public function postCancel(Request $request)
    {
        $item = Item::findOrFail($request->input('item_id'));

        if ($item->userId != Auth::user()->userId) {
            return redirect()->back()->withErrors(['You can only end your own items.']);
        }

        if ($item->endDate < time()) {
            return redirect()->back()->withErrors(['This item has already ended.']);
        }

        $item->cancel();

        return redirect('/inventory/unsold')
            ->withStatus($item->name.' has been cancelled.');
    }