Fix discounts that require a user to be logged in

CHANGELOG.md

@@ -9,6 +9,7 @@
 - Fixed a bug where sales weren’t respecting site element statuses. ([#3328](https://github.com/craftcms/commerce/issues/3328))
 - Fixed a bug where soft-deleted order statuses and line item statuses would not being restored when applying project config changes. ([#3164](https://github.com/craftcms/commerce/issues/3164))
 - Fixed a bug where carts weren’t being restored after logging in.
+- Fixed a bug where guest customers could use a discount with a per-user usage limit. ([#3326](https://github.com/craftcms/commerce/issues/3326))
 - Fixed a bug where orders with a processing transaction weren’t being completed.
 
 ## 4.3.2 - 2023-10-31

src/services/Discounts.php

@@ -423,10 +423,8 @@ public function orderCouponAvailable(Order $order, string &$explanation = null):
             $explanation = Craft::t('commerce', 'Discount use has reached its limit.');
             return false;
         }
-
-        $user = $order->getCustomer();
-
-        if (!$this->_isDiscountPerUserUsageValid($discount, $user)) {
+
+        if (!$this->_isDiscountPerUserUsageValid($discount, $order->getCustomer())) {
             $explanation = Craft::t('commerce', 'This coupon is for registered users and limited to {limit} uses.', [
                 'limit' => $discount->perUserLimit,
             ]);
@@ -600,13 +598,11 @@ public function matchOrder(Order $order, Discount $discount): bool
             return false;
         }
 
-        $user = $order->getCustomer();
-
         if (!$this->_isDiscountTotalUseLimitValid($discount)) {
             return false;
         }
-
-        if (!$this->_isDiscountPerUserUsageValid($discount, $user)) {
+        
+        if (!$this->_isDiscountPerUserUsageValid($discount, $order->getCustomer())) {
             return false;
         }
 
@@ -1124,6 +1120,15 @@ private function _isDiscountPerUserUsageValid(Discount $discount, ?User $user):
                 return false;
             }
 
+            if (Craft::$app->getRequest()->getIsSiteRequest()) {
+                $currentUser = Craft::$app->getUser()->getIdentity();
+                $isCustomerCurrentUser = ($currentUser && $currentUser->id == $user->id);
+
+                if (!$isCustomerCurrentUser) {
+                    return false;
+                }
+            }
+
             $usage = (new Query())
                 ->select(['uses'])
                 ->from([Table::CUSTOMER_DISCOUNTUSES])

tests/unit/services/DiscountsTest.php

@@ -825,9 +825,15 @@ protected function orderCouponAvailableTest(array $orderConfig, bool $desiredRes
     protected function _before()
     {
         parent::_before();
-
         $this->discounts = Plugin::getInstance()->getDiscounts();
         $customerFixture = $this->tester->grabFixture('customers');
         $this->_user = $customerFixture->getElement('customer1');
+        Craft::$app->getUser()->setIdentity($this->_user);
+    }
+
+    protected function _after()
+    {
+        Craft::$app->getUser()->setIdentity(null);
+        parent::_after();
     }
 }