public function updateRawMaterialQty($raw_material_data) {
        if (!empty($raw_material_data)) {
    
            // Handle composite product_id (e.g. "1924|B2|" or "1919||")
            $composite   = explode('|', $raw_material_data['product_id']);
            $product_id = $raw_material_data['product_id'];
            $batch_no   = $raw_material_data['batch_no'] ? $raw_material_data['batch_no'] : null;
            $expiry     = $raw_material_data['expiry'] ? $raw_material_data['expiry'] : null;
            $location_id = $raw_material_data['location_id'];
            $raw_material_quantity = $raw_material_data['quantity'];
    
            // --- Fetch existing purchase item ---
            $this->db->where('product_id', $product_id);
            $this->db->where('warehouse_id', $location_id);
    
            if ($batch_no) {
                $this->db->where('batch_number', $batch_no);
            } else {
                // Handle NULL, empty string, or no batch
                $this->db->where("(batch_number IS NULL OR batch_number = '')", NULL, FALSE);
            }
    
            if ($expiry) {
                $this->db->where('expiry', $expiry);
            } else {
                // Handle NULL, empty string, or legacy '0000-00-00'
                $this->db->where("(expiry IS NULL OR expiry = '' OR expiry = '0000-00-00')", NULL, FALSE);
            }                                  
    
            $purchase_item = $this->db->get('purchase_items')->row();
    
            // --- Warehouse stock record ---
            $Warehouse_products = $this->site->getWarehouseProductQuantity($location_id, $product_id);
    
            // --- Update purchase_items table ---
            if ($purchase_item) {
                $quantity_balance = $purchase_item->quantity_balance - $raw_material_quantity;
                $this->db->update('purchase_items', ['quantity_balance' => $quantity_balance], ['id' => $purchase_item->id]);
            } else {
                $pr = $this->site->getProductByID($product_id);
                $item = [
                    'product_id'       => $product_id,
                    'product_code'     => $pr->code,
                    'product_name'     => $pr->name,
                    'net_unit_cost'    => $pr->cost,
                    'unit_cost'        => $pr->cost,
                    'real_unit_cost'   => $pr->cost,
                    'quantity'         => $raw_material_quantity,
                    'option_id'        => 0,
                    'quantity_balance' => $raw_material_quantity,
                    'item_tax'         => 0,
                    'tax_rate_id'      => 1,
                    'tax'              => 0,
                    'tax_method'       => $pr->tax_method,
                    'subtotal'         => ($pr->cost * $raw_material_quantity),
                    'warehouse_id'     => $location_id,
                    'date'             => date('Y-m-d'),
                    'status'           => 'received',
                    'expiry'           => $expiry,
                    'batch_number'     => $batch_no,
                    'product_unit_id'  => $pr->purchase_unit,
                    'hsn_code'         => $pr->hsn_code,
                    'unit_quantity'    => $raw_material_quantity ?: 1
                ];
                $this->db->insert('purchase_items', $item);
            }
    
            // --- Update warehouse quantity ---
            if ($Warehouse_products) {
                $existing_stock = $Warehouse_products->quantity;
                $new_stock = $existing_stock - $raw_material_quantity;
    
                $this->db->where('product_id', $product_id);
                $this->db->where('warehouse_id', $location_id);
                $this->db->update('sma_warehouses_products', ['quantity' => $new_stock]);
            }
    
            // --- Sync master product quantity ---
            $this->site->syncProductQtyForPU($product_id, $location_id);
        }
    }