opt(download): force cache downloads to use http/1.1 (#1870)

* opt(download): force cache downloads to use http/1.1

* refactor(http): lazily initialize fallback http/1.1 client

* fix(http): keep fallback client decision consistent at startup

* opt: use clone

* fix

* fix

---------

Co-authored-by: My-Responsitories <107370289+My-Responsitories@users.noreply.github.com>

lib/http/init.dart

@@ -27,7 +27,11 @@ class Request {
 
   static final Request _instance = Request._internal();
   static late AccountManager accountManager;
+  static final _enableHttp2 = Pref.enableHttp2;
   static late final Dio dio;
+  static Dio? _http11Dio;
+  static Dio get http11Dio =>
+      _http11Dio ??= _enableHttp2 ? _cloneHttp11Dio() : dio;
   factory Request() => _instance;
 
   /// 设置cookie
@@ -95,11 +99,26 @@ class Request {
     } catch (_) {}
   }
 
+  static Dio _cloneHttp11Dio() {
+    final h11 = dio.clone(
+      httpClientAdapter:
+          (dio.httpClientAdapter as Http2Adapter).fallbackAdapter,
+    );
+    final interceptors = h11.interceptors;
+    for (var i = 0; i < interceptors.length; i++) {
+      final elem = interceptors[i];
+      if (elem is RetryInterceptor) {
+        interceptors[i] = elem.copyWith(client: h11);
+        break;
+      }
+    }
+    return h11;
+  }
+
   /*
    * config it and create
    */
   Request._internal() {
-    final enableHttp2 = Pref.enableHttp2;
     //BaseOptions、Options、RequestOptions 都可以配置参数，优先级别依次递增，且可以根据优先级别覆盖参数
     BaseOptions options = BaseOptions(
       //请求基地址,可以包含子路径
@@ -111,7 +130,7 @@ class Request {
       //Http请求头.
       headers: {
         'user-agent': 'Dart/3.6 (dart:io)', // Http2Adapter不会自动添加标头
-        if (!enableHttp2) 'connection': 'keep-alive',
+        if (!_enableHttp2) 'connection': 'keep-alive',
         'accept-encoding': 'br,gzip',
       },
       responseDecoder: _responseDecoder, // Http2Adapter没有自动解压
@@ -142,7 +161,7 @@ class Request {
     );
 
     dio = Dio(options)
-      ..httpClientAdapter = enableHttp2
+      ..httpClientAdapter = _enableHttp2
           ? Http2Adapter(
               ConnectionManager(
                 idleTimeout: const Duration(seconds: 15),
@@ -167,7 +186,11 @@ class Request {
           : http11Adapter;
 
     // 先于其他Interceptor
-    dio.interceptors.add(RetryInterceptor(Pref.retryCount, Pref.retryDelay));
+    if (Pref.retryCount != 0) {
+      dio.interceptors.add(
+        RetryInterceptor(dio, Pref.retryCount, Pref.retryDelay),
+      );
+    }
 
     // 日志拦截器 输出请求、响应内容
     if (kDebugMode) {

lib/http/retry_interceptor.dart

@@ -1,12 +1,12 @@
-import 'package:PiliPlus/http/init.dart';
 import 'package:dio/dio.dart';
 import 'package:http2/http2.dart';
 
 class RetryInterceptor extends Interceptor {
+  final Dio _client;
   final int _count;
   final int _delay;
 
-  RetryInterceptor(this._count, this._delay);
+  RetryInterceptor(this._client, this._count, this._delay);
 
   @override
   void onError(DioException err, ErrorInterceptorHandler handler) {
@@ -31,7 +31,7 @@ class RetryInterceptor extends Interceptor {
                 ..data = null
                 ..method = 'GET';
             }
-            Request.dio
+            _client
                 .fetch(options)
                 .then(
                   (i) => handler.resolve(
@@ -62,7 +62,7 @@ class RetryInterceptor extends Interceptor {
               Duration(
                 milliseconds: ++err.requestOptions.extra['_rt'] * _delay,
               ),
-              () => Request.dio
+              () => _client
                   .fetch(err.requestOptions)
                   .then(handler.resolve)
                   .onError<DioException>((error, _) => handler.reject(error)),
@@ -76,4 +76,7 @@ class RetryInterceptor extends Interceptor {
       }
     }
   }
+
+  RetryInterceptor copyWith({Dio? client, int? count, int? delay}) =>
+      .new(client ?? _client, count ?? _count, delay ?? _delay);
 }

lib/services/download/download_manager.dart

@@ -58,7 +58,7 @@ class DownloadManager {
 
     Response<ResponseBody> response;
     try {
-      response = await Request.dio.get<ResponseBody>(
+      response = await Request.http11Dio.get<ResponseBody>(
         url.http2https,
         options: Options(
           headers: {'range': 'bytes=$received-'},