downloadToOPFS method

Future<void> downloadToOPFS(String url, String filename, { String? authToken, required void onProgress(int percentage), JSAny? abortSignal, })

Download a model to OPFS with progress tracking and cancellation support

Parameters:

• url: Download URL (HTTP/HTTPS)
• filename: Filename to save in OPFS (used as cache key)
• authToken: Optional authentication token (HuggingFace, etc.)
• onProgress: Progress callback (receives percentage 0-100)
• abortSignal: Optional JS AbortSignal for cancellation

Throws:

• Exception on download failure
• Exception if storage quota exceeded
• Exception if download is aborted

Implementation

Future<void> downloadToOPFS(
  String url,
  String filename, {
  String? authToken,
  required void Function(int percentage) onProgress,
  JSAny? abortSignal,
}) async {
  try {
    debugPrint('[WebOPFSService] Starting download: $filename');

    // Create JS callback for progress
    final jsProgressCallback = (JSNumber percentJs) {
      final percent = percentJs.toDartInt;
      onProgress(percent);
    }.toJS;

    // Call OPFS download with abort signal
    final result = await _opfs
        .downloadToOPFS(
          url.toJS,
          filename.toJS,
          authToken?.toJS,
          jsProgressCallback,
          abortSignal,
        )
        .toDart;

    if (!result.toDart) {
      throw Exception('OPFS download returned false');
    }

    debugPrint('[WebOPFSService] Download complete: $filename');
  } catch (e, stackTrace) {
    debugPrint('[WebOPFSService] Download failed: $e');
    debugPrint('[WebOPFSService] Stack trace: $stackTrace');
    throw Exception('Failed to download to OPFS: $e');
  }
}