Frontend first draft

frontend/pshared/lib/widgets/locale.dart

@@ -0,0 +1,65 @@
+import 'package:flutter/material.dart';
+
+import 'package:provider/provider.dart';
+
+import 'package:pshared/provider/locale.dart';
+import 'package:pshared/utils/flagged_locale.dart';
+
+
+class LocaleChangerDropdown extends StatelessWidget {
+  final List<Locale> availableLocales;
+  final bool lettersMode;
+  const LocaleChangerDropdown({
+    super.key,
+    required this.availableLocales,
+    this.lettersMode = false,
+  });
+
+  Widget textLabel(BuildContext context, Locale locale) {
+    return Container(
+      padding: EdgeInsets.symmetric(horizontal: 8, vertical: 4),
+      decoration: BoxDecoration(
+        color: Theme.of(context).primaryColor.withAlpha(26),
+        borderRadius: BorderRadius.circular(12),
+      ),
+      child: Row(
+        children: [
+          Icon(Icons.language),
+          Container(width: 4.0),
+          Text(
+            locale.languageCode.toUpperCase(),
+            style: TextStyle(
+              fontSize: 14,
+              fontWeight: FontWeight.bold,
+              color: Theme.of(context).textTheme.bodyMedium?.color,
+            ),
+          ),
+          Icon(Icons.arrow_drop_down, color: Theme.of(context).iconTheme.color),
+        ],
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (availableLocales.length <= 1) {
+      // If only one locale is available, do not show the button.
+      return const SizedBox.shrink();
+    }  
+
+    var localeProvider = Provider.of<LocaleProvider>(context);
+
+    return PopupMenuButton<Locale>(
+      icon: lettersMode ? textLabel(context, localeProvider.locale) : getCountryFlag(localeProvider.locale),
+      onSelected: localeProvider.setLocale,
+      itemBuilder: (BuildContext context) {
+        return availableLocales.map((Locale locale) {
+          return PopupMenuItem<Locale>(
+            value: locale,
+            child: lettersMode ? getLocaleNameWidget(locale) : getFlaggedLocale(locale),
+          );
+        }).toList();
+      },
+    );
+  }
+}

frontend/pshared/lib/widgets/template.dart

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+import 'package:flutter/material.dart';
+
+import 'package:provider/provider.dart';
+
+import 'package:pshared/provider/template.dart';
+
+
+class ResourceContainer<T extends GenericProvider> extends StatelessWidget {
+  final Widget Function(BuildContext context, T provider) builder;
+  final Widget? loading;
+  final Widget? error;
+  final Widget? empty;
+
+  const ResourceContainer({
+    required this.builder,
+    this.loading,
+    this.error,
+    this.empty,
+  });
+
+  @override
+  Widget build(BuildContext context) => Consumer<T>(builder: (context, provider, _) {
+    if (provider.isLoading) return loading ?? Center(child: CircularProgressIndicator());
+    if (provider.error != null) return error ?? Text('Error while loading data. Try again'); //TODO: need to implement localizations and add more details to the error
+    if (provider.isEmpty) return empty ?? Text('Empty data'); //TODO: need to implement localizations too
+    return builder(context, provider);
+  });
+}