add basic oauth methods

lib/business_logic/auth/oauth.dart

@@ -0,0 +1,53 @@
+import 'package:http/http.dart' as http;
+import 'package:url_launcher/url_launcher.dart';
+import '../../global.dart' as global;
+
+class App {
+  late String clientSecret;
+  late String clientId;
+  late String id;
+  late String name;
+  late String website;
+  late String redirectUri;
+  App(
+      {required this.clientSecret,
+      required this.clientId,
+      required this.id,
+      required this.name,
+      required this.website,
+      required this.redirectUri});
+  factory App.fromJson(Map<String, dynamic> json) {
+    return App(
+        id: json["id"].toString(),
+        name: json["name"].toString(),
+        website: json["website"].toString(),
+        redirectUri: json["redirect_uri"].toString(),
+        clientId: json["client_id"].toString(),
+        clientSecret: json["client_secret"].toString());
+  }
+}
+
+Future<http.Response> registerApp(String baseurl) async {
+  //String url = baseurl Uri."api/v1/apps";
+  Uri url = Uri.https(baseurl, "/api/v1/apps");
+  var response = await http.post(url, headers: global.defaultHeaders, body: {
+    'client_name': global.name,
+    'redirect_uris': "ietf:wg:oauth:2.0:oob",
+    'scopes': "read write",
+    'website': global.website
+  });
+  return response;
+}
+
+void openBrowserForAuthCode(String baseurl, App app) {
+  Uri url = Uri.https(
+      baseurl,
+      // ignore: prefer_interpolation_to_compose_strings
+      "/oauth/authorize" +
+          "?client_id=" +
+          app.clientId +
+          "&scope=read+write" +
+          "&redirect_uri=urn:ietf:wg:oauth:2.0:oob" +
+          "&response_type=code");
+  launchUrl(url);
+}

lib/business_logic/user.dart

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+bool isValidUsername({required String name}) {
+  if (name.isEmpty) {
+    return false;
+  }
+  return RegExp(r".+\@.+\..+").hasMatch(cleanUpUsername(name: name));
+}
+
+String cleanUpUsername({required String name}) {
+  name = name.replaceAll(" ", "");
+  if (name.isNotEmpty) {
+    if (name[0] == "@") {
+      name = name.substring(1);
+    }
+  }
+  return name;
+}
+
+Uri urlFromUsername({required String name}) {
+  name = cleanUpUsername(name: name);
+  return Uri.parse("https://${name.substring(name.indexOf("@") + 1)}");
+}
+
+String userFromUsername({required String name}) {
+  name = cleanUpUsername(name: name);
+  return name.substring(0, name.indexOf("@"));
+}
+
+// A fully qualified and valid username for example (@)hello@world.com
+// The first @ is ignored
+class Username {
+  late final String user;
+  late final Uri url;
+  Username(String username) {
+    assert(isValidUsername(name: username));
+    user = userFromUsername(name: username);
+    url = urlFromUsername(name: username);
+  }
+}

lib/business_logic/webfinger.dart

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+