fitResponseFrame static method

@visibleForTesting Map<String, dynamic>? fitResponseFrame(Map<String, dynamic> json, int maxBytes)

Shrink a request/response frame the backend is WAITING on so it fits maxBytes, instead of letting the transport cap drop it: find_candidates_response sheds its lowest-ranked (trailing) candidates, info_query_response shortens value. Null for any other type, or when even the minimal frame cannot fit (the queue then substitutes a failure).

Implementation

@visibleForTesting
static Map<String, dynamic>? fitResponseFrame(
    Map<String, dynamic> json, int maxBytes) {
  int size(Map<String, dynamic> m) => utf8.encode(jsonEncode(m)).length;
  switch (json['type']) {
    case FindCandidatesResponseMessage.kType:
      final all = json['candidates'];
      if (all is! List) return null;
      final out = Map<String, dynamic>.of(json);
      for (var keep = all.length - 1; keep >= 0; keep--) {
        out['candidates'] = all.sublist(0, keep);
        if (size(out) <= maxBytes) return out;
      }
      return null;
    case InfoQueryResponseMessage.kType:
      final value = json['value'];
      if (value is! String || value.isEmpty) return null;
      final out = Map<String, dynamic>.of(json);
      var keep = value.length;
      while (keep > 0) {
        keep = keep ~/ 2;
        out['value'] = keep == 0 ? '' : '${value.substring(0, keep)}…';
        if (size(out) <= maxBytes) return out;
      }
      return null;
    default:
      return null;
  }
}