/**
 * RFC 6266 / RFC 5987 attachment disposition. Branch and tag names may contain `"`, `;` and non-ASCII,
 * so the quoted `filename` only carries a sanitized ASCII fallback and the real name goes in `filename*`.
 */
export function attachmentDisposition(filename: string): string {
  const ascii = filename.replace(/[^\x20-\x7e]/g, "_").replace(/["\\;]/g, "_");
  const encoded = encodeURIComponent(filename).replace(
    /[!'()*]/g,
    (char) => `%${char.charCodeAt(0).toString(16).toUpperCase()}`,
  );
  return `attachment; filename="${ascii}"; filename*=UTF-8''${encoded}`;
}