opt: webdav classification (#794)

* 优化设置备份[#739](https://github.com/bggRGjQaUbCoE/PiliPlus/issues/739)

lib/pages/webdav/webdav.dart

@@ -1,8 +1,10 @@
+import 'dart:io';
 import 'dart:convert';
 import 'package:PiliPlus/common/widgets/pair.dart';
 import 'package:PiliPlus/utils/extension.dart';
 import 'package:PiliPlus/utils/storage.dart';
 import 'package:flutter_smart_dialog/flutter_smart_dialog.dart';
+import 'package:device_info_plus/device_info_plus.dart';
 import 'package:webdav_client/webdav_client.dart' as webdav;
 
 class WebDav {
@@ -44,6 +46,34 @@ class WebDav {
       return Pair(first: false, second: e.toString());
     }
   }
+  
+  Future<bool> _isPhone() async {
+    final deviceInfoPlugin = DeviceInfoPlugin();
+    if (Platform.isAndroid) {
+      AndroidDeviceInfo androidInfo = await deviceInfoPlugin.androidInfo;
+      return androidInfo.systemFeatures.contains("android.hardware.telephony");
+    } else if (Platform.isIOS) {
+      IosDeviceInfo iosInfo = await deviceInfoPlugin.iosInfo;
+      return _isIosPhone(iosInfo.utsname.machine);
+    } else {
+      return true;
+    }
+  }
+  bool _isIosPhone(String machine) {
+    if (machine.startsWith("iPhone")) {
+      return true;
+    } else if (machine.startsWith("iPad")) {
+      return false;
+    }
+    return true;
+  }
+
+  Future<String> _getFileName() async {
+    final isPhoneDevice = await _isPhone();
+    return isPhoneDevice
+        ? 'piliplus_settings_phone.json'
+        : 'piliplus_settings_pad.json';
+  }
 
   Future backup() async {
     if (_client == null) {
@@ -55,7 +85,9 @@ class WebDav {
     }
     try {
       String data = await GStorage.exportAllSettings();
-      final path = '$_webdavDirectory/piliplus_settings.json';
+      final isPhoneDevice = await _isPhone();
+      final fileName = await _getFileName();
+      final path = '$_webdavDirectory/$fileName';
       try {
         await _client!.remove(path);
       } catch (_) {}
@@ -75,7 +107,9 @@ class WebDav {
       }
     }
     try {
-      final path = '$_webdavDirectory/piliplus_settings.json';
+      final isPhoneDevice = await _isPhone();
+      final fileName = await _getFileName();
+      final path = '$_webdavDirectory/$fileName';
       final data = await _client!.read(path);
       await GStorage.importAllSettings(utf8.decode(data));
       SmartDialog.showToast('恢复成功');