feat(purchase): implement purchase limit enforcement and custom exception handling

app/Domains/Cart/Models/Cart.php

@@ -103,9 +103,14 @@ class Cart extends Model
             $cartQuantity = (int) $this->items()
                 ->where('catalog_item_id', $catalogItemId)
                 ->sum('cantidad');
-            $this->assertUserPurchaseLimit($selectedItem, $cartQuantity + $quantity);
             $inventoryService = app(CatalogInventoryService::class);
             $availableQuantity = $inventoryService->availableQuantity($selectedItem);
+            $this->assertUserPurchaseLimit(
+                $selectedItem,
+                $cartQuantity + $quantity,
+                heldQuantity: $cartQuantity,
+                maximumAddableCeiling: $availableQuantity,
+            );
 
             if ($availableQuantity !== null && $availableQuantity < $quantity) {
                 throw ValidationException::withMessages([
@@ -181,10 +186,13 @@ class Cart extends Model
                     ->where('catalog_item_id', $item->catalog_item_id)
                     ->whereKeyNot($item->getKey())
                     ->sum('cantidad');
+                $nextAvailableQuantity = $inventoryService->availableQuantity($nextSelection);
                 $this->assertUserPurchaseLimit(
                     $nextSelection,
                     $otherVariantsQuantity + $quantity,
                     $excludedPurchaseId,
+                    $otherVariantsQuantity + $item->cantidad,
+                    $nextAvailableQuantity,
                 );
 
                 app(StockReservationService::class)->release($item, $currentSelection, $item->cantidad);
@@ -222,6 +230,7 @@ class Cart extends Model
             }
 
             $delta = $quantity - $item->cantidad;
+            $availableQuantity = $inventoryService->availableQuantity($currentSelection);
 
             if ($delta > 0) {
                 $otherVariantsQuantity = (int) $this->items()
@@ -232,11 +241,11 @@ class Cart extends Model
                     $currentSelection,
                     $otherVariantsQuantity + $quantity,
                     $excludedPurchaseId,
+                    $otherVariantsQuantity + $item->cantidad,
+                    $availableQuantity,
                 );
             }
 
-            $availableQuantity = $inventoryService->availableQuantity($currentSelection);
-
             if ($delta > 0 && $availableQuantity !== null && $availableQuantity < $delta) {
                 $maxAvailable = $availableQuantity + $item->cantidad;
                 throw ValidationException::withMessages([
@@ -355,6 +364,8 @@ class Cart extends Model
         CatalogItem|Variant $selectedItem,
         int $cartQuantity,
         ?int $excludedPurchaseId = null,
+        int $heldQuantity = 0,
+        ?int $maximumAddableCeiling = null,
     ): void {
         if ($this->user_id === null) {
             return;
@@ -370,6 +381,8 @@ class Cart extends Model
             $cartQuantity,
             $excludedPurchaseId,
             $this->getKey(),
+            $heldQuantity,
+            $maximumAddableCeiling,
             field: 'cantidad',
         );
     }

app/Domains/Catalog/Resources/CatalogFeaturedItemResource.php

@@ -36,7 +36,6 @@ class CatalogFeaturedItemResource extends JsonResource
             'nombre' => $catalogItem->nombre,
             'descripcion' => $catalogItem->descripcion,
             'precio' => $catalogItem->precio,
-            'stock_tecnico' => $catalogItem->availableStock(),
             'maximum_addable_quantity' => $this->maximumAddable(
                 $catalogItem->availableStock(),
                 $remainingUserQuota,
@@ -50,9 +49,6 @@ class CatalogFeaturedItemResource extends JsonResource
                     'event_dates' => $variant->selectedEventDates()->map(fn ($eventDate): string => $eventDate->date->format('Y-m-d'))->values(),
                     'descripcion' => $variant->getDescription(),
                     'precio' => number_format($variant->getPrice(), 2, '.', ''),
-                    'stock_tecnico' => $catalogItem->inventory_policy === InventoryPolicy::Unlimited
-                        ? null
-                        : $variant->inventory->availableStock(),
                     'maximum_addable_quantity' => $this->maximumAddable(
                         $catalogItem->inventory_policy === InventoryPolicy::Unlimited
                             ? null

app/Domains/Catalog/Resources/CatalogItemDetailResource.php

@@ -38,10 +38,6 @@ class CatalogItemDetailResource extends JsonResource
             'max_units_per_user' => $this->max_units_per_user,
             'has_tickets' => $this->has_tickets,
             'attributes' => $this->attributesData(),
-            'stock_tecnico' => $this->when(
-                $selectedVariant === null,
-                fn () => $this->availableStock(),
-            ),
             'maximum_addable_quantity' => $this->when(
                 $selectedVariant === null,
                 fn () => $this->maximumAddable($this->availableStock()),
@@ -172,7 +168,6 @@ class CatalogItemDetailResource extends JsonResource
             'event_dates' => $eventDates->map(fn ($eventDate): string => $eventDate->date->format('Y-m-d'))->values(),
             'descripcion' => $variant->getDescription(),
             'precio' => number_format($variant->getPrice(), 2, '.', ''),
-            'stock_tecnico' => $this->variantStock($variant),
             'maximum_addable_quantity' => $this->maximumAddable($this->variantStock($variant)),
             'values' => $values,
         ];

app/Domains/Catalog/Resources/CatalogSearchItemResource.php

@@ -27,7 +27,6 @@ class CatalogSearchItemResource extends JsonResource
             'descripcion' => $this->descripcion,
             'precio' => $this->precio,
             'image' => $attachment?->getTemporaryUrl(1440),
-            'stock_tecnico' => $this->availableStock(),
             'maximum_addable_quantity' => $this->maximumAddable($this->availableStock()),
             'variants' => $this->visibleVariants()
                 ->map(fn (Variant $variant): array => [
@@ -38,9 +37,6 @@ class CatalogSearchItemResource extends JsonResource
                     'event_dates' => $variant->selectedEventDates()->map(fn ($eventDate): string => $eventDate->date->format('Y-m-d'))->values(),
                     'descripcion' => $variant->getDescription(),
                     'precio' => number_format($variant->getPrice(), 2, '.', ''),
-                    'stock_tecnico' => $this->inventory_policy === InventoryPolicy::Unlimited
-                        ? null
-                        : $variant->inventory?->availableStock(),
                     'maximum_addable_quantity' => $this->maximumAddable(
                         $this->inventory_policy === InventoryPolicy::Unlimited
                             ? null

app/Domains/Purchase/Exceptions/PurchaseLimitExceededException.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Domains\Purchase\Exceptions;
+
+use App\Domains\Catalog\Models\CatalogItem;
+use Illuminate\Validation\ValidationException;
+
+class PurchaseLimitExceededException extends ValidationException
+{
+    public readonly int $catalogItemId;
+
+    public readonly string $catalogItemName;
+
+    public readonly int $maximumAddableQuantity;
+
+    public function __construct(CatalogItem $catalogItem, int $maximumAddableQuantity, string $field)
+    {
+        $this->catalogItemId = (int) $catalogItem->getKey();
+        $this->catalogItemName = $catalogItem->nombre;
+        $this->maximumAddableQuantity = $maximumAddableQuantity;
+
+        parent::__construct(validator([], []));
+
+        $message = trans_choice('api.purchase_limit.exceeded', $maximumAddableQuantity, [
+            'max' => $maximumAddableQuantity,
+            'product' => $this->catalogItemName,
+        ]);
+        $this->message = $message;
+        $this->validator->errors()->add($field, $message);
+    }
+}

app/Domains/Purchase/Services/Checkout/StartCheckoutService.php

@@ -120,10 +120,16 @@ class StartCheckoutService
             ->each(function (Collection $catalogLines) use ($userId): void {
                 /** @var CatalogItem $catalogItem */
                 $catalogItem = $catalogLines->first()['catalog_item'];
+                $availableQuantities = $catalogLines
+                    ->map(fn (array $line): ?int => $this->inventory->availableQuantity($line['selection']));
+                $maximumAddableCeiling = $availableQuantities->contains(null)
+                    ? null
+                    : (int) $availableQuantities->sum();
                 $this->purchaseLimits->assertCanPurchase(
                     $catalogItem,
                     $userId,
                     (int) $catalogLines->sum('quantity'),
+                    maximumAddableCeiling: $maximumAddableCeiling,
                     field: 'direct_items',
                 );
             });
@@ -335,6 +341,7 @@ class StartCheckoutService
                 $userId,
                 $quantity,
                 excludedCartId: $cartId,
+                heldQuantity: $quantity,
                 field: 'cart_id',
             );
         }

app/Domains/Purchase/Services/UserPurchaseLimitService.php

@@ -4,11 +4,11 @@ namespace App\Domains\Purchase\Services;
 
 use App\Domains\Cart\Models\CartItem;
 use App\Domains\Catalog\Models\CatalogItem;
+use App\Domains\Purchase\Exceptions\PurchaseLimitExceededException;
 use App\Domains\Purchase\Models\Purchase;
 use App\Domains\Purchase\Models\PurchaseItem;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Facades\DB;
-use Illuminate\Validation\ValidationException;
 
 class UserPurchaseLimitService
 {
@@ -18,6 +18,8 @@ class UserPurchaseLimitService
         int $requestedQuantity,
         ?int $excludedPurchaseId = null,
         ?int $excludedCartId = null,
+        int $heldQuantity = 0,
+        ?int $maximumAddableCeiling = null,
         string $field = 'quantity',
     ): void {
         DB::transaction(function () use (
@@ -26,6 +28,8 @@ class UserPurchaseLimitService
             $requestedQuantity,
             $excludedPurchaseId,
             $excludedCartId,
+            $heldQuantity,
+            $maximumAddableCeiling,
             $field,
         ): void {
             /** @var CatalogItem $catalogItem */
@@ -86,9 +90,20 @@ class UserPurchaseLimitService
                 ->sum('cantidad');
 
             if ($purchasedQuantity + $checkoutQuantity + $reservedCartQuantity + $requestedQuantity > $limit) {
-                throw ValidationException::withMessages([
-                    $field => __('api.purchase_limit.exceeded', ['max' => $limit]),
-                ]);
+                $remainingQuota = max(
+                    0,
+                    $limit - $purchasedQuantity - $checkoutQuantity - $reservedCartQuantity,
+                );
+
+                $maximumAddableQuantity = max(0, $remainingQuota - $heldQuantity);
+
+                throw new PurchaseLimitExceededException(
+                    $catalogItem,
+                    $maximumAddableCeiling === null
+                        ? $maximumAddableQuantity
+                        : min($maximumAddableQuantity, $maximumAddableCeiling),
+                    $field,
+                );
             }
         });
     }