from django.db.models import Case
from django.db.models import F, Q
from django.db.models import Sum
from django.db.models import Value
from django.db.models import When
from django.utils import timezone
from registrasion.models import commerce
from registrasion.models import conditions
_BIG_QUANTITY = 99999999 # A big quantity
class ConditionController(object):
''' Base class for testing conditions that activate Flag
or Discount objects. '''
def __init__(self, condition):
self.condition = condition
@staticmethod
def _controllers():
return {
conditions.CategoryFlag: CategoryConditionController,
conditions.GroupMemberDiscount: GroupMemberConditionController,
conditions.GroupMemberFlag: GroupMemberConditionController,
conditions.IncludedProductDiscount: ProductConditionController,
conditions.ProductFlag: ProductConditionController,
conditions.SpeakerFlag: SpeakerConditionController,
conditions.SpeakerDiscount: SpeakerConditionController,
conditions.TimeOrStockLimitDiscount:
TimeOrStockLimitDiscountController,
conditions.TimeOrStockLimitFlag:
TimeOrStockLimitFlagController,
conditions.VoucherDiscount: VoucherConditionController,
conditions.VoucherFlag: VoucherConditionController,
}
@staticmethod
def for_type(cls):
return ConditionController._controllers()[cls]
@staticmethod
def for_condition(condition):
try:
return ConditionController.for_type(type(condition))(condition)
except KeyError:
return ConditionController()
@classmethod
def pre_filter(cls, queryset, user):
''' Returns only the flag conditions that might be available for this
user. It should hopefully reduce the number of queries that need to be
executed to determine if a flag is met.
If this filtration implements the same query as is_met, then you should
be able to implement ``is_met()`` in terms of this.
Arguments:
queryset (Queryset[c]): The canditate conditions.
user (User): The user for whom we're testing these conditions.
Returns:
Queryset[c]: A subset of the conditions that pass the pre-filter
test for this user.
'''
# Default implementation does NOTHING.
return queryset
def passes_filter(self, user):
''' Returns true if the condition passes the filter '''
cls = type(self.condition)
qs = cls.objects.filter(pk=self.condition.id)
return self.condition in self.pre_filter(qs, user)
def user_quantity_remaining(self, user, filtered=False):
''' Returns the number of items covered by this flag condition the
user can add to the current cart. This default implementation returns
a big number if is_met() is true, otherwise 0.
Either this method, or is_met() must be overridden in subclasses.
'''
return _BIG_QUANTITY if self.is_met(user, filtered) else 0
def is_met(self, user, filtered=False):
''' Returns True if this flag condition is met, otherwise returns
False.
Either this method, or user_quantity_remaining() must be overridden
in subclasses.
Arguments:
user (User): The user for whom this test must be met.
filter (bool): If true, this condition was part of a queryset
returned by pre_filter() for this user.
'''
return self.user_quantity_remaining(user, filtered) > 0
class IsMetByFilter(object):
def is_met(self, user, filtered=False):
''' Returns True if this flag condition is met, otherwise returns
False. It determines if the condition is met by calling pre_filter
with a queryset containing only self.condition. '''
if filtered:
return True # Why query again?
return self.passes_filter(user)
class RemainderSetByFilter(object):
def user_quantity_remaining(self, user, filtered=True):
''' returns 0 if the date range is violated, otherwise, it will return
the quantity remaining under the stock limit.
The filter for this condition must add an annotation called "remainder"
in order for this to work.
'''
if filtered:
if hasattr(self.condition, "remainder"):
return self.condition.remainder
# Mark self.condition with a remainder
qs = type(self.condition).objects.filter(pk=self.condition.id)
qs = self.pre_filter(qs, user)
if len(qs) > 0:
return qs[0].remainder
else:
return 0
class CategoryConditionController(IsMetByFilter, ConditionController):
@classmethod
def pre_filter(self, queryset, user):
''' Returns all of the items from queryset where the user has a
product from a category invoking that item's condition in one of their
carts. '''
in_user_carts = Q(
enabling_category__product__productitem__cart__user=user
)
released = commerce.Cart.STATUS_RELEASED
in_released_carts = Q(
enabling_category__product__productitem__cart__status=released
)
queryset = queryset.filter(in_user_carts)
queryset = queryset.exclude(in_released_carts)
return queryset
class ProductConditionController(IsMetByFilter, ConditionController):
''' Condition tests for ProductFlag and
IncludedProductDiscount. '''
@classmethod
def pre_filter(self, queryset, user):
''' Returns all of the items from queryset where the user has a
product invoking that item's condition in one of their carts. '''
in_user_carts = Q(enabling_products__productitem__cart__user=user)
released = commerce.Cart.STATUS_RELEASED
paid = commerce.Cart.STATUS_PAID
active = commerce.Cart.STATUS_ACTIVE
in_released_carts = Q(
enabling_products__productitem__cart__status=released
)
not_in_paid_or_active_carts = ~(
Q(enabling_products__productitem__cart__status=paid) |
Q(enabling_products__productitem__cart__status=active)
)
queryset = queryset.filter(in_user_carts)
queryset = queryset.exclude(
in_released_carts & not_in_paid_or_active_carts
)
return queryset
class TimeOrStockLimitConditionController(
RemainderSetByFilter,
ConditionController,
):
''' Common condition tests for TimeOrStockLimit Flag and
Discount.'''
@classmethod
def pre_filter(self, queryset, user):
''' Returns all of the items from queryset where the date falls into
any specified range, but not yet where the stock limit is not yet
reached.'''
now = timezone.now()
# Keep items with no start time, or start time not yet met.
queryset = queryset.filter(Q(start_time=None) | Q(start_time__lte=now))
queryset = queryset.filter(Q(end_time=None) | Q(end_time__gte=now))
# Filter out items that have been reserved beyond the limits
quantity_or_zero = self._calculate_quantities(user)
remainder = Case(
When(limit=None, then=Value(_BIG_QUANTITY)),
default=F("limit") - Sum(quantity_or_zero),
)
queryset = queryset.annotate(remainder=remainder)
queryset = queryset.filter(remainder__gt=0)
return queryset
@classmethod
def _relevant_carts(cls, user):
reserved_carts = commerce.Cart.reserved_carts()
reserved_carts = reserved_carts.exclude(
user=user,
status=commerce.Cart.STATUS_ACTIVE,
)
return reserved_carts
class TimeOrStockLimitFlagController(
TimeOrStockLimitConditionController):
@classmethod
def _calculate_quantities(cls, user):
reserved_carts = cls._relevant_carts(user)
# Calculate category lines
item_cats = F('categories__product__productitem__product__category')
reserved_category_products = (
Q(categories=item_cats) &
Q(categories__product__productitem__cart__in=reserved_carts)
)
# Calculate product lines
reserved_products = (
Q(products=F('products__productitem__product')) &
Q(products__productitem__cart__in=reserved_carts)
)
category_quantity_in_reserved_carts = When(
reserved_category_products,
then="categories__product__productitem__quantity",
)
product_quantity_in_reserved_carts = When(
reserved_products,
then="products__productitem__quantity",
)
quantity_or_zero = Case(
category_quantity_in_reserved_carts,
product_quantity_in_reserved_carts,
default=Value(0),
)
return quantity_or_zero
class TimeOrStockLimitDiscountController(TimeOrStockLimitConditionController):
@classmethod
def _calculate_quantities(cls, user):
reserved_carts = cls._relevant_carts(user)
quantity_in_reserved_carts = When(
discountitem__cart__in=reserved_carts,
then="discountitem__quantity"
)
quantity_or_zero = Case(
quantity_in_reserved_carts,
default=Value(0)
)
return quantity_or_zero
class VoucherConditionController(IsMetByFilter, ConditionController):
''' Condition test for VoucherFlag and VoucherDiscount.'''
@classmethod
def pre_filter(self, queryset, user):
''' Returns all of the items from queryset where the user has entered
a voucher that invokes that item's condition in one of their carts. '''
return queryset.filter(voucher__cart__user=user)
class SpeakerConditionController(IsMetByFilter, ConditionController):
@classmethod
def pre_filter(self, queryset, user):
''' Returns all of the items from queryset which are enabled by a user
being a presenter or copresenter of a non-cancelled proposal. '''
# Filter out cancelled proposals
queryset = queryset.filter(
proposal_kind__proposalbase__presentation__cancelled=False
)
u = user
# User is a presenter
user_is_presenter = Q(
is_presenter=True,
proposal_kind__proposalbase__presentation__speaker__user=u,
)
# User is a copresenter
user_is_copresenter = Q(
is_copresenter=True,
proposal_kind__proposalbase__presentation__additional_speakers__user=u, # NOQA
)
return queryset.filter(user_is_presenter | user_is_copresenter)
class GroupMemberConditionController(IsMetByFilter, ConditionController):
@classmethod
def pre_filter(self, conditions, user):
''' Returns all of the items from conditions which are enabled by a
user being member of a Django Auth Group. '''
return conditions.filter(group__in=user.groups.all())
