from decimal import Decimal from django.core.exceptions import ObjectDoesNotExist from django.core.exceptions import ValidationError from django.db import transaction from django.db.models import Sum from registrasion import models as rego from cart import CartController class InvoiceController(object): def __init__(self, invoice): self.invoice = invoice self.update_validity() # Make sure this invoice is up-to-date @classmethod def for_cart(cls, cart): ''' Returns an invoice object for a given cart at its current revision. If such an invoice does not exist, the cart is validated, and if valid, an invoice is generated.''' try: invoice = rego.Invoice.objects.get( cart=cart, cart_revision=cart.revision, void=False, ) except ObjectDoesNotExist: cart_controller = CartController(cart) cart_controller.validate_cart() # Raises ValidationError on fail. # Void past invoices for this cart rego.Invoice.objects.filter(cart=cart).update(void=True) invoice = cls._generate(cart) return InvoiceController(invoice) @classmethod def resolve_discount_value(cls, item): try: condition = rego.DiscountForProduct.objects.get( discount=item.discount, product=item.product ) except ObjectDoesNotExist: condition = rego.DiscountForCategory.objects.get( discount=item.discount, category=item.product.category ) if condition.percentage is not None: value = item.product.price * (condition.percentage / 100) else: value = condition.price return value @classmethod @transaction.atomic def _generate(cls, cart): ''' Generates an invoice for the given cart. ''' invoice = rego.Invoice.objects.create( user=cart.user, cart=cart, cart_revision=cart.revision, value=Decimal() ) product_items = rego.ProductItem.objects.filter(cart=cart) if len(product_items) == 0: raise ValidationError("Your cart is empty.") product_items = product_items.order_by( "product__category__order", "product__order" ) discount_items = rego.DiscountItem.objects.filter(cart=cart) invoice_value = Decimal() for item in product_items: product = item.product line_item = rego.LineItem.objects.create( invoice=invoice, description="%s - %s" % (product.category.name, product.name), quantity=item.quantity, price=product.price, ) invoice_value += line_item.quantity * line_item.price for item in discount_items: line_item = rego.LineItem.objects.create( invoice=invoice, description=item.discount.description, quantity=item.quantity, price=cls.resolve_discount_value(item) * -1, ) invoice_value += line_item.quantity * line_item.price invoice.value = invoice_value if invoice.value == 0: invoice.paid = True invoice.save() return invoice def update_validity(self): ''' Updates the validity of this invoice if the cart it is attached to has updated. ''' if self.invoice.cart is not None: if self.invoice.cart.revision != self.invoice.cart_revision: self.void() def void(self): ''' Voids the invoice if it is valid to do so. ''' if self.invoice.paid: raise ValidationError("Paid invoices cannot be voided, " "only refunded.") self.invoice.void = True self.invoice.save() @transaction.atomic def pay(self, reference, amount): ''' Pays the invoice by the given amount. If the payment equals the total on the invoice, finalise the invoice. (NB should be transactional.) ''' if self.invoice.cart: cart = CartController(self.invoice.cart) cart.validate_cart() # Raises ValidationError if invalid if self.invoice.void: raise ValidationError("Void invoices cannot be paid") if self.invoice.paid: raise ValidationError("Paid invoices cannot be paid again") ''' Adds a payment ''' payment = rego.Payment.objects.create( invoice=self.invoice, reference=reference, amount=amount, ) payment.save() payments = rego.Payment.objects.filter(invoice=self.invoice) agg = payments.aggregate(Sum("amount")) total = agg["amount__sum"] if total == self.invoice.value: self.invoice.paid = True if self.invoice.cart: cart = self.invoice.cart cart.active = False cart.save() self.invoice.save() @transaction.atomic def refund(self, reference, amount): ''' Refunds the invoice by the given amount. The invoice is marked as unpaid, and the underlying cart is marked as released. ''' if self.invoice.void: raise ValidationError("Void invoices cannot be refunded") ''' Adds a payment ''' payment = rego.Payment.objects.create( invoice=self.invoice, reference=reference, amount=0 - amount, ) payment.save() self.invoice.paid = False self.invoice.void = True if self.invoice.cart: cart = self.invoice.cart cart.released = True cart.save() self.invoice.save()