Frontend first draft

frontend/pweb/lib/widgets/error/content.dart

@@ -0,0 +1,29 @@
+import 'package:flutter/material.dart';
+
+import 'package:pweb/widgets/vspacer.dart';
+
+
+class ErrorSnackBarContent extends StatelessWidget {
+  final String situation;
+  final String localizedError;
+
+  const ErrorSnackBarContent({
+    super.key,
+    required this.situation,
+    required this.localizedError,
+  });
+
+  @override
+  Widget build(BuildContext context) => Column(
+    mainAxisSize: MainAxisSize.min, // wrap to content
+    crossAxisAlignment: CrossAxisAlignment.start,
+    children: [
+      Text(
+        situation,
+        style: const TextStyle(fontWeight: FontWeight.bold),
+      ),
+      const VSpacer(multiplier: 0.25),
+      Text(localizedError),
+    ],
+  );
+}

frontend/pweb/lib/widgets/error/snackbar.dart

@@ -0,0 +1,132 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+
+import 'package:pweb/utils/error_handler.dart';
+import 'package:pweb/widgets/error/content.dart'; 
+
+import 'package:pweb/generated/i18n/app_localizations.dart';
+
+
+ScaffoldFeatureController<SnackBar, SnackBarClosedReason> notifyUserOfErrorX({
+  required ScaffoldMessengerState scaffoldMessenger,
+  required String errorSituation,
+  required Object exception,
+  required AppLocalizations appLocalizations,
+  int delaySeconds = 3,
+}) {
+  // A. Localized user-friendly error message
+  final String localizedError = ErrorHandler.handleErrorLocs(appLocalizations, exception);
+
+  // B. Technical details for advanced reference
+  final String technicalDetails = exception.toString();
+
+  // C. Build the snack bar
+  final snackBar = _buildMainErrorSnackBar(
+    errorSituation: errorSituation,
+    localizedError: localizedError,
+    technicalDetails: technicalDetails,
+    loc: appLocalizations,
+    scaffoldMessenger: scaffoldMessenger,
+    delaySeconds: delaySeconds,
+  );
+
+  // D. Show it
+  return scaffoldMessenger.showSnackBar(snackBar);
+}
+
+ScaffoldFeatureController<SnackBar, SnackBarClosedReason> notifyUserOfError({
+  required BuildContext context,
+  required String errorSituation,
+  required Object exception,
+  int delaySeconds = 3,
+}) => notifyUserOfErrorX(
+  scaffoldMessenger: ScaffoldMessenger.of(context), 
+  errorSituation: errorSituation, 
+  exception: exception, 
+  appLocalizations: AppLocalizations.of(context)!,
+  delaySeconds: delaySeconds,
+);
+
+Future<T?> executeActionWithNotification<T>({
+  required BuildContext context,
+  required Future<T> Function() action,
+  required String errorMessage,
+  int delaySeconds = 3,
+}) async {
+  final scaffoldMessenger = ScaffoldMessenger.of(context);
+  final localizations = AppLocalizations.of(context)!;
+
+  try {
+    return await action();
+  } catch (e) {
+    // Report the error using your existing notifier.
+    notifyUserOfErrorX(
+      scaffoldMessenger: scaffoldMessenger,
+      errorSituation: errorMessage,
+      exception: e,
+      appLocalizations: localizations,
+      delaySeconds: delaySeconds,
+    );
+  }
+  return null;
+}
+
+Future<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>> postNotifyUserOfError({
+  required ScaffoldMessengerState scaffoldMessenger,
+  required String errorSituation,
+  required Object exception,
+  required AppLocalizations appLocalizations,
+  int delaySeconds = 3,
+}) {
+
+  final completer = Completer<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>>();
+
+  WidgetsBinding.instance.addPostFrameCallback((_) => completer.complete(notifyUserOfErrorX(
+      scaffoldMessenger: scaffoldMessenger,
+      errorSituation: errorSituation,
+      exception: exception,
+      appLocalizations: appLocalizations,
+      delaySeconds: delaySeconds,
+    )),
+  );
+
+  return completer.future;
+}
+
+Future<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>> postNotifyUserOfErrorX({
+  required BuildContext context,
+  required String errorSituation,
+  required Object exception,
+  int delaySeconds = 3,
+}) => postNotifyUserOfError(
+  scaffoldMessenger: ScaffoldMessenger.of(context), 
+  errorSituation: errorSituation, 
+  exception: exception, 
+  appLocalizations: AppLocalizations.of(context)!,
+  delaySeconds: delaySeconds,
+);
+
+
+/// 2) A helper function that returns the main SnackBar widget
+SnackBar _buildMainErrorSnackBar({
+  required String errorSituation,
+  required String localizedError,
+  required String technicalDetails,
+  required AppLocalizations loc,
+  required ScaffoldMessengerState scaffoldMessenger,
+  int delaySeconds = 3,
+}) => SnackBar(
+  duration: Duration(seconds: delaySeconds),
+  content: ErrorSnackBarContent(
+    situation: errorSituation,
+    localizedError: localizedError,
+  ),
+  action: SnackBarAction(
+    label: loc.showDetailsAction, 
+    onPressed: () => scaffoldMessenger.showSnackBar(SnackBar(
+      content: Text(technicalDetails),
+      duration: const Duration(seconds: 6),
+    )),
+  ),
+);