getFallbackRelay method

String? getFallbackRelay({ required String primaryRelayUrl, required List<String> availableRelays, })

Get fallback relay (healthy alternative relay).

Implementation

String? getFallbackRelay({
  required String primaryRelayUrl,
  required List<String> availableRelays,
}) {
  final healthyRelays = availableRelays
      .where((url) =>
          url != primaryRelayUrl &&
          getCircuitBreakerState(url) != CircuitBreakerState.open)
      .toList();

  if (healthyRelays.isEmpty) {
    logger.log('No healthy fallback relay found for $primaryRelayUrl');
    return null;
  }

  // Sort by error count (prefer relays with fewer recent errors)
  healthyRelays.sort((a, b) {
    final aErrors = _errorHistory
        .where((e) =>
            e.relayUrl == a &&
            DateTime.now().difference(e.timestamp).inMinutes < 5)
        .length;
    final bErrors = _errorHistory
        .where((e) =>
            e.relayUrl == b &&
            DateTime.now().difference(e.timestamp).inMinutes < 5)
        .length;
    return aErrors.compareTo(bErrors);
  });

  logger.log(
      'Fallback relay selected: ${healthyRelays.first} for $primaryRelayUrl');
  return healthyRelays.first;
}