from decimal import Decimal as D
from django.utils.translation import ugettext_lazy as _
from oscar.apps.offer import conditions, results, utils
from oscar.core.loading import get_model
from oscar.templatetags.currency_filters import currency
Benefit = get_model('offer', 'Benefit')
__all__ = [
'PercentageDiscountBenefit', 'AbsoluteDiscountBenefit', 'FixedPriceBenefit',
'ShippingBenefit', 'MultibuyDiscountBenefit',
'ShippingAbsoluteDiscountBenefit', 'ShippingFixedPriceBenefit',
'ShippingPercentageDiscountBenefit',
]
def apply_discount(line, discount, quantity):
"""
Apply a given discount to the passed basket
"""
line.discount(discount, quantity, incl_tax=False)
[docs]class PercentageDiscountBenefit(Benefit):
"""
An offer benefit that gives a percentage discount
"""
_description = _("%(value)s%% discount on %(range)s")
@property
def name(self):
return self._description % {
'value': self.value,
'range': self.range.name}
@property
def description(self):
return self._description % {
'value': self.value,
'range': utils.range_anchor(self.range)}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Percentage discount benefit")
verbose_name_plural = _("Percentage discount benefits")
def apply(self, basket, condition, offer, discount_percent=None,
max_total_discount=None):
if discount_percent is None:
discount_percent = self.value
discount_amount_available = max_total_discount
line_tuples = self.get_applicable_lines(offer, basket)
discount_percent = min(discount_percent, D('100.0'))
discount = D('0.00')
affected_items = 0
max_affected_items = self._effective_max_affected_items()
affected_lines = []
for price, line in line_tuples:
if affected_items >= max_affected_items:
break
if discount_amount_available == 0:
break
quantity_affected = min(line.quantity_without_discount,
max_affected_items - affected_items)
line_discount = self.round(discount_percent / D('100.0') * price
* int(quantity_affected))
if discount_amount_available is not None:
line_discount = min(line_discount, discount_amount_available)
discount_amount_available -= line_discount
apply_discount(line, line_discount, quantity_affected)
affected_lines.append((line, line_discount, quantity_affected))
affected_items += quantity_affected
discount += line_discount
if discount > 0:
condition.consume_items(offer, basket, affected_lines)
return results.BasketDiscount(discount)
[docs]class AbsoluteDiscountBenefit(Benefit):
"""
An offer benefit that gives an absolute discount
"""
_description = _("%(value)s discount on %(range)s")
@property
def name(self):
return self._description % {
'value': currency(self.value),
'range': self.range.name.lower()}
@property
def description(self):
return self._description % {
'value': currency(self.value),
'range': utils.range_anchor(self.range)}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Absolute discount benefit")
verbose_name_plural = _("Absolute discount benefits")
def apply(self, basket, condition, offer, discount_amount=None,
max_total_discount=None):
if discount_amount is None:
discount_amount = self.value
# Fetch basket lines that are in the range and available to be used in
# an offer.
line_tuples = self.get_applicable_lines(offer, basket)
# Determine which lines can have the discount applied to them
max_affected_items = self._effective_max_affected_items()
num_affected_items = 0
affected_items_total = D('0.00')
lines_to_discount = []
for price, line in line_tuples:
if num_affected_items >= max_affected_items:
break
qty = min(line.quantity_without_discount,
max_affected_items - num_affected_items)
lines_to_discount.append((line, price, qty))
num_affected_items += qty
affected_items_total += qty * price
# Ensure we don't try to apply a discount larger than the total of the
# matching items.
discount = min(discount_amount, affected_items_total)
if max_total_discount is not None:
discount = min(discount, max_total_discount)
if discount == 0:
return results.ZERO_DISCOUNT
# Apply discount equally amongst them
affected_lines = []
applied_discount = D('0.00')
for i, (line, price, qty) in enumerate(lines_to_discount):
if i == len(lines_to_discount) - 1:
# If last line, then take the delta as the discount to ensure
# the total discount is correct and doesn't mismatch due to
# rounding.
line_discount = discount - applied_discount
else:
# Calculate a weighted discount for the line
line_discount = self.round(
((price * qty) / affected_items_total) * discount)
apply_discount(line, line_discount, qty)
affected_lines.append((line, line_discount, qty))
applied_discount += line_discount
condition.consume_items(offer, basket, affected_lines)
return results.BasketDiscount(discount)
[docs]class FixedPriceBenefit(Benefit):
"""
An offer benefit that gives the items in the condition for a
fixed price. This is useful for "bundle" offers.
Note that we ignore the benefit range here and only give a fixed price
for the products in the condition range. The condition cannot be a value
condition.
We also ignore the max_affected_items setting.
"""
_description = _("The products that meet the condition are sold "
"for %(amount)s")
@property
def name(self):
return self._description % {
'amount': currency(self.value)}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Fixed price benefit")
verbose_name_plural = _("Fixed price benefits")
def apply(self, basket, condition, offer): # noqa (too complex (10))
if isinstance(condition, conditions.ValueCondition):
return results.ZERO_DISCOUNT
# Fetch basket lines that are in the range and available to be used in
# an offer.
line_tuples = self.get_applicable_lines(offer, basket,
range=condition.range)
if not line_tuples:
return results.ZERO_DISCOUNT
# Determine the lines to consume
num_permitted = int(condition.value)
num_affected = 0
value_affected = D('0.00')
covered_lines = []
for price, line in line_tuples:
if isinstance(condition, conditions.CoverageCondition):
quantity_affected = 1
else:
quantity_affected = min(
line.quantity_without_discount,
num_permitted - num_affected)
num_affected += quantity_affected
value_affected += quantity_affected * price
covered_lines.append((price, line, quantity_affected))
if num_affected >= num_permitted:
break
discount = max(value_affected - self.value, D('0.00'))
if not discount:
return results.ZERO_DISCOUNT
# Apply discount to the affected lines
discount_applied = D('0.00')
last_line = covered_lines[-1][1]
for price, line, quantity in covered_lines:
if line == last_line:
# If last line, we just take the difference to ensure that
# rounding doesn't lead to an off-by-one error
line_discount = discount - discount_applied
else:
line_discount = self.round(
discount * (price * quantity) / value_affected)
apply_discount(line, line_discount, quantity)
discount_applied += line_discount
return results.BasketDiscount(discount)
[docs]class MultibuyDiscountBenefit(Benefit):
_description = _("Cheapest product from %(range)s is free")
@property
def name(self):
return self._description % {
'range': self.range.name.lower()}
@property
def description(self):
return self._description % {
'range': utils.range_anchor(self.range)}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Multibuy discount benefit")
verbose_name_plural = _("Multibuy discount benefits")
def apply(self, basket, condition, offer):
line_tuples = self.get_applicable_lines(offer, basket)
if not line_tuples:
return results.ZERO_DISCOUNT
# Cheapest line gives free product
discount, line = line_tuples[0]
apply_discount(line, discount, 1)
affected_lines = [(line, discount, 1)]
condition.consume_items(offer, basket, affected_lines)
return results.BasketDiscount(discount)
# =================
# Shipping benefits
# =================
[docs]class ShippingBenefit(Benefit):
def apply(self, basket, condition, offer):
condition.consume_items(offer, basket, affected_lines=())
return results.SHIPPING_DISCOUNT
class Meta:
app_label = 'offer'
proxy = True
[docs]class ShippingAbsoluteDiscountBenefit(ShippingBenefit):
_description = _("%(amount)s off shipping cost")
@property
def name(self):
return self._description % {
'amount': currency(self.value)}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Shipping absolute discount benefit")
verbose_name_plural = _("Shipping absolute discount benefits")
def shipping_discount(self, charge):
return min(charge, self.value)
[docs]class ShippingFixedPriceBenefit(ShippingBenefit):
_description = _("Get shipping for %(amount)s")
@property
def name(self):
return self._description % {
'amount': currency(self.value)}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Fixed price shipping benefit")
verbose_name_plural = _("Fixed price shipping benefits")
def shipping_discount(self, charge):
if charge < self.value:
return D('0.00')
return charge - self.value
[docs]class ShippingPercentageDiscountBenefit(ShippingBenefit):
_description = _("%(value)s%% off of shipping cost")
@property
def name(self):
return self._description % {
'value': self.value}
class Meta:
app_label = 'offer'
proxy = True
verbose_name = _("Shipping percentage discount benefit")
verbose_name_plural = _("Shipping percentage discount benefits")
def shipping_discount(self, charge):
discount = charge * self.value / D('100.0')
return discount.quantize(D('0.01'))