fix(android): restore backups selected without a file path

lib/common/picker.dart

@@ -6,6 +6,18 @@ import 'package:fl_clash/common/common.dart';
 import 'package:image_picker/image_picker.dart';
 import 'package:mobile_scanner/mobile_scanner.dart';
 
+Future<void> copyPickedFileToPath(
+  PlatformFile file,
+  String destinationPath,
+) async {
+  final sourcePath = file.path;
+  if (sourcePath != null) {
+    await File(sourcePath).safeCopy(destinationPath);
+    return;
+  }
+  await File(destinationPath).safeWriteAsBytes(await file.readBytes());
+}
+
 class Picker {
   Future<PlatformFile?> pickerFile() async {
     return FilePicker.pickFile(initialDirectory: await appPath.downloadDirPath);

lib/views/backup_and_restore.dart

@@ -1,5 +1,3 @@
-import 'dart:io';
-
 import 'package:dynamic_color/dynamic_color.dart';
 import 'package:fl_clash/common/common.dart';
 import 'package:fl_clash/common/dav_client.dart';
@@ -139,9 +137,8 @@ class _BackupAndRestoreState extends ConsumerState<BackupAndRestore>
   Future<void> _restoreOnLocal(RestoreOption option) async {
     final appLocalizations = context.appLocalizations;
     final file = await picker.pickerFile();
-    final path = file?.path;
-    if (path == null) return;
-    await File(path).safeCopy(await appPath.backupFilePath);
+    if (file == null) return;
+    await copyPickedFileToPath(file, await appPath.backupFilePath);
     final res = await globalState.loadingRun<bool>(
       () async {
         await globalState.container

test/common/picker_test.dart

@@ -1,4 +1,5 @@
 import 'dart:io';
+import 'dart:typed_data';
 
 import 'package:file_picker/file_picker.dart';
 import 'package:fl_clash/common/picker.dart';
@@ -25,5 +26,47 @@ void main() {
 
       expect(String.fromCharCodes(bytes), 'mixed-port: 7890');
     });
+
+    test(
+      'copies a bytes-only picked file to the restore destination',
+      () async {
+        final directory = await Directory.systemTemp.createTemp(
+          'fl_clash_picker_restore_test_',
+        );
+        addTearDown(() => directory.delete(recursive: true));
+        final destination = File('${directory.path}/backup.zip');
+        final platformFile = PlatformFile(
+          name: 'backup.zip',
+          size: 3,
+          bytes: Uint8List.fromList([1, 2, 3]),
+        );
+
+        await copyPickedFileToPath(platformFile, destination.path);
+
+        expect(await destination.readAsBytes(), [1, 2, 3]);
+      },
+    );
+
+    test(
+      'copies a path-backed picked file to the restore destination',
+      () async {
+        final directory = await Directory.systemTemp.createTemp(
+          'fl_clash_picker_restore_path_test_',
+        );
+        addTearDown(() => directory.delete(recursive: true));
+        final source = File('${directory.path}/source.zip');
+        final destination = File('${directory.path}/backup.zip');
+        await source.writeAsBytes([4, 5, 6]);
+        final platformFile = PlatformFile(
+          name: 'source.zip',
+          path: source.path,
+          size: 3,
+        );
+
+        await copyPickedFileToPath(platformFile, destination.path);
+
+        expect(await destination.readAsBytes(), [4, 5, 6]);
+      },
+    );
   });
 }