intercept method

@override Future<HttpResponse> intercept(HttpRequest request, CancellationToken token, HttpRequestHandler next)

Implementation

@override
Future<HttpResponse> intercept(HttpRequest request, CancellationToken token,
    HttpRequestHandler next) async {
  if (!{HttpMethod.get, HttpMethod.head, HttpMethod.options}
          .contains(request.method) ||
      request.body?.isReplayable == false) {
    return next(request, token);
  }
  final destinations = [
    request.uri,
    ...origins.map((origin) => request.uri
        .replace(scheme: origin.scheme, host: origin.host, port: origin.port))
  ];
  for (var index = 0;; index++) {
    token.throwIfCanceled();
    final target = destinations[index];
    final outgoing = request.copyWith(
        uri: target,
        headers: target.origin == request.uri.origin
            ? request.headers
            : request.headers
                .without(['authorization', 'proxy-authorization', 'cookie']));
    try {
      final response = await next(outgoing, token);
      if (index == destinations.length - 1 || response.statusCode < 500) {
        return response;
      }
      await response.dispose();
    } catch (error) {
      if (token.isCanceled ||
          index == destinations.length - 1 ||
          (error is! NetworkException && error is! RequestTimeoutException)) {
        rethrow;
      }
    }
  }
}