slot_transfer_model.Status.PENDING, ancestor=org_key)
  return bool(query.count())