major update

app/lib/utils/form_validators.dart

@@ -0,0 +1,30 @@
+import 'package:lensai/extensions/nullable.dart';
+import 'package:lensai/utils/uri_parser.dart' as uri_parser;
+
+String? validateUrl(
+  String? value, {
+  bool requireAuthority = true,
+  bool eagerParsing = true,
+  bool onlyHttpProtocol = false,
+  bool required = true,
+}) {
+  if (value.isEmpty) {
+    if (required) {
+      return 'URL must be provided';
+    } else {
+      return null;
+    }
+  }
+
+  if (uri_parser.tryParseUrl(value, eagerParsing: eagerParsing)
+      case final Uri url) {
+    if (!requireAuthority || url.authority.isNotEmpty) {
+      if (!onlyHttpProtocol ||
+          (url.isScheme('https') || url.isScheme('http'))) {
+        return null;
+      }
+    }
+  }
+
+  return 'Inavlid URL';
+}

app/lib/utils/lru_cache.dart

@@ -23,6 +23,10 @@ class LRUCache<K, V> {
     _capacity = capacity;
   }
 
+  bool contains(K key) {
+    return _cache.containsKey(key);
+  }
+
   V? get(K key) {
     final value = _cache.remove(key); // Temporarily remove the item.