/**
 * Generic browser-side download helpers.
 *
 * - `downloadTextFile` for plain-text payloads (X12, JSON, CSV, ...).
 *   Mirrors `downloadCsv` in `./csv.ts` but takes an explicit MIME type
 *   so the same code path can serve any text format without growing a
 *   one-off helper per format.
 *
 * - `downloadBlob` for binary payloads (the resubmit ZIP, future PDF
 *   exports, etc.) where the caller already has a `Blob` and just needs
 *   it handed to the browser.
 *
 * Both implementations skip the BOM prepend that `downloadCsv` uses (we
 * want byte-faithful X12 and ZIP — a BOM would corrupt the ISA segment
 * and confuse ZIP readers respectively).
 *
 * Safe to call from SSR/Node — guards against a missing `document`.
 */
export function downloadTextFile(
  filename: string,
  mimeType: string,
  text: string,
): void {
  downloadBlob(filename, new Blob([text], { type: `${mimeType};charset=utf-8` }));
}

export function downloadBlob(filename: string, blob: Blob): void {
  if (typeof document === "undefined" || typeof URL === "undefined") return;
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  // Some browsers require the link to be in the DOM before .click() works.
  a.style.display = "none";
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  // Defer revoke so the browser has the URL handle when the download kicks off.
  queueMicrotask(() => URL.revokeObjectURL(url));
}