feat: add user agent (#1380)

Co-authored-by: Pun Butrach <pun.butrach@gmail.com>

lib/services/download_manager.dart

@@ -0,0 +1,75 @@
+import 'package:dio/dio.dart';
+import 'package:dio_cache_interceptor/dio_cache_interceptor.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_cache_manager/file.dart';
+import 'package:flutter_cache_manager/flutter_cache_manager.dart';
+import 'package:injectable/injectable.dart';
+import 'package:revanced_manager/app/app.locator.dart';
+import 'package:revanced_manager/services/manager_api.dart';
+
+@lazySingleton
+class DownloadManager {
+  final ManagerAPI _managerAPI = locator<ManagerAPI>();
+  late final String _userAgent;
+
+  final _cacheOptions = CacheOptions(
+    store: MemCacheStore(),
+    maxStale: const Duration(days: 1),
+    priority: CachePriority.high,
+  );
+
+  Future<void> initialize() async {
+    _userAgent = 'ReVanced-Manager/${await _managerAPI.getCurrentManagerVersion()}';
+  }
+
+  Dio initDio(String url) {
+    var dio = Dio();
+    try {
+      dio = Dio(
+        BaseOptions(
+          baseUrl: url,
+          headers: {
+            'User-Agent': _userAgent,
+          },
+        ),
+      );
+    } on Exception catch (e) {
+      if (kDebugMode) {
+        print(e);
+      }
+    }
+
+    dio.interceptors.add(DioCacheInterceptor(options: _cacheOptions));
+    return dio;
+  }
+
+  Future<void> clearAllCache() async {
+    try {
+      await _cacheOptions.store!.clean();
+    } on Exception catch (e) {
+      if (kDebugMode) {
+        print(e);
+      }
+    }
+  }
+
+  Future<File> getSingleFile(String url) async {
+    return DefaultCacheManager().getSingleFile(
+      url,
+      headers: {
+        'User-Agent': _userAgent,
+      },
+    );
+  }
+
+  Stream<FileResponse> getFileStream(String url) {
+    return DefaultCacheManager().getFileStream(
+      url,
+      withProgress: true,
+      headers: {
+        'User-Agent': _userAgent,
+      },
+    );
+  }
+}
+