actions-test/lib/backend/resolve_url.dart

import 'package:http/http.dart' as http;
import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

const String wellKnownPath = "/.well-known/outbag/server";
const int defaultPort = 7223;

Future<Uri> fetchWellKnown(String host, int port) async {
  Uri uri = Uri(path: wellKnownPath, host: host, port: port, scheme: "https");
  final resp = await http.get(uri);
  final json = jsonDecode(resp.body);

  return Uri(host: host, path: json['path'], port: json['port']);
}

class OutbagServer {
  final String host;
  final int port;
  final String path;

  final String tag;

  const OutbagServer(
      {required this.host,
      required this.port,
      required this.path,
      required this.tag});

  String get base {
    return Uri(
      host: host,
      port: port,
      path: path,
      scheme: 'https',
    ).toString();
  }

  factory OutbagServer.fromMap(Map<String, dynamic> data) {
    return OutbagServer(
        tag: data['tag'],
        host: data['host'],
        path: data['path'],
        port: data['port']);
  }

  Map<String, dynamic> toMap() {
    return {'host': host, 'port': port, 'path': path, 'tag': tag};
  }

  Future<void> toDisk() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    await prefs.setString('server-host', host);
    await prefs.setInt('server-port', port);
    await prefs.setString('server-path', path);
    await prefs.setString('server-tag', tag);
  }

  static Future<OutbagServer> fromDisk() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    return OutbagServer(
        path: prefs.getString('server-path')!,
        port: prefs.getInt('server-port')!,
        tag: prefs.getString('server-tag')!,
        host: prefs.getString('server-host')!);
  }

  static Future<void> removeDisk() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();

    await prefs.remove('server-host');
    await prefs.remove('server-port');
    await prefs.remove('server-path');
    await prefs.remove('server-tag');
  }
}

Future<OutbagServer> getOutbagServerUrl(String tag) async {
  final rootUri = Uri.parse(tag.startsWith('https://') ? tag : 'https://$tag');

  bool onRoot = rootUri.port == 443;

  try {
    final uri = await fetchWellKnown(rootUri.host, rootUri.port);
    return OutbagServer(
        host: rootUri.host,
        port: uri.port,
        path: uri.path,
        tag: onRoot ? rootUri.host : '${rootUri.host}:${uri.port}');
  } catch (_) {
    if (onRoot) {
      final uri = await fetchWellKnown(rootUri.host, defaultPort);
      return OutbagServer(
          host: rootUri.host,
          port: uri.port,
          path: uri.path,
          tag: onRoot ? rootUri.host : '${rootUri.host}:${uri.port}');
    }
  }
  throw Error();
}