feat: 實作 POS API 整合功能，包含商品與銷售訂單同步及韌性機制

app/Modules/Inventory/Services/InventoryService.php

@@ -59,9 +59,9 @@ class InventoryService implements InventoryServiceInterface
         return $stock >= $quantity;
     }
 
-    public function decreaseStock(int $productId, int $warehouseId, float $quantity, ?string $reason = null): void
+    public function decreaseStock(int $productId, int $warehouseId, float $quantity, ?string $reason = null, bool $force = false): void
     {
-        DB::transaction(function () use ($productId, $warehouseId, $quantity, $reason) {
+        DB::transaction(function () use ($productId, $warehouseId, $quantity, $reason, $force) {
             $inventories = Inventory::where('product_id', $productId)
                 ->where('warehouse_id', $warehouseId)
                 ->where('quantity', '>', 0)
@@ -79,8 +79,30 @@ class InventoryService implements InventoryServiceInterface
             }
 
             if ($remainingToDecrease > 0) {
-                // 這裡可以選擇報錯或允許負庫存，目前為了嚴謹拋出異常
-                throw new \Exception("庫存不足，無法扣除所有請求的數量。");
+                if ($force) {
+                    // Find any existing inventory record in this warehouse to subtract from, or create one
+                    $inventory = Inventory::where('product_id', $productId)
+                        ->where('warehouse_id', $warehouseId)
+                        ->first();
+                    
+                    if (!$inventory) {
+                        $inventory = Inventory::create([
+                            'warehouse_id' => $warehouseId,
+                            'product_id' => $productId,
+                            'quantity' => 0,
+                            'unit_cost' => 0,
+                            'total_value' => 0,
+                            'batch_number' => 'POS-AUTO-' . time(),
+                            'arrival_date' => now(),
+                            'origin_country' => 'TW',
+                            'quality_status' => 'normal',
+                        ]);
+                    }
+                    
+                    $this->decreaseInventoryQuantity($inventory->id, $remainingToDecrease, $reason);
+                } else {
+                    throw new \Exception("庫存不足，無法扣除所有請求的數量。");
+                }
             }
         });
     }