public function getDetails($purchaseId) {
        $purchase = Purchase::findOrFail($purchaseId);

        if (!in_array(Auth::user()->userId, [
            $purchase->item->seller->userId,
            $purchase->buyer->userId
        ])) {
            return redirect('/inventory')->withErrors([
                "You are not the buyer or seller of this item."
            ]);
        }

        return view('mustard::purchase.details', [
            'purchase' => $purchase,
        ]);
    }