function sortJSON<T>(obj: T): T {
  if (typeof obj !== "object" || Array.isArray(obj) || obj === null) {
    return obj;
  }

  return Object.fromEntries(
    Object.entries(obj as Record<string, unknown>).sort((a, b) =>
      a[0].localeCompare(b[0])
    ).map(([k, v]) => [k, sortJSON(v)]),
  ) as unknown as T;
}

if (import.meta.main) {
  if (Deno.args.length !== 1) {
    console.error("Usage: jsort <file>");
    Deno.exit(1);
  }

  const filename = Deno.args[0];

  const json_text = Deno.readTextFileSync(filename);
  const json = JSON.parse(json_text);
  const sorted = sortJSON(json);
  const sorted_json_text = JSON.stringify(sorted);

  Deno.writeTextFileSync(filename, sorted_json_text);
}