fix(mobile): adds support for Internationalized Domain Name (IDN) (#17461)

mobile/lib/utils/url_helper.dart

@@ -1,5 +1,6 @@
 import 'package:immich_mobile/domain/models/store.model.dart';
 import 'package:immich_mobile/entities/store.entity.dart';
+import 'package:punycode/punycode.dart';
 
 String sanitizeUrl(String url) {
   // Add schema if none is set
@@ -11,13 +12,80 @@ String sanitizeUrl(String url) {
 }
 
 String? getServerUrl() {
-  final serverUrl = Store.tryGet(StoreKey.serverEndpoint);
+  final serverUrl = punycodeDecodeUrl(Store.tryGet(StoreKey.serverEndpoint));
   final serverUri = serverUrl != null ? Uri.tryParse(serverUrl) : null;
   if (serverUri == null) {
     return null;
   }
 
-  return serverUri.hasPort
-      ? "${serverUri.scheme}://${serverUri.host}:${serverUri.port}"
-      : "${serverUri.scheme}://${serverUri.host}";
+  return Uri.decodeFull(
+    serverUri.hasPort
+        ? "${serverUri.scheme}://${serverUri.host}:${serverUri.port}"
+        : "${serverUri.scheme}://${serverUri.host}",
+  );
+}
+
+/// Converts a Unicode URL to its ASCII-compatible encoding (Punycode).
+///
+/// This is especially useful for internationalized domain names (IDNs),
+/// where parts of the URL (typically the host) contain non-ASCII characters.
+///
+/// Example:
+/// ```dart
+/// final encodedUrl = punycodeEncodeUrl('https://bücher.de');
+/// print(encodedUrl); // Outputs: https://xn--bcher-kva.de
+/// ```
+///
+/// Notes:
+/// - If the input URL is invalid, an empty string is returned.
+/// - Only the host part of the URL is converted to Punycode; the scheme,
+///   path, and port remain unchanged.
+///
+String punycodeEncodeUrl(String serverUrl) {
+  final serverUri = Uri.tryParse(serverUrl);
+  if (serverUri == null || serverUri.host.isEmpty) return '';
+
+  final encodedHost = Uri.decodeComponent(serverUri.host).split('.').map(
+    (segment) {
+      // If segment is already ASCII, then return as it is.
+      if (segment.runes.every((c) => c < 0x80)) return segment;
+      return 'xn--${punycodeEncode(segment)}';
+    },
+  ).join('.');
+
+  return serverUri.replace(host: encodedHost).toString();
+}
+
+/// Decodes an ASCII-compatible (Punycode) URL back to its original Unicode representation.
+///
+/// This method is useful for converting internationalized domain names (IDNs)
+/// that were previously encoded with Punycode back to their human-readable Unicode form.
+///
+/// Example:
+/// ```dart
+/// final decodedUrl = punycodeDecodeUrl('https://xn--bcher-kva.de');
+/// print(decodedUrl); // Outputs: https://bücher.de
+/// ```
+///
+/// Notes:
+/// - If the input URL is invalid the method returns `null`.
+/// - Only the host part of the URL is decoded. The scheme and port (if any) are preserved.
+/// - The method assumes that the input URL only contains: scheme, host, port (optional).
+/// - Query parameters, fragments, and user info are not handled (by design, as per constraints).
+///
+String? punycodeDecodeUrl(String? serverUrl) {
+  final serverUri = serverUrl != null ? Uri.tryParse(serverUrl) : null;
+  if (serverUri == null || serverUri.host.isEmpty) return null;
+
+  final decodedHost = serverUri.host.split('.').map(
+    (segment) {
+      if (segment.toLowerCase().startsWith('xn--')) {
+        return punycodeDecode(segment.substring(4));
+      }
+      // If segment is not punycode encoded, then return as it is.
+      return segment;
+    },
+  ).join('.');
+
+  return Uri.decodeFull(serverUri.replace(host: decodedHost).toString());
 }