from decimal import Decimal from django.core.exceptions import ObjectDoesNotExist 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 @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) except ObjectDoesNotExist: cart_controller = CartController(cart) cart_controller.validate_cart() # Raises ValidationError on fail. 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 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() ) invoice.save() # TODO: calculate line items. product_items = rego.ProductItem.objects.filter(cart=cart) discount_items = rego.DiscountItem.objects.filter(cart=cart) invoice_value = Decimal() for item in product_items: line_item = rego.LineItem.objects.create( invoice=invoice, description=item.product.name, quantity=item.quantity, price=item.product.price, ) line_item.save() 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, ) line_item.save() invoice_value += line_item.quantity * line_item.price # TODO: calculate line items from discounts invoice.value = invoice_value invoice.save() return invoice def is_valid(self): ''' Returns true if the attached invoice is not void and it represents a valid cart. ''' if self.invoice.void: return False if self.invoice.cart is not None: if self.invoice.cart.revision != self.invoice.cart_revision: return False return True def void(self): ''' Voids the invoice. ''' self.invoice.void = True 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 is not None: cart = CartController(self.invoice.cart) cart.validate_cart() # Raises ValidationError if invalid ''' 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 cart = self.invoice.cart cart.active = False cart.save() self.invoice.save()