precache method

@override Future<StreamController<Map>?> precache(String url, Map<String, Object>? headers, int cacheSegments, bool downloadNow, bool progressListen,)

Pre-caches data from the network.

cacheSegments: Number of segments to cache. downloadNow: If true, downloads immediately; otherwise, pushes tasks to the queue. progressListen: If true, returns a StreamController with progress updates.

Returns a StreamController emitting progress maps, or null if not listening.

Implementation

@override
Future<StreamController<Map>?> precache(
  String url,
  Map<String, Object>? headers,
  int cacheSegments,
  bool downloadNow,
  bool progressListen,
) async {
  StreamController<Map>? _streamController;
  if (progressListen) _streamController = StreamController();
  int contentLength = await head(url.toSafeUri(), headers: headers);
  if (contentLength > 0) {
    int segmentSize = contentLength ~/ Config.segmentSize +
        (contentLength % Config.segmentSize > 0 ? 1 : 0);
    if (cacheSegments > segmentSize) {
      cacheSegments = segmentSize;
    }
  }
  int downloadedSize = 0;
  int totalSize = cacheSegments;
  int count = 0;
  while (count < cacheSegments) {
    DownloadTask task = DownloadTask(uri: url.toSafeUri(), headers: headers);
    // Set the start and end range for each segment
    task.startRange += Config.segmentSize * count;
    task.endRange = task.startRange + Config.segmentSize - 1;
    count++;
    if (downloadNow) {
      Uint8List? data = await cache(task);
      if (data != null) {
        downloadedSize += 1;
        _streamController?.sink.add({
          'progress': downloadedSize / totalSize,
          'url': task.url,
          'startRange': task.startRange,
          'endRange': task.endRange,
        });
        continue;
      }
      download(task).whenComplete(() {
        downloadedSize += 1;
        _streamController?.sink.add({
          'progress': downloadedSize / totalSize,
          'url': task.url,
          'startRange': task.startRange,
          'endRange': task.endRange,
        });
      });
    } else {
      push(task);
    }
  }
  return _streamController;
}