import 'package:dio/dio.dart';

/// Lightweight cancel handle around a single `Dio.download` call. The download
/// itself is started by [run]; the handle returns synchronously so callers can
/// install it into shared state before the first progress event can fire.
class FileDownloader {
  FileDownloader();

  final CancelToken _cancelToken = CancelToken();
  bool _cancelled = false;

  bool get isCancelled => _cancelled;

  void cancel() {
    if (_cancelled) return;
    _cancelled = true;
    _cancelToken.cancel('user cancelled');
  }

  /// Kicks off the download. Returns immediately; the download progresses in
  /// the background and events are delivered via callbacks. Callbacks are not
  /// invoked once [cancel] has been called.
  void run({
    required Dio client,
    required String url,
    required String savePath,
    required void Function(double percent) onProgress,
    required void Function() onDone,
    required void Function(Object error) onError,
  }) {
    client.download(
      url,
      savePath,
      cancelToken: _cancelToken,
      onReceiveProgress: (received, total) {
        if (_cancelled || total <= 0) return;
        onProgress((received / total) * 100);
      },
    ).then((_) {
      if (_cancelled) return;
      onDone();
    }).catchError((Object error) {
      if (_cancelled) return;
      onError(error);
    }).ignore();
  }
}