Add models for manual invoicing

Advances #2

aleksis/apps/tezor/models/invoice.py

@@ -2,6 +2,7 @@ from django.conf import settings
 from django.contrib.contenttypes.fields import GenericForeignKey
 from django.contrib.contenttypes.models import ContentType
 from django.db import models
+from django.db.models import Q
 from django.shortcuts import reverse
 from django.utils.translation import gettext_lazy as _
 
@@ -10,6 +11,7 @@ from payments import PurchasedItem
 from payments.models import BasePayment
 
 from aleksis.core.mixins import ExtensibleModel, PureDjangoModel
+from aleksis.core.models import Person
 
 from .base import Client
 from ..tables import PurchasedItemsTable, TotalsTable
@@ -51,6 +53,10 @@ class Invoice(BasePayment, PureDjangoModel):
     for_object_id = models.PositiveIntegerField()
     for_object = GenericForeignKey("for_content_type", "for_object_id")
 
+    # For manual invoicing
+    person = models.ForeignKey(Person, on_delete=models.SET_NULL, verbose_name=_("Invoice recipient (person)"), blank=True, null=True)
+    items = models.ManyToManyField("InvoiceItem", verbose_name=_("Invoice items"))
+
     @classmethod
     def get_variant_choices(cls):
         choices = []
@@ -65,10 +71,15 @@ class Invoice(BasePayment, PureDjangoModel):
         return self.__class__.VARIANT_DISPLAY[self.variant][1]
 
     def get_purchased_items(self):
-        return self.for_object.get_purchased_items()
+        for item in self.items.all():
+            yield item.as_purchased_item()
+        else:
+            return self.for_object.get_purchased_items()
 
     def get_person(self):
-        if hasattr(self.for_object, "person"):
+        if self.person:
+            return self.person
+        elif hasattr(self.for_object, "person"):
             return self.for_object.person
         elif hasattr(self.for_object, "get_person"):
             return self.for_object.get_person()
@@ -77,7 +88,8 @@ class Invoice(BasePayment, PureDjangoModel):
 
     class Meta:
         constraints = [
-            models.UniqueConstraint(fields=["number", "group"], name="number_uniq_per_group")
+            models.UniqueConstraint(fields=["number", "group"], name="number_uniq_per_group"),
+            models.CheckConstraint(Q(for_object_id__isnull=True) | Q(person__isnull=True)),
         ]
 
     @property
@@ -113,3 +125,14 @@ class Invoice(BasePayment, PureDjangoModel):
 
     def get_failure_url(self):
         return reverse("invoice_by_token", kwargs={"slug": self.token})
+
+
+class InvoiceItem(ExtensibleModel):
+    sku = models.CharField(max_length=255, verbose_name=_("Article no."), blank=True)
+    description = models.CharField(max_length=255, verbose_name=_("Purchased item"))
+    price = models.DecimalField(verbose_name=_("Item gross price"), max_digits=9, decimal_places=2, default="0.0")
+    currency = models.CharField(max_length=10, verbose_name=_("Currency"))
+    tax_rate = models.DecimalField(verbose_name=_("Tax rate"), max_digits=4, decimal_places=1, default="0.0")
+
+    def as_purchased_item(self):
+        yield PurchasedItem(name=self.description, quantity=1, price=self.price, currency=self.currency, sku=self.sku, tax_rate=self.tax_rate)