refactor: Projektstruktur in app/ und backend/ aufgeteilt

app/lib/routing_view.dart

@@ -0,0 +1,141 @@
+import 'package:flutter/material.dart';
+import 'package:webview_flutter/webview_flutter.dart';
+import 'l10n/app_localizations.dart';
+import 'package:url_launcher/url_launcher.dart';
+import 'widgets/offline_banner.dart';
+
+// Routing view that immediately opens a Google Maps navigation inside a WebView
+// It receives an address string and optionally a title.
+class RoutingView extends StatefulWidget {
+  final String address;
+  final String? title;
+  final bool isDelivery; // to distinguish pickup/delivery if needed later
+
+  const RoutingView({super.key, required this.address, this.title, this.isDelivery = true});
+
+  @override
+  State<RoutingView> createState() => _RoutingViewState();
+}
+
+class _RoutingViewState extends State<RoutingView> {
+  bool _initialized = false;
+  late final WebViewController _controller;
+  double _progress = 0.0;
+
+  String _buildDirectionsUrl(String rawAddress) {
+    const apiKey = 'AIzaSyDnbitL06iLp3elmj-WtPudCykX9xvXcVE';
+    final query = Uri.encodeComponent(rawAddress);
+    // Google Maps Directions URL with API key appended.
+    return 'https://www.google.com/maps/dir/?api=1&destination=$query&travelmode=driving&key=$apiKey';
+  }
+
+  String? _extractBrowserFallbackUrl(String intentUrl) {
+    const key = 'S.browser_fallback_url=';
+    final idx = intentUrl.indexOf(key);
+    if (idx == -1) return null;
+    final start = idx + key.length;
+    final end = intentUrl.indexOf(';', start);
+    final encoded = end == -1 ? intentUrl.substring(start) : intentUrl.substring(start, end);
+    try {
+      return Uri.decodeComponent(encoded);
+    } catch (_) {
+      return encoded;
+    }
+  }
+
+  String? _convertIntentToHttps(String intentUrl) {
+    const prefix = 'intent://';
+    if (!intentUrl.startsWith(prefix)) return null;
+    final after = intentUrl.substring(prefix.length);
+    final hashIndex = after.indexOf('#');
+    final pathPart = hashIndex == -1 ? after : after.substring(0, hashIndex);
+
+    // default scheme is https unless specified
+    var scheme = 'https';
+    final schemeKey = '#Intent;scheme=';
+    final schemeIdx = intentUrl.indexOf(schemeKey);
+    if (schemeIdx != -1) {
+      final start = schemeIdx + schemeKey.length;
+      final end = intentUrl.indexOf(';', start);
+      if (end > start) {
+        scheme = intentUrl.substring(start, end);
+      }
+    }
+    return '$scheme://$pathPart';
+  }
+
+  @override
+  void initState() {
+    assert(!_initialized);
+    super.initState();
+    final url = _buildDirectionsUrl(widget.address);
+    _controller =
+        WebViewController()
+          ..setJavaScriptMode(JavaScriptMode.unrestricted)
+          ..setNavigationDelegate(
+            NavigationDelegate(
+              onNavigationRequest: (NavigationRequest request) async {
+                final uri = Uri.tryParse(request.url);
+                if (uri == null) {
+                  return NavigationDecision.prevent;
+                }
+
+                // Handle intent:// and other non-http(s) schemes by launching externally or using fallback.
+                if (uri.scheme == 'intent') {
+                  final fallback = _extractBrowserFallbackUrl(request.url);
+                  if (fallback != null) {
+                    await _controller.loadRequest(Uri.parse(fallback));
+                  } else {
+                    // Try converting to https as a naive fallback
+                    final httpsCandidate = _convertIntentToHttps(request.url);
+                    if (httpsCandidate != null && await canLaunchUrl(Uri.parse(httpsCandidate))) {
+                      await launchUrl(Uri.parse(httpsCandidate), mode: LaunchMode.externalApplication);
+                    } else {
+                      // As a last resort, prevent navigation and show a hint
+                      if (mounted) {
+                        ScaffoldMessenger.maybeOf(context)?.showSnackBar(SnackBar(content: Text(AppLocalizations.of(context).connectionError)));
+                      }
+                    }
+                  }
+                  return NavigationDecision.prevent;
+                }
+
+                if (uri.scheme != 'http' && uri.scheme != 'https' && uri.scheme != 'about' && uri.scheme != 'data') {
+                  if (await canLaunchUrl(uri)) {
+                    await launchUrl(uri, mode: LaunchMode.externalApplication);
+                  }
+                  return NavigationDecision.prevent;
+                }
+
+                return NavigationDecision.navigate;
+              },
+              onProgress: (int progress) {
+                setState(() {
+                  _progress = progress / 100.0;
+                });
+              },
+              onWebResourceError: (WebResourceError error) {
+                // Optionally show a snackbar on error
+                if (mounted) {
+                  ScaffoldMessenger.maybeOf(context)?.showSnackBar(SnackBar(content: Text('${AppLocalizations.of(context).error}: ${error.errorCode}')));
+                }
+              },
+            ),
+          )
+          ..loadRequest(Uri.parse(url));
+    _initialized = true;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: Text(widget.title?.isNotEmpty == true ? widget.title! : (widget.isDelivery ? 'Route zur Zustelladresse' : 'Route zur Abholadresse'))),
+      body: Column(
+        children: [
+          OfflineBanner(),
+          Expanded(child: Stack(children: [WebViewWidget(key: const ValueKey('routing-webview'), controller: _controller), if (_progress < 1.0) LinearProgressIndicator(value: _progress)])),
+        ],
+      ),
+    );
+  }
+}