huangguo_android/lib/hj_utils/detect_line_manager.dart

// ignore_for_file: use_build_context_synchronously

import 'dart:async';

import 'package:dio/dio.dart';
import 'package:hgdj/config/config.dart';
import 'package:hgdj/hj_utils/dns_solve/dnsolve.dart';
import 'package:hgdj/hj_utils/light_model.dart';
import 'package:hgdj/hj_utils/store_keys.dart';
import 'package:hgdj/hj_utils/text_util.dart';
import 'package:hgdj/tools_base/debug_log.dart';
import 'package:hgdj/tools_base/net/http_manager.dart';

//选线管理
class DetectLineManager {
  // 在途请求的取消列表，超时时统一取消
  final _cancelList = <CancelToken>[];

  Future<String> detectLineOnce() async {
    // 硬兜底：整个选线流程最多 20s，超时按"无可用线路"处理，避免 UI 永久卡在"选线中..."
    String line;
    try {
      line = await _detectLineOnce().timeout(const Duration(seconds: 20));
    } catch (e) {
      debugLog("selectLine", "detectLineOnce()...timeout or error:$e");
      line = "";
    }
    _cancelInflight();
    _cancelList.clear();
    return line;
  }

  // 取消在途请求；except 为本次胜出的线路，不取消自己
  void _cancelInflight({CancelToken? except}) {
    for (final t in _cancelList) {
      if (t != except) t.cancel();
    }
  }

  /// 一次完整的批量选线过程
  Future<String> _detectLineOnce() async {
    final saved = await lightKV.getStringList(StoreKeys.DETECT_LINE);
    final lines = saved?.isNotEmpty == true ? saved! : Config.lineList;
    var successLine = await _pingCheckBatch(lines);
    // 本地线路全部失败，回退 DNS 解析
    if (TextUtil.isEmpty(successLine)) {
      successLine = await _dnsSolve();
    }
    return successLine;
  }

  ///检查一批线路：并发 ping，谁先成功用谁；全失败返回 ""
  Future<String> _pingCheckBatch(List<String> lines) async {
    final validLines = lines.where(TextUtil.isNotEmpty).toList();
    if (validLines.isEmpty) return "";

    final completer = Completer<String>();
    final tasks = validLines.map((line) async {
      debugLog("selectLine", "_pingCheckBatch()...开始选线:$line");
      final cancelToken = CancelToken();
      _cancelList.add(cancelToken);
      try {
        if (await _pingCheck(line, cancelToken)) {
          if (!completer.isCompleted) {
            debugLog("selectLine", "_pingCheckBatch()...选线成功:$line");
            completer.complete(line);
            // 竞速：已选到最快线路，立即取消其余在途请求
            _cancelInflight(except: cancelToken);
          }
        } else {
          debugLog("selectLine", "_pingCheckBatch()...线路不可用:$line");
        }
      } catch (e) {
        debugLog("selectLine", "_pingCheckBatch()...线路异常:$line $e");
      } finally {
        _cancelList.remove(cancelToken);
      }
    }).toList();

    // 全部结束仍无成功 → 返回空
    Future.wait(tasks).whenComplete(() {
      if (!completer.isCompleted) completer.complete("");
    });
    return completer.future;
  }

  /// 单次网络请求，业务码 200 才算成功
  Future<bool> _pingCheck(String line, [CancelToken? cancelToken]) async {
    final startTime = DateTime.now();
    final resp = await httpManager.fetchDetectLineResponse(
      "$line/api/app/ping/check",
      options: Options(
        method: "GET",
        sendTimeout: const Duration(seconds: 10),
        receiveTimeout: const Duration(seconds: 10),
      ),
      cancelToken: cancelToken,
    );
    debugLog("ping",
        "pingCheck()...line:$line cost ${DateTime.now().difference(startTime).inMilliseconds} milSeconds");
    if (TextUtil.isNotEmpty(resp.time)) {
      httpManager.setServerTime(resp.time);
    }
    return resp.isSuccess;
  }

  //本地域名不通的情况下，使用 dns 解析
  Future<String> _dnsSolve() async {
    final response = await DNSolve().lookup(
      Config.dns,
      dnsSec: true,
      type: RecordType.txt,
      provider: DNSProvider.aliyun,
    );

    //必须先取出来判空，不能写成 `?? []`：那个空字面量会被推成 List<dynamic>，
    //整行 LUB 退化后 record 也成了 dynamic，record.data.split().map().toList()
    //一路 dynamic 下去，运行期是 List<dynamic>，传给 setStringList(List<String>) 直接抛。
    //全程 dynamic，analyze 一个警告都不会给
    final records = response.answer?.records;
    if (records == null) return '';
    for (final record in records) {
      if (record.data.isEmpty) continue;
      debugLog("selectLine", "dnsSolve ==== ${record.data}");
      //DNS TXT 值带引号，去掉后按 _ 拆成多条线路
      final lines = record.data
          .split('_')
          .map((e) => e.replaceAll("\"", ""))
          .where(TextUtil.isNotEmpty)
          .toList();
      if (lines.isEmpty) continue; // 这条记录没解析出线路，接着看下一条，别直接放弃
      lightKV.setStringList(StoreKeys.DETECT_LINE, lines);
      return await _pingCheckBatch(lines);
    }
    return '';
  }
}