/** Download CSV (UTF-8 BOM) so Excel opens Chinese columns correctly. */
export function downloadExcelCsv(csv: string, filename: string) {
  const blob = new Blob([csv], { type: 'text/csv;charset=utf-8;' });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename.endsWith('.csv') ? filename : `${filename}.csv`;
  a.click();
  URL.revokeObjectURL(url);
}

/** Download binary file from base64 payload returned by HQ export APIs. */
export function downloadBase64File(contentBase64: string, filename: string, mimeType: string) {
  const binary = atob(contentBase64);
  const bytes = new Uint8Array(binary.length);
  for (let i = 0; i < binary.length; i += 1) {
    bytes[i] = binary.charCodeAt(i);
  }
  const blob = new Blob([bytes], { type: mimeType });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}