feat(vat-declaration): implement RC basis gap detection and correctio… (#466)

* feat(vat-declaration): implement RC basis gap detection and correction functionality * fix(vat-declaration): improve error handling and validation for RC basis account selection
2026-05-13 16:13:45 +02:00
parent a9c98da243
commit f0a2577b8b
4 changed files with 623 additions and 0 deletions
@@ -0,0 +1,182 @@
+import { NextResponse } from 'next/server'
+import { z } from 'zod'
+import { withRouteContext } from '@/lib/api/with-route-context'
+import { validateBody } from '@/lib/api/validate'
+import { errorResponseFromCode } from '@/lib/errors/get-structured-error'
+import { correctEntry } from '@/lib/core/bookkeeping/storno-service'
+import type { CreateJournalEntryLineInput, JournalEntryLine } from '@/types'
+
+/**
+ * POST /api/reports/vat-declaration/rc-basis-gaps/fix
+ *
+ * Adds the missing basbelopp pair (44xx/45xx debit + 4598 credit) to a
+ * posted journal entry that has reverse-charge output VAT (2614/2624/2634)
+ * but no corresponding basis lines. Uses correctEntry() so the original
+ * voucher is preserved in compliance with BFL (storno + corrected entry).
+ */
+
+const SUPPLIER_TYPE = z.enum(['eu_business', 'non_eu_business', 'swedish_business'])
+const SERVICE_OR_GOODS = z.enum(['service', 'goods'])
+
+const FixGapSchema = z.object({
+  entryId: z.string().uuid(),
+  supplierType: SUPPLIER_TYPE,
+  supplyType: SERVICE_OR_GOODS,
+})
+
+const RC_OUTPUT_ACCOUNTS = new Set(['2614', '2624', '2634'])
+const RATE_BY_OUTPUT: Record<string, number> = {
+  '2614': 0.25,
+  '2624': 0.12,
+  '2634': 0.06,
+}
+
+function pickBasisAccount(
+  outputAccount: string,
+  supplierType: 'eu_business' | 'non_eu_business' | 'swedish_business',
+  supplyType: 'service' | 'goods',
+): { account: string; error?: undefined } | { account?: undefined; error: string } {
+  const rateIdx = outputAccount === '2614' ? 0 : outputAccount === '2624' ? 1 : outputAccount === '2634' ? 2 : -1
+  if (rateIdx < 0) return { error: 'Okänt RC-utgående konto.' }
+
+  // EU services 4535/4536/4537, EU goods 4515/4516/4517,
+  // non-EU services 4531/4532/4533, domestic services 4425/4426/4427,
+  // domestic goods 4415/4416/4417.
+  // Non-EU goods is NOT reverse charge — it's import VAT (ruta 50/60-62 via
+  // 4545-4547), a separate flow that doesn't belong on this correction path.
+  if (supplierType === 'eu_business' && supplyType === 'service') return { account: ['4535', '4536', '4537'][rateIdx] }
+  if (supplierType === 'eu_business' && supplyType === 'goods') return { account: ['4515', '4516', '4517'][rateIdx] }
+  if (supplierType === 'non_eu_business' && supplyType === 'service') return { account: ['4531', '4532', '4533'][rateIdx] }
+  if (supplierType === 'non_eu_business' && supplyType === 'goods') {
+    return {
+      error:
+        'Varor från leverantörer utanför EU hanteras som import (ruta 50/60-62), inte omvänd skattskyldighet. ' +
+        'Korrigera verifikationen manuellt med importmoms på 2615/4545.',
+    }
+  }
+  if (supplierType === 'swedish_business' && supplyType === 'service') return { account: ['4425', '4426', '4427'][rateIdx] }
+  if (supplierType === 'swedish_business' && supplyType === 'goods') return { account: ['4415', '4416', '4417'][rateIdx] }
+  return { error: 'Kunde inte välja basbeloppskonto för angiven leverantörstyp.' }
+}
+
+export const POST = withRouteContext(
+  'report.vat_declaration.rc_basis_gaps.fix',
+  async (request, ctx) => {
+    const { user, supabase, companyId, log, requestId } = ctx
+
+    const result = await validateBody(request, FixGapSchema)
+    if (!result.success) return result.response
+    const { entryId, supplierType, supplyType } = result.data
+
+    // Fetch the entry + its lines (RLS + explicit company filter)
+    const { data: entry, error: fetchErr } = await supabase
+      .from('journal_entries')
+      .select('id, status, lines:journal_entry_lines(*)')
+      .eq('id', entryId)
+      .eq('company_id', companyId)
+      .single()
+
+    if (fetchErr || !entry) {
+      return errorResponseFromCode('JOURNAL_ENTRY_NOT_FOUND', log, { requestId, details: { entryId } })
+    }
+
+    if (entry.status !== 'posted') {
+      return errorResponseFromCode('JOURNAL_ENTRY_NOT_FOUND', log, {
+        requestId,
+        details: { entryId, reason: `entry is ${entry.status}, expected posted` },
+      })
+    }
+
+    const originalLines = (entry.lines as JournalEntryLine[]) || []
+
+    // Identify the RC output account and amount (sum across multiple lines if any)
+    let outputAccount: string | null = null
+    let outputAmount = 0
+    for (const line of originalLines) {
+      if (RC_OUTPUT_ACCOUNTS.has(line.account_number)) {
+        const net = (Number(line.credit_amount) || 0) - (Number(line.debit_amount) || 0)
+        if (net > 0) {
+          if (outputAccount && outputAccount !== line.account_number) {
+            return errorResponseFromCode('VAT_REPORT_GENERATION_FAILED', log, {
+              requestId,
+              details: {
+                reason: 'Verifikationen har RC-moms på flera räntesatser. Korrigera manuellt.',
+              },
+            })
+          }
+          outputAccount = line.account_number
+          outputAmount += net
+        }
+      }
+    }
+
+    if (!outputAccount || outputAmount <= 0) {
+      return errorResponseFromCode('VAT_REPORT_GENERATION_FAILED', log, {
+        requestId,
+        details: { reason: 'Ingen RC-utgående moms hittades i verifikationen.' },
+      })
+    }
+
+    const rate = RATE_BY_OUTPUT[outputAccount]
+    const pick = pickBasisAccount(outputAccount, supplierType, supplyType)
+    if (!pick.account) {
+      return errorResponseFromCode('VAT_REPORT_GENERATION_FAILED', log, {
+        requestId,
+        details: { reason: pick.error ?? 'Kunde inte välja basbeloppskonto.' },
+      })
+    }
+    const basisAccount: string = pick.account
+
+    const basisAmount = Math.round((outputAmount / rate) * 100) / 100
+    const rateLabel = `${Math.round(rate * 100)}%`
+
+    // Build corrected lines = original lines + basis pair (44xx debit + 4598 credit)
+    const correctedLines: CreateJournalEntryLineInput[] = [
+      ...originalLines.map((l) => {
+        const line: CreateJournalEntryLineInput = {
+          account_number: l.account_number,
+          debit_amount: Number(l.debit_amount) || 0,
+          credit_amount: Number(l.credit_amount) || 0,
+        }
+        if (l.currency) line.currency = l.currency
+        if (l.amount_in_currency != null) line.amount_in_currency = Number(l.amount_in_currency)
+        if (l.exchange_rate != null) line.exchange_rate = Number(l.exchange_rate)
+        if (l.line_description) line.line_description = l.line_description
+        if (l.tax_code) line.tax_code = l.tax_code
+        if (l.cost_center) line.cost_center = l.cost_center
+        if (l.project) line.project = l.project
+        return line
+      }),
+      {
+        account_number: basisAccount,
+        debit_amount: basisAmount,
+        credit_amount: 0,
+        line_description: `Basbelopp omvänd skattskyldighet ${rateLabel}`,
+      },
+      {
+        account_number: '4598',
+        debit_amount: 0,
+        credit_amount: basisAmount,
+        line_description: `Motkonto beräknad omvänd moms ${rateLabel}`,
+      },
+    ]
+
+    try {
+      const correction = await correctEntry(supabase, companyId, user.id, entryId, correctedLines)
+      return NextResponse.json({
+        data: {
+          reversalId: correction.reversal.id,
+          correctedId: correction.corrected.id,
+          basisAccount,
+          basisAmount,
+        },
+      })
+    } catch (err) {
+      log.error('rc-basis-gap fix failed', err as Error, { entryId })
+      return errorResponseFromCode('VAT_REPORT_GENERATION_FAILED', log, {
+        requestId,
+        details: { reason: err instanceof Error ? err.message : 'unknown' },
+      })
+    }
+  },
+)
@@ -0,0 +1,47 @@
+import { NextResponse } from 'next/server'
+import { withRouteContext } from '@/lib/api/with-route-context'
+import { errorResponseFromCode } from '@/lib/errors/get-structured-error'
+import { findRcBasisGaps } from '@/lib/reports/rc-basis-gaps'
+import type { VatPeriodType } from '@/types'
+
+export const GET = withRouteContext(
+  'report.vat_declaration.rc_basis_gaps',
+  async (request, ctx) => {
+    const { supabase, companyId, log, requestId } = ctx
+
+    const { searchParams } = new URL(request.url)
+    const periodType = searchParams.get('periodType') as VatPeriodType | null
+    const yearStr = searchParams.get('year')
+    const periodStr = searchParams.get('period')
+
+    if (!periodType || !yearStr || !periodStr) {
+      return errorResponseFromCode('VAT_REPORT_MISSING_PARAMS', log, { requestId })
+    }
+    if (!['monthly', 'quarterly', 'yearly'].includes(periodType)) {
+      return errorResponseFromCode('VAT_REPORT_INVALID_PERIOD_TYPE', log, {
+        requestId,
+        details: { received: periodType },
+      })
+    }
+
+    const year = parseInt(yearStr, 10)
+    const period = parseInt(periodStr, 10)
+    if (isNaN(year) || isNaN(period)) {
+      return errorResponseFromCode('VAT_REPORT_INVALID_PERIOD', log, {
+        requestId,
+        details: { year: yearStr, period: periodStr },
+      })
+    }
+
+    try {
+      const gaps = await findRcBasisGaps(supabase, companyId, periodType, year, period)
+      return NextResponse.json({ data: { gaps } })
+    } catch (err) {
+      log.error('rc-basis-gaps detection failed', err as Error, { periodType, year, period })
+      return errorResponseFromCode('VAT_REPORT_GENERATION_FAILED', log, {
+        requestId,
+        details: { reason: err instanceof Error ? err.message : 'unknown' },
+      })
+    }
+  },
+)