Fix/invoice numbers (#365)

* feat: make invoice_number nullable and assign on send

- Updated the invoices table to allow invoice_number to be nullable.
- Modified the logic to assign invoice numbers only when the invoice status transitions to 'sent'.
- Refactored related code to handle nullable invoice numbers, including UI components and API routes.
- Added tests to ensure correct behavior when handling invoices with null invoice numbers.
- Introduced a utility function to display invoice numbers, defaulting to '(Utkast)' for drafts.

* fix: update fiscal period handling to return names of open periods in error messages

* fix: enhance period creation logic to account for company-wide bookkeeping lock-through

* fix: remove unnecessary customer_type field from customer insertion query

* fix: scope invoice number count query to specific companies to avoid test interference

* feat: Implement atomic invoice number generation and ensure compliance with invoice numbering rules

- Introduced `ensureInvoiceNumber` function to assign invoice numbers atomically, handling concurrency and ensuring compliance with document types.
- Updated invoice-related components to utilize the new `invoiceNumberDisplay` utility for consistent invoice number formatting.
- Added checks to ensure that invoices in non-draft statuses have valid invoice numbers, preventing violations of legal requirements.
- Created tests for the new invoice number generation logic, ensuring correct behavior under various scenarios, including concurrent requests.
- Added a draft banner to PDF templates for invoices without assigned numbers, clarifying their status to users.
- Updated database migrations to support the new atomic invoice number generation logic and enforce constraints on invoice statuses.

app/api/pending-operations/[id]/commit/__tests__/route.test.ts

@@ -217,20 +217,20 @@ describe('POST /api/pending-operations/:id/commit', () => {
       enqueueMany([
         { data: pendingOp },                          // fetch pending op
         { data: customer },                           // fetch customer
-        { data: '20260001' },                         // generate invoice number (rpc)
-        { data: { id: 'inv-1' } },                    // insert invoice
+        { data: { id: 'inv-1', invoice_number: null } }, // insert invoice (no number — assigned at send)
         { data: null, error: null },                  // insert items
-        { data: { id: 'inv-1', customer: customer, items: [] } }, // fetch complete invoice
+        { data: { id: 'inv-1', invoice_number: null, customer: customer, items: [] } }, // fetch complete invoice
         { data: null, error: null },                  // update pending op status
       ])
 
       const request = createMockRequest('/api/pending-operations/op-1/commit', { method: 'POST' })
       const response = await POST(request, routeParams)
-      const { status, body } = await parseJsonResponse<{ data: { invoice_id: string; invoice_number: string } }>(response)
+      const { status, body } = await parseJsonResponse<{ data: { invoice_id: string; invoice_number: string | null } }>(response)
 
       expect(status).toBe(200)
       expect(body.data.invoice_id).toBe('inv-1')
-      expect(body.data.invoice_number).toBe('20260001')
+      // Drafts no longer reserve a number — assigned at send time instead
+      expect(body.data.invoice_number).toBeNull()
     })
 
     it('returns 404 when customer not found', async () => {

app/api/pending-operations/[id]/commit/route.ts

@@ -30,6 +30,7 @@ import {
 import { uploadDocument } from '@/lib/core/documents/document-service'
 import { renderToBuffer } from '@react-pdf/renderer'
 import { InvoicePDF } from '@/lib/invoices/pdf-template'
+import { ensureInvoiceNumber } from '@/lib/invoices/ensure-invoice-number'
 import { createLogger } from '@/lib/logger'
 import { appendProcessingHistory } from '@/lib/processing-history/append'
 import type {
@@ -391,10 +392,8 @@ async function commitCreateInvoice(
   const uniqueRates = new Set(items.map((item) => item.vat_rate ?? vatRules.rate))
   const isMixedRate = uniqueRates.size > 1
 
-  // Generate invoice number
-  const { data: invoiceNumber } = await supabase.rpc('generate_invoice_number', {
-    p_company_id: companyId,
-  })
+  // Invoice number is assigned later when the draft is sent — leave null here
+  // so a discarded draft never consumes a number.
 
   // Create invoice
   const { data: invoice, error: invoiceError } = await supabase
@@ -403,7 +402,7 @@ async function commitCreateInvoice(
       user_id: userId,
       company_id: companyId,
       customer_id: customerId,
-      invoice_number: invoiceNumber,
+      invoice_number: null,
       invoice_date: (params.invoice_date as string) || new Date().toISOString().split('T')[0],
       due_date: (params.due_date as string) || null,
       currency,
@@ -472,7 +471,7 @@ async function commitCreateInvoice(
     })
   }
 
-  return { data: { invoice_id: invoice.id, invoice_number: invoiceNumber } }
+  return { data: { invoice_id: invoice.id, invoice_number: invoice.invoice_number } }
 }
 
 async function commitMarkInvoicePaid(
@@ -570,6 +569,14 @@ async function commitSendInvoice(
 
   if (companyError || !company) return { error: 'Company settings missing', status: 500 }
 
+  // Assign invoice number now if this draft doesn't have one yet —
+  // mutates `invoice.invoice_number` so PDF, email, JE all see it.
+  try {
+    await ensureInvoiceNumber(supabase, companyId, invoice as Invoice)
+  } catch (err) {
+    return { error: `Failed to assign invoice number: ${err instanceof Error ? err.message : 'unknown'}`, status: 500 }
+  }
+
   const items = (invoice.items as InvoiceItem[]).sort(
     (a: InvoiceItem, b: InvoiceItem) => a.sort_order - b.sort_order
   )
@@ -682,6 +689,12 @@ async function commitMarkInvoiceSent(
   if (invoiceError || !invoice) return { error: 'Invoice not found', status: 404 }
   if (invoice.status !== 'draft') return { error: 'Only draft invoices can be marked as sent', status: 409 }
 
+  try {
+    await ensureInvoiceNumber(supabase, companyId, invoice as Invoice)
+  } catch (err) {
+    return { error: `Failed to assign invoice number: ${err instanceof Error ? err.message : 'unknown'}`, status: 500 }
+  }
+
   const { error: updateError } = await supabase
     .from('invoices')
     .update({ status: 'sent' })