public function viewInvoice($id)
 {
     if (Order::find($id)->count() <= 0) {
         return redirect_errors('Invoice not exist!');
     }
     $model = new Order();
     $invoice = array_get($model->viewInvoice($id), 'order');
     return view('frontend.invoice')->with(['invoice' => $invoice, 'id' => $id]);
 }