from django.db.models import Q from django.db.models import Sum from django.utils import timezone from registrasion import models as rego 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: TimeOrStockLimitConditionController, rego.TimeOrStockLimitEnablingCondition: TimeOrStockLimitConditionController, rego.VoucherDiscount: VoucherConditionController, rego.VoucherEnablingCondition: VoucherConditionController, } try: return CONTROLLERS[type(condition)](condition) except KeyError: return ConditionController() def is_met(self, user, quantity): return True class CategoryConditionController(ConditionController): def __init__(self, condition): self.condition = condition def is_met(self, user, quantity): ''' 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 = rego.ProductItem.objects.filter( cart=carts, product=enabling_products) return len(products) > 0 class ProductConditionController(ConditionController): ''' Condition tests for ProductEnablingCondition and IncludedProductDiscount. ''' def __init__(self, condition): self.condition = condition def is_met(self, user, quantity): ''' 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 = rego.ProductItem.objects.filter( cart=carts, product=self.condition.enabling_products.all()) return len(products) > 0 class TimeOrStockLimitConditionController(ConditionController): ''' Condition tests for TimeOrStockLimit EnablingCondition and Discount.''' def __init__(self, ceiling): self.ceiling = ceiling def is_met(self, user, quantity): ''' returns True if adding _quantity_ of _product_ will not vioilate this ceiling. ''' # Test date range if not self.test_date_range(): return False # Test limits if not self.test_limits(quantity): return False # All limits have been met return True 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 _products(self): ''' Abstracts away the product list, becuase enabling conditions list products differently to discounts. ''' if isinstance(self.ceiling, rego.TimeOrStockLimitEnablingCondition): category_products = rego.Product.objects.filter( category=self.ceiling.categories.all() ) return self.ceiling.products.all() | category_products else: categories = rego.Category.objects.filter( discountforcategory__discount=self.ceiling ) return rego.Product.objects.filter( Q(discountforproduct__discount=self.ceiling) | Q(category=categories.all()) ) def test_limits(self, quantity): if self.ceiling.limit is None: return True reserved_carts = rego.Cart.reserved_carts() product_items = rego.ProductItem.objects.filter( product=self._products().all() ) product_items = product_items.filter(cart=reserved_carts) agg = product_items.aggregate(Sum("quantity")) count = agg["quantity__sum"] if count is None: count = 0 if count + quantity > self.ceiling.limit: return False return True class VoucherConditionController(ConditionController): ''' Condition test for VoucherEnablingCondition and VoucherDiscount.''' def __init__(self, condition): self.condition = condition def is_met(self, user, quantity): ''' returns True if the user has the given voucher attached. ''' carts = rego.Cart.objects.filter( user=user, vouchers=self.condition.voucher) return len(carts) > 0