255 lines
8.9 KiB
Python
255 lines
8.9 KiB
Python
import datetime
|
|
import discount
|
|
|
|
from django.core.exceptions import ObjectDoesNotExist
|
|
from django.core.exceptions import ValidationError
|
|
from django.db.models import Max
|
|
from django.utils import timezone
|
|
|
|
from registrasion import models as rego
|
|
|
|
from conditions import ConditionController
|
|
from product import ProductController
|
|
|
|
|
|
class CartController(object):
|
|
|
|
def __init__(self, cart):
|
|
self.cart = cart
|
|
|
|
@staticmethod
|
|
def for_user(user):
|
|
''' Returns the user's current cart, or creates a new cart
|
|
if there isn't one ready yet. '''
|
|
|
|
try:
|
|
existing = rego.Cart.objects.get(user=user, active=True)
|
|
except ObjectDoesNotExist:
|
|
existing = rego.Cart.objects.create(
|
|
user=user,
|
|
time_last_updated=timezone.now(),
|
|
reservation_duration=datetime.timedelta(),
|
|
)
|
|
existing.save()
|
|
return CartController(existing)
|
|
|
|
def extend_reservation(self):
|
|
''' Updates the cart's time last updated value, which is used to
|
|
determine whether the cart has reserved the items and discounts it
|
|
holds. '''
|
|
|
|
reservations = [datetime.timedelta()]
|
|
|
|
# If we have vouchers, we're entitled to an hour at minimum.
|
|
if len(self.cart.vouchers.all()) >= 1:
|
|
reservations.append(rego.Voucher.RESERVATION_DURATION)
|
|
|
|
# Else, it's the maximum of the included products
|
|
items = rego.ProductItem.objects.filter(cart=self.cart)
|
|
agg = items.aggregate(Max("product__reservation_duration"))
|
|
product_max = agg["product__reservation_duration__max"]
|
|
|
|
if product_max is not None:
|
|
reservations.append(product_max)
|
|
|
|
self.cart.time_last_updated = timezone.now()
|
|
self.cart.reservation_duration = max(reservations)
|
|
|
|
def end_batch(self):
|
|
''' Performs operations that occur occur at the end of a batch of
|
|
product changes/voucher applications etc. '''
|
|
self.recalculate_discounts()
|
|
|
|
self.extend_reservation()
|
|
self.cart.revision += 1
|
|
self.cart.save()
|
|
|
|
def set_quantity(self, product, quantity, batched=False):
|
|
''' Sets the _quantity_ of the given _product_ in the cart to the given
|
|
_quantity_. '''
|
|
|
|
if quantity < 0:
|
|
raise ValidationError("Cannot have fewer than 0 items in cart.")
|
|
|
|
try:
|
|
product_item = rego.ProductItem.objects.get(
|
|
cart=self.cart,
|
|
product=product)
|
|
old_quantity = product_item.quantity
|
|
|
|
if quantity == 0:
|
|
product_item.delete()
|
|
return
|
|
except ObjectDoesNotExist:
|
|
if quantity == 0:
|
|
return
|
|
|
|
product_item = rego.ProductItem.objects.create(
|
|
cart=self.cart,
|
|
product=product,
|
|
quantity=0,
|
|
)
|
|
|
|
old_quantity = 0
|
|
|
|
# Validate the addition to the cart
|
|
adjustment = quantity - old_quantity
|
|
prod = ProductController(product)
|
|
|
|
if not prod.can_add_with_enabling_conditions(
|
|
self.cart.user, adjustment):
|
|
raise ValidationError("Not enough of that product left (ec)")
|
|
|
|
if not prod.user_can_add_within_limit(self.cart.user, adjustment):
|
|
raise ValidationError("Not enough of that product left (user)")
|
|
|
|
product_item.quantity = quantity
|
|
product_item.save()
|
|
|
|
if not batched:
|
|
self.end_batch()
|
|
|
|
def add_to_cart(self, product, quantity):
|
|
''' Adds _quantity_ of the given _product_ to the cart. Raises
|
|
ValidationError if constraints are violated.'''
|
|
|
|
try:
|
|
product_item = rego.ProductItem.objects.get(
|
|
cart=self.cart,
|
|
product=product)
|
|
old_quantity = product_item.quantity
|
|
except ObjectDoesNotExist:
|
|
old_quantity = 0
|
|
self.set_quantity(product, old_quantity + quantity)
|
|
|
|
def apply_voucher(self, voucher_code):
|
|
''' Applies the voucher with the given code to this cart. '''
|
|
|
|
# TODO: is it valid for a cart to re-add a voucher that they have?
|
|
|
|
# Is voucher exhausted?
|
|
active_carts = rego.Cart.reserved_carts()
|
|
|
|
# Try and find the voucher
|
|
voucher = rego.Voucher.objects.get(code=voucher_code.upper())
|
|
|
|
carts_with_voucher = active_carts.filter(vouchers=voucher)
|
|
if len(carts_with_voucher) >= voucher.limit:
|
|
raise ValidationError("This voucher is no longer available")
|
|
|
|
# If successful...
|
|
self.cart.vouchers.add(voucher)
|
|
self.end_batch()
|
|
|
|
def validate_cart(self):
|
|
''' Determines whether the status of the current cart is valid;
|
|
this is normally called before generating or paying an invoice '''
|
|
|
|
is_reserved = self.cart in rego.Cart.reserved_carts()
|
|
|
|
# TODO: validate vouchers
|
|
|
|
items = rego.ProductItem.objects.filter(cart=self.cart)
|
|
for item in items:
|
|
# NOTE: per-user limits are tested at add time
|
|
# and are unliklely to change
|
|
prod = ProductController(item.product)
|
|
|
|
# If the cart is not reserved, we need to see if we can re-reserve
|
|
quantity = 0 if is_reserved else item.quantity
|
|
|
|
if not prod.can_add_with_enabling_conditions(
|
|
self.cart.user, quantity):
|
|
raise ValidationError("Products are no longer available")
|
|
|
|
# Validate the discounts
|
|
discount_items = rego.DiscountItem.objects.filter(cart=self.cart)
|
|
seen_discounts = set()
|
|
|
|
for discount_item in discount_items:
|
|
discount = discount_item.discount
|
|
if discount in seen_discounts:
|
|
continue
|
|
seen_discounts.add(discount)
|
|
real_discount = rego.DiscountBase.objects.get_subclass(
|
|
pk=discount.pk)
|
|
cond = ConditionController.for_condition(real_discount)
|
|
|
|
quantity = 0 if is_reserved else discount_item.quantity
|
|
|
|
if not cond.is_met(self.cart.user, quantity):
|
|
raise ValidationError("Discounts are no longer available")
|
|
|
|
def recalculate_discounts(self):
|
|
''' Calculates all of the discounts available for this product.
|
|
NB should be transactional, and it's terribly inefficient.
|
|
'''
|
|
|
|
# Delete the existing entries.
|
|
rego.DiscountItem.objects.filter(cart=self.cart).delete()
|
|
|
|
product_items = self.cart.productitem_set.all()
|
|
|
|
products = [i.product for i in product_items]
|
|
discounts = discount.available_discounts(self.cart.user, [], products)
|
|
|
|
# The highest-value discounts will apply to the highest-value
|
|
# products first.
|
|
product_items = self.cart.productitem_set.all()
|
|
product_items = product_items.order_by('product__price')
|
|
product_items = reversed(product_items)
|
|
for item in product_items:
|
|
self._add_discount(item.product, item.quantity, discounts)
|
|
|
|
def _add_discount(self, product, quantity, discounts):
|
|
''' Applies the best discounts on the given product, from the given
|
|
discounts.'''
|
|
|
|
def matches(discount):
|
|
''' Returns True if and only if the given discount apples to
|
|
our product. '''
|
|
if isinstance(discount.clause, rego.DiscountForCategory):
|
|
return discount.clause.category == product.category
|
|
else:
|
|
return discount.clause.product == product
|
|
|
|
def value(discount):
|
|
''' Returns the value of this discount clause
|
|
as applied to this product '''
|
|
if discount.clause.percentage is not None:
|
|
return discount.clause.percentage * product.price
|
|
else:
|
|
return discount.clause.price
|
|
|
|
discounts = [i for i in discounts if matches(i)]
|
|
discounts.sort(key=value)
|
|
|
|
for candidate in reversed(discounts):
|
|
if quantity == 0:
|
|
break
|
|
elif candidate.quantity == 0:
|
|
# This discount clause has been exhausted by this cart
|
|
continue
|
|
|
|
# Get a provisional instance for this DiscountItem
|
|
# with the quantity set to as much as we have in the cart
|
|
discount_item = rego.DiscountItem.objects.create(
|
|
product=product,
|
|
cart=self.cart,
|
|
discount=candidate.discount,
|
|
quantity=quantity,
|
|
)
|
|
|
|
# Truncate the quantity for this DiscountItem if we exceed quantity
|
|
ours = discount_item.quantity
|
|
allowed = candidate.quantity
|
|
if ours > allowed:
|
|
discount_item.quantity = allowed
|
|
# Update the remaining quantity.
|
|
quantity = ours - allowed
|
|
else:
|
|
quantity = 0
|
|
|
|
candidate.quantity -= discount_item.quantity
|
|
|
|
discount_item.save()
|