auto-claude: subtask-3-1 - Create GrpcCqrsApiClient class with channel management
Implements the foundational gRPC client class with: - Lazy ClientChannel initialization with proper credentials - DeliveryServiceClient lazy initialization - Authentication via Bearer token in gRPC metadata - CallOptions builder with token injection - gRPC error to ApiError mapping (status codes -> HTTP equivalents) - Token refresh on UNAUTHENTICATED errors (single retry) - Proper channel shutdown/terminate methods The core _executeWithAuth and _executeCommandWithAuth methods provide the foundation for query and command methods in subsequent subtasks. Co-Authored-By: Claude <noreply@anthropic.com>
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import 'dart:async';
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import 'package:grpc/grpc.dart';
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import '../generated/delivery_service.pbgrpc.dart';
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import '../services/auth_service.dart';
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import 'grpc_config.dart';
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import 'types.dart';
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// ignore_for_file: unused_element
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/// gRPC-based CQRS API client for Plan B Logistics.
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///
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/// This client wraps the generated DeliveryServiceClient with `Result<T>` error
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/// handling patterns consistent with [CqrsApiClient]. It provides:
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/// - Lazy channel initialization
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/// - Authentication via Bearer token in gRPC metadata
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/// - Automatic token refresh on UNAUTHENTICATED errors
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/// - Proper gRPC error to [ApiError] mapping
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///
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/// Usage:
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/// ```dart
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/// final client = GrpcCqrsApiClient(
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/// config: GrpcConfig.development,
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/// authService: authService,
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/// );
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///
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/// final result = await client.getDeliveryRoutes();
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/// result.when(
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/// success: (routes) => handleRoutes(routes),
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/// onError: (error) => handleError(error),
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/// );
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/// ```
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class GrpcCqrsApiClient {
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final GrpcConfig config;
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final AuthService? authService;
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ClientChannel? _channel;
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DeliveryServiceClient? _deliveryClient;
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GrpcCqrsApiClient({
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required this.config,
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this.authService,
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});
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/// Returns the gRPC channel, creating it lazily if needed.
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///
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/// The channel is configured based on [config.useTls] for development
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/// (insecure) vs production (TLS) environments.
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ClientChannel get channel {
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if (_channel == null) {
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final credentials = config.useTls
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? const ChannelCredentials.secure()
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: const ChannelCredentials.insecure();
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_channel = ClientChannel(
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config.host,
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port: config.port,
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options: ChannelOptions(
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credentials: credentials,
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connectionTimeout: config.timeout,
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idleTimeout: const Duration(minutes: 5),
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),
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);
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}
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return _channel!;
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}
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/// Returns the DeliveryService client, creating it lazily if needed.
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DeliveryServiceClient get deliveryClient {
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_deliveryClient ??= DeliveryServiceClient(channel);
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return _deliveryClient!;
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}
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/// Builds [CallOptions] with authentication metadata.
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///
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/// Includes Bearer token in metadata if [authService] is configured and
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/// a valid token is available. Uses [AuthService.ensureValidToken] to
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/// proactively refresh tokens that are expiring soon.
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Future<CallOptions> _buildCallOptions() async {
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final metadata = <String, String>{};
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if (authService != null) {
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final token = await authService!.ensureValidToken();
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if (token != null) {
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metadata['authorization'] = 'Bearer $token';
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}
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}
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return CallOptions(
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metadata: metadata,
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timeout: config.timeout,
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);
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}
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/// Merges base [CallOptions] with additional options for a specific call.
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CallOptions _mergeOptions(CallOptions base, CallOptions? additional) {
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if (additional == null) return base;
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return CallOptions(
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metadata: {
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...base.metadata,
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...additional.metadata,
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},
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timeout: additional.timeout ?? base.timeout,
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providers: [
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...base.metadataProviders,
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...additional.metadataProviders,
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],
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);
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}
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/// Maps gRPC [GrpcError] to [ApiError] for consistent error handling.
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///
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/// Maps common gRPC status codes to appropriate [ApiErrorType]:
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/// - UNAUTHENTICATED (16) -> HTTP 401
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/// - PERMISSION_DENIED (7) -> HTTP 403
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/// - NOT_FOUND (5) -> HTTP 404
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/// - INVALID_ARGUMENT (3) -> Validation error
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/// - DEADLINE_EXCEEDED (4) -> Timeout
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/// - UNAVAILABLE (14) -> Network error
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/// - Other codes -> Unknown error
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ApiError _mapGrpcError(GrpcError error) {
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switch (error.code) {
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case StatusCode.unauthenticated:
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return ApiError.http(
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statusCode: 401,
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message: error.message ?? 'Authentication required',
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);
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case StatusCode.permissionDenied:
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return ApiError.http(
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statusCode: 403,
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message: error.message ?? 'Permission denied',
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);
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case StatusCode.notFound:
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return ApiError.http(
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statusCode: 404,
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message: error.message ?? 'Resource not found',
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);
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case StatusCode.invalidArgument:
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return ApiError.validation(
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error.message ?? 'Invalid request',
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null,
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);
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case StatusCode.deadlineExceeded:
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return ApiError.timeout();
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case StatusCode.unavailable:
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return ApiError.network(
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error.message ?? 'Service unavailable',
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);
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case StatusCode.internal:
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return ApiError.http(
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statusCode: 500,
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message: error.message ?? 'Internal server error',
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);
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default:
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return ApiError.unknown(
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error.message ?? 'gRPC error: ${error.codeName}',
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exception: error,
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);
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}
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}
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/// Executes a gRPC call with `Result<T>` error handling and authentication.
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///
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/// This is the core method that wraps gRPC calls with:
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/// - Authentication token injection
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/// - Automatic token refresh on UNAUTHENTICATED errors (single retry)
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/// - gRPC error to ApiError mapping
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/// - Timeout handling
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///
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/// [grpcCall] is the actual gRPC method invocation.
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/// [isRetry] tracks whether this is a retry after token refresh.
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Future<Result<T>> _executeWithAuth<T>(
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Future<T> Function(CallOptions options) grpcCall, {
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bool isRetry = false,
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}) async {
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try {
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final options = await _buildCallOptions();
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final result = await grpcCall(options);
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return Result.success(result);
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} on GrpcError catch (error) {
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// Handle UNAUTHENTICATED by attempting token refresh (once)
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if (error.code == StatusCode.unauthenticated &&
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!isRetry &&
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authService != null) {
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final refreshResult = await authService!.refreshAccessToken();
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return refreshResult.when(
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success: (token) => _executeWithAuth(grpcCall, isRetry: true),
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onError: (refreshError) => Result.error(_mapGrpcError(error)),
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cancelled: () => Result.error(_mapGrpcError(error)),
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);
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}
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return Result.error(_mapGrpcError(error));
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} on TimeoutException {
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return Result.error(ApiError.timeout());
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} catch (e, stackTrace) {
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return Result.error(
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ApiError.unknown(
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'gRPC call failed: ${e.toString()}',
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exception: Exception(stackTrace.toString()),
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),
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);
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}
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}
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/// Executes a gRPC call that returns void (for commands).
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///
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/// Similar to [_executeWithAuth] but for operations that don't return
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/// meaningful data (commands that return success/failure).
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Future<Result<void>> _executeCommandWithAuth(
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Future<void> Function(CallOptions options) grpcCall, {
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bool isRetry = false,
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}) async {
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try {
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final options = await _buildCallOptions();
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await grpcCall(options);
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return Result.success(null);
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} on GrpcError catch (error) {
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if (error.code == StatusCode.unauthenticated &&
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!isRetry &&
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authService != null) {
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final refreshResult = await authService!.refreshAccessToken();
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return refreshResult.when(
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success: (token) =>
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_executeCommandWithAuth(grpcCall, isRetry: true),
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onError: (refreshError) => Result.error(_mapGrpcError(error)),
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cancelled: () => Result.error(_mapGrpcError(error)),
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);
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}
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return Result.error(_mapGrpcError(error));
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} on TimeoutException {
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return Result.error(ApiError.timeout());
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} catch (e, stackTrace) {
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return Result.error(
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ApiError.unknown(
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'gRPC command failed: ${e.toString()}',
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exception: Exception(stackTrace.toString()),
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),
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);
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}
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}
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/// Shuts down the gRPC channel and releases resources.
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///
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/// Should be called when the client is no longer needed to properly
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/// clean up network resources.
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Future<void> shutdown() async {
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await _channel?.shutdown();
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_channel = null;
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_deliveryClient = null;
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}
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/// Terminates the gRPC channel immediately.
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///
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/// Unlike [shutdown], this does not wait for pending calls to complete.
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/// Use this for emergency cleanup or when the app is terminating.
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Future<void> terminate() async {
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await _channel?.terminate();
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_channel = null;
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_deliveryClient = null;
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}
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/// Returns true if the channel is currently active.
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bool get isConnected => _channel != null;
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}
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