added minimal error handling and user feedback

lib/assets/constants.dart

@@ -0,0 +1,3 @@
+const String appName = 'Maps Bookmarks';
+const String jsonFileName = 'MapsBookmarksData.json';
+const String defaultAndroidExportDirectory = '/storage/emulated/0/Documents';

lib/l10n/app_de.arb

@@ -25,10 +25,19 @@
     "url": "Url",
     "description": "Beschreibung",
     "settings": "Einstellungen",
-    "activateJsonExport": "Json-Export aktivieren",
+    "appData": "App-Daten",
+    "export": "Exportieren",
+    "import": "Importieren",
+    "activateJsonExport": "Immer als JSON speichern",
+
+    "@@comment": "Info",
+    "exportSuccess": "Daten exportiert",
+    "importSuccess": "Daten importiert",
 
     "@@comment": "Errors",
     "errorStoragePermisson": "Zugriff auf Speicher verwehrt",
     "errorCouldNotLaunchUrl": "Konnte Url nicht öffnen",
-    "errorInvalidUrl": "Fehlerhafte Url"
+    "errorInvalidUrl": "Fehlerhafte Url",
+    "exportFailed": "Export fehlgeschlagen",
+    "importFailed": "Import fehlgeschlagen"
 }

lib/l10n/app_en.arb

@@ -25,10 +25,20 @@
     "url": "Url",
     "description": "Description",
     "settings": "Settings",
-    "activateJsonExport": "Activate json export",
+    "appData": "App data",
+    "export": "Export",
+    "import": "Import",
+    "activateJsonExport": "Always save to JSON",
+
+    
+    "@@comment": "Info",
+    "exportSuccess": "Exported data",
+    "importSuccess": "Imported data",
     
     "@@comment": "Errors",
     "errorStoragePermisson": "Storage permissions denied",
     "errorCouldNotLaunchUrl": "Could not launch Url",
-    "errorInvalidUrl": "Invalid Url"
+    "errorInvalidUrl": "Invalid Url",
+    "exportFailed": "Export failed",
+    "importFailed": "Import failed"
 }

lib/pages/settings_page.dart

@@ -1,15 +1,86 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
+import 'package:permission_handler/permission_handler.dart';
 
 import '../l10n/app_localizations.dart';
+import '../service/notifying.dart';
+import '../service/permission_service.dart';
+import '../service/storage.dart';
 
-class SettingsPage extends StatelessWidget {
+class SettingsPage extends StatefulWidget {
   static const routeName = '/settings';
   const SettingsPage({super.key});
 
+  @override
+  State<SettingsPage> createState() => _SettingsPageState();
+}
+
+class _SettingsPageState extends State<SettingsPage> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(title: Text(AppLocalizations.of(context)!.settings)),
+      body: SizedBox(
+        width: MediaQuery.of(context).size.width * 0.9,
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.center,
+          children: [
+            Text(
+              AppLocalizations.of(context)!.appData,
+              style: Theme.of(context).textTheme.titleLarge,
+            ),
+            ElevatedButton(
+              onPressed: () => onActivateJsonImportPressed(),
+              child: Text(AppLocalizations.of(context)!.import),
+            ),
+            ElevatedButton(
+              onPressed: () => onActivateJsonExportPressed(),
+              child: Text(AppLocalizations.of(context)!.export),
+            ),
+          ],
+        ),
+      ),
     );
   }
+
+  void onActivateJsonExportPressed() async {
+    if (!await checkStoragePermission) return;
+
+    Storage.exportToJsonFile().then(showExportInfo);
+  }
+
+  void onActivateJsonImportPressed() async {
+    if (!await checkStoragePermission) return;
+    Storage.importFromJsonFile().then(showImportInfo);
+  }
+
+  Future<bool> get checkStoragePermission async {
+    if (!(await PermissionService.requestStoragePermission).isGranted) {
+      if (mounted) {
+        Notifying.showErrorSnackbar(
+          context,
+          AppLocalizations.of(context)!.errorStoragePermisson,
+        );
+        return false;
+      }
+    }
+    return true;
+  }
+
+  void showExportInfo(bool success) => Notifying.showSnackbar(
+    context,
+    text: success
+        ? AppLocalizations.of(context)!.exportSuccess
+        : AppLocalizations.of(context)!.exportFailed,
+    isError: success,
+  );
+
+  void showImportInfo(bool success) => Notifying.showSnackbar(
+    context,
+    text: success
+        ? AppLocalizations.of(context)!.importSuccess
+        : AppLocalizations.of(context)!.importFailed,
+    isError: success,
+  );
 }

lib/service/json_file_service.dart

@@ -0,0 +1,77 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:file_selector/file_selector.dart';
+import 'package:flutter/services.dart';
+
+import '../model/bookmark.dart';
+import '../model/collection.dart';
+import '../assets/constants.dart' as constants;
+
+class JsonFileService {
+  static Future<bool> exportToJson({
+    required List<Collection> collections,
+    required List<Bookmark> bookmarks,
+  }) async {
+    try {
+      final dir = await _directoryPath;
+      if (dir.isEmpty) return false;
+
+      final data = {
+        'collections': collections.map((c) => c.toJson()).toList(),
+        'bookmarks': bookmarks.map((b) => b.toJson()).toList(),
+      };
+      final json = jsonEncode(data).codeUnits;
+      final file = XFile.fromData(
+        Uint8List.fromList(json),
+        mimeType: 'application/json',
+        name: constants.jsonFileName,
+      );
+
+      file.saveTo('$dir/${constants.jsonFileName}');
+    } catch (e) {
+      return false;
+    }
+    return false;
+  }
+
+  static Future<({List<Collection> collections, List<Bookmark> bookmarks})>
+  importFromJson() async {
+    try {
+      const typeGroup = XTypeGroup(label: 'json', extensions: <String>['json']);
+      final XFile? file = await openFile(
+        acceptedTypeGroups: <XTypeGroup>[typeGroup],
+      );
+
+      if (file == null) {
+        return (collections: <Collection>[], bookmarks: <Bookmark>[]);
+      }
+
+      final jsonString = await file.readAsString();
+
+      final data = jsonDecode(jsonString) as Map<String, dynamic>;
+
+      final collections = (data['collections'] as List<dynamic>? ?? [])
+          .map((json) => Collection.fromJson(json as Map<String, dynamic>))
+          .toList();
+
+      final bookmarks = (data['bookmarks'] as List<dynamic>? ?? [])
+          .map((json) => Bookmark.fromJson(json as Map<String, dynamic>))
+          .toList();
+
+      return (collections: collections, bookmarks: bookmarks);
+    } catch (e) {
+      return (collections: <Collection>[], bookmarks: <Bookmark>[]);
+    }
+  }
+
+  static Future<String> get _directoryPath async {
+    if (Platform.isAndroid) {
+      return await getDirectoryPath(
+            initialDirectory: constants.defaultAndroidExportDirectory,
+          ) ??
+          '';
+    }
+    return await getDirectoryPath() ?? '';
+  }
+}

lib/service/notifying.dart

@@ -54,11 +54,11 @@ class Notifying {
     showSnackbar(context, text: errorText, isError: true);
   }
 
-  static void showStoragePermissionErrorSnackbar(BuildContext context) {
-    showSnackbar(
-      context,
-      text: AppLocalizations.of(context)!.errorStoragePermisson,
-      isError: true,
-    );
+  static void showErrorSnackbar(BuildContext context, String message) {
+    showSnackbar(context, text: message, isError: true);
+  }
+
+  static void showMessageSnackbar(BuildContext context, String message) {
+    showSnackbar(context, text: message, isError: false);
   }
 }

lib/service/permission_service.dart

@@ -0,0 +1,9 @@
+import 'package:permission_handler/permission_handler.dart';
+
+class PermissionService {
+  static Future<PermissionStatus> get storagePermissionStatus =>
+      Permission.manageExternalStorage.status;
+
+  static Future<PermissionStatus> get requestStoragePermission =>
+      Permission.manageExternalStorage.request();
+}

lib/service/storage.dart

@@ -4,6 +4,7 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 import '../model/bookmark.dart';
 import '../model/collection.dart';
+import 'json_file_service.dart';
 
 class Storage {
   static const String _bookmarksKey = 'bookmarks';
@@ -163,4 +164,20 @@ class Storage {
     }
     return _prefsWithCache!;
   }
+
+  static Future<bool> exportToJsonFile() => JsonFileService.exportToJson(
+    collections: loadCollections(),
+    bookmarks: loadBookmarks(),
+  );
+
+  static Future<bool> importFromJsonFile() async {
+    final import = await JsonFileService.importFromJson();
+
+    if (import.bookmarks.isNotEmpty || import.collections.isNotEmpty) {
+      saveBookmarks(import.bookmarks);
+      saveCollections(import.collections);
+      return true;
+    }
+    return false;
+  }
 }

pubspec.lock

@@ -41,14 +41,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.2"
-  code_assets:
-    dependency: transitive
-    description:
-      name: code_assets
-      sha256: "83ccdaa064c980b5596c35dd64a8d3ecc68620174ab9b90b6343b753aa721687"
-      url: "https://pub.dev"
-    source: hosted
-    version: "1.0.0"
   collection:
     dependency: transitive
     description:
@@ -57,14 +49,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.19.1"
-  crypto:
+  cross_file:
     dependency: transitive
     description:
-      name: crypto
-      sha256: c8ea0233063ba03258fbcf2ca4d6dadfefe14f02fab57702265467a19f27fadf
+      name: cross_file
+      sha256: "701dcfc06da0882883a2657c445103380e53e647060ad8d9dfb710c100996608"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.7"
+    version: "0.3.5+1"
   csslib:
     dependency: transitive
     description:
@@ -105,6 +97,70 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "7.0.1"
+  file_selector:
+    dependency: "direct main"
+    description:
+      name: file_selector
+      sha256: bd15e43e9268db636b53eeaca9f56324d1622af30e5c34d6e267649758c84d9a
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
+  file_selector_android:
+    dependency: transitive
+    description:
+      name: file_selector_android
+      sha256: "51e8fd0446de75e4b62c065b76db2210c704562d072339d333bd89c57a7f8a7c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.2+4"
+  file_selector_ios:
+    dependency: transitive
+    description:
+      name: file_selector_ios
+      sha256: e2ecf2885c121691ce13b60db3508f53c01f869fb6e8dc5c1cfa771e4c46aeca
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.3+5"
+  file_selector_linux:
+    dependency: transitive
+    description:
+      name: file_selector_linux
+      sha256: "2567f398e06ac72dcf2e98a0c95df2a9edd03c2c2e0cacd4780f20cdf56263a0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.4"
+  file_selector_macos:
+    dependency: transitive
+    description:
+      name: file_selector_macos
+      sha256: "5e0bbe9c312416f1787a68259ea1505b52f258c587f12920422671807c4d618a"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.5"
+  file_selector_platform_interface:
+    dependency: transitive
+    description:
+      name: file_selector_platform_interface
+      sha256: "35e0bd61ebcdb91a3505813b055b09b79dfdc7d0aee9c09a7ba59ae4bb13dc85"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.7.0"
+  file_selector_web:
+    dependency: transitive
+    description:
+      name: file_selector_web
+      sha256: c4c0ea4224d97a60a7067eca0c8fd419e708ff830e0c83b11a48faf566cec3e7
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.4+2"
+  file_selector_windows:
+    dependency: transitive
+    description:
+      name: file_selector_windows
+      sha256: "62197474ae75893a62df75939c777763d39c2bc5f73ce5b88497208bc269abfd"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.3+5"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -133,22 +189,6 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
-  glob:
-    dependency: transitive
-    description:
-      name: glob
-      sha256: c3f1ee72c96f8f78935e18aa8cecced9ab132419e8625dc187e1c2408efc20de
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.1.3"
-  hooks:
-    dependency: transitive
-    description:
-      name: hooks
-      sha256: "5d309c86e7ce34cd8e37aa71cb30cb652d3829b900ab145e4d9da564b31d59f7"
-      url: "https://pub.dev"
-    source: hosted
-    version: "1.0.0"
   html:
     dependency: transitive
     description:
@@ -213,14 +253,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
-  logging:
-    dependency: transitive
-    description:
-      name: logging
-      sha256: c8245ada5f1717ed44271ed1c26b8ce85ca3228fd2ffdb75468ab01979309d61
-      url: "https://pub.dev"
-    source: hosted
-    version: "1.3.0"
   matcher:
     dependency: transitive
     description:
@@ -253,14 +285,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.4.2"
-  native_toolchain_c:
-    dependency: transitive
-    description:
-      name: native_toolchain_c
-      sha256: "89e83885ba09da5fdf2cdacc8002a712ca238c28b7f717910b34bcd27b0d03ac"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.17.4"
   nested:
     dependency: transitive
     description:
@@ -269,14 +293,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.0.0"
-  objective_c:
-    dependency: transitive
-    description:
-      name: objective_c
-      sha256: "9922a1ad59ac5afb154cc948aa6ded01987a75003651d0a2866afc23f4da624e"
-      url: "https://pub.dev"
-    source: hosted
-    version: "9.2.3"
   path:
     dependency: transitive
     description:
@@ -285,30 +301,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
-  path_provider:
-    dependency: "direct main"
-    description:
-      name: path_provider
-      sha256: "50c5dd5b6e1aaf6fb3a78b33f6aa3afca52bf903a8a5298f53101fdaee55bbcd"
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.1.5"
-  path_provider_android:
-    dependency: transitive
-    description:
-      name: path_provider_android
-      sha256: f2c65e21139ce2c3dad46922be8272bb5963516045659e71bb16e151c93b580e
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.2.22"
-  path_provider_foundation:
-    dependency: transitive
-    description:
-      name: path_provider_foundation
-      sha256: "2a376b7d6392d80cd3705782d2caa734ca4727776db0b6ec36ef3f1855197699"
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.6.0"
   path_provider_linux:
     dependency: transitive
     description:
@@ -405,14 +397,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.1.5+1"
-  pub_semver:
-    dependency: transitive
-    description:
-      name: pub_semver
-      sha256: "5bfcf68ca79ef689f8990d1160781b4bad40a3bd5e5218ad4076ddb7f4081585"
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.2.0"
   shared_preferences:
     dependency: "direct main"
     description:
@@ -634,14 +618,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
-  yaml:
-    dependency: transitive
-    description:
-      name: yaml
-      sha256: b9da305ac7c39faa3f030eccd175340f968459dae4af175130b3fc47e40d76ce
-      url: "https://pub.dev"
-    source: hosted
-    version: "3.1.3"
 sdks:
-  dart: ">=3.10.3 <4.0.0"
-  flutter: ">=3.38.4"
+  dart: ">=3.10.0 <4.0.0"
+  flutter: ">=3.38.0"

pubspec.yaml

@@ -21,8 +21,8 @@ dependencies:
   flutter_localizations:
     sdk: flutter
   intl: any
-  path_provider: ^2.1.5
   permission_handler: ^12.0.1
+  file_selector: ^1.1.0
 
 dev_dependencies:
   flutter_test: