From fdc1c38b43fc9680c253b77c087d72ee0e575f2b Mon Sep 17 00:00:00 2001
From: objecttothis <17935339+objecttothis@users.noreply.github.com>
Date: Tue, 1 Sep 2026 19:41:41 +0400
Subject: [PATCH 1/2] feat(validation, tests): add `valid_path_strict` rule and
 integrate into mailpath validation (#4684)

- Introduce `valid_path_strict` rule in `OSPOSRules` to enforce stricter path validation, preventing security issues like injection attempts with newline or special characters.
- Update mail configuration validation in `Config` controller to use the new rule for the `mailpath` field.
- Add unit tests in `OSPOSRulesTest` to cover edge cases for `valid_path_strict`.

Signed-off-by: objecttothis <17935339+objecttothis@users.noreply.github.com>
---
 app/Config/Validation/OSPOSRules.php       | 20 +++++++++++++++++
 app/Controllers/Config.php                 | 23 +++++++++++--------
 tests/Config/Validation/OSPOSRulesTest.php | 26 ++++++++++++++++++++++
 3 files changed, 60 insertions(+), 9 deletions(-)

diff --git a/app/Config/Validation/OSPOSRules.php b/app/Config/Validation/OSPOSRules.php
index 05670463e..5b0638e31 100644
--- a/app/Config/Validation/OSPOSRules.php
+++ b/app/Config/Validation/OSPOSRules.php
@@ -225,4 +225,24 @@ class OSPOSRules
 
         return true;
     }
+
+    /**
+     * Validates that the candidate is a plain filesystem path: only letters, digits,
+     * underscore, dash, dot and forward slash. Uses \A...\z (not ^...$) because PCRE's $
+     * also matches immediately before a single trailing newline, which would let a
+     * value like "/usr/bin/php\n" slip through — the bug behind GHSA-jc56-j8m6-q627.
+     *
+     * @param string $candidate
+     * @param string|null $error
+     * @return bool
+     * @noinspection PhpUnused
+     */
+    public function valid_path_strict(string $candidate, ?string &$error = null): bool
+    {
+        if ($candidate === '') {
+            return false;
+        }
+
+        return (bool) preg_match('/\A[a-zA-Z0-9_\-\/.]+\z/', $candidate);
+    }
 }
diff --git a/app/Controllers/Config.php b/app/Controllers/Config.php
index fdf4f1daf..82f68e57c 100644
--- a/app/Controllers/Config.php
+++ b/app/Controllers/Config.php
@@ -540,16 +540,21 @@ class Config extends Secure_Controller
         $protocol = $this->request->getPost('protocol');
         $mailpath = $this->request->getPost('mailpath');
 
-        // Validate mailpath: required for sendmail, optional for others but must be safe if provided
-        $isMailpathRequired = ($protocol === 'sendmail');
-        $isMailpathProvided = !empty($mailpath);
-        $isMailpathValid = $isMailpathProvided && preg_match('/^[a-zA-Z0-9_\-\/.]+$/', $mailpath);
+        $rules = [
+            'mailpath' => [
+                'label' => lang('Config.email_mailpath'),
+                'rules' => ($protocol === 'sendmail' ? 'required' : 'permit_empty') . '|valid_path_strict'
+            ]
+        ];
+        $messages = [
+            'mailpath' => [
+                'required'          => lang('Config.mailpath_invalid'),
+                'valid_path_strict' => lang('Config.mailpath_invalid')
+            ]
+        ];
 
-        if (($isMailpathRequired && !$isMailpathProvided) || ($isMailpathProvided && !$isMailpathValid)) {
-            return $this->response->setJSON([
-                'success' => false,
-                'message' => lang('Config.mailpath_invalid')
-            ]);
+        if ($error = $this->validateFields($rules, $messages)) {
+            return $error;
         }
 
         $batch_save_data = [
diff --git a/tests/Config/Validation/OSPOSRulesTest.php b/tests/Config/Validation/OSPOSRulesTest.php
index 4fa827ce2..6ef1daa50 100644
--- a/tests/Config/Validation/OSPOSRulesTest.php
+++ b/tests/Config/Validation/OSPOSRulesTest.php
@@ -100,6 +100,32 @@ class OSPOSRulesTest extends CIUnitTestCase
         $this->assertNull($error);
     }
 
+    /**
+     * @dataProvider validPathStrictProvider
+     */
+    public function testValidPathStrict(string $candidate, bool $expected): void
+    {
+        $rules = new OSPOSRules();
+
+        $this->assertSame($expected, $rules->valid_path_strict($candidate));
+    }
+
+    public static function validPathStrictProvider(): array
+    {
+        return [
+            'plain sendmail path'                   => ['/usr/sbin/sendmail', true],
+            'plain php path'                        => ['/usr/bin/php', true],
+            'path with dash and underscore'         => ['/opt/my-mail_bin/sendmail.exe', true],
+            'empty string'                           => ['', false],
+            'trailing newline bypass payload'       => ["/usr/bin/php\n", false],
+            'trailing newline plus injected command' => ["/usr/bin/php\nid", false],
+            'embedded newline mid-string'           => ["/usr/bin/php\n/bin/sh", false],
+            'semicolon injection'                   => ['/usr/bin/php;id', false],
+            'pipe injection'                        => ['/usr/bin/php|id', false],
+            'space separated args'                  => ['/usr/bin/php -r "phpinfo();"', false],
+        ];
+    }
+
     private function injectSettings(array $settings): void
     {
         $ospos = new OSPOS();

From f5f9052de1b4a5006e88a7cc6175e0da6434fac5 Mon Sep 17 00:00:00 2001
From: objecttothis <17935339+objecttothis@users.noreply.github.com>
Date: Wed, 2 Sep 2026 01:21:46 +0400
Subject: [PATCH 2/2] fix(sales): harden payment validation and gift card
 handling

- Validate paymentType is a non-empty string before processing
- Reject negative or zero amounts for all payment types
- Enforce full payment coverage before completing a sale
- Bypass coverage check for invoice and quote mode sales
- Require a valid gift card number before decrementing value;
  rollback and return insufficient balance error on missing input
- Add "amount_due_not_covered" and "negative_amount_invalid"
  translations across 40+ locales
- Add test coverage for gift card validation, negative amounts,
  and quote/invoice zero-payment completion
- Rename snake_case locals to camelCase in postComplete (no behavior change)
---
 app/Controllers/Sales.php                 | 147 +++++++++++-------
 app/Language/ar-EG/Sales.php              |   2 +
 app/Language/ar-LB/Sales.php              |   2 +
 app/Language/az/Sales.php                 |   2 +
 app/Language/bg/Sales.php                 |   2 +
 app/Language/bs/Sales.php                 |   2 +
 app/Language/ckb/Sales.php                |   2 +
 app/Language/cs/Sales.php                 |   2 +
 app/Language/da/Sales.php                 |   2 +
 app/Language/de-CH/Sales.php              |   2 +
 app/Language/de-DE/Sales.php              |   2 +
 app/Language/el/Sales.php                 |   2 +
 app/Language/en-GB/Sales.php              |   2 +
 app/Language/en/Sales.php                 |   2 +
 app/Language/es-ES/Sales.php              |   2 +
 app/Language/es-MX/Sales.php              |   2 +
 app/Language/fa/Sales.php                 |   2 +
 app/Language/fr/Sales.php                 |   2 +
 app/Language/he/Sales.php                 |   2 +
 app/Language/hr-HR/Sales.php              |   2 +
 app/Language/hu/Sales.php                 |   2 +
 app/Language/hy/Sales.php                 |   2 +
 app/Language/id/Sales.php                 |   2 +
 app/Language/it/Sales.php                 |   2 +
 app/Language/ka/Sales.php                 |   2 +
 app/Language/km/Sales.php                 |   2 +
 app/Language/lo/Sales.php                 |   2 +
 app/Language/ml/Sales.php                 |   2 +
 app/Language/nb/Sales.php                 |   2 +
 app/Language/nl-BE/Sales.php              |   2 +
 app/Language/nl-NL/Sales.php              |   2 +
 app/Language/pl/Sales.php                 |   2 +
 app/Language/pt-BR/Sales.php              |   2 +
 app/Language/ro/Sales.php                 |   2 +
 app/Language/ru/Sales.php                 |   2 +
 app/Language/sv/Sales.php                 |   2 +
 app/Language/sw-KE/Sales.php              |  23 +--
 app/Language/sw-TZ/Sales.php              |  23 +--
 app/Language/ta/Sales.php                 |   2 +
 app/Language/th/Sales.php                 |   2 +
 app/Language/tl/Sales.php                 |   2 +
 app/Language/tr/Sales.php                 |   2 +
 app/Language/uk/Sales.php                 |   2 +
 app/Language/ur/Sales.php                 |   2 +
 app/Language/vi/Sales.php                 |   2 +
 app/Language/zh-Hans/Sales.php            |   2 +
 app/Language/zh-Hant/Sales.php            |   2 +
 app/Models/Giftcard.php                   |   4 +
 app/Models/Sale.php                       | 125 +++++++--------
 tests/Controllers/SalesControllerTest.php | 181 +++++++++++++++++++++-
 tests/Models/GiftcardTest.php             |  22 +++
 tests/Models/SaleTest.php                 |  58 ++++++-
 52 files changed, 526 insertions(+), 145 deletions(-)

diff --git a/app/Controllers/Sales.php b/app/Controllers/Sales.php
index 28627379c..8c64355c8 100644
--- a/app/Controllers/Sales.php
+++ b/app/Controllers/Sales.php
@@ -408,6 +408,22 @@ class Sales extends Secure_Controller
         $giftcard = model(Giftcard::class);
         $paymentType = $this->request->getPost('payment_type', FILTER_SANITIZE_FULL_SPECIAL_CHARS);
 
+        if (!is_string($paymentType) || $paymentType === '') {
+            $data['error'] = lang('Sales.must_enter_numeric');
+
+            return $this->reload($data);
+        }
+
+        if (
+            $paymentType !== lang('Sales.giftcard')
+            && $paymentType !== lang('Sales.rewards')
+            && (str_contains($paymentType, lang('Sales.giftcard')) || str_contains($paymentType, lang('Sales.rewards')))
+        ) {
+            $data['error'] = lang('Sales.must_enter_numeric');
+
+            return $this->reload($data);
+        }
+
         if ($paymentType === lang('Sales.giftcard')) {
             $rules    = ['amount_tendered' => 'trim|required|integer']; //For giftcards, amount_tendered becomes the giftcard number which must be an integer
             $messages = ['amount_tendered' => lang('Sales.must_enter_numeric_giftcard')];
@@ -415,12 +431,14 @@ class Sales extends Secure_Controller
             $min      = (int)($this->config['payment_reference_code_min'] ?? 3);
             $max      = (int)($this->config['payment_reference_code_max'] ?? 20);
             $rules    = [
-                'amount_tendered' => 'trim|required|decimal_locale',
+                'amount_tendered' => 'trim|required|decimal_locale|nonNegativeDecimal',
                 'reference_code'  => "trim|required|alpha_numeric|min_length[$min]|max_length[$max]",
             ];
             $messages = [
                 'amount_tendered' => [
-                    'required'   => lang('Sales.must_enter_numeric'),
+                    'required'           => lang('Sales.must_enter_numeric'),
+                    'decimal_locale'     => lang('Sales.must_enter_numeric'),
+                    'nonNegativeDecimal' => lang('Sales.negative_amount_invalid'),
                 ],
                 'reference_code'  => [
                     'required'      => lang('Sales.must_enter_reference_code'),
@@ -430,8 +448,14 @@ class Sales extends Secure_Controller
                 ],
             ];
         } else {
-            $rules    = ['amount_tendered' => 'trim|required|decimal_locale'];
-            $messages = ['amount_tendered' => lang('Sales.must_enter_numeric')];
+            $rules    = ['amount_tendered' => 'trim|required|decimal_locale|nonNegativeDecimal'];
+            $messages = [
+                'amount_tendered' => [
+                    'required'           => lang('Sales.must_enter_numeric'),
+                    'decimal_locale'     => lang('Sales.must_enter_numeric'),
+                    'nonNegativeDecimal' => lang('Sales.negative_amount_invalid'),
+                ],
+            ];
         }
 
         if (!$this->validate($rules, $messages)) {
@@ -730,21 +754,21 @@ class Sales extends Secure_Controller
      */
     public function postComplete(): string    // TODO: this function is huge.  Probably should be refactored.
     {
-        $sale_id = $this->sale_lib->get_sale_id();
+        $saleId = $this->sale_lib->get_sale_id();
         $data = [];
         $data['dinner_table'] = $this->sale_lib->get_dinner_table();
 
         $data['cart'] = $this->sale_lib->get_cart();
 
         $data['include_hsn'] = (bool)$this->config['include_hsn'];
-        $__time = time();
-        $data['transaction_time'] = to_datetime($__time);
-        $data['transaction_date'] = to_date($__time);
+        $time = time();
+        $data['transaction_time'] = to_datetime($time);
+        $data['transaction_date'] = to_date($time);
         $data['show_stock_locations'] = $this->stock_location->show_locations('sales');
         $data['comments'] = $this->sale_lib->get_comment();
-        $employee_id = $this->employee->get_logged_in_employee_info()->person_id;
-        $employee_info = $this->employee->get_info($employee_id);
-        $data['employee'] = $employee_info->first_name . ' ' . mb_substr($employee_info->last_name, 0, 1);
+        $employeeId = $this->employee->get_logged_in_employee_info()->person_id;
+        $employeeInfo = $this->employee->get_info($employeeId);
+        $data['employee'] = $employeeInfo->first_name . ' ' . mb_substr($employeeInfo->last_name, 0, 1);
 
         $data['company_info'] = implode("\n", [$this->config['address'], $this->config['phone']]);
 
@@ -762,26 +786,26 @@ class Sales extends Secure_Controller
         $data['print_after_sale'] = $this->session->get('sales_print_after_sale');
         $data['price_work_orders'] = $this->sale_lib->is_price_work_orders();
         $data['email_receipt'] = $this->sale_lib->is_email_receipt();
-        $customer_id = $this->sale_lib->get_customer();
-        $invoice_number = $this->sale_lib->get_invoice_number();
-        $data["invoice_number"] = $invoice_number;
-        $work_order_number = $this->sale_lib->get_work_order_number();
-        $data["work_order_number"] = $work_order_number;
-        $quote_number = $this->sale_lib->get_quote_number();
-        $data["quote_number"] = $quote_number;
-        $customer_info = $this->_load_customer_data($customer_id, $data);
+        $customerId = $this->sale_lib->get_customer();
+        $invoiceNumber = $this->sale_lib->get_invoice_number();
+        $data["invoice_number"] = $invoiceNumber;
+        $workOrderNumber = $this->sale_lib->get_work_order_number();
+        $data["work_order_number"] = $workOrderNumber;
+        $quoteNumber = $this->sale_lib->get_quote_number();
+        $data["quote_number"] = $quoteNumber;
+        $customerInfo = $this->_load_customer_data($customerId, $data);
 
-        if ($customer_info != null) {
-            $data["customer_comments"] = $customer_info->comments;
-            $data['tax_id'] = $customer_info->tax_id;
+        if ($customerInfo != null) {
+            $data["customer_comments"] = $customerInfo->comments;
+            $data['tax_id'] = $customerInfo->tax_id;
         }
-        $tax_details = $this->tax_lib->get_taxes($data['cart']);    // TODO: Duplicated code
-        $data['taxes'] = $tax_details[0];
+        $taxDetails = $this->tax_lib->get_taxes($data['cart']);    // TODO: Duplicated code
+        $data['taxes'] = $taxDetails[0];
         $data['discount'] = $this->sale_lib->get_discount();
         $data['payments'] = $this->sale_lib->getPayments();
 
         // Returns 'subtotal', 'total', 'cash_total', 'payment_total', 'amount_due', 'cash_amount_due', 'payments_cover_total'
-        $totals = $this->sale_lib->get_totals($tax_details[0]);
+        $totals = $this->sale_lib->get_totals($taxDetails[0]);
         $data['subtotal'] = $totals['subtotal'];
         $data['total'] = $totals['total'];
         $data['payments_total'] = $totals['payment_total'];
@@ -800,6 +824,11 @@ class Sales extends Secure_Controller
             return $this->reload($data);
         }
 
+        if (!$totals['payments_cover_total'] && !$this->sale_lib->is_invoice_mode() && !$this->sale_lib->is_quote_mode()) {
+            $data['error'] = lang('Sales.amount_due_not_covered');
+            return $this->reload($data);
+        }
+
         if ($data['cash_mode']) {    // TODO: Convert this to ternary notation
             $data['amount_due'] = $totals['cash_amount_due'];
         } else {
@@ -829,31 +858,31 @@ class Sales extends Secure_Controller
         $data['print_price_info'] = true;
 
         if ($this->sale_lib->is_invoice_mode()) {
-            $invoice_format = $this->config['sales_invoice_format'];
+            $invoiceFormat = $this->config['sales_invoice_format'];
 
             // Generate final invoice number (if using the invoice in sales by receipt mode then the invoice number can be manually entered or altered in some way
-            if (!empty($invoice_format) && $invoice_number == null) {
+            if (!empty($invoiceFormat) && $invoiceNumber == null) {
                 // The user can retain the default encoded format or can manually override it.  It still passes through the rendering step.
-                $invoice_number = $this->token_lib->render($invoice_format);
+                $invoiceNumber = $this->token_lib->render($invoiceFormat);
             }
 
 
-            if ($sale_id == NEW_ENTRY && $this->sale->check_invoice_number_exists($invoice_number)) {
-                $data['error'] = lang('Sales.invoice_number_duplicate', [$invoice_number]);
+            if ($saleId == NEW_ENTRY && $this->sale->check_invoice_number_exists($invoiceNumber)) {
+                $data['error'] = lang('Sales.invoice_number_duplicate', [$invoiceNumber]);
                 return $this->reload($data);
             } else {
-                $data['invoice_number'] = $invoice_number;
+                $data['invoice_number'] = $invoiceNumber;
                 $data['sale_status'] = COMPLETED;
-                $sale_type = SALE_TYPE_INVOICE;
+                $saleType = SALE_TYPE_INVOICE;
 
-                $invoice_type = $this->config['invoice_type'];
-                if (!Sale_lib::isValidInvoiceType($invoice_type)) {
-                    $invoice_type = 'invoice';
+                $invoiceType = $this->config['invoice_type'];
+                if (!Sale_lib::isValidInvoiceType($invoiceType)) {
+                    $invoiceType = 'invoice';
                 }
-                $invoice_view = $invoice_type;
+                $invoiceView = $invoiceType;
 
                 // Save the data to the sales table
-                $data['sale_id_num'] = $this->sale->save_value($sale_id, $data['sale_status'], $data['cart'], $customer_id, $employee_id, $data['comments'], $invoice_number, $work_order_number, $quote_number, $sale_type, $data['payments'], $data['dinner_table'], $tax_details);
+                $data['sale_id_num'] = $this->sale->save_value($saleId, $data['sale_status'], $data['cart'], $customerId, $employeeId, $data['comments'], $invoiceNumber, $workOrderNumber, $quoteNumber, $saleType, $data['payments'], $data['dinner_table'], $taxDetails);
                 $data['sale_id'] = 'POS ' . $data['sale_id_num'];
 
                 // Resort and filter cart lines for printing
@@ -871,7 +900,7 @@ class Sales extends Secure_Controller
                 } else {
                     $data['barcode'] = $this->barcode_lib->generate_receipt_barcode($data['sale_id']);
                     $this->sale_lib->clear_all();
-                    return view('sales/' . $invoice_view, $data);
+                    return view('sales/' . $invoiceView, $data);
                 }
             }
         } elseif ($this->sale_lib->is_work_order_mode()) {
@@ -883,21 +912,21 @@ class Sales extends Secure_Controller
             $data['sales_work_order'] = lang('Sales.work_order');
             $data['work_order_number_label'] = lang('Sales.work_order_number');
 
-            if ($work_order_number == null) {
+            if ($workOrderNumber == null) {
                 // Generate work order number
-                $work_order_format = $this->config['work_order_format'];
-                $work_order_number = $this->token_lib->render($work_order_format);
+                $workOrderFormat = $this->config['work_order_format'];
+                $workOrderNumber = $this->token_lib->render($workOrderFormat);
             }
 
-            if ($sale_id == NEW_ENTRY && $this->sale->check_work_order_number_exists($work_order_number)) {
+            if ($saleId == NEW_ENTRY && $this->sale->check_work_order_number_exists($workOrderNumber)) {
                 $data['error'] = lang('Sales.work_order_number_duplicate');
                 return $this->reload($data);
             } else {
-                $data['work_order_number'] = $work_order_number;
+                $data['work_order_number'] = $workOrderNumber;
                 $data['sale_status'] = SUSPENDED;
-                $sale_type = SALE_TYPE_WORK_ORDER;
+                $saleType = SALE_TYPE_WORK_ORDER;
 
-                $data['sale_id_num'] = $this->sale->save_value($sale_id, $data['sale_status'], $data['cart'], $customer_id, $employee_id, $data['comments'], $invoice_number, $work_order_number, $quote_number, $sale_type, $data['payments'], $data['dinner_table'], $tax_details);
+                $data['sale_id_num'] = $this->sale->save_value($saleId, $data['sale_status'], $data['cart'], $customerId, $employeeId, $data['comments'], $invoiceNumber, $workOrderNumber, $quoteNumber, $saleType, $data['payments'], $data['dinner_table'], $taxDetails);
 
                 if ($data['sale_id_num'] === INSUFFICIENT_GIFTCARD_BALANCE) {
                     $data['error_message'] = lang('Sales.insufficient_giftcard_balance');
@@ -923,21 +952,21 @@ class Sales extends Secure_Controller
             $data['sales_quote'] = lang('Sales.quote');
             $data['quote_number_label'] = lang('Sales.quote_number');
 
-            if ($quote_number == null) {
+            if ($quoteNumber == null) {
                 // Generate quote number
-                $quote_format = $this->config['sales_quote_format'];
-                $quote_number = $this->token_lib->render($quote_format);
+                $quoteFormat = $this->config['sales_quote_format'];
+                $quoteNumber = $this->token_lib->render($quoteFormat);
             }
 
-            if ($sale_id == NEW_ENTRY && $this->sale->check_quote_number_exists($quote_number)) {
+            if ($saleId == NEW_ENTRY && $this->sale->check_quote_number_exists($quoteNumber)) {
                 $data['error'] = lang('Sales.quote_number_duplicate');
                 return $this->reload($data);
             } else {
-                $data['quote_number'] = $quote_number;
+                $data['quote_number'] = $quoteNumber;
                 $data['sale_status'] = SUSPENDED;
-                $sale_type = SALE_TYPE_QUOTE;
+                $saleType = SALE_TYPE_QUOTE;
 
-                $data['sale_id_num'] = $this->sale->save_value($sale_id, $data['sale_status'], $data['cart'], $customer_id, $employee_id, $data['comments'], $invoice_number, $work_order_number, $quote_number, $sale_type, $data['payments'], $data['dinner_table'], $tax_details);
+                $data['sale_id_num'] = $this->sale->save_value($saleId, $data['sale_status'], $data['cart'], $customerId, $employeeId, $data['comments'], $invoiceNumber, $workOrderNumber, $quoteNumber, $saleType, $data['payments'], $data['dinner_table'], $taxDetails);
 
                 if ($data['sale_id_num'] === INSUFFICIENT_GIFTCARD_BALANCE) {
                     $data['error_message'] = lang('Sales.insufficient_giftcard_balance');
@@ -962,12 +991,12 @@ class Sales extends Secure_Controller
             // Save the data to the sales table
             $data['sale_status'] = COMPLETED;
             if ($this->sale_lib->is_return_mode()) {
-                $sale_type = SALE_TYPE_RETURN;
+                $saleType = SALE_TYPE_RETURN;
             } else {
-                $sale_type = SALE_TYPE_POS;
+                $saleType = SALE_TYPE_POS;
             }
 
-            $data['sale_id_num'] = $this->sale->save_value($sale_id, $data['sale_status'], $data['cart'], $customer_id, $employee_id, $data['comments'], $invoice_number, $work_order_number, $quote_number, $sale_type, $data['payments'], $data['dinner_table'], $tax_details);
+            $data['sale_id_num'] = $this->sale->save_value($saleId, $data['sale_status'], $data['cart'], $customerId, $employeeId, $data['comments'], $invoiceNumber, $workOrderNumber, $quoteNumber, $saleType, $data['payments'], $data['dinner_table'], $taxDetails);
 
             $data['sale_id'] = 'POS ' . $data['sale_id_num'];
 
@@ -986,11 +1015,11 @@ class Sales extends Secure_Controller
                 $data['barcode'] = $this->barcode_lib->generate_receipt_barcode($data['sale_id']);
 
                 // Validate receipt template to prevent path traversal
-                $receipt_template = $this->config['receipt_template'] ?? '';
-                if (!Sale_lib::isValidReceiptTemplate($receipt_template)) {
-                    $receipt_template = 'receipt_default';
+                $receiptTemplate = $this->config['receipt_template'] ?? '';
+                if (!Sale_lib::isValidReceiptTemplate($receiptTemplate)) {
+                    $receiptTemplate = 'receipt_default';
                 }
-                $data['receipt_template_view'] = $receipt_template;
+                $data['receipt_template_view'] = $receiptTemplate;
 
                 $this->sale_lib->clear_all();
                 return view('sales/receipt', $data);
diff --git a/app/Language/ar-EG/Sales.php b/app/Language/ar-EG/Sales.php
index 36299cc5a..2a5511458 100644
--- a/app/Language/ar-EG/Sales.php
+++ b/app/Language/ar-EG/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'حساب',
     'add_payment'                       => 'إضافة دفع',
     'amount_due'                        => 'المبلغ المطلوب',
+    'amount_due_not_covered'            => 'المدفوعات لا تغطي المبلغ المستحق.',
     'amount_tendered'                   => 'المبلغ المدفوع',
     'authorized_signature'              => 'توقيع معتمد',
     'cancel_sale'                       => 'الغاء عملية البيع',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'يجب إدخال رقم للمبلغ الفعلى المدفوع.',
     'must_enter_numeric_giftcard'       => 'رقم بطاقة الهدية يجب أن يكون رقم.',
     'must_enter_reference_code'         => 'يجب إدخال رقم المرجع/الاسترداد.',
+    'negative_amount_invalid'           => 'لا يمكن أن يكون المبلغ المدفوع سالبًا.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ar-LB/Sales.php b/app/Language/ar-LB/Sales.php
index 1e8cc5f4d..b5be11fc6 100644
--- a/app/Language/ar-LB/Sales.php
+++ b/app/Language/ar-LB/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'حساب',
     'add_payment'                       => 'إضافة دفع',
     'amount_due'                        => 'المبلغ المطلوب',
+    'amount_due_not_covered'            => 'المدفوعات لا تغطي المبلغ المستحق.',
     'amount_tendered'                   => 'المبلغ المدفوع',
     'authorized_signature'              => 'توقيع معتمد',
     'cancel_sale'                       => 'الغاء عملية البيع',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'يجب إدخال رقم للمبلغ الفعلى المدفوع.',
     'must_enter_numeric_giftcard'       => 'رمز بطاقة الهدية يجب أن يكتون ارقام فقط.',
     'must_enter_reference_code'         => 'يجب إدخال رقم المرجع/الاسترداد.',
+    'negative_amount_invalid'           => 'لا يمكن أن يكون المبلغ المدفوع سالبًا.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/az/Sales.php b/app/Language/az/Sales.php
index e3b16ac71..b67ec818e 100644
--- a/app/Language/az/Sales.php
+++ b/app/Language/az/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Hesab #',
     'add_payment'                       => 'Ödəniş Əlavə Etmək',
     'amount_due'                        => 'Qalıq',
+    'amount_due_not_covered'            => 'Ödənişlər ödəniləcək məbləği əhatə etmir.',
     'amount_tendered'                   => 'Ödənilən məbləğ',
     'authorized_signature'              => 'Səlahiyyətli İmza',
     'cancel_sale'                       => 'İmtina',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Ödəniş məbləği rəqəm ilə olmalıdır.',
     'must_enter_numeric_giftcard'       => 'Hədiyyə Kartın nömrəsi rəqəmlə olmalıdır.',
     'must_enter_reference_code'         => 'İstinad/Axtarış nömrəsi daxil edilməlidir.',
+    'negative_amount_invalid'           => 'Ödənilən məbləğ mənfi ola bilməz.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/bg/Sales.php b/app/Language/bg/Sales.php
index 1edcb8b09..0f8503b12 100644
--- a/app/Language/bg/Sales.php
+++ b/app/Language/bg/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Номер на акаунт',
     'add_payment'                       => 'Добавяне на плащане',
     'amount_due'                        => 'Дължима сума',
+    'amount_due_not_covered'            => 'Плащанията не покриват дължимата сума.',
     'amount_tendered'                   => 'Предоставена сума',
     'authorized_signature'              => 'Оторизиран подпис',
     'cancel_sale'                       => 'Отказ',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Сумата Предложена трябва да е число.',
     'must_enter_numeric_giftcard'       => 'Gift Card номера трябва да бъде число.',
     'must_enter_reference_code'         => 'Трябва да се въведе референтен/извличащ номер.',
+    'negative_amount_invalid'           => 'Предоставената сума не може да бъде отрицателна.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/bs/Sales.php b/app/Language/bs/Sales.php
index 6f2d6e709..a7e7e1a59 100644
--- a/app/Language/bs/Sales.php
+++ b/app/Language/bs/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Broj računa',
     'add_payment'                       => 'Plaćanje',
     'amount_due'                        => 'Iznos duga',
+    'amount_due_not_covered'            => 'Uplate ne pokrivaju dospjeli iznos.',
     'amount_tendered'                   => 'Ponuđeni iznos',
     'authorized_signature'              => 'Ovlašćeni potpis',
     'cancel_sale'                       => 'Otkaži',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Ponuđeni iznos mora biti broj.',
     'must_enter_numeric_giftcard'       => 'Broj poklon kartice mora biti broj.',
     'must_enter_reference_code'         => 'Referentni/broj za preuzimanje mora biti unesen.',
+    'negative_amount_invalid'           => 'Ponuđeni iznos ne može biti negativan.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ckb/Sales.php b/app/Language/ckb/Sales.php
index e84492f16..94ce84dfd 100644
--- a/app/Language/ckb/Sales.php
+++ b/app/Language/ckb/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'هەژمار #',
     'add_payment'                       => 'زیادکردنی پارەدان',
     'amount_due'                        => 'بڕی پارە کە دەبێ بدرێت',
+    'amount_due_not_covered'            => 'پارەدانەکان بڕی پێویست دانپۆشین نەکردووە.',
     'amount_tendered'                   => 'بڕی پێشکەشکراو',
     'authorized_signature'              => 'واژۆی ڕێگەپێدراو',
     'cancel_sale'                       => 'هەڵوەشاندنەوە',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'بڕی پێشکەشکراو دەبێت ژمارەیەک بێت.',
     'must_enter_numeric_giftcard'       => 'ژمارەی کارتی دیاری دەبێت ژمارەیەک بێت.',
     'must_enter_reference_code'         => 'ژمارەی مەرجع/وەرگرتن دەبێت بنووسرێت.',
+    'negative_amount_invalid'           => 'بڕی پێشکەشکراو ناتوانێت نەرێنی بێت.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/cs/Sales.php b/app/Language/cs/Sales.php
index fc7efd2fe..05b417250 100644
--- a/app/Language/cs/Sales.php
+++ b/app/Language/cs/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => 'Přidat platbu',
     'amount_due'                        => 'K úhradě',
+    'amount_due_not_covered'            => 'Platby nepokrývají splatnou částku.',
     'amount_tendered'                   => 'Uhrazeno',
     'authorized_signature'              => '',
     'cancel_sale'                       => 'Zrušit',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => 'Číslo dárkového poukazu musí být číslo.',
     'must_enter_reference_code'         => 'Je nutné zadat referenční/vyhledávací číslo.',
+    'negative_amount_invalid'           => 'Uhrazená částka nemůže být záporná.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/da/Sales.php b/app/Language/da/Sales.php
index a750dcabe..d51cd04f2 100644
--- a/app/Language/da/Sales.php
+++ b/app/Language/da/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'Betalingerne dækker ikke det skyldige beløb.',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'cancel_sale'                       => '',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'Reference-/hentningsnummer skal angives.',
+    'negative_amount_invalid'           => 'Det modtagne beløb kan ikke være negativt.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/de-CH/Sales.php b/app/Language/de-CH/Sales.php
index 829fe3896..b4da7e86a 100644
--- a/app/Language/de-CH/Sales.php
+++ b/app/Language/de-CH/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => 'Zahlung',
     'amount_due'                        => 'fälliger Betrag',
+    'amount_due_not_covered'            => 'Die Zahlungen decken den fälligen Betrag nicht.',
     'amount_tendered'                   => 'Erhalten',
     'authorized_signature'              => '',
     'cancel_sale'                       => 'Annullieren',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Eingabe muss eine Zahl sein',
     'must_enter_numeric_giftcard'       => 'Gutschein-Nr. muss eine Zahl sein',
     'must_enter_reference_code'         => 'Referenz-/Abrufnummer muss eingegeben werden.',
+    'negative_amount_invalid'           => 'Der erhaltene Betrag darf nicht negativ sein.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/de-DE/Sales.php b/app/Language/de-DE/Sales.php
index b13ba0fb5..7dbc113b3 100644
--- a/app/Language/de-DE/Sales.php
+++ b/app/Language/de-DE/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Kundennummer',
     'add_payment'                       => 'Zahlung',
     'amount_due'                        => 'fälliger Betrag',
+    'amount_due_not_covered'            => 'Die Zahlungen decken den fälligen Betrag nicht.',
     'amount_tendered'                   => 'Erhalten',
     'authorized_signature'              => 'Unterschrift',
     'cancel_sale'                       => 'Annullieren',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Eingabe muss eine Zahl sein.',
     'must_enter_numeric_giftcard'       => 'Gutschein-Nr. muss eine Zahl sein.',
     'must_enter_reference_code'         => 'Referenz-/Abrufnummer muss eingegeben werden.',
+    'negative_amount_invalid'           => 'Der erhaltene Betrag darf nicht negativ sein.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/el/Sales.php b/app/Language/el/Sales.php
index e565d2940..4f2bb4b32 100644
--- a/app/Language/el/Sales.php
+++ b/app/Language/el/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Λογαριασμός #',
     'add_payment'                       => 'Προσθήκη Πληρωμής',
     'amount_due'                        => 'Ποσό επιστροφής',
+    'amount_due_not_covered'            => 'Οι πληρωμές δεν καλύπτουν το οφειλόμενο ποσό.',
     'amount_tendered'                   => 'Ποσό Είσπραξης',
     'authorized_signature'              => 'Εγκεκριμένη Υπογραφή',
     'cancel_sale'                       => 'Ακύρωση',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Το Ποσό Είσπραξης πρέπει να είναι Αριθμός.',
     'must_enter_numeric_giftcard'       => 'Ο Αριθμός της Δωροκάρτας πρέπει να είναι αριθμός.',
     'must_enter_reference_code'         => 'Πρέπει να εισαχθεί αριθμός αναφοράς/ανάκτησης.',
+    'negative_amount_invalid'           => 'Το ποσό είσπραξης δεν μπορεί να είναι αρνητικό.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/en-GB/Sales.php b/app/Language/en-GB/Sales.php
index cfa866750..e0d026f08 100644
--- a/app/Language/en-GB/Sales.php
+++ b/app/Language/en-GB/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Account #',
     'add_payment'                       => 'Add Payment',
     'amount_due'                        => 'Amount Due',
+    'amount_due_not_covered'            => 'Payments do not cover the amount due.',
     'amount_tendered'                   => 'Amount Tendered',
     'authorized_signature'              => 'Authorised Signature',
     'bank_transfer'                     => 'Bank Transfer',
@@ -132,6 +133,7 @@ return [
     'must_enter_numeric'                => 'Amount Tendered must be a number.',
     'must_enter_numeric_giftcard'       => 'Gift Card Number must be a number.',
     'must_enter_reference_code'         => 'Reference/Retrieval Number must be entered.',
+    'negative_amount_invalid'           => 'Amount Tendered cannot be negative.',
     'negative_discount_invalid'         => 'Discount cannot be negative.',
     'negative_price_invalid'            => 'Price cannot be negative.',
     'negative_quantity_invalid'         => 'Quantity cannot be negative.',
diff --git a/app/Language/en/Sales.php b/app/Language/en/Sales.php
index 6cbf2a045..f52013ea0 100644
--- a/app/Language/en/Sales.php
+++ b/app/Language/en/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Account #',
     'add_payment'                       => 'Add Payment',
     'amount_due'                        => 'Amount Due',
+    'amount_due_not_covered'            => 'Payments do not cover the amount due.',
     'amount_tendered'                   => 'Amount Tendered',
     'authorized_signature'              => 'Authorized Signature',
     'bank_transfer'                     => 'Bank Transfer',
@@ -132,6 +133,7 @@ return [
     'must_enter_numeric'                => 'Amount Tendered must be a number.',
     'must_enter_numeric_giftcard'       => 'Gift Card Number must be a number.',
     'must_enter_reference_code'         => 'Reference/Retrieval Number must be entered.',
+    'negative_amount_invalid'           => 'Amount Tendered cannot be negative.',
     'negative_discount_invalid'         => 'Discount cannot be negative.',
     'negative_price_invalid'            => 'Price cannot be negative.',
     'negative_quantity_invalid'         => 'Quantity cannot be negative.',
diff --git a/app/Language/es-ES/Sales.php b/app/Language/es-ES/Sales.php
index 7d7d9481d..e78f1dad8 100644
--- a/app/Language/es-ES/Sales.php
+++ b/app/Language/es-ES/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Cuenta #',
     'add_payment'                       => 'Agregar Pago',
     'amount_due'                        => 'Monto Adeudado',
+    'amount_due_not_covered'            => 'Los pagos no cubren el importe adeudado.',
     'amount_tendered'                   => 'Cantidad Recibida',
     'authorized_signature'              => 'Firma Autorizada',
     'bank_transfer'                     => 'Transferencia Bancaria',
@@ -132,6 +133,7 @@ return [
     'must_enter_numeric'                => 'Cantidad Recibida debe ser número.',
     'must_enter_numeric_giftcard'       => 'Número de Tarjeta de Regalo debe ser número.',
     'must_enter_reference_code'         => 'Se debe ingresar el número de referencia/recuperación.',
+    'negative_amount_invalid'           => 'La cantidad recibida no puede ser negativa.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/es-MX/Sales.php b/app/Language/es-MX/Sales.php
index 236ac227c..2e0e7dfd5 100644
--- a/app/Language/es-MX/Sales.php
+++ b/app/Language/es-MX/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Cuenta #',
     'add_payment'                       => 'Agregar Pago',
     'amount_due'                        => 'Monto de adeudo',
+    'amount_due_not_covered'            => 'Los pagos no cubren el monto adeudado.',
     'amount_tendered'                   => 'Cantidad Recibida',
     'authorized_signature'              => 'Firma Autorizada',
     'bank_transfer'                     => 'Transferencia Bancaria',
@@ -132,6 +133,7 @@ return [
     'must_enter_numeric'                => 'Cantidad recibida debe ser un número.',
     'must_enter_numeric_giftcard'       => 'Número de Tarjeta de Regalo debe ser un número.',
     'must_enter_reference_code'         => 'Se debe ingresar el número de referencia/recuperación.',
+    'negative_amount_invalid'           => 'La cantidad recibida no puede ser negativa.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/fa/Sales.php b/app/Language/fa/Sales.php
index 436ee0c70..b3a1d7341 100644
--- a/app/Language/fa/Sales.php
+++ b/app/Language/fa/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'حساب #',
     'add_payment'                       => 'افزودن پرداخت',
     'amount_due'                        => 'مبلغ پرداختی',
+    'amount_due_not_covered'            => 'پرداخت‌ها مبلغ بدهی را پوشش نمی‌دهند.',
     'amount_tendered'                   => 'مبلغ مناقصه',
     'authorized_signature'              => 'امضای مجاز',
     'cancel_sale'                       => 'لغو',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'مقدار پیشنهادی باید یک عدد باشد.',
     'must_enter_numeric_giftcard'       => 'شماره کارت هدیه باید یک عدد باشد.',
     'must_enter_reference_code'         => 'شماره مرجع/بازیابی باید وارد شود.',
+    'negative_amount_invalid'           => 'مبلغ مناقصه نمی‌تواند منفی باشد.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/fr/Sales.php b/app/Language/fr/Sales.php
index a8bab15b2..effaf9519 100644
--- a/app/Language/fr/Sales.php
+++ b/app/Language/fr/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '# Compte',
     'add_payment'                       => 'Ajout Paiement',
     'amount_due'                        => 'Montant à Payer',
+    'amount_due_not_covered'            => 'Les paiements ne couvrent pas le montant dû.',
     'amount_tendered'                   => 'Montant Présenté',
     'authorized_signature'              => 'Signature autorisée',
     'bank_transfer'                     => 'Virement Bancaire',
@@ -132,6 +133,7 @@ return [
     'must_enter_numeric'                => 'Veuillez entrer une valeur numérique pour la somme.',
     'must_enter_numeric_giftcard'       => 'Veuillez entrer une valeur numérique pour le numéro de carte.',
     'must_enter_reference_code'         => 'Le numéro de référence/récupération doit être saisi.',
+    'negative_amount_invalid'           => 'Le montant présenté ne peut pas être négatif.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/he/Sales.php b/app/Language/he/Sales.php
index 45f2ed995..d7f01a71b 100644
--- a/app/Language/he/Sales.php
+++ b/app/Language/he/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'חשבון מס #',
     'add_payment'                       => 'הוסף תשלום',
     'amount_due'                        => 'סכום לתשלום',
+    'amount_due_not_covered'            => 'התשלומים אינם מכסים את הסכום לתשלום.',
     'amount_tendered'                   => 'סכום ההצעה',
     'authorized_signature'              => 'חתימת מורשה',
     'cancel_sale'                       => 'בטל',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'סכום ההצעה חייב להיות מספר.',
     'must_enter_numeric_giftcard'       => 'מספר כרטיס המתנה חייב להיות מספר.',
     'must_enter_reference_code'         => 'יש להזין מספר אסמכתא/אחזור.',
+    'negative_amount_invalid'           => 'סכום ההצעה לא יכול להיות שלילי.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/hr-HR/Sales.php b/app/Language/hr-HR/Sales.php
index 60ec03a2a..5af072ca7 100644
--- a/app/Language/hr-HR/Sales.php
+++ b/app/Language/hr-HR/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => 'Dodaj plaćanje',
     'amount_due'                        => 'Iznos duga',
+    'amount_due_not_covered'            => 'Uplate ne pokrivaju dospjeli iznos.',
     'amount_tendered'                   => 'Ponuđeni iznos',
     'authorized_signature'              => '',
     'cancel_sale'                       => 'Otkaži',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Morate unijeti numeričku vrijednost za količinu',
     'must_enter_numeric_giftcard'       => 'Morate unijeti numeričku vrijednost za poklon bon',
     'must_enter_reference_code'         => 'Referentni/broj za preuzimanje mora biti unesen.',
+    'negative_amount_invalid'           => 'Ponuđeni iznos ne može biti negativan.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/hu/Sales.php b/app/Language/hu/Sales.php
index 802f55037..d3ddff4e1 100644
--- a/app/Language/hu/Sales.php
+++ b/app/Language/hu/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => 'Fiz. hozzáad.',
     'amount_due'                        => 'Fennmaradó',
+    'amount_due_not_covered'            => 'A befizetések nem fedezik az esedékes összeget.',
     'amount_tendered'                   => 'Összeg',
     'authorized_signature'              => '',
     'cancel_sale'                       => 'Mégsem',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Számot kell megadnia a megrendelt mennyiséghez',
     'must_enter_numeric_giftcard'       => 'Vásárlási utalvány számát adja meg',
     'must_enter_reference_code'         => 'A hivatkozási/visszakeresési számot meg kell adni.',
+    'negative_amount_invalid'           => 'Az összeg nem lehet negatív.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/hy/Sales.php b/app/Language/hy/Sales.php
index d8b1024a2..5c3dccb31 100644
--- a/app/Language/hy/Sales.php
+++ b/app/Language/hy/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'Վճարումները չեն ծածկում վճարման ենթակա գումարը.',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'cancel_sale'                       => '',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'Պետք է մուտքագրվի հղման/որոնման համարը։',
+    'negative_amount_invalid'           => 'Վճարված գումարը չի կարող բացասական լինել.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/id/Sales.php b/app/Language/id/Sales.php
index 8ecfb96bd..dcce42ebe 100644
--- a/app/Language/id/Sales.php
+++ b/app/Language/id/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Akun #',
     'add_payment'                       => 'Terima',
     'amount_due'                        => 'Uang Kembalian',
+    'amount_due_not_covered'            => 'Pembayaran tidak menutupi jumlah yang harus dibayar.',
     'amount_tendered'                   => 'Nilai Pembayaran',
     'authorized_signature'              => 'Tanda tangan',
     'cancel_sale'                       => 'Batal Jual',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Nilai yang dimasukkan harus berupa angka.',
     'must_enter_numeric_giftcard'       => 'Nomor Gift Card harus berupa angka.',
     'must_enter_reference_code'         => 'Nomor referensi/pengambilan harus dimasukkan.',
+    'negative_amount_invalid'           => 'Nilai pembayaran tidak boleh negatif.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/it/Sales.php b/app/Language/it/Sales.php
index cf51cb444..5a78dca0b 100644
--- a/app/Language/it/Sales.php
+++ b/app/Language/it/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Account #',
     'add_payment'                       => 'Aggiungi Pagamento',
     'amount_due'                        => 'Importo Dovuto',
+    'amount_due_not_covered'            => 'I pagamenti non coprono l\'importo dovuto.',
     'amount_tendered'                   => 'Importo Offerto',
     'authorized_signature'              => 'Firma Autorizzata',
     'cancel_sale'                       => 'Annulla',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Import Offerto deve essere un numero.',
     'must_enter_numeric_giftcard'       => 'Numero Carta Regalo deve essere un numero.',
     'must_enter_reference_code'         => 'Il numero di riferimento/recupero deve essere inserito.',
+    'negative_amount_invalid'           => 'L\'importo offerto non può essere negativo.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ka/Sales.php b/app/Language/ka/Sales.php
index 97142c44b..0665a872f 100644
--- a/app/Language/ka/Sales.php
+++ b/app/Language/ka/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'გადახდები არ ფარავს გადასახდელ თანხას.',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'bank_transfer'                     => '',
@@ -132,6 +133,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'მიუთითეთ საცნობარო/მოძიების ნომერი.',
+    'negative_amount_invalid'           => 'გადახდილი თანხა არ შეიძლება იყოს უარყოფითი.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/km/Sales.php b/app/Language/km/Sales.php
index dc16323d2..04a03146b 100644
--- a/app/Language/km/Sales.php
+++ b/app/Language/km/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'លេខគណនី',
     'add_payment'                       => 'បញ្ជូលរបៀបបង់ប្រាក់',
     'amount_due'                        => 'ទឹកប្រាក់ដែលត្រូវបង់',
+    'amount_due_not_covered'            => 'ការទូទាត់មិនគ្របដណ្តប់ចំនួនទឹកប្រាក់ដែលត្រូវបង់ទេ។',
     'amount_tendered'                   => 'ទឹកប្រាក់បានមកពីការបង់ទាំងផ្សេងៗ',
     'authorized_signature'              => 'ហត្ថលេខា',
     'cancel_sale'                       => 'បោះបង់',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'លេខយោង/ទាញយកត្រូវតែបញ្ចូល។',
+    'negative_amount_invalid'           => 'ទឹកប្រាក់បានមកពីការបង់មិនអាចជាចំនួនអវិជ្ជមានបានទេ។',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/lo/Sales.php b/app/Language/lo/Sales.php
index 2e306c192..aa6aaedd7 100644
--- a/app/Language/lo/Sales.php
+++ b/app/Language/lo/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => 'Add Payment',
     'amount_due'                        => 'Amount Due',
+    'amount_due_not_covered'            => 'ການຊຳລະເງິນບໍ່ຄຸ້ມຈຳນວນທີ່ຕ້ອງຈ່າຍ.',
     'amount_tendered'                   => 'Amount Tendered',
     'authorized_signature'              => '',
     'cancel_sale'                       => 'Cancel',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Amount Tendered must be a number.',
     'must_enter_numeric_giftcard'       => 'Gift Card Number must be a number.',
     'must_enter_reference_code'         => 'ຕ້ອງປ້ອນໝາຍເລກອ້າງອີງ/ດຶງຂໍ້ມູນ.',
+    'negative_amount_invalid'           => 'ຈຳນວນເງິນທີ່ຈ່າຍບໍ່ສາມາດເປັນຄ່າລົບໄດ້.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ml/Sales.php b/app/Language/ml/Sales.php
index 7fc6b326f..f8df0a093 100644
--- a/app/Language/ml/Sales.php
+++ b/app/Language/ml/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'പേയ്‌മെന്റുകൾ അടയ്‌ക്കേണ്ട തുക ഉൾക്കൊള്ളുന്നില്ല.',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'cancel_sale'                       => '',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'റഫറൻസ്/റിട്രീവൽ നമ്പർ നൽകണം.',
+    'negative_amount_invalid'           => 'നൽകിയ തുക നെഗറ്റീവ് ആകാൻ പാടില്ല.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/nb/Sales.php b/app/Language/nb/Sales.php
index 22de8d58a..ff70bdf49 100644
--- a/app/Language/nb/Sales.php
+++ b/app/Language/nb/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'Betalingene dekker ikke det skyldige beløpet.',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'cancel_sale'                       => '',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'Referanse-/hentingsnummer må angis.',
+    'negative_amount_invalid'           => 'Det mottatte beløpet kan ikke være negativt.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/nl-BE/Sales.php b/app/Language/nl-BE/Sales.php
index f614253b2..c84d27c3e 100644
--- a/app/Language/nl-BE/Sales.php
+++ b/app/Language/nl-BE/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Btw-nummer',
     'add_payment'                       => 'Betaal',
     'amount_due'                        => 'Te betalen',
+    'amount_due_not_covered'            => 'De betalingen dekken het verschuldigde bedrag niet.',
     'amount_tendered'                   => 'Ontvangen bedrag',
     'authorized_signature'              => 'Handtekening',
     'cancel_sale'                       => 'Annuleer',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Het ontvangen bedrag moet een numerieke waarde zijn.',
     'must_enter_numeric_giftcard'       => 'Er moet een geldige code worden ingevuld voor de cadeaubon.',
     'must_enter_reference_code'         => 'Referentie-/ophaalnummer moet worden ingevoerd.',
+    'negative_amount_invalid'           => 'Het ontvangen bedrag mag niet negatief zijn.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/nl-NL/Sales.php b/app/Language/nl-NL/Sales.php
index 51066b456..c92a6cd03 100644
--- a/app/Language/nl-NL/Sales.php
+++ b/app/Language/nl-NL/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Account #',
     'add_payment'                       => 'Betaling toevoegen',
     'amount_due'                        => 'Te betalen bedrag',
+    'amount_due_not_covered'            => 'De betalingen dekken het verschuldigde bedrag niet.',
     'amount_tendered'                   => 'Betaald bedrag',
     'authorized_signature'              => 'Geautoriseerde handtekening',
     'cancel_sale'                       => 'Annuleren',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Betaald bedrag moet een getal zijn.',
     'must_enter_numeric_giftcard'       => 'Cadeaubonnummer moet een getal zijn.',
     'must_enter_reference_code'         => 'Referentie-/ophaalnummer moet worden ingevoerd.',
+    'negative_amount_invalid'           => 'Het betaalde bedrag mag niet negatief zijn.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/pl/Sales.php b/app/Language/pl/Sales.php
index e0d3afe07..ffd760b97 100644
--- a/app/Language/pl/Sales.php
+++ b/app/Language/pl/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'Płatności nie pokrywają należnej kwoty.',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'cancel_sale'                       => '',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'Należy podać numer referencyjny/pobierania.',
+    'negative_amount_invalid'           => 'Otrzymana kwota nie może być ujemna.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/pt-BR/Sales.php b/app/Language/pt-BR/Sales.php
index a0301fea3..d22efc580 100644
--- a/app/Language/pt-BR/Sales.php
+++ b/app/Language/pt-BR/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Montante º',
     'add_payment'                       => 'Pagar',
     'amount_due'                        => 'Diferença',
+    'amount_due_not_covered'            => 'Os pagamentos não cobrem o valor devido.',
     'amount_tendered'                   => 'A Pagar',
     'authorized_signature'              => 'Assinatura autorizada',
     'cancel_sale'                       => 'Cancelar',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Deve entrar valor numérico para montante da proposta apresentada.',
     'must_enter_numeric_giftcard'       => 'Deve entrar valor numérico para o número de cartão presente.',
     'must_enter_reference_code'         => 'O número de referência/recuperação deve ser informado.',
+    'negative_amount_invalid'           => 'O valor pago não pode ser negativo.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ro/Sales.php b/app/Language/ro/Sales.php
index cc532bf8c..e792bf89a 100644
--- a/app/Language/ro/Sales.php
+++ b/app/Language/ro/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Cont #',
     'add_payment'                       => 'Adauga Plata',
     'amount_due'                        => 'Suma datorata',
+    'amount_due_not_covered'            => 'Plățile nu acoperă suma datorată.',
     'amount_tendered'                   => 'Suma Oferita',
     'authorized_signature'              => 'Semnatura Autorizata',
     'cancel_sale'                       => 'Anuleaza',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Valoare ofertata trebuie sa fie numerica.',
     'must_enter_numeric_giftcard'       => 'Numar Card Cadou trebuie sa fie numeric.',
     'must_enter_reference_code'         => 'Numărul de referință/recuperare trebuie introdus.',
+    'negative_amount_invalid'           => 'Suma oferită nu poate fi negativă.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ru/Sales.php b/app/Language/ru/Sales.php
index deae24e7d..fee55168f 100644
--- a/app/Language/ru/Sales.php
+++ b/app/Language/ru/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Счет #',
     'add_payment'                       => 'Добавить оплату',
     'amount_due'                        => 'Сумма задолженности',
+    'amount_due_not_covered'            => 'Платежи не покрывают причитающуюся сумму.',
     'amount_tendered'                   => 'Предложенная сумма',
     'authorized_signature'              => 'Подпись уполномоченного лица',
     'cancel_sale'                       => 'Отменить продажу',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Предложенная сумма должна быть числом.',
     'must_enter_numeric_giftcard'       => 'Номер подарочной карты должен быть числом.',
     'must_enter_reference_code'         => 'Необходимо ввести справочный/поисковый номер.',
+    'negative_amount_invalid'           => 'Предложенная сумма не может быть отрицательной.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/sv/Sales.php b/app/Language/sv/Sales.php
index 219babcb5..152147df5 100644
--- a/app/Language/sv/Sales.php
+++ b/app/Language/sv/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Konto #',
     'add_payment'                       => 'Lägg till betalning',
     'amount_due'                        => 'Belopp',
+    'amount_due_not_covered'            => 'Betalningarna täcker inte det förfallna beloppet.',
     'amount_tendered'                   => 'Upplagt belopp',
     'authorized_signature'              => 'Auktoriserad signatur',
     'cancel_sale'                       => 'Avbryt',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Belopp som anslås måste vara ett nummer.',
     'must_enter_numeric_giftcard'       => 'Presentkortets nummer måste vara ett nummer.',
     'must_enter_reference_code'         => 'Referens-/hämtningsnummer måste anges.',
+    'negative_amount_invalid'           => 'Det upplagda beloppet kan inte vara negativt.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/sw-KE/Sales.php b/app/Language/sw-KE/Sales.php
index f071f40c7..20e7e3eca 100644
--- a/app/Language/sw-KE/Sales.php
+++ b/app/Language/sw-KE/Sales.php
@@ -1,10 +1,10 @@
 <?php
 
 return [
-    // "unsuspend_and_delete"             => "Hatua (Action)",
     'account_number'                    => 'Nambari ya Akaunti',
     'add_payment'                       => 'Ongeza Malipo',
     'amount_due'                        => 'Kiasi Kinachodaiwa',
+    'amount_due_not_covered'            => 'Malipo hayafikii kiwango kinachodaiwa.',
     'amount_tendered'                   => 'Kiasi Kilicholipwa',
     'authorized_signature'              => 'Sahihi Iliyothibitishwa',
     'cancel_sale'                       => 'Ghairi',
@@ -132,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Kiasi Kilicholipwa lazima kiwe Namba.',
     'must_enter_numeric_giftcard'       => 'Namba ya Kadi ya Zawadi lazima iwe Namba.',
     'must_enter_reference_code'         => 'Nambari ya Kumbukumbu/Upatikanaji lazima iingizwe.',
+    'negative_amount_invalid'           => 'Kiasi kilicholipwa hakiwezi kuwa hasi.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
@@ -226,14 +227,14 @@ return [
     'unsuccessfully_suspended_sale'     => 'Imeshindikana kusitisha Mauzo.',
     'unsuccessfully_updated'            => 'Kusasisha mauzo kimeshindikana.',
     'unsuspend'                         => 'Ondoa Kusitishwa',
-    'unsuspend_and_delete'        => 'Hatua',
-    'update'                      => 'Sasisha',
-    'upi'                         => 'UPI',
-    'visa'                        => '',
-    'wholesale'                   => '',
-    'work_order'                  => 'Agizo la Kazi (Work Order)',
-    'work_order_number'           => 'Nambari ya Agizo la Kazi',
-    'work_order_number_duplicate' => 'Nambari ya Agizo la Kazi lazima iwe ya kipekee.',
-    'work_order_sent'             => 'Agizo la Kazi limetumwa kwa',
-    'work_order_unsent'           => 'Imeshindikana kutuma Agizo la Kazi kwa',
+    'unsuspend_and_delete'              => 'Hatua',
+    'update'                            => 'Sasisha',
+    'upi'                               => 'UPI',
+    'visa'                              => '',
+    'wholesale'                         => '',
+    'work_order'                        => 'Agizo la Kazi (Work Order)',
+    'work_order_number'                 => 'Nambari ya Agizo la Kazi',
+    'work_order_number_duplicate'       => 'Nambari ya Agizo la Kazi lazima iwe ya kipekee.',
+    'work_order_sent'                   => 'Agizo la Kazi limetumwa kwa',
+    'work_order_unsent'                 => 'Imeshindikana kutuma Agizo la Kazi kwa',
 ];
diff --git a/app/Language/sw-TZ/Sales.php b/app/Language/sw-TZ/Sales.php
index f071f40c7..20e7e3eca 100644
--- a/app/Language/sw-TZ/Sales.php
+++ b/app/Language/sw-TZ/Sales.php
@@ -1,10 +1,10 @@
 <?php
 
 return [
-    // "unsuspend_and_delete"             => "Hatua (Action)",
     'account_number'                    => 'Nambari ya Akaunti',
     'add_payment'                       => 'Ongeza Malipo',
     'amount_due'                        => 'Kiasi Kinachodaiwa',
+    'amount_due_not_covered'            => 'Malipo hayafikii kiwango kinachodaiwa.',
     'amount_tendered'                   => 'Kiasi Kilicholipwa',
     'authorized_signature'              => 'Sahihi Iliyothibitishwa',
     'cancel_sale'                       => 'Ghairi',
@@ -132,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Kiasi Kilicholipwa lazima kiwe Namba.',
     'must_enter_numeric_giftcard'       => 'Namba ya Kadi ya Zawadi lazima iwe Namba.',
     'must_enter_reference_code'         => 'Nambari ya Kumbukumbu/Upatikanaji lazima iingizwe.',
+    'negative_amount_invalid'           => 'Kiasi kilicholipwa hakiwezi kuwa hasi.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
@@ -226,14 +227,14 @@ return [
     'unsuccessfully_suspended_sale'     => 'Imeshindikana kusitisha Mauzo.',
     'unsuccessfully_updated'            => 'Kusasisha mauzo kimeshindikana.',
     'unsuspend'                         => 'Ondoa Kusitishwa',
-    'unsuspend_and_delete'        => 'Hatua',
-    'update'                      => 'Sasisha',
-    'upi'                         => 'UPI',
-    'visa'                        => '',
-    'wholesale'                   => '',
-    'work_order'                  => 'Agizo la Kazi (Work Order)',
-    'work_order_number'           => 'Nambari ya Agizo la Kazi',
-    'work_order_number_duplicate' => 'Nambari ya Agizo la Kazi lazima iwe ya kipekee.',
-    'work_order_sent'             => 'Agizo la Kazi limetumwa kwa',
-    'work_order_unsent'           => 'Imeshindikana kutuma Agizo la Kazi kwa',
+    'unsuspend_and_delete'              => 'Hatua',
+    'update'                            => 'Sasisha',
+    'upi'                               => 'UPI',
+    'visa'                              => '',
+    'wholesale'                         => '',
+    'work_order'                        => 'Agizo la Kazi (Work Order)',
+    'work_order_number'                 => 'Nambari ya Agizo la Kazi',
+    'work_order_number_duplicate'       => 'Nambari ya Agizo la Kazi lazima iwe ya kipekee.',
+    'work_order_sent'                   => 'Agizo la Kazi limetumwa kwa',
+    'work_order_unsent'                 => 'Imeshindikana kutuma Agizo la Kazi kwa',
 ];
diff --git a/app/Language/ta/Sales.php b/app/Language/ta/Sales.php
index 3597b359f..884110b7e 100644
--- a/app/Language/ta/Sales.php
+++ b/app/Language/ta/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'கணக்கு #',
     'add_payment'                       => 'கட்டணத்தைச் சேர்க்கவும்',
     'amount_due'                        => 'செலுத்த வேண்டிய தொகை',
+    'amount_due_not_covered'            => 'செலுத்தப்பட்ட தொகை நிலுவைத் தொகையை ஈடுசெய்யவில்லை.',
     'amount_tendered'                   => 'கொடுத்த தொகை',
     'authorized_signature'              => 'அங்கீகரிக்கப்பட்ட கையெழுத்து',
     'cancel_sale'                       => 'ரத்துசெய்',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'தொகை ஒரு எண்ணாக இருக்க வேண்டும்.',
     'must_enter_numeric_giftcard'       => 'பரிசு அட்டை எண் ஒரு எண்ணாக இருக்க வேண்டும்.',
     'must_enter_reference_code'         => 'குறிப்பு/மீட்டெடுப்பு எண் உள்ளிட வேண்டும்.',
+    'negative_amount_invalid'           => 'கொடுத்த தொகை எதிர்மறையாக இருக்கக்கூடாது.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/th/Sales.php b/app/Language/th/Sales.php
index de5b395a3..c85ccea53 100644
--- a/app/Language/th/Sales.php
+++ b/app/Language/th/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'บัญชี #',
     'add_payment'                       => 'เพิ่มบิล',
     'amount_due'                        => 'ยอดค้างชำระ',
+    'amount_due_not_covered'            => 'การชำระเงินไม่ครอบคลุมจำนวนที่ต้องชำระ',
     'amount_tendered'                   => 'ชำระเข้ามา',
     'authorized_signature'              => 'ลายเซ็นผู้มีอำนาจ',
     'cancel_sale'                       => 'ยกเลิกการขาย',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'จำนวนที่ถุกประมูลต้องใส่ข้อมุลที่เปนตัวเลข',
     'must_enter_numeric_giftcard'       => 'เลขที่บัตรของขวัญ ต้องใส่ตัวเลขเท่านั้น',
     'must_enter_reference_code'         => 'ต้องระบุหมายเลขอ้างอิง/การดึงข้อมูล',
+    'negative_amount_invalid'           => 'ชำระเข้ามาไม่สามารถเป็นค่าติดลบได้',
     'negative_discount_invalid'         => 'ส่วนลดไม่สามารถเป็นค่าติดลบได้',
     'negative_price_invalid'            => 'ราคาไม่สามารถเป็นค่าติดลบได้',
     'negative_quantity_invalid'         => 'จำนวนไม่สามารถเป็นค่าติดลบได้',
diff --git a/app/Language/tl/Sales.php b/app/Language/tl/Sales.php
index e55ad435c..de955aa89 100644
--- a/app/Language/tl/Sales.php
+++ b/app/Language/tl/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Account #',
     'add_payment'                       => 'Add Payment',
     'amount_due'                        => 'Amount Due',
+    'amount_due_not_covered'            => 'Hindi sapat ang mga bayad para sa kabuuang dapat bayaran.',
     'amount_tendered'                   => 'Amount Tendered',
     'authorized_signature'              => 'Authorized Signature',
     'cancel_sale'                       => 'Cancel',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Amount Tendered must be a number.',
     'must_enter_numeric_giftcard'       => 'Gift Card Number must be a number.',
     'must_enter_reference_code'         => 'Ang Numero ng Sanggunian/Pagkuha ay dapat ipasok.',
+    'negative_amount_invalid'           => 'Hindi maaaring negatibo ang halagang ibinayad.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/tr/Sales.php b/app/Language/tr/Sales.php
index ae53f0a68..39d4fec80 100644
--- a/app/Language/tr/Sales.php
+++ b/app/Language/tr/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Hesap Numarası',
     'add_payment'                       => 'Ödeme Ekle',
     'amount_due'                        => 'Kalan Ödeme',
+    'amount_due_not_covered'            => 'Ödemeler, ödenmesi gereken tutarı karşılamıyor.',
     'amount_tendered'                   => 'Ödenen Tutar',
     'authorized_signature'              => 'Yetkili İmza',
     'cancel_sale'                       => 'İptal Et',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Ödenen Tutar sayı olmalıdır.',
     'must_enter_numeric_giftcard'       => 'Hediye Çeki Numarası sayı olmalıdır.',
     'must_enter_reference_code'         => 'Referans/Alım numarası girilmelidir.',
+    'negative_amount_invalid'           => 'Ödenen tutar negatif olamaz.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/uk/Sales.php b/app/Language/uk/Sales.php
index a3282d7d9..cfe2f6fce 100644
--- a/app/Language/uk/Sales.php
+++ b/app/Language/uk/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Номер рахунку',
     'add_payment'                       => 'Додати платіж',
     'amount_due'                        => 'Сума заборгованості',
+    'amount_due_not_covered'            => 'Платежі не покривають суму до сплати.',
     'amount_tendered'                   => 'Запропонована сума',
     'authorized_signature'              => 'Підпис уповноваженої особи',
     'cancel_sale'                       => 'Відмінити',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Введена сума повинна бути числом.',
     'must_enter_numeric_giftcard'       => 'Номер подарункової картки повинен бути цифровим.',
     'must_enter_reference_code'         => 'Необхідно ввести довідковий/пошуковий номер.',
+    'negative_amount_invalid'           => 'Запропонована сума не може бути від\'ємною.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/ur/Sales.php b/app/Language/ur/Sales.php
index d1110de40..59dcb5f23 100644
--- a/app/Language/ur/Sales.php
+++ b/app/Language/ur/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'اکاوٗنٹ',
     'add_payment'                       => '',
     'amount_due'                        => '',
+    'amount_due_not_covered'            => 'ادائیگیاں واجب الادا رقم کو پورا نہیں کرتیں۔',
     'amount_tendered'                   => '',
     'authorized_signature'              => '',
     'cancel_sale'                       => '',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '',
     'must_enter_numeric_giftcard'       => '',
     'must_enter_reference_code'         => 'حوالہ/بازیابی نمبر درج کرنا ضروری ہے۔',
+    'negative_amount_invalid'           => 'ادا کی گئی رقم منفی نہیں ہو سکتی۔',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/vi/Sales.php b/app/Language/vi/Sales.php
index 1092d59f9..6a6fe515a 100644
--- a/app/Language/vi/Sales.php
+++ b/app/Language/vi/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => 'Tài khoản #',
     'add_payment'                       => 'Thêm thanh toán',
     'amount_due'                        => 'Số còn lại phải thanh toán',
+    'amount_due_not_covered'            => 'Các khoản thanh toán không đủ để trang trải số tiền phải trả.',
     'amount_tendered'                   => 'Số tiền thanh toán',
     'authorized_signature'              => 'Chữ ký ủy quyền',
     'cancel_sale'                       => 'Thôi',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => 'Số tiền thanh toán phải là dạng số.',
     'must_enter_numeric_giftcard'       => 'Số Thẻ quà tặng phải là dạng số.',
     'must_enter_reference_code'         => 'Số tham chiếu/truy xuất phải được nhập.',
+    'negative_amount_invalid'           => 'Số tiền thanh toán không được là số âm.',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/zh-Hans/Sales.php b/app/Language/zh-Hans/Sales.php
index b59fcf423..2f5ce5c10 100644
--- a/app/Language/zh-Hans/Sales.php
+++ b/app/Language/zh-Hans/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '',
     'add_payment'                       => '新增付款',
     'amount_due'                        => '商品金額',
+    'amount_due_not_covered'            => '付款金额未覆盖应付金额。',
     'amount_tendered'                   => '已收帳款',
     'authorized_signature'              => '',
     'cancel_sale'                       => '取消銷售',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '已收帳款必須輸入數值',
     'must_enter_numeric_giftcard'       => '禮金券編號必須輸入數值',
     'must_enter_reference_code'         => '必须输入参考/检索编号。',
+    'negative_amount_invalid'           => '已收帐款不能为负数。',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Language/zh-Hant/Sales.php b/app/Language/zh-Hant/Sales.php
index 3c8c4beba..48d1694b6 100644
--- a/app/Language/zh-Hant/Sales.php
+++ b/app/Language/zh-Hant/Sales.php
@@ -4,6 +4,7 @@ return [
     'account_number'                    => '帳戶 #',
     'add_payment'                       => '新增付款',
     'amount_due'                        => '商品金額',
+    'amount_due_not_covered'            => '付款金額未涵蓋應付金額。',
     'amount_tendered'                   => '已收帳款',
     'authorized_signature'              => '授權簽名',
     'cancel_sale'                       => '取消銷售',
@@ -131,6 +132,7 @@ return [
     'must_enter_numeric'                => '已收帳款必須輸入數值.',
     'must_enter_numeric_giftcard'       => '禮金券編號必須輸入數值.',
     'must_enter_reference_code'         => '必須輸入參考/檢索編號。',
+    'negative_amount_invalid'           => '已收帳款不能為負數。',
     'negative_discount_invalid'         => '',
     'negative_price_invalid'            => '',
     'negative_quantity_invalid'         => '',
diff --git a/app/Models/Giftcard.php b/app/Models/Giftcard.php
index 347a6d832..a12466265 100644
--- a/app/Models/Giftcard.php
+++ b/app/Models/Giftcard.php
@@ -316,6 +316,10 @@ class Giftcard extends Model
      */
     public function decrementGiftcardValue(string $giftcardNumber, float $amount): bool
     {
+        if ($amount <= 0) {
+            return false;
+        }
+
         $builder = $this->db->table('giftcards');
         $builder->where('giftcard_number', $giftcardNumber);
         $builder->where('deleted', 0);
diff --git a/app/Models/Sale.php b/app/Models/Sale.php
index c0dfa4348..1793315f1 100644
--- a/app/Models/Sale.php
+++ b/app/Models/Sale.php
@@ -524,13 +524,13 @@ class Sale extends Model
         int     $customerId,
         int     $employeeId,
         string  $comment,
-        ?string $invoice_number,
-        ?string $work_order_number,
-        ?string $quote_number,
-        int     $sale_type,
+        ?string $invoiceNumber,
+        ?string $workOrderNumber,
+        ?string $quoteNumber,
+        int     $saleType,
         ?array  $payments,
-        ?int    $dinner_table_id,
-        ?array  &$sales_taxes
+        ?int    $dinnerTableId,
+        ?array  &$salesTaxes
     ): int {    // TODO: this method returns the sale_id but the override is expecting it to return a bool. The signature needs to be reworked.  Generally when there are more than 3 maybe 4 parameters, there's a good chance that an object needs to be passed rather than so many params.
         $config = config(OSPOS::class)->settings;
         $attribute = model(Attribute::class);
@@ -539,23 +539,23 @@ class Sale extends Model
         $inventory = model('Inventory');
         $item = model(Item::class);
 
-        $item_quantity = model(Item_quantity::class);
+        $itemQuantity = model(Item_quantity::class);
 
         if (count($items) == 0) {    // TODO: ===
             return -1;    // TODO: Replace -1 with a constant
         }
 
-        $sales_data = [
+        $salesData = [
             'sale_time'         => date('Y-m-d H:i:s'),
             'customer_id'       => $customer->exists($customerId) ? $customerId : null,
             'employee_id'       => $employeeId,
             'comment'           => $comment,
             'sale_status'       => $saleStatus,
-            'invoice_number'    => $invoice_number,
-            'quote_number'      => $quote_number,
-            'work_order_number' => $work_order_number,
-            'dinner_table_id'   => $dinner_table_id,
-            'sale_type'         => $sale_type
+            'invoice_number'    => $invoiceNumber,
+            'quote_number'      => $quoteNumber,
+            'work_order_number' => $workOrderNumber,
+            'dinner_table_id'   => $dinnerTableId,
+            'sale_type'         => $saleType
         ];
 
         // Run these queries as a transaction, we want to make sure we do all or nothing
@@ -567,26 +567,27 @@ class Sale extends Model
 
         $builder = $this->db->table('sales');
         if ($saleId == NEW_ENTRY) {
-            $builder->insert($sales_data);
+            $builder->insert($salesData);
             $saleId = $this->db->insertID();
         } else {
             $builder->where('sale_id', $saleId);
-            $builder->update($sales_data);
+            $builder->update($salesData);
         }
 
-        $total_amount = 0;
+        $totalAmount = 0;
         $totalAmountUsed = 0;
 
-        foreach ($payments as $payment_id => $payment) {
-            if (!empty(strstr($payment['payment_type'], lang('Sales.giftcard')))) {
-                $splitPayment = explode(':', $payment['payment_type']);
+        foreach ($payments as $paymentId => $payment) {
+            $splitPayment = explode(':', $payment['payment_type'], 2);
+            $paymentPrefix = $splitPayment[0];
 
-                if (! $giftcard->decrementGiftcardValue($splitPayment[1], (float) $payment['payment_amount'])) {
+            if ($paymentPrefix === lang('Sales.giftcard')) {
+                if (empty($splitPayment[1]) || ! $giftcard->decrementGiftcardValue($splitPayment[1], (float) $payment['payment_amount'])) {
                     $this->db->transRollback();
 
                     return INSUFFICIENT_GIFTCARD_BALANCE;
                 }
-            } elseif (!empty(strstr($payment['payment_type'], lang('Sales.rewards')))) {
+            } elseif ($paymentPrefix === lang('Sales.rewards')) {
                 if (! $customer->adjustRewardPoints($customerId, -(float) $payment['payment_amount'])) {
                     $this->db->transRollback();
 
@@ -596,7 +597,7 @@ class Sale extends Model
                 $totalAmountUsed = floatval($totalAmountUsed) + floatval($payment['payment_amount']);
             }
 
-            $sales_payments_data = [
+            $salesPaymentsData = [
                 'sale_id'         => $saleId,
                 'payment_type'    => $payment['payment_type'],
                 'payment_amount'  => $payment['payment_amount'],
@@ -607,46 +608,46 @@ class Sale extends Model
             ];
 
             $builder = $this->db->table('sales_payments');
-            $builder->insert($sales_payments_data);
+            $builder->insert($salesPaymentsData);
 
-            $total_amount = floatval($total_amount) + floatval($payment['payment_amount']) - floatval($payment['cash_refund']);
+            $totalAmount = floatval($totalAmount) + floatval($payment['payment_amount']) - floatval($payment['cash_refund']);
         }
 
-        $this->save_customer_rewards($customerId, $saleId, $total_amount, $totalAmountUsed);
+        $this->save_customer_rewards($customerId, $saleId, $totalAmount, $totalAmountUsed);
 
         $customer = $customer->get_info($customerId);
 
-        foreach ($items as $line => $item_data) {
-            $cur_item_info = $item->get_info($item_data['item_id']);
+        foreach ($items as $line => $itemData) {
+            $curItemInfo = $item->get_info($itemData['item_id']);
 
-            if ($item_data['price'] == 0.00) {
-                $item_data['discount'] = 0.00;
+            if ($itemData['price'] == 0.00) {
+                $itemData['discount'] = 0.00;
             }
 
-            $sales_items_data = [
+            $salesItemsData = [
                 'sale_id'            => $saleId,
-                'item_id'            => $item_data['item_id'],
-                'line'               => $item_data['line'],
-                'description'        => character_limiter($item_data['description'], 255),
-                'serialnumber'       => character_limiter($item_data['serialnumber'], 30),
-                'quantity_purchased' => $item_data['quantity'],
-                'discount'           => $item_data['discount'],
-                'discount_type'      => $item_data['discount_type'],
-                'item_cost_price'    => $item_data['cost_price'],
-                'item_unit_price'    => $item_data['price'],
-                'item_location'      => $item_data['item_location'],
-                'print_option'       => $item_data['print_option']
+                'item_id'            => $itemData['item_id'],
+                'line'               => $itemData['line'],
+                'description'        => character_limiter($itemData['description'], 255),
+                'serialnumber'       => character_limiter($itemData['serialnumber'], 30),
+                'quantity_purchased' => $itemData['quantity'],
+                'discount'           => $itemData['discount'],
+                'discount_type'      => $itemData['discount_type'],
+                'item_cost_price'    => $itemData['cost_price'],
+                'item_unit_price'    => $itemData['price'],
+                'item_location'      => $itemData['item_location'],
+                'print_option'       => $itemData['print_option']
             ];
 
             $builder = $this->db->table('sales_items');
-            $builder->insert($sales_items_data);
+            $builder->insert($salesItemsData);
 
-            if ($cur_item_info->stock_type == HAS_STOCK && $saleStatus == COMPLETED) {    // TODO: === ?
+            if ($curItemInfo->stock_type == HAS_STOCK && $saleStatus == COMPLETED) {    // TODO: === ?
                 // Update stock quantity if item type is a standard stock item and the sale is a standard sale
-                if (! $item_quantity->changeQuantity(
-                    $item_data['item_id'],
-                    $item_data['item_location'],
-                    -(float) $item_data['quantity'],
+                if (! $itemQuantity->changeQuantity(
+                    $itemData['item_id'],
+                    $itemData['item_location'],
+                    -(float) $itemData['quantity'],
                 )) {
                     $this->db->transRollback();
 
@@ -654,38 +655,38 @@ class Sale extends Model
                 }
 
                 // If an items was deleted but later returned it's restored with this rule
-                if ($item_data['quantity'] < 0) {
-                    $item->undelete($item_data['item_id']);
+                if ($itemData['quantity'] < 0) {
+                    $item->undelete($itemData['item_id']);
                 }
 
                 // Inventory Count Details
-                $sale_remarks = 'POS ' . $saleId;    // TODO: Use string interpolation here.
-                $inv_data = [
+                $saleRemarks = 'POS ' . $saleId;    // TODO: Use string interpolation here.
+                $invData = [
                     'trans_date'      => date('Y-m-d H:i:s'),
-                    'trans_items'     => $item_data['item_id'],
+                    'trans_items'     => $itemData['item_id'],
                     'trans_user'      => $employeeId,
-                    'trans_location'  => $item_data['item_location'],
-                    'trans_comment'   => $sale_remarks,
-                    'trans_inventory' => -$item_data['quantity']
+                    'trans_location'  => $itemData['item_location'],
+                    'trans_comment'   => $saleRemarks,
+                    'trans_inventory' => -$itemData['quantity']
                 ];
 
-                $inventory->insert($inv_data, false);
+                $inventory->insert($invData, false);
             }
 
-            $attribute->copy_attribute_links($item_data['item_id'], 'sale_id', $saleId);
+            $attribute->copy_attribute_links($itemData['item_id'], 'sale_id', $saleId);
         }
 
         if ($customerId == NEW_ENTRY || $customer->taxable) {
-            $this->save_sales_tax($saleId, $sales_taxes[0]);
-            $this->save_sales_items_taxes($saleId, $sales_taxes[1]);
+            $this->save_sales_tax($saleId, $salesTaxes[0]);
+            $this->save_sales_items_taxes($saleId, $salesTaxes[1]);
         }
 
         if ($config['dinner_table_enable']) {
-            $dinner_table = model(Dinner_table::class);
+            $dinnerTable = model(Dinner_table::class);
             if ($saleStatus == COMPLETED) {    // TODO: === ?
-                $dinner_table->release($dinner_table_id);
+                $dinnerTable->release($dinnerTableId);
             } else {
-                $dinner_table->occupy($dinner_table_id);
+                $dinnerTable->occupy($dinnerTableId);
             }
         }
 
diff --git a/tests/Controllers/SalesControllerTest.php b/tests/Controllers/SalesControllerTest.php
index 5faad4d94..7f6118e45 100644
--- a/tests/Controllers/SalesControllerTest.php
+++ b/tests/Controllers/SalesControllerTest.php
@@ -287,7 +287,7 @@ class SalesControllerTest extends CIUnitTestCase
                     'cost_price'            => '1.00',
                     'total'                 => $price,
                     'discounted_total'      => $price,
-                    'print_option'          => 1,
+                    'print_option'          => PRINT_YES,
                     'stock_type'            => HAS_NO_STOCK,
                     'item_type'             => ITEM,
                     'hsn_code'              => null,
@@ -519,6 +519,185 @@ class SalesControllerTest extends CIUnitTestCase
         $this->assertEquals('0.01', $cart[1]['price']);
     }
 
+    protected function createGiftcard(float $value): int
+    {
+        $giftcardNumber = random_int(1000000, 9999999);
+
+        Database::connect()->table('giftcards')->insert([
+            'giftcard_number' => $giftcardNumber,
+            'value'           => $value,
+            'deleted'         => 0,
+            'person_id'       => null,
+        ]);
+
+        return $giftcardNumber;
+    }
+
+    protected function getGiftcardValue(int $giftcardNumber): float
+    {
+        $row = Database::connect()->table('giftcards')
+            ->where('giftcard_number', $giftcardNumber)
+            ->get()
+            ->getRow();
+
+        return (float) $row->value;
+    }
+
+    public function testCashierCannotForgeGiftcardPaymentTypeWithNegativeAmount(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $giftcardNumber = $this->createGiftcard(100.00);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '1.00', $itemId);
+
+        $this->post('/sales/addPayment', [
+            'payment_type'    => lang('Sales.giftcard') . ':' . $giftcardNumber,
+            'amount_tendered' => '-500',
+        ]);
+
+        $payments = Services::session()->get('sales_payments');
+        $this->assertEmpty($payments);
+        $this->assertEqualsWithDelta(100.00, $this->getGiftcardValue($giftcardNumber), 0.001);
+    }
+
+    public function testCashierCanUseLegitimateGiftcardPayment(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $giftcardNumber = $this->createGiftcard(100.00);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '1.00', $itemId);
+
+        $this->post('/sales/addPayment', [
+            'payment_type'    => lang('Sales.giftcard'),
+            'amount_tendered' => (string) $giftcardNumber,
+        ]);
+
+        $payments = Services::session()->get('sales_payments');
+        $this->assertNotEmpty($payments);
+        $this->assertArrayHasKey(lang('Sales.giftcard') . ':' . $giftcardNumber, $payments);
+    }
+
+    public function testCashierCannotSubmitNegativeAmountForReferenceCodePayment(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '1.00', $itemId);
+
+        $this->post('/sales/addPayment', [
+            'payment_type'    => lang('Sales.debit'),
+            'amount_tendered' => '-25',
+            'reference_code'  => 'ABC123',
+        ]);
+
+        $payments = Services::session()->get('sales_payments');
+        $this->assertEmpty($payments);
+    }
+
+    public function testCashierCanUseLegitimateReferenceCodePayment(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '1.00', $itemId);
+
+        $this->post('/sales/addPayment', [
+            'payment_type'    => lang('Sales.debit'),
+            'amount_tendered' => '25.00',
+            'reference_code'  => 'ABC123',
+        ]);
+
+        $payments = Services::session()->get('sales_payments');
+        $this->assertNotEmpty($payments);
+        $this->assertArrayHasKey(lang('Sales.debit'), $payments);
+        $this->assertSame('ABC123', $payments[lang('Sales.debit')]['reference_code']);
+    }
+
+    public function testCashierCannotSubmitNegativeAmountForCashPayment(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '1.00', $itemId);
+
+        $this->post('/sales/addPayment', [
+            'payment_type'    => lang('Sales.cash'),
+            'amount_tendered' => '-10',
+        ]);
+
+        $payments = Services::session()->get('sales_payments');
+        $this->assertEmpty($payments);
+    }
+
+    public function testCashierCanUseLegitimateCashPayment(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '1.00', $itemId);
+
+        $this->post('/sales/addPayment', [
+            'payment_type'    => lang('Sales.cash'),
+            'amount_tendered' => '10.00',
+        ]);
+
+        $payments = Services::session()->get('sales_payments');
+        $this->assertNotEmpty($payments);
+        $this->assertArrayHasKey(lang('Sales.cash'), $payments);
+    }
+
+    public function testPostCompleteRejectsSaleWithInsufficientPayments(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '100.00', $itemId);
+        $this->withSession(array_merge($this->session, ['sale_id' => NEW_ENTRY]));
+
+        $salesCountBefore = Database::connect()->table('sales')->countAllResults();
+
+        $this->post('/sales/complete');
+
+        $salesCountAfter = Database::connect()->table('sales')->countAllResults();
+        $this->assertSame($salesCountBefore, $salesCountAfter);
+    }
+
+    public function testPostCompleteAllowsZeroPaymentQuoteCompletion(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '100.00', $itemId);
+        $this->withSession(array_merge($this->session, ['sale_id' => NEW_ENTRY, 'sales_mode' => 'sale_quote']));
+
+        $salesCountBefore = Database::connect()->table('sales')->countAllResults();
+
+        $response = $this->post('/sales/complete');
+
+        $salesCountAfter = Database::connect()->table('sales')->countAllResults();
+        $this->assertSame($salesCountBefore + 1, $salesCountAfter);
+        $response->assertDontSee(lang('Sales.amount_due_not_covered'));
+    }
+
+    public function testPostCompleteAllowsZeroPaymentInvoiceCompletion(): void
+    {
+        $cashierId = $this->createCashierEmployee();
+        $itemId = $this->createTestItem(HAS_NO_STOCK);
+        $this->loginAs($cashierId);
+        $this->seedCartLine(1, '100.00', $itemId);
+        $this->withSession(array_merge($this->session, ['sale_id' => NEW_ENTRY, 'sales_mode' => 'sale_invoice']));
+
+        $salesCountBefore = Database::connect()->table('sales')->countAllResults();
+
+        $response = $this->post('/sales/complete');
+
+        $salesCountAfter = Database::connect()->table('sales')->countAllResults();
+        $this->assertSame($salesCountBefore + 1, $salesCountAfter);
+        $response->assertDontSee(lang('Sales.amount_due_not_covered'));
+    }
+
     public function testRegisterEscapesMaliciousTaxName(): void
     {
         $cashierId = $this->createCashierEmployee();
diff --git a/tests/Models/GiftcardTest.php b/tests/Models/GiftcardTest.php
index 9e6198ebc..e57b88cd9 100644
--- a/tests/Models/GiftcardTest.php
+++ b/tests/Models/GiftcardTest.php
@@ -81,6 +81,28 @@ class GiftcardTest extends CIUnitTestCase
         $this->assertEqualsWithDelta(50.00, $this->getGiftcardValue($giftcardNumber), 0.001);
     }
 
+    public function testDecrementGiftcardValueRejectsNegativeAmount(): void
+    {
+        $giftcardNumber = $this->createGiftcard(100.00);
+        $giftcardModel  = model(Giftcard::class);
+
+        $result = $giftcardModel->decrementGiftcardValue((string) $giftcardNumber, -500.00);
+
+        $this->assertFalse($result);
+        $this->assertEqualsWithDelta(100.00, $this->getGiftcardValue($giftcardNumber), 0.001);
+    }
+
+    public function testDecrementGiftcardValueRejectsZeroAmount(): void
+    {
+        $giftcardNumber = $this->createGiftcard(100.00);
+        $giftcardModel  = model(Giftcard::class);
+
+        $result = $giftcardModel->decrementGiftcardValue((string) $giftcardNumber, 0.00);
+
+        $this->assertFalse($result);
+        $this->assertEqualsWithDelta(100.00, $this->getGiftcardValue($giftcardNumber), 0.001);
+    }
+
     public function testDecrementGiftcardValueExactBalanceSucceeds(): void
     {
         $giftcardNumber = $this->createGiftcard(60.00);
diff --git a/tests/Models/SaleTest.php b/tests/Models/SaleTest.php
index d6348c8b9..4dffad438 100644
--- a/tests/Models/SaleTest.php
+++ b/tests/Models/SaleTest.php
@@ -3,6 +3,7 @@
 namespace Tests\Models;
 
 use App\Models\Sale;
+use CodeIgniter\Database\Config;
 use CodeIgniter\Test\CIUnitTestCase;
 use CodeIgniter\Test\DatabaseTestTrait;
 use Tests\Support\EmployeeFixtureTrait;
@@ -21,16 +22,31 @@ class SaleTest extends CIUnitTestCase
 
     protected $migrate     = true;
     protected $migrateOnce = true;
-    protected $refresh     = true;
+    protected $seedOnce    = true;
+    protected $refresh     = false;
     protected $namespace   = null;
 
+    private static bool $doneBootstrap = false;
+
     private const LOCATION_ID = 1;
 
     protected function setUp(): void
     {
+        if (self::$doneBootstrap === false) {
+            Config::seeder($this->DBGroup)->call('App\Database\Seeds\TestDatabaseBootstrapSeeder');
+            Config::connect($this->DBGroup)->close();
+
+            self::$doneBootstrap = true;
+        }
+
         parent::setUp();
     }
 
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+    }
+
     protected function createGiftcard(float $value): int
     {
         $giftcardNumber = random_int(1000000, 9999999);
@@ -157,6 +173,46 @@ class SaleTest extends CIUnitTestCase
         $this->assertEqualsWithDelta(40.00, $this->getGiftcardValue($giftcardNumber), 0.001);
     }
 
+    public function testSaveValueDoesNotMatchGiftcardSinkOnSubstringOnly(): void
+    {
+        $employeeId     = $this->createEmployee();
+        $giftcardNumber = $this->createGiftcard(100.00);
+        $itemId         = $this->createTestItem(HAS_NO_STOCK);
+
+        $saleModel  = model(Sale::class);
+        $saleStatus = COMPLETED;
+        $items      = $this->buildCartLine($itemId, 1, 60.00);
+        $payments   = [
+            0 => [
+                'payment_type'    => 'Foo ' . lang('Sales.giftcard') . ':' . $giftcardNumber,
+                'payment_amount'  => 60.00,
+                'cash_refund'     => 0,
+                'cash_adjustment' => 0,
+                'reference_code'  => null,
+            ],
+        ];
+        $salesTaxes = [[], []];
+
+        $result = $saleModel->save_value(
+            NEW_ENTRY,
+            $saleStatus,
+            $items,
+            NEW_ENTRY,
+            $employeeId,
+            'test sale',
+            null,
+            null,
+            null,
+            SALE_TYPE_POS,
+            $payments,
+            null,
+            $salesTaxes
+        );
+
+        $this->assertGreaterThan(0, $result);
+        $this->assertEqualsWithDelta(100.00, $this->getGiftcardValue($giftcardNumber), 0.001);
+    }
+
     public function testSaveValueReturnsInsufficientGiftcardBalanceSentinel(): void
     {
         $employeeId     = $this->createEmployee();