fix(cart): invalidate checkout on mutation

app/Domains/Cart/Models/Cart.php

@@ -106,7 +106,7 @@ class Cart extends Model
         }
 
         return DB::transaction(function () use ($catalogItemId, $variantId, $quantity): CartItem {
-            self::query()->whereKey($this->getKey())->lockForUpdate()->firstOrFail();
+            $this->invalidateCurrentCheckout();
             $selectedItem = $this->resolveScopedItem($catalogItemId, $variantId, true);
             $cartQuantity = (int) $this->items()
                 ->where('catalog_item_id', $catalogItemId)
@@ -171,6 +171,8 @@ class Cart extends Model
             $updateVariant,
             $excludedPurchaseId,
         ): CartItem {
+            $this->invalidateCurrentCheckout();
+
             /** @var CartItem $item */
             $item = $this->items()
                 ->where('id', $cartItemId)
@@ -279,6 +281,8 @@ class Cart extends Model
     public function removeItem(int $cartItemId): void
     {
         DB::transaction(function () use ($cartItemId): void {
+            $this->invalidateCurrentCheckout();
+
             /** @var CartItem $item */
             $item = $this->items()
                 ->where('id', $cartItemId)
@@ -299,6 +303,58 @@ class Cart extends Model
         });
     }
 
+    private function invalidateCurrentCheckout(): void
+    {
+        $candidatePurchaseId = self::query()
+            ->whereKey($this->getKey())
+            ->value('current_purchase_id');
+        $currentPurchase = $candidatePurchaseId === null
+            ? null
+            : Purchase::query()->lockForUpdate()->find($candidatePurchaseId);
+
+        /** @var self $cart */
+        $cart = self::query()->lockForUpdate()->findOrFail($this->getKey());
+
+        if ($cart->current_purchase_id !== $candidatePurchaseId) {
+            if ($cart->current_purchase_id !== null) {
+                throw ValidationException::withMessages([
+                    'cart' => __('api.purchase.checkout_in_progress'),
+                ]);
+            }
+
+            $this->current_purchase_id = null;
+
+            return;
+        }
+
+        if ($currentPurchase === null) {
+            return;
+        }
+
+        if ($currentPurchase->status === Purchase::STATUS_PAID) {
+            throw ValidationException::withMessages([
+                'cart' => __('api.cart.editing_disabled'),
+            ]);
+        }
+
+        if (in_array($currentPurchase->status, [
+            Purchase::STATUS_CREATED,
+            Purchase::STATUS_PENDING_PAYMENT,
+        ], true)) {
+            $currentPurchase->update([
+                'status' => Purchase::STATUS_SUPERSEDED,
+                'expires_at' => null,
+            ]);
+        }
+
+        app(StockReservationService::class)->detachFromPurchase($currentPurchase);
+        self::query()
+            ->whereKey($cart->getKey())
+            ->where('current_purchase_id', $currentPurchase->getKey())
+            ->update(['current_purchase_id' => null]);
+        $this->current_purchase_id = null;
+    }
+
     protected function resolveScopedItem(
         int $catalogItemId,
         ?int $variantId,

tests/Feature/Purchase/StorePurchaseTest.php

@@ -13,6 +13,7 @@ use App\Domains\Catalog\Models\Inventory;
 use App\Domains\Catalog\Models\Variant;
 use App\Domains\Purchase\Models\Purchase;
 use App\Domains\Purchase\Services\CheckoutService;
+use App\Domains\Purchase\Services\UserPurchaseLimitService;
 use App\Domains\Tenant\Models\Tenant;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Support\Facades\Queue;
@@ -562,6 +563,50 @@ class StorePurchaseTest extends TestCase
         ]);
     }
 
+    public function test_removing_a_checkout_item_supersedes_the_purchase_and_restores_the_user_quota(): void
+    {
+        $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
+        $user = User::factory()->create();
+        $variant = $this->createVariantForTenant('sonder', 10, '50.00');
+        $variant->catalogItem->update(['max_units_per_user' => 3]);
+        $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 2);
+        $cart = $purchase->cart;
+        $cartItem = $cart->items()->firstOrFail();
+
+        $cart->removeItem($cartItem->id);
+
+        $this->assertDatabaseHas('compras', [
+            'id' => $purchase->id,
+            'status' => Purchase::STATUS_SUPERSEDED,
+        ]);
+        $this->assertDatabaseHas('compra_items', [
+            'compra_id' => $purchase->id,
+            'source_catalog_item_id' => $variant->catalog_item_id,
+            'cantidad' => 2,
+        ]);
+        $this->assertDatabaseHas('carritos', [
+            'id' => $cart->id,
+            'current_purchase_id' => null,
+        ]);
+        $this->assertDatabaseHas('stock_reservations', [
+            'inventory_id' => $variant->inventory_id,
+            'cart_item_id' => null,
+            'purchase_id' => null,
+            'quantity' => 0,
+            'status' => 'released',
+        ]);
+        $this->assertDatabaseHas('inventories', [
+            'id' => $variant->inventory_id,
+            'reserved_stock' => 0,
+        ]);
+
+        $remaining = app(UserPurchaseLimitService::class)
+            ->remainingByCatalogItem(collect([$variant->catalogItem->fresh()]), $user->id)
+            ->get($variant->catalog_item_id);
+
+        $this->assertSame(3, $remaining);
+    }
+
     public function test_it_expires_the_purchase_without_mutating_the_active_cart(): void
     {
         $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');