public function index(Plan $plan)
    {
        // If the plan is null, get a plan
        if (is_null($plan) || ($plan && !$plan->exists)) {
            $plan = Plan::where('on_install', true)->first();
        }

        // Get the confirmation URL
        $bp = new BillingPlan(ShopifyApp::shop(), $plan);
        $url = $bp->confirmationUrl();

        // Do a fullpage redirect
        return View::make('shopify-app::billing.fullpage_redirect', compact('url'));
    }