import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../core/api/api_client.dart';
import '../core/auth/auth_state.dart';

/// 登录态心跳：已登录时每 30s 打一次 POST /auth/ping。
/// 若会话已被撤销（被踢/管理员强制下线），后端返回 401，
/// ApiClient 的拦截器会触发 refresh→失败→onAuthFailed→logout，
/// 因此空闲用户也能在 ~30s 内感知到被下线。
final sessionHeartbeatProvider = Provider<SessionHeartbeat>((ref) {
  final hb = SessionHeartbeat(ref);
  ref.onDispose(hb.dispose);
  hb.start();
  return hb;
});

class SessionHeartbeat {
  final Ref _ref;
  Timer? _timer;

  SessionHeartbeat(this._ref);

  void start() {
    _timer?.cancel();
    _timer = Timer.periodic(const Duration(seconds: 30), (_) => _ping());
  }

  Future<void> _ping() async {
    if (!_ref.read(authStateProvider).isLoggedIn) return;
    try {
      await _ref.read(apiClientProvider).post('/auth/ping');
    } catch (e) {
      // 401 已由 ApiClient 拦截器处理（触发登出）；其余错误忽略
      debugPrint('[Heartbeat] ping failed: $e');
    }
  }

  void dispose() => _timer?.cancel();
}