diff --git a/registrasion/controllers.py b/registrasion/controllers.py
new file mode 100644
index 0000000000000000000000000000000000000000..795c2d48abbbdc1f690dd1578dfbb265393c1748
--- /dev/null
+++ b/registrasion/controllers.py
@@ -0,0 +1,99 @@
+import itertools
+
+from collections import namedtuple
+
+from django.db.models import F, Q
+from registrasion import models as rego
+
+from conditions import ConditionController
+
+DiscountEnabler = namedtuple("DiscountEnabler", ("discount", "condition", "value"))
+
+class ProductController(object):
+
+    def __init__(self, product):
+        self.product = product
+
+    def user_can_add_within_limit(self, user, quantity):
+        ''' Return true if the user is able to add _quantity_ to their count of
+        this Product without exceeding _limit_per_user_.'''
+
+        carts = rego.Cart.objects.filter(user=user)
+        items = rego.ProductItem.objects.filter(product=self.product, cart=carts)
+
+        count = 0
+        for item in items:
+            count += item.quantity
+
+        if quantity + count > self.product.limit_per_user:
+            return False
+        else:
+            return True
+
+    def can_add_with_enabling_conditions(self, user, quantity):
+        ''' Returns true if the user is able to add _quantity_ to their count
+        of this Product without exceeding the ceilings the product is attached
+        to. '''
+
+        conditions = rego.EnablingConditionBase.objects.filter(
+            Q(products=self.product) | Q(categories=self.product.category)
+        ).select_subclasses()
+
+        mandatory_violated = False
+        non_mandatory_met = False
+
+        for condition in conditions:
+            cond = ConditionController.for_condition(condition)
+            met = cond.is_met(user, quantity)
+
+            if condition.mandatory and not met:
+                mandatory_violated = True
+                break
+            if met:
+                non_mandatory_met = True
+
+        if mandatory_violated:
+            # All mandatory conditions must be met
+            return False
+
+        if len(conditions) > 0 and not non_mandatory_met:
+            # If there's any non-mandatory conditions, one must be met
+            return False
+
+        return True
+
+
+    def get_enabler(self, condition):
+        if condition.percentage is not None:
+            value = condition.percentage * self.product.price
+        else:
+            value = condition.price
+        return DiscountEnabler(
+            discount=condition.discount,
+            condition=condition,
+            value=value
+        )
+
+    def available_discounts(self, user):
+        ''' Returns the set of available discounts for this user, for this
+        product. '''
+
+        product_discounts = rego.DiscountForProduct.objects.filter(
+            product=self.product)
+        category_discounts = rego.DiscountForCategory.objects.filter(
+            category=self.product.category
+        )
+
+        potential_discounts = set(itertools.chain(
+            (self.get_enabler(i) for i in product_discounts),
+            (self.get_enabler(i) for i in category_discounts),
+        ))
+
+        discounts = []
+        for discount in potential_discounts:
+            real_discount = rego.DiscountBase.objects.get_subclass(pk=discount.discount.pk)
+            cond = ConditionController.for_condition(real_discount)
+            if cond.is_met(user, 0):
+                discounts.append(discount)
+
+        return discounts