class SseFrameAccumulator {
  String _pending = '';

  List<String> add(String chunk) {
    _pending = (_pending + chunk).replaceAll('\r\n', '\n');
    final frames = <String>[];
    var separator = _pending.indexOf('\n\n');
    while (separator >= 0) {
      final frame = _pending.substring(0, separator);
      _pending = _pending.substring(separator + 2);
      if (frame.trim().isNotEmpty) frames.add(frame);
      separator = _pending.indexOf('\n\n');
    }
    return frames;
  }

  List<String> close() {
    final trailing = _pending.trim();
    _pending = '';
    return trailing.isEmpty ? const [] : [trailing];
  }
}