implemented a backend-independent emergency notice system

2026-07-15 20:30:20 +02:00
parent e8c6ac1c65
commit 7c1f5c06df
11 changed files with 599 additions and 3 deletions
@@ -0,0 +1,145 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:flutter_markdown_plus/flutter_markdown_plus.dart';
+import 'package:url_launcher/url_launcher_string.dart';
+
+import '../../api/emergency/emergency_notice.dart';
+import '../../api/emergency/emergency_notice_client.dart';
+import '../../state/app/modules/settings/bloc/settings_cubit.dart';
+
+/// Wraps the app and surfaces a backend-independent emergency notice on cold
+/// start and on resume. Transparent otherwise: renders [child] unchanged and
+/// only overlays a dialog when the foreign source has an active message.
+///
+/// Independent of MarianumConnect and of the login state by design — this is
+/// the disaster fallback for when the backend is gone. Any failure to load or
+/// parse is swallowed by [EmergencyNoticeClient], so a missing/broken source
+/// simply shows nothing.
+class EmergencyNoticeGate extends StatefulWidget {
+  final Widget child;
+
+  const EmergencyNoticeGate({required this.child, super.key});
+
+  @override
+  State<EmergencyNoticeGate> createState() => _EmergencyNoticeGateState();
+}
+
+class _EmergencyNoticeGateState extends State<EmergencyNoticeGate>
+    with WidgetsBindingObserver {
+  final EmergencyNoticeClient _client = const EmergencyNoticeClient();
+  bool _showing = false;
+
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+    WidgetsBinding.instance.addPostFrameCallback((_) => unawaited(_check()));
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    if (state == AppLifecycleState.resumed) unawaited(_check());
+  }
+
+  Future<void> _check() async {
+    if (_showing || !mounted) return;
+    final url = context
+        .read<SettingsCubit>()
+        .val()
+        .devToolsSettings
+        .resolveEmergencyNoticeUrl();
+    if (url == null) return;
+
+    final notice = await _client.fetch(url);
+    if (notice == null || !mounted || _showing) return;
+
+    _showing = true;
+    try {
+      await showDialog<void>(
+        context: context,
+        barrierDismissible: notice.dismissible,
+        builder: (_) => _EmergencyNoticeDialog(notice: notice),
+      );
+    } finally {
+      _showing = false;
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) => widget.child;
+}
+
+class _EmergencyNoticeDialog extends StatelessWidget {
+  final EmergencyNotice notice;
+
+  const _EmergencyNoticeDialog({required this.notice});
+
+  Future<void> _openLink(String? href) async {
+    if (href == null) return;
+    if (await canLaunchUrlString(href)) {
+      await launchUrlString(href);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final body = MarkdownBody(
+      data: notice.body,
+      onTapLink: (_, href, _) => unawaited(_openLink(href)),
+    );
+
+    if (notice.dismissible) {
+      return AlertDialog(
+        title: notice.title == null ? null : Text(notice.title!),
+        content: SingleChildScrollView(child: body),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.of(context).pop(),
+            child: const Text('Schließen'),
+          ),
+        ],
+      );
+    }
+
+    // Full-screen, non-dismissible: no close affordance, back is blocked.
+    return PopScope(
+      canPop: false,
+      child: Dialog.fullscreen(
+        child: SafeArea(
+          child: Padding(
+            padding: const EdgeInsets.all(24),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                if (notice.title != null) ...[
+                  Text(
+                    notice.title!,
+                    style: theme.textTheme.headlineSmall?.copyWith(
+                      fontWeight: FontWeight.w600,
+                    ),
+                  ),
+                  const SizedBox(height: 16),
+                ],
+                Expanded(
+                  child: SingleChildScrollView(
+                    physics: const AlwaysScrollableScrollPhysics(),
+                    child: body,
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}