import itertools from collections import defaultdict from collections import namedtuple from django.db.models import Count from django.db.models import Q from .batch import BatchController from .conditions import ConditionController from registrasion.models import conditions from registrasion.models import inventory class FlagController(object): @classmethod def test_flags( cls, user, products=None, product_quantities=None): ''' Evaluates all of the flag 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 flag 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 = {} if products: # Simplify the query. all_conditions = cls._filtered_flags(user) else: all_conditions = [] # All disable-if-false conditions on a product need to be met do_not_disable = defaultdict(lambda: True) # At least one enable-if-true condition on a product must be met do_enable = defaultdict(lambda: False) # (if either sort of condition is present) # Count the number of conditions for a product dif_count = defaultdict(int) eit_count = defaultdict(int) messages = {} for condition in all_conditions: cond = ConditionController.for_condition(condition) remainder = cond.user_quantity_remaining(user, filtered=True) # Get all products covered by this condition, and the products # from the categories covered by this condition ids = [product.id for product in products] # TODO: This is re-evaluated a lot. all_products = inventory.Product.objects.filter(id__in=ids) cond = ( Q(flagbase_set=condition) | Q(category__in=condition.categories.all()) ) all_products = all_products.filter(cond) all_products = all_products.select_related("category") if quantities: consumed = sum(quantities[i] for i in all_products) else: consumed = 1 met = consumed <= remainder if not met: message = cls._error_message(all_products, remainder) for product in all_products: if condition.is_disable_if_false: do_not_disable[product] &= met dif_count[product] += 1 else: do_enable[product] |= met eit_count[product] += 1 if not met and product not in messages: messages[product] = message total_flags = FlagCounter.count(user) valid = {} # the problem is that now, not every condition falls into # do_not_disable or do_enable ''' # You should look into this, chris :) for product in products: if quantities: if quantities[product] == 0: continue f = total_flags.get(product) if f.dif > 0 and f.dif != dif_count[product]: do_not_disable[product] = False if product not in messages: messages[product] = cls._error_message([product], 0) if f.eit > 0 and product not in do_enable: do_enable[product] = False if product not in messages: messages[product] = cls._error_message([product], 0) for product in itertools.chain(do_not_disable, do_enable): f = total_flags.get(product) if product in do_enable: # If there's an enable-if-true, we need need of those met too. # (do_not_disable will default to true otherwise) valid[product] = do_not_disable[product] and do_enable[product] elif product in do_not_disable: # If there's a disable-if-false condition, all must be met valid[product] = do_not_disable[product] error_fields = [ (product, messages[product]) for product in valid if not valid[product] ] return error_fields 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 _error_message(cls, affected, remainder): product_strings = (str(product) for product in affected) items = ", ".join(product_strings) base = cls.MESSAGE[remainder == 0][len(affected) == 1] message = base % {"items": items, "remainder": remainder} return message @classmethod @BatchController.memoise def _filtered_flags(cls, user): ''' Returns: Sequence[flagbase]: All flags that passed the filter function. ''' types = list(ConditionController._controllers()) flagtypes = [i for i in types if issubclass(i, conditions.FlagBase)] all_subsets = [] for flagtype in flagtypes: flags = flagtype.objects.all() ctrl = ConditionController.for_type(flagtype) flags = ctrl.pre_filter(flags, user) all_subsets.append(flags) return list(itertools.chain(*all_subsets)) ConditionAndRemainder = namedtuple( "ConditionAndRemainder", ( "condition", "remainder", ), ) _FlagCounter = namedtuple( "_FlagCounter", ( "products", "categories", ), ) _ConditionsCount = namedtuple( "ConditionsCount", ( "dif", "eit", ), ) class FlagCounter(_FlagCounter): @classmethod @BatchController.memoise def count(cls, user): # Get the count of how many conditions should exist per product flagbases = conditions.FlagBase.objects types = ( conditions.FlagBase.ENABLE_IF_TRUE, conditions.FlagBase.DISABLE_IF_FALSE, ) keys = ("eit", "dif") flags = [ flagbases.filter( condition=condition_type ).values( 'products', 'categories' ).annotate( count=Count('id') ) for condition_type in types ] cats = defaultdict(lambda: defaultdict(int)) prod = defaultdict(lambda: defaultdict(int)) for key, flagcounts in zip(keys, flags): for row in flagcounts: if row["products"] is not None: prod[row["products"]][key] = row["count"] if row["categories"] is not None: cats[row["categories"]][key] = row["count"] return cls(products=prod, categories=cats) def get(self, product): p = self.products[product.id] c = self.categories[product.category.id] eit = p["eit"] + c["eit"] dif = p["dif"] + c["dif"] return _ConditionsCount(dif=dif, eit=eit)