scripts/import-tax-tables.ts
Rama main · réplica de lectura del repositorio original.
/**
* Parse Skatteverket SKV 434 monthly tax tables (fixed-width TXT) and emit a
* TypeScript module used as an emergency fallback when Skatteverket's open-data
* API is unavailable.
*
* Input: scripts/data/tax-tables/{year}/allmanna-tabeller-manad.txt
* Output: lib/salary/tax-tables-fallback.ts
*
* Record format (49 chars per line):
* chars 0-4 (width 5): prefix : "30B29" = monthly/belopp, table 29;
* "30%29" = monthly/percent, table 29
* chars 5-11 (width 7): income_from
* chars 12-18 (width 7): income_to (blank on the open-ended top %-row)
* chars 19-23 (width 5): column 1 (SEK on B-rows, percent on %-rows)
* chars 24-28 (width 5): column 2
* chars 29-33 (width 5): column 3
* chars 34-38 (width 5): column 4
* chars 39-43 (width 5): column 5
* chars 44-48 (width 5): column 6
*
* Both B-rows (absolute amounts, incomes up to 80 000 kr/month) and %-rows
* (percent of the whole income, above 80 000 kr/month) are imported. The
* emitted tuple carries an isPercent flag as its last element.
*
* Usage:
* npx tsx scripts/import-tax-tables.ts --year 2026
*/
import { readFileSync, writeFileSync } from 'fs'
import { resolve } from 'path'
import { fileURLToPath } from 'url'
type TaxRow = readonly [number, number, number, number, number, number, number, number, number]
interface ParsedTable {
tableNumber: number
rows: TaxRow[]
}
function parseArgs(): { year: number } {
const args = process.argv.slice(2)
const yearIdx = args.indexOf('--year')
if (yearIdx === -1 || !args[yearIdx + 1]) {
throw new Error('Missing --year argument')
}
const year = parseInt(args[yearIdx + 1], 10)
if (!Number.isInteger(year) || year < 2000 || year > 2100) {
throw new Error(`Invalid year: ${args[yearIdx + 1]}`)
}
return { year }
}
export function parseLine(line: string): { table: number; row: TaxRow } | null {
// Strip BOM if present on the first line
const clean = line.replace(/^\uFEFF/, '')
if (clean.length < 49) return null
const prefix = clean.slice(0, 5)
// B-rows carry absolute SEK amounts, %-rows carry percentages for incomes
// above the highest B-row bracket. Both are needed for correct withholding.
if (prefix[2] !== 'B' && prefix[2] !== '%') return null
// The day-count prefix must be "30" (monthly). Skatteverket also publishes
// two-week tables whose rows differ only in this prefix ("14B29" vs "30B29"):
// a two-week row must fail the import loudly, never merge silently into the
// monthly fallback data.
const dayCount = prefix.slice(0, 2)
if (dayCount === '14') {
throw new Error(
`Two-week table row (prefix "${prefix}") in monthly import: wrong source file? Line: ${clean}`
)
}
if (dayCount !== '30') return null
const isPercent = prefix[2] === '%'
const tableStr = prefix.slice(3, 5)
const table = parseInt(tableStr, 10)
if (!Number.isInteger(table)) return null
// Column values must be well-formed whole numbers. A malformed value falling
// back to 0 would bake 0 kr / 0 % withholding into the emitted fallback data,
// so fail the import instead.
const parseColumn = (start: number): number => {
const raw = clean.slice(start, start + 5).trim()
if (!/^\d+$/.test(raw)) {
throw new Error(`Malformed column value "${raw}" in line: ${clean}`)
}
return parseInt(raw, 10)
}
// Income boundaries get the same digits-only rule: parseInt would accept
// "100abc" and turn other garbage into 0, silently corrupting bracket
// ranges. A blank income_to is legal only on the open-ended top %-row
// (emitted as 0, mapped to the open-ended sentinel by the loader).
const parseIncome = (start: number, allowBlank: boolean): number => {
const raw = clean.slice(start, start + 7).trim()
if (raw === '') {
if (!allowBlank) throw new Error(`Missing income boundary in line: ${clean}`)
return 0
}
if (!/^\d+$/.test(raw)) {
throw new Error(`Malformed income boundary "${raw}" in line: ${clean}`)
}
return parseInt(raw, 10)
}
const incomeFrom = parseIncome(5, false)
const incomeTo = parseIncome(12, isPercent)
const c1 = parseColumn(19)
const c2 = parseColumn(24)
const c3 = parseColumn(29)
const c4 = parseColumn(34)
const c5 = parseColumn(39)
const c6 = parseColumn(44)
return {
table,
row: [incomeFrom, incomeTo, c1, c2, c3, c4, c5, c6, isPercent ? 1 : 0] as const,
}
}
function parseFile(path: string): ParsedTable[] {
const content = readFileSync(path, 'utf-8')
const byTable = new Map<number, TaxRow[]>()
for (const rawLine of content.split(/\r?\n/)) {
if (!rawLine.trim()) continue
const parsed = parseLine(rawLine)
if (!parsed) continue
const existing = byTable.get(parsed.table)
if (existing) {
existing.push(parsed.row)
} else {
byTable.set(parsed.table, [parsed.row])
}
}
const tables = Array.from(byTable.entries())
.map(([tableNumber, rows]) => ({
tableNumber,
rows: rows.sort((a, b) => a[0] - b[0]),
}))
.sort((a, b) => a.tableNumber - b.tableNumber)
return tables
}
function formatRow(row: TaxRow): string {
return `[${row.join(', ')}]`
}
function emitModule(year: number, tables: ParsedTable[]): string {
const totalRows = tables.reduce((sum, t) => sum + t.rows.length, 0)
const tableNumbers = tables.map(t => t.tableNumber).join(', ')
const entries = tables
.map(t => {
const rows = t.rows.map(formatRow).join(',\n ')
return ` ${t.tableNumber}: [\n ${rows},\n ]`
})
.join(',\n')
return `/**
* AUTO-GENERATED: do not edit by hand.
*
* Source: scripts/data/tax-tables/${year}/allmanna-tabeller-manad.txt (Skatteverket SKV 434)
* Generator: scripts/import-tax-tables.ts
*
* Emergency fallback for lib/salary/tax-tables.ts when the Skatteverket
* open-data API is unreachable. Do not use as the primary source: the API
* is authoritative.
*
* Rows: ${totalRows} across tables ${tableNumbers}
*/
/**
* [incomeFrom, incomeTo, col1, col2, col3, col4, col5, col6, isPercent]
*
* isPercent 0: columns are SEK amounts (incomes up to 80 000 kr/month).
* isPercent 1: columns are percent of the whole monthly income (above
* 80 000 kr/month). incomeTo 0 marks the open-ended top row.
*/
export type FallbackTaxRow = readonly [
number, number, number, number, number, number, number, number, number,
]
/** Tables keyed by municipal tax rate number (29-42). */
export type FallbackTaxYear = Readonly<Record<number, readonly FallbackTaxRow[]>>
export const FALLBACK_TAX_TABLES_${year}: FallbackTaxYear = {
${entries},
}
export const FALLBACK_TAX_TABLES: Readonly<Record<number, FallbackTaxYear>> = {
${year}: FALLBACK_TAX_TABLES_${year},
}
export const FALLBACK_TAX_TABLE_YEARS: ReadonlySet<number> = new Set([${year}])
`
}
function main() {
const { year } = parseArgs()
const inputPath = resolve(process.cwd(), `scripts/data/tax-tables/${year}/allmanna-tabeller-manad.txt`)
const outputPath = resolve(process.cwd(), 'src/lib/salary/tax-tables-fallback.ts')
console.log(`Reading ${inputPath}`)
const tables = parseFile(inputPath)
if (tables.length === 0) {
throw new Error('No rows parsed: check input file format')
}
// Every table must have both sections: a B-only table would clamp high
// incomes to the last krona bracket and silently under-withhold.
for (const t of tables) {
const percentRows = t.rows.filter(r => r[8] === 1).length
if (percentRows === 0 || percentRows === t.rows.length) {
throw new Error(`Table ${t.tableNumber}: expected both B-rows and %-rows, got ${percentRows}/${t.rows.length} percent rows`)
}
}
const totalRows = tables.reduce((sum, t) => sum + t.rows.length, 0)
const percentTotal = tables.reduce((sum, t) => sum + t.rows.filter(r => r[8] === 1).length, 0)
console.log(`Parsed ${tables.length} tables (${tables.map(t => t.tableNumber).join(', ')}), ${totalRows} rows total (${percentTotal} percent rows)`)
const moduleSource = emitModule(year, tables)
writeFileSync(outputPath, moduleSource, 'utf-8')
console.log(`Wrote ${outputPath} (${moduleSource.length.toLocaleString()} bytes)`)
}
// Run only when executed directly (npx tsx scripts/import-tax-tables.ts), not
// when parseLine is imported by tests. Same pattern as generate-crontabs.ts.
if (process.argv[1] && fileURLToPath(import.meta.url) === resolve(process.argv[1])) {
main()
}