import 'dart:async';
import 'package:dio/dio.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../core/config/app_config.dart';

/// 每次从离线恢复到在线时自增。
/// 数据 provider 通过 watch 此值实现网络恢复后自动刷新。
final networkRecoveryCountProvider = StateProvider<int>((ref) => 0);

final connectivityProvider =
    StateNotifierProvider<ConnectivityNotifier, bool>((ref) {
  return ConnectivityNotifier(
    onRecovered: () {
      ref.read(networkRecoveryCountProvider.notifier).update((s) => s + 1);
    },
  );
});

class ConnectivityNotifier extends StateNotifier<bool> {
  final void Function()? onRecovered;

  ConnectivityNotifier({this.onRecovered, bool skipInit = false}) : super(true) {
    if (!skipInit) {
      _check();
      _startOnlineTimer();
    }
  }

  Timer? _timer;

  // 独立轻量 Dio：短超时，无拦截器
  final _dio = Dio(BaseOptions(
    connectTimeout: const Duration(seconds: 3),
    receiveTimeout: const Duration(seconds: 3),
  ));

  /// 在线时：每 30 秒检测一次
  void _startOnlineTimer() {
    _timer?.cancel();
    _timer = Timer.periodic(const Duration(seconds: 30), (_) => _check());
  }

  /// 离线时：每 1 分钟嗅探一次，降低频率节省资源
  void _startOfflineTimer() {
    _timer?.cancel();
    _timer = Timer.periodic(const Duration(minutes: 1), (_) => _check());
  }

  /// 立即触发一次检测（供外部调用，如 API 请求失败 / 启动时）
  Future<void> forceCheck() => _check();

  Future<void> _check() async {
    try {
      await _dio.get(AppConfig.healthUrl);
      if (!state) {
        // 离线 → 在线：切回高频检测，广播恢复事件
        state = true;
        onRecovered?.call();
        _startOnlineTimer();
      }
    } catch (_) {
      if (state) {
        // 在线 → 离线：切换为低频嗅探
        state = false;
        _startOfflineTimer();
      }
    }
  }

  @override
  void dispose() {
    _timer?.cancel();
    _dio.close(force: true);
    super.dispose();
  }
}