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/invoices/[id]/convert/route.ts

@@ -4,6 +4,7 @@ import { eventBus } from '@/lib/events'
 import { ensureInitialized } from '@/lib/init'
 import { requireCompanyId } from '@/lib/company/context'
 import { requireWritePermission } from '@/lib/auth/require-write'
+import { ensureInvoiceNumber } from '@/lib/invoices/ensure-invoice-number'
 import type { Invoice } from '@/types'
 
 ensureInitialized()
@@ -58,19 +59,16 @@ export async function POST(
     )
   }
 
-  // Generate real invoice number
-  const { data: invoiceNumber } = await supabase.rpc('generate_invoice_number', {
-    p_company_id: companyId,
-  })
-
-  // Create the real invoice
+  // Create the real invoice with invoice_number=null; assign atomically below.
+  // generate_invoice_number now requires the target row to exist so it can lock
+  // it (FOR UPDATE) and persist the number in the same transaction.
   const { data: invoice, error: invoiceError } = await supabase
     .from('invoices')
     .insert({
       user_id: user.id,
       company_id: companyId,
       customer_id: proforma.customer_id,
-      invoice_number: invoiceNumber,
+      invoice_number: null,
       invoice_date: new Date().toISOString().split('T')[0],
       due_date: proforma.due_date,
       currency: proforma.currency,
@@ -99,6 +97,20 @@ export async function POST(
     return NextResponse.json({ error: invoiceError.message }, { status: 500 })
   }
 
+  // Now that the row exists, allocate the F-series number. Mutates invoice
+  // in place so the response includes the assigned number.
+  try {
+    await ensureInvoiceNumber(supabase, companyId, invoice as Invoice)
+  } catch (err) {
+    // Roll back the partially-created invoice so the company counter is the
+    // only side effect to clean up (manually in worst case).
+    await supabase.from('invoices').delete().eq('id', invoice.id)
+    return NextResponse.json(
+      { error: err instanceof Error ? err.message : 'Failed to assign invoice number' },
+      { status: 500 }
+    )
+  }
+
   // Copy invoice items
   const items = (proforma.items || []).map((item: { sort_order: number; description: string; quantity: number; unit: string; unit_price: number; line_total: number }) => ({
     invoice_id: invoice.id,

app/api/invoices/[id]/mark-sent/route.ts

@@ -1,6 +1,7 @@
 import { createClient } from '@/lib/supabase/server'
 import { NextResponse } from 'next/server'
 import { createInvoiceJournalEntry } from '@/lib/bookkeeping/invoice-entries'
+import { ensureInvoiceNumber } from '@/lib/invoices/ensure-invoice-number'
 import { ensureInitialized } from '@/lib/init'
 import { requireCompanyId } from '@/lib/company/context'
 import { requireWritePermission } from '@/lib/auth/require-write'
@@ -52,6 +53,17 @@ export async function POST(
     )
   }
 
+  // Assign invoice number now if this draft doesn't have one yet
+  try {
+    await ensureInvoiceNumber(supabase, companyId, invoice as Invoice)
+  } catch (err) {
+    console.error('Failed to assign invoice number on mark-sent:', err)
+    return NextResponse.json(
+      { error: 'Kunde inte tilldela fakturanummer. Försök igen.' },
+      { status: 500 }
+    )
+  }
+
   // Update status to sent
   const { error: updateError } = await supabase
     .from('invoices')

app/api/invoices/[id]/pdf/route.ts

@@ -81,9 +81,10 @@ export async function GET(
 
     // Return PDF as response
     const isCreditNote = !!invoice.credited_invoice_id
+    const filenameNumber = invoice.invoice_number ?? `utkast-${String(invoice.id).slice(0, 8)}`
     const filename = isCreditNote
-      ? `kreditfaktura-${invoice.invoice_number}.pdf`
-      : `faktura-${invoice.invoice_number}.pdf`
+      ? `kreditfaktura-${filenameNumber}.pdf`
+      : `faktura-${filenameNumber}.pdf`
 
     return new NextResponse(uint8Array, {
       status: 200,

app/api/invoices/[id]/send/__tests__/route.test.ts

@@ -240,6 +240,69 @@ describe('POST /api/invoices/[id]/send', () => {
     expect(body.success).toBe(true)
   })
 
+  it('assigns an invoice number when sending a draft with no number', async () => {
+    const draftWithoutNumber = makeInvoice({
+      id: 'inv-1',
+      status: 'draft',
+      invoice_number: null,
+      customer,
+      items: invoice.items,
+    })
+
+    // Fetch invoice (no number)
+    enqueue({ data: draftWithoutNumber, error: null })
+    // Fetch company settings
+    enqueue({ data: company, error: null })
+    // ensureInvoiceNumber: rpc generate_invoice_number (RPC now persists internally)
+    enqueue({ data: 'F-2026010', error: null })
+
+    mockSendEmail.mockResolvedValue({ success: true, messageId: 'msg-99' })
+    mockCreateInvoiceJournalEntry.mockResolvedValue({ id: 'je-1' })
+
+    // Update status to 'sent'
+    enqueue({ data: null, error: null })
+    // Update with journal_entry_id
+    enqueue({ data: null, error: null })
+
+    const request = createMockRequest('/api/invoices/inv-1/send', { method: 'POST' })
+    const response = await POST(request, createMockRouteParams({ id: 'inv-1' }))
+    const { status, body } = await parseJsonResponse<{ success: boolean }>(response)
+
+    expect(status).toBe(200)
+    expect(body.success).toBe(true)
+    expect(mockSupabase.rpc).toHaveBeenCalledWith('generate_invoice_number', {
+      p_company_id: 'company-1',
+      p_invoice_id: 'inv-1',
+      p_document_type: 'invoice',
+    })
+    // The journal entry should see the freshly-assigned number
+    expect(mockCreateInvoiceJournalEntry).toHaveBeenCalledWith(
+      expect.anything(),
+      'company-1',
+      'user-1',
+      expect.objectContaining({ invoice_number: 'F-2026010' }),
+      'enskild_firma'
+    )
+  })
+
+  it('does not re-assign number when draft already has one (idempotency)', async () => {
+    enqueue({ data: invoice, error: null })
+    enqueue({ data: company, error: null })
+
+    mockSendEmail.mockResolvedValue({ success: true, messageId: 'msg-100' })
+    mockCreateInvoiceJournalEntry.mockResolvedValue({ id: 'je-2' })
+
+    enqueue({ data: null, error: null })
+    enqueue({ data: null, error: null })
+
+    const request = createMockRequest('/api/invoices/inv-1/send', { method: 'POST' })
+    const response = await POST(request, createMockRouteParams({ id: 'inv-1' }))
+    const { status } = await parseJsonResponse(response)
+
+    expect(status).toBe(200)
+    expect(mockSupabase.rpc).not.toHaveBeenCalledWith('generate_invoice_number', expect.anything())
+  })
+
   it('returns 500 when email sending fails', async () => {
     enqueue({ data: invoice, error: null })
     enqueue({ data: company, error: null })

app/api/invoices/[id]/send/route.ts

@@ -12,6 +12,7 @@ import {
 } from '@/lib/email/invoice-templates'
 import { createInvoiceJournalEntry } from '@/lib/bookkeeping/invoice-entries'
 import { uploadDocument } from '@/lib/core/documents/document-service'
+import { ensureInvoiceNumber } from '@/lib/invoices/ensure-invoice-number'
 import { requireCompanyId } from '@/lib/company/context'
 import { requireWritePermission } from '@/lib/auth/require-write'
 import type { Invoice, InvoiceItem, Customer, CompanySettings } from '@/types'
@@ -84,6 +85,19 @@ export async function POST(
     )
   }
 
+  // Assign invoice number now if this is a draft being sent for the first time.
+  // Mutates `invoice.invoice_number` so the rest of this flow (PDF render,
+  // email subject, journal entry description) sees the new value.
+  try {
+    await ensureInvoiceNumber(supabase, companyId, invoice as Invoice)
+  } catch (err) {
+    console.error('Failed to assign invoice number on send:', err)
+    return NextResponse.json(
+      { error: 'Kunde inte tilldela fakturanummer. Försök igen.' },
+      { status: 500 }
+    )
+  }
+
   // Sort items by sort_order
   const items = (invoice.items as InvoiceItem[]).sort(
     (a, b) => a.sort_order - b.sort_order

app/api/invoices/__tests__/route.test.ts

@@ -187,9 +187,7 @@ describe('POST /api/invoices (create invoice)', () => {
 
     // Fetch customer
     enqueue({ data: customer, error: null })
-    // RPC generate_invoice_number
-    enqueue({ data: 'F-2024001' })
-    // Insert invoice
+    // Insert invoice (no number generated for drafts — assigned at send time)
     enqueue({ data: createdInvoice, error: null })
     // Insert items
     enqueue({ data: null, error: null })
@@ -237,7 +235,6 @@ describe('POST /api/invoices (create invoice)', () => {
     ])
 
     enqueue({ data: customer, error: null })
-    enqueue({ data: 'F-2024001' })
     enqueue({ data: createdInvoice, error: null })
     // Items insertion fails
     enqueue({ data: null, error: { message: 'Items insert failed' } })

app/api/invoices/route.ts

@@ -166,20 +166,15 @@ export async function POST(request: Request) {
     }
   }
 
-  // Generate document number from the appropriate sequence
-  let invoiceNumber: string
+  // Generate document number — eagerly for delivery notes (separate sequence,
+  // separate UX), lazily for invoices and proformas (assigned at first send so
+  // discarded drafts never consume a number).
+  let invoiceNumber: string | null = null
   if (documentType === 'delivery_note') {
     const { data: dnNumber } = await supabase.rpc('generate_delivery_note_number', {
       p_company_id: companyId,
     })
     invoiceNumber = dnNumber
-  } else {
-    const { data: baseNumber } = await supabase.rpc('generate_invoice_number', {
-      p_company_id: companyId,
-    })
-    invoiceNumber = documentType === 'proforma'
-      ? `PF-${baseNumber}`
-      : baseNumber
   }
 
   // Create invoice