import itertools import operator from collections import defaultdict from collections import namedtuple from django.db.models import Sum from django.utils import timezone from registrasion import models as rego ConditionAndRemainder = namedtuple( "ConditionAndRemainder", ( "condition", "remainder", ), ) class ConditionController(object): ''' Base class for testing conditions that activate EnablingCondition or Discount objects. ''' def __init__(self): pass @staticmethod def for_condition(condition): CONTROLLERS = { rego.CategoryEnablingCondition: CategoryConditionController, rego.IncludedProductDiscount: ProductConditionController, rego.ProductEnablingCondition: ProductConditionController, rego.TimeOrStockLimitDiscount: TimeOrStockLimitDiscountController, rego.TimeOrStockLimitEnablingCondition: TimeOrStockLimitEnablingConditionController, rego.VoucherDiscount: VoucherConditionController, rego.VoucherEnablingCondition: VoucherConditionController, } try: return CONTROLLERS[type(condition)](condition) except KeyError: return ConditionController() SINGLE = True PLURAL = False NONE = True SOME = False MESSAGE = { NONE: { SINGLE: "%(items)s is no longer available to you", PLURAL: "%(items)s are no longer available to you", }, SOME: { SINGLE: "Only %(remainder)d of the following item remains: %(items)s", PLURAL: "Only %(remainder)d of the following items remain: %(items)s" }, } @classmethod def test_enabling_conditions( cls, user, products=None, product_quantities=None): ''' Evaluates all of the enabling conditions on the given products. If `product_quantities` is supplied, the condition is only met if it will permit the sum of the product quantities for all of the products it covers. Otherwise, it will be met if at least one item can be accepted. If all enabling conditions pass, an empty list is returned, otherwise a list is returned containing all of the products that are *not enabled*. ''' if products is not None and product_quantities is not None: raise ValueError("Please specify only products or " "product_quantities") elif products is None: products = set(i[0] for i in product_quantities) quantities = dict((product, quantity) for product, quantity in product_quantities) elif product_quantities is None: products = set(products) quantities = {} # Get the conditions covered by the products themselves prods = ( product.enablingconditionbase_set.select_subclasses() for product in products ) # Get the conditions covered by their categories cats = ( category.enablingconditionbase_set.select_subclasses() for category in set(product.category for product in products) ) if products: # Simplify the query. all_conditions = reduce(operator.or_, itertools.chain(prods, cats)) else: all_conditions = [] # All mandatory conditions on a product need to be met mandatory = defaultdict(lambda: True) # At least one non-mandatory condition on a product must be met # if there are no mandatory conditions non_mandatory = defaultdict(lambda: False) messages = {} for condition in all_conditions: cond = cls.for_condition(condition) remainder = cond.user_quantity_remaining(user) # Get all products covered by this condition, and the products # from the categories covered by this condition cond_products = condition.products.all() from_category = rego.Product.objects.filter( category__in=condition.categories.all(), ).all() all_products = cond_products | from_category all_products = all_products.select_related("category") # Remove the products that we aren't asking about all_products = [ product for product in all_products if product in products ] if quantities: consumed = sum(quantities[i] for i in all_products) else: consumed = 1 met = consumed <= remainder if not met: items = ", ".join(str(product) for product in all_products) base = cls.MESSAGE[remainder == 0][len(all_products) == 1] message = base % {"items": items, "remainder": remainder} for product in all_products: if condition.mandatory: mandatory[product] &= met else: non_mandatory[product] |= met if not met and product not in messages: messages[product] = message valid = defaultdict(lambda: True) for product in itertools.chain(mandatory, non_mandatory): if product in mandatory: # If there's a mandatory condition, all must be met valid[product] = mandatory[product] else: # Otherwise, we need just one non-mandatory condition met valid[product] = non_mandatory[product] error_fields = [ (product, messages[product]) for product in valid if not valid[product] ] return error_fields def user_quantity_remaining(self, user): ''' Returns the number of items covered by this enabling 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 99999999 if self.is_met(user) else 0 def is_met(self, user): ''' Returns True if this enabling condition is met, otherwise returns False. Either this method, or user_quantity_remaining() must be overridden in subclasses. ''' return self.user_quantity_remaining(user) > 0 class CategoryConditionController(ConditionController): def __init__(self, condition): self.condition = condition def is_met(self, user): ''' returns True if the user has a product from a category that invokes this condition in one of their carts ''' carts = rego.Cart.objects.filter(user=user, released=False) enabling_products = rego.Product.objects.filter( category=self.condition.enabling_category, ) products_count = rego.ProductItem.objects.filter( cart__in=carts, product__in=enabling_products, ).count() return products_count > 0 class ProductConditionController(ConditionController): ''' Condition tests for ProductEnablingCondition and IncludedProductDiscount. ''' def __init__(self, condition): self.condition = condition def is_met(self, user): ''' returns True if the user has a product that invokes this condition in one of their carts ''' carts = rego.Cart.objects.filter(user=user, released=False) products_count = rego.ProductItem.objects.filter( cart__in=carts, product__in=self.condition.enabling_products.all(), ).count() return products_count > 0 class TimeOrStockLimitConditionController(ConditionController): ''' Common condition tests for TimeOrStockLimit EnablingCondition and Discount.''' def __init__(self, ceiling): self.ceiling = ceiling def user_quantity_remaining(self, user): ''' returns 0 if the date range is violated, otherwise, it will return the quantity remaining under the stock limit. ''' # Test date range if not self._test_date_range(): return 0 return self._get_remaining_stock(user) def _test_date_range(self): now = timezone.now() if self.ceiling.start_time is not None: if now < self.ceiling.start_time: return False if self.ceiling.end_time is not None: if now > self.ceiling.end_time: return False return True def _get_remaining_stock(self, user): ''' Returns the stock that remains under this ceiling, excluding the user's current cart. ''' if self.ceiling.limit is None: return 99999999 # We care about all reserved carts, but not the user's current cart reserved_carts = rego.Cart.reserved_carts() reserved_carts = reserved_carts.exclude( user=user, active=True, ) items = self._items() items = items.filter(cart__in=reserved_carts) count = items.aggregate(Sum("quantity"))["quantity__sum"] or 0 return self.ceiling.limit - count class TimeOrStockLimitEnablingConditionController( TimeOrStockLimitConditionController): def _items(self): category_products = rego.Product.objects.filter( category__in=self.ceiling.categories.all(), ) products = self.ceiling.products.all() | category_products product_items = rego.ProductItem.objects.filter( product__in=products.all(), ) return product_items class TimeOrStockLimitDiscountController(TimeOrStockLimitConditionController): def _items(self): discount_items = rego.DiscountItem.objects.filter( discount=self.ceiling, ) return discount_items class VoucherConditionController(ConditionController): ''' Condition test for VoucherEnablingCondition and VoucherDiscount.''' def __init__(self, condition): self.condition = condition def is_met(self, user): ''' returns True if the user has the given voucher attached. ''' carts_count = rego.Cart.objects.filter( user=user, vouchers=self.condition.voucher, ).count() return carts_count > 0