feat: add Bankgiro number validation and formatting, update settings and invoice templates (#60)

app/(dashboard)/settings/page.tsx

@@ -33,6 +33,7 @@ import {
 } from 'lucide-react'
 import { useTheme } from 'next-themes'
 import type { CompanySettings } from '@/types'
+import { validateBankgiroNumber, formatBankgiroNumber } from '@/lib/bankgiro/luhn'
 import { CalendarFeedSettings } from '@/components/settings/CalendarFeedSettings'
 import { getSettingsPanel } from '@/lib/extensions/settings-panel-registry'
 import { SecuritySettings } from '@/components/settings/SecuritySettings'
@@ -52,6 +53,7 @@ export default function SettingsPage() {
   const hasBankingExtension = ENABLED_EXTENSION_IDS.has('enable-banking')
   const hasCalendarExtension = ENABLED_EXTENSION_IDS.has('calendar')
   const [bankConnectionError, setBankConnectionError] = useState<string | null>(null)
+  const [bankgiroError, setBankgiroError] = useState<string | null>(null)
   const [showDeleteDialog, setShowDeleteDialog] = useState(false)
   const [deleteConfirmText, setDeleteConfirmText] = useState('')
   const [isDeleting, setIsDeleting] = useState(false)
@@ -158,6 +160,7 @@ export default function SettingsPage() {
       bank_name: formData.get('bank_name') as string,
       clearing_number: formData.get('clearing_number') as string,
       account_number: formData.get('account_number') as string,
+      bankgiro: (formData.get('bankgiro') as string) || null,
       preliminary_tax_monthly: parseFloat(formData.get('preliminary_tax_monthly') as string) || null,
       invoice_prefix: formData.get('invoice_prefix') as string || null,
       next_invoice_number: parseInt(formData.get('next_invoice_number') as string) || 1,
@@ -379,7 +382,7 @@ export default function SettingsPage() {
                   Betalningsuppgifter som visas på dina fakturor
                 </CardDescription>
               </CardHeader>
-              <CardContent>
+              <CardContent className="space-y-4">
                 <div className="grid grid-cols-3 gap-4">
                   <div className="space-y-2">
                     <Label htmlFor="bank_name">Bank</Label>
@@ -406,6 +409,31 @@ export default function SettingsPage() {
                     />
                   </div>
                 </div>
+                <div className="max-w-xs space-y-2">
+                  <Label htmlFor="bankgiro">Bankgiro</Label>
+                  <Input
+                    id="bankgiro"
+                    name="bankgiro"
+                    placeholder="XXX-XXXX"
+                    defaultValue={settings?.bankgiro || ''}
+                    onBlur={(e) => {
+                      const val = e.target.value.trim()
+                      if (!val) {
+                        setBankgiroError(null)
+                        return
+                      }
+                      if (validateBankgiroNumber(val)) {
+                        e.target.value = formatBankgiroNumber(val)
+                        setBankgiroError(null)
+                      } else {
+                        setBankgiroError('Ogiltigt bankgironummer (7-8 siffror med kontrollsiffra)')
+                      }
+                    }}
+                  />
+                  {bankgiroError && (
+                    <p className="text-xs text-destructive">{bankgiroError}</p>
+                  )}
+                </div>
               </CardContent>
             </Card>
 

lib/api/schemas.ts

@@ -372,6 +372,7 @@ export const UpdateSettingsSchema = z.object({
   bank_name: z.string().optional(),
   clearing_number: z.string().optional(),
   account_number: z.string().optional(),
+  bankgiro: z.string().nullable().optional(),
   iban: z.string().optional(),
   bic: z.string().optional(),
   accounting_method: AccountingMethodSchema.optional(),

lib/bankgiro/__tests__/luhn.test.ts

@@ -0,0 +1,154 @@
+import {
+  luhnCheckDigit,
+  luhnValidate,
+  validateBankgiroNumber,
+  formatBankgiroNumber,
+  generateOcrReference,
+  validateOcrReference,
+} from '../luhn'
+
+// -- Luhn core --
+
+describe('luhnCheckDigit', () => {
+  it('calculates check digit for Bankgiro 991-2346', () => {
+    expect(luhnCheckDigit('991234')).toBe(6)
+  })
+
+  it('calculates check digit for Bankgiro 5555-5551', () => {
+    expect(luhnCheckDigit('5555555')).toBe(1)
+  })
+
+  it('returns 0 when sum is already a multiple of 10', () => {
+    // 0: weight 2, product 0. Sum=0 → check=0
+    expect(luhnCheckDigit('0')).toBe(0)
+  })
+})
+
+describe('luhnValidate', () => {
+  it('validates correct numbers', () => {
+    expect(luhnValidate('9912346')).toBe(true)
+    expect(luhnValidate('55555551')).toBe(true)
+  })
+
+  it('rejects incorrect check digits', () => {
+    expect(luhnValidate('9912345')).toBe(false)
+    expect(luhnValidate('55555552')).toBe(false)
+  })
+
+  it('rejects single-digit input', () => {
+    expect(luhnValidate('5')).toBe(false)
+  })
+})
+
+// -- Bankgiro --
+
+describe('validateBankgiroNumber', () => {
+  it('validates 7-digit bankgiro with hyphen', () => {
+    expect(validateBankgiroNumber('991-2346')).toBe(true)
+  })
+
+  it('validates 8-digit bankgiro with hyphen', () => {
+    expect(validateBankgiroNumber('5555-5551')).toBe(true)
+  })
+
+  it('validates raw digits without hyphen', () => {
+    expect(validateBankgiroNumber('9912346')).toBe(true)
+    expect(validateBankgiroNumber('55555551')).toBe(true)
+  })
+
+  it('rejects wrong check digit', () => {
+    expect(validateBankgiroNumber('991-2345')).toBe(false)
+  })
+
+  it('rejects wrong length', () => {
+    expect(validateBankgiroNumber('12345')).toBe(false)
+    expect(validateBankgiroNumber('123456789')).toBe(false)
+  })
+
+  it('rejects non-numeric input', () => {
+    expect(validateBankgiroNumber('abc-defg')).toBe(false)
+  })
+
+  it('handles spaces', () => {
+    expect(validateBankgiroNumber('991 2346')).toBe(true)
+  })
+})
+
+describe('formatBankgiroNumber', () => {
+  it('formats 7-digit as XXX-XXXX', () => {
+    expect(formatBankgiroNumber('9912346')).toBe('991-2346')
+  })
+
+  it('formats 8-digit as XXXX-XXXX', () => {
+    expect(formatBankgiroNumber('55555551')).toBe('5555-5551')
+  })
+
+  it('handles already-formatted input', () => {
+    expect(formatBankgiroNumber('991-2346')).toBe('991-2346')
+  })
+
+  it('returns input unchanged for invalid lengths', () => {
+    expect(formatBankgiroNumber('12345')).toBe('12345')
+  })
+})
+
+// -- OCR reference --
+
+describe('generateOcrReference', () => {
+  it('appends correct check digit to numeric invoice number', () => {
+    const ocr = generateOcrReference('12345')
+    // 12345 → check digit 5 → '123455'
+    expect(ocr).toBe('123455')
+    expect(validateOcrReference(ocr)).toBe(true)
+  })
+
+  it('strips non-numeric characters from invoice number', () => {
+    const ocr = generateOcrReference('INV-2024-001')
+    // digits: 2024001
+    expect(ocr).toBe(generateOcrReference('2024001'))
+    expect(validateOcrReference(ocr)).toBe(true)
+  })
+
+  it('handles pure-numeric invoice numbers', () => {
+    const ocr = generateOcrReference('20240001')
+    expect(validateOcrReference(ocr)).toBe(true)
+    expect(ocr.length).toBe(9)
+  })
+
+  it('returns original if no digits found', () => {
+    expect(generateOcrReference('ABC')).toBe('ABC')
+  })
+
+  it('returns original if digits exceed 24 characters', () => {
+    const long = '1'.repeat(25)
+    expect(generateOcrReference(long)).toBe(long)
+  })
+
+  it('generates valid OCR for single-digit invoice number', () => {
+    const ocr = generateOcrReference('7')
+    expect(ocr.length).toBe(2)
+    expect(validateOcrReference(ocr)).toBe(true)
+  })
+})
+
+describe('validateOcrReference', () => {
+  it('validates correct OCR', () => {
+    expect(validateOcrReference('123455')).toBe(true)
+  })
+
+  it('rejects non-numeric', () => {
+    expect(validateOcrReference('12345a')).toBe(false)
+  })
+
+  it('rejects too short', () => {
+    expect(validateOcrReference('5')).toBe(false)
+  })
+
+  it('rejects too long (>25 digits)', () => {
+    expect(validateOcrReference('1'.repeat(26))).toBe(false)
+  })
+
+  it('rejects incorrect check digit', () => {
+    expect(validateOcrReference('123459')).toBe(false)
+  })
+})

lib/bankgiro/luhn.ts

@@ -0,0 +1,79 @@
+/**
+ * Luhn (modulus 10) check digit calculation and validation utilities.
+ * Used for Swedish Bankgiro numbers and OCR payment references.
+ *
+ * Algorithm source: Bankgirot "Beräkning av kontrollsiffra 10-modulen"
+ */
+
+/**
+ * Calculate the Luhn check digit for a string of digits.
+ * Weights alternate 2,1 starting from the rightmost digit.
+ */
+export function luhnCheckDigit(digits: string): number {
+  let sum = 0
+  for (let i = digits.length - 1; i >= 0; i--) {
+    const posFromRight = digits.length - 1 - i
+    const weight = posFromRight % 2 === 0 ? 2 : 1
+    let product = parseInt(digits[i], 10) * weight
+    if (product > 9) product -= 9
+    sum += product
+  }
+  return (10 - (sum % 10)) % 10
+}
+
+/**
+ * Validate that the last digit of a number string is a correct Luhn check digit.
+ */
+export function luhnValidate(number: string): boolean {
+  if (number.length < 2) return false
+  const payload = number.slice(0, -1)
+  const checkDigit = parseInt(number[number.length - 1], 10)
+  return luhnCheckDigit(payload) === checkDigit
+}
+
+// -- Bankgiro --
+
+/**
+ * Validate a Swedish Bankgiro number (7-8 digits, Luhn check digit).
+ * Accepts formats: "XXX-XXXX", "XXXX-XXXX", or raw digits.
+ */
+export function validateBankgiroNumber(input: string): boolean {
+  const digits = input.replace(/[-\s]/g, '')
+  if (!/^\d+$/.test(digits)) return false
+  if (digits.length !== 7 && digits.length !== 8) return false
+  return luhnValidate(digits)
+}
+
+/**
+ * Format a Bankgiro number with the standard hyphen placement.
+ * 7 digits → XXX-XXXX, 8 digits → XXXX-XXXX.
+ */
+export function formatBankgiroNumber(input: string): string {
+  const digits = input.replace(/[-\s]/g, '')
+  if (digits.length === 7) return digits.slice(0, 3) + '-' + digits.slice(3)
+  if (digits.length === 8) return digits.slice(0, 4) + '-' + digits.slice(4)
+  return input
+}
+
+// -- OCR reference --
+
+/**
+ * Generate a Swedish OCR reference from an invoice number.
+ * Strips non-numeric characters and appends a Luhn check digit.
+ * Result is 2-25 digits.
+ */
+export function generateOcrReference(invoiceNumber: string): string {
+  const digits = invoiceNumber.replace(/\D/g, '')
+  if (digits.length === 0 || digits.length > 24) return invoiceNumber
+  const checkDigit = luhnCheckDigit(digits)
+  return digits + checkDigit.toString()
+}
+
+/**
+ * Validate a Swedish OCR reference number (2-25 digits, Luhn check digit).
+ */
+export function validateOcrReference(ocr: string): boolean {
+  if (!/^\d+$/.test(ocr)) return false
+  if (ocr.length < 2 || ocr.length > 25) return false
+  return luhnValidate(ocr)
+}

lib/invoices/pdf-template.tsx

@@ -6,6 +6,7 @@ import {
   StyleSheet,
 } from '@react-pdf/renderer'
 import type { Invoice, InvoiceItem, Customer, CompanySettings, InvoiceDocumentType } from '@/types'
+import { generateOcrReference } from '@/lib/bankgiro/luhn'
 
 // Create styles
 const styles = StyleSheet.create({
@@ -484,6 +485,12 @@ export function InvoicePDF({ invoice, customer, items, company, originalInvoiceN
                 </Text>
               </View>
             )}
+            {company.bankgiro && (
+              <View style={styles.paymentRow}>
+                <Text style={styles.paymentLabel}>Bankgiro:</Text>
+                <Text style={styles.paymentValue}>{company.bankgiro}</Text>
+              </View>
+            )}
             {company.iban && (
               <View style={styles.paymentRow}>
                 <Text style={styles.paymentLabel}>IBAN:</Text>
@@ -502,7 +509,7 @@ export function InvoicePDF({ invoice, customer, items, company, originalInvoiceN
             </View>
             <View style={styles.paymentRow}>
               <Text style={styles.paymentLabel}>OCR/Referens:</Text>
-              <Text style={[styles.paymentValue, { fontWeight: 'bold' }]}>{invoice.invoice_number}</Text>
+              <Text style={[styles.paymentValue, { fontWeight: 'bold' }]}>{generateOcrReference(invoice.invoice_number)}</Text>
             </View>
           </View>
         )}

tests/helpers.ts

@@ -437,6 +437,7 @@ export function makeCompanySettings(
     bank_name: null,
     clearing_number: null,
     account_number: null,
+    bankgiro: null,
     iban: null,
     bic: null,
     accounting_method: 'accrual',

types/index.ts

@@ -118,6 +118,7 @@ export interface CompanySettings {
   bank_name: string | null
   clearing_number: string | null
   account_number: string | null
+  bankgiro: string | null
   iban: string | null
   bic: string | null