build-csv.mjs

#!/usr/bin/env node
/**
 * Rebuild the flattened CSVs from the canonical JSON envelopes.
 *
 * The JSON files (rates.json, limits.json, changes.json) are the source of
 * truth, fetched from https://wha.tools/api/data by the refresh workflow. This
 * derives the convenience CSVs from them so the two never disagree. Node stdlib
 * only — no dependencies, no install step.
 *
 * Mirrors the CSV shape produced by wha.tools' own scripts/export-open-data.mjs.
 */
import { readFileSync, writeFileSync } from 'node:fs';

const read = (f) => JSON.parse(readFileSync(new URL(`../${f}`, import.meta.url), 'utf8'));

// RFC 4180 quoting + spreadsheet formula-injection guard.
function csvCell(v) {
  if (v === null || v === undefined) return '';
  let s = String(v);
  if (/^[=+\-@\t\r]/.test(s)) s = `'${s}`;
  if (/[",\n\r]/.test(s)) s = `"${s.replace(/"/g, '""')}"`;
  return s;
}
const toCsv = (headers, rows) =>
  [headers, ...rows].map((r) => r.map(csvCell).join(',')).join('\r\n') + '\r\n';

const write = (file, contents) => {
  writeFileSync(new URL(`../${file}`, import.meta.url), contents);
  console.log(`  wrote ${file}`);
};

// --- rates.csv : one row per (currency, market) --------------------------
const rates = read('rates.json');
const rateRows = [];
for (const c of rates.currencies) {
  const byMarket = rates.rates[c.code];
  if (!byMarket) continue;
  for (const m of rates.markets) {
    const tuple = byMarket[m.id];
    if (!tuple) continue;
    const [marketing, utility, authentication, authInternational] = tuple;
    rateRows.push([
      c.code,
      c.name,
      m.id,
      m.name,
      m.isRegion,
      marketing,
      utility,
      authentication,
      authInternational ?? '',
    ]);
  }
}
write(
  'rates.csv',
  toCsv(
    [
      'currency',
      'currency_name',
      'market_id',
      'market_name',
      'is_region',
      'marketing',
      'utility',
      'authentication',
      'authentication_international',
    ],
    rateRows,
  ),
);

// --- limits.csv : flatten the per-area tables ----------------------------
const limits = read('limits.json');
const limitRows = [];
for (const area of limits.areas) {
  for (const row of area.rows) {
    limitRows.push([area.heading, row.id, row.label, row.value, row.appliesTo, row.note]);
  }
}
write('limits.csv', toCsv(['area', 'id', 'label', 'value', 'applies_to', 'note'], limitRows));

// --- changes.csv : the dated ledger --------------------------------------
const changes = read('changes.json');
const changeRows = changes.changes.map((e) => [
  e.effective,
  e.announced ?? '',
  e.area,
  e.key ?? '',
  e.from ?? '',
  e.to ?? '',
  e.currency ?? '',
  e.provenance,
  e.verifiedBy ?? '',
  e.summary,
  (e.sources ?? []).map((s) => `${s.label} (${s.url})`).join(' | '),
]);
write(
  'changes.csv',
  toCsv(
    [
      'effective',
      'announced',
      'area',
      'key',
      'from',
      'to',
      'currency',
      'provenance',
      'verified_by',
      'summary',
      'sources',
    ],
    changeRows,
  ),
);

console.log(
  `Done. ${rateRows.length} rate rows, ${limitRows.length} limit rows, ${changeRows.length} change rows.`,
);