App\services\InvoiceService::save PHP Method

    public function save(array $data, Invoice $invoice = null)
    {
        if (isset($data['client'])) {
            $canSaveClient = false;
            $canViewClient = false;
            $clientPublicId = array_get($data, 'client.public_id') ?: array_get($data, 'client.id');
            if (empty($clientPublicId) || $clientPublicId == '-1') {
                $canSaveClient = Auth::user()->can('create', ENTITY_CLIENT);
            } else {
                $client = Client::scope($clientPublicId)->first();
                $canSaveClient = Auth::user()->can('edit', $client);
                $canViewClient = Auth::user()->can('view', $client);
            }
            if ($canSaveClient) {
                $client = $this->clientRepo->save($data['client']);
            }
            if ($canSaveClient || $canViewClient) {
                $data['client_id'] = $client->id;
            }
        }
        $invoice = $this->invoiceRepo->save($data, $invoice);
        $client = $invoice->client;
        $client->load('contacts');
        $sendInvoiceIds = [];
        foreach ($client->contacts as $contact) {
            if ($contact->send_invoice) {
                $sendInvoiceIds[] = $contact->id;
            }
        }
        // if no contacts are selected auto-select the first to enusre there's an invitation
        if (!count($sendInvoiceIds)) {
            $sendInvoiceIds[] = $client->contacts[0]->id;
        }
        foreach ($client->contacts as $contact) {
            $invitation = Invitation::scope()->whereContactId($contact->id)->whereInvoiceId($invoice->id)->first();
            if (in_array($contact->id, $sendInvoiceIds) && !$invitation) {
                $invitation = Invitation::createNew();
                $invitation->invoice_id = $invoice->id;
                $invitation->contact_id = $contact->id;
                $invitation->invitation_key = str_random(RANDOM_KEY_LENGTH);
                $invitation->save();
            } elseif (!in_array($contact->id, $sendInvoiceIds) && $invitation) {
                $invitation->delete();
            }
        }
        return $invoice;
    }

 public function handleBuyNow(ClientRepository $clientRepo, InvoiceService $invoiceService, $gatewayTypeAlias = false)
 {
     if (Crawler::isCrawler()) {
         return redirect()->to(NINJA_WEB_URL, 301);
     }
     $account = Account::whereAccountKey(Input::get('account_key'))->first();
     $redirectUrl = Input::get('redirect_url', URL::previous());
     if (!$account || !$account->enable_buy_now_buttons || !$account->hasFeature(FEATURE_BUY_NOW_BUTTONS)) {
         return redirect()->to("{$redirectUrl}/?error=invalid account");
     }
     Auth::onceUsingId($account->users[0]->id);
     $product = Product::scope(Input::get('product_id'))->first();
     if (!$product) {
         return redirect()->to("{$redirectUrl}/?error=invalid product");
     }
     $rules = ['first_name' => 'string|max:100', 'last_name' => 'string|max:100', 'email' => 'email|string|max:100'];
     $validator = Validator::make(Input::all(), $rules);
     if ($validator->fails()) {
         return redirect()->to("{$redirectUrl}/?error=" . $validator->errors()->first());
     }
     $data = ['currency_id' => $account->currency_id, 'contact' => Input::all()];
     $client = $clientRepo->save($data);
     $data = ['client_id' => $client->id, 'tax_rate1' => $account->default_tax_rate ? $account->default_tax_rate->rate : 0, 'tax_name1' => $account->default_tax_rate ? $account->default_tax_rate->name : '', 'invoice_items' => [['product_key' => $product->product_key, 'notes' => $product->notes, 'cost' => $product->cost, 'qty' => 1, 'tax_rate1' => $product->default_tax_rate ? $product->default_tax_rate->rate : 0, 'tax_name1' => $product->default_tax_rate ? $product->default_tax_rate->name : '']]];
     $invoice = $invoiceService->save($data);
     $invitation = $invoice->invitations[0];
     $link = $invitation->getLink();
     if ($gatewayTypeAlias) {
         return redirect()->to($invitation->getLink('payment') . "/{$gatewayTypeAlias}");
     } else {
         return redirect()->to($invitation->getLink());
     }
 }