App\Ninja\Repositories\InvoiceRepository::findInvoiceByInvitation PHP Method

    public function findInvoiceByInvitation($invitationKey)
    {
        /** @var \App\Models\Invitation $invitation */
        $invitation = Invitation::where('invitation_key', '=', $invitationKey)->first();
        if (!$invitation) {
            return false;
        }
        $invoice = $invitation->invoice;
        if (!$invoice || $invoice->is_deleted) {
            return false;
        }
        $invoice->load('user', 'invoice_items', 'documents', 'invoice_design', 'account.country', 'client.contacts', 'client.country');
        $client = $invoice->client;
        if (!$client || $client->is_deleted) {
            return false;
        }
        return $invitation;
    }

 /**
  * @param $invitationKey
  * @param bool $gatewayType
  * @param bool $sourceId
  * @return \Illuminate\Http\RedirectResponse
  */
 public function showPayment($invitationKey, $gatewayTypeAlias = false, $sourceId = false)
 {
     if (!($invitation = $this->invoiceRepo->findInvoiceByInvitation($invitationKey))) {
         return response()->view('error', ['error' => trans('texts.invoice_not_found'), 'hideHeader' => true]);
     }
     if (!$invitation->invoice->canBePaid()) {
         return redirect()->to('view/' . $invitation->invitation_key);
     }
     $invitation = $invitation->load('invoice.client.account.account_gateways.gateway');
     $account = $invitation->account;
     $account->loadLocalizationSettings($invitation->invoice->client);
     if (!$gatewayTypeAlias) {
         $gatewayTypeId = Session::get($invitation->id . 'gateway_type');
     } elseif ($gatewayTypeAlias != GATEWAY_TYPE_TOKEN) {
         $gatewayTypeId = GatewayType::getIdFromAlias($gatewayTypeAlias);
     } else {
         $gatewayTypeId = $gatewayTypeAlias;
     }
     $paymentDriver = $account->paymentDriver($invitation, $gatewayTypeId);
     try {
         return $paymentDriver->startPurchase(Input::all(), $sourceId);
     } catch (Exception $exception) {
         return $this->error($paymentDriver, $exception);
     }
 }