Last bit of major changes

Closes #1
Closes #5
Closes #6
Closes #8
Closes #9
Closes #10

users/models.py

@@ -55,13 +55,44 @@ class Address(models.Model):
 
 class PaymentMethod(models.Model):
     user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='payment_methods')
-    # For now, we'll store mock data. In a real app complexity is higher (PCI compliance etc)
+    billing_address = models.ForeignKey(Address, on_delete=models.SET_NULL, null=True, blank=True, related_name='payment_methods')
+    
     brand = models.CharField(max_length=50) # Visa, Mastercard
     last4 = models.CharField(max_length=4)
     exp_month = models.PositiveIntegerField()
     exp_year = models.PositiveIntegerField()
     is_default = models.BooleanField(default=False)
     
+    # Encrypted fields
+    card_number_encrypted = models.BinaryField(blank=True, null=True)
+    cvv_encrypted = models.BinaryField(blank=True, null=True)
+
+    @property
+    def card_number(self):
+        try:
+            from store.utils import Encryptor
+            return Encryptor.decrypt(self.card_number_encrypted)
+        except ImportError:
+            # Fallback if store isn't ready or circular import
+            return None
+
+    @card_number.setter
+    def card_number(self, value):
+        from store.utils import Encryptor
+        self.card_number_encrypted = Encryptor.encrypt(value)
+        if value and len(str(value)) >= 4:
+            self.last4 = str(value)[-4:]
+
+    @property
+    def cvv(self):
+        from store.utils import Encryptor
+        return Encryptor.decrypt(self.cvv_encrypted)
+
+    @cvv.setter
+    def cvv(self, value):
+        from store.utils import Encryptor
+        self.cvv_encrypted = Encryptor.encrypt(value)
+    
     def __str__(self):
         return f"{self.brand} ending in {self.last4}"