negotiateWithDateFallback static method

String? negotiateWithDateFallback(String? clientVersion, List<String> serverVersions)

Advanced version negotiation with date-based compatibility

Implementation

static String? negotiateWithDateFallback(String? clientVersion, List<String> serverVersions) {
  if (clientVersion == null) {
    // Client didn't specify version, use latest
    return serverVersions.first;
  }

  if (serverVersions.contains(clientVersion)) {
    // Exact match
    return clientVersion;
  }

  // Try date-based compatibility
  try {
    final clientDate = DateTime.parse(clientVersion);

    // Find server versions that are equal or older than client version
    final compatibleVersions = serverVersions
        .map((v) => DateTime.tryParse(v))
        .where((d) => d != null && d.compareTo(clientDate) <= 0)
        .cast<DateTime>()
        .toList();

    if (compatibleVersions.isNotEmpty) {
      // Sort in descending order and take newest compatible
      compatibleVersions.sort((a, b) => b.compareTo(a));
      final index = serverVersions.indexWhere(
        (v) => DateTime.tryParse(v)?.isAtSameMomentAs(compatibleVersions.first) ?? false
      );
      return index >= 0 ? serverVersions[index] : null;
    }
  } catch (e) {
    // Invalid date format, fall back to null
  }

  return null;
}