// Small JSON files written atomically: the gateway's whole state is files
// under its root, so a backup is a copy of one folder.

import fs from 'node:fs';
import path from 'node:path';

export function readJson(file, fallback) {
  try { return JSON.parse(fs.readFileSync(file, 'utf8')); } catch { return fallback; }
}

export function writeJson(file, value) {
  fs.mkdirSync(path.dirname(file), { recursive: true });
  const tmp = `${file}.${process.pid}.tmp`;
  fs.writeFileSync(tmp, JSON.stringify(value, null, 2), { mode: 0o600 });
  fs.renameSync(tmp, file);
}