import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../providers/auth_provider.dart';
import '../add/add_page.dart';
import '../home/home_page.dart';
import '../login/login_page.dart';
import '../mine/mine_page.dart';
import '../statistics/statistics_page.dart';

class MainShell extends ConsumerStatefulWidget {
  const MainShell({super.key});

  @override
  ConsumerState<MainShell> createState() => _MainShellState();
}

class _MainShellState extends ConsumerState<MainShell> {
  int _index = 0; // 默认选中「首页」

  @override
  void initState() {
    super.initState();
    // 兜底：未登录直接回登录页
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!ref.read(authProvider).isLoggedIn) {
        _goLogin();
      }
    });
  }

  void _goLogin() {
    Navigator.of(context).pushAndRemoveUntil(
      MaterialPageRoute(builder: (_) => const LoginPage()),
      (route) => false,
    );
  }

  @override
  Widget build(BuildContext context) {
    // IndexedStack 保证四个页面常驻：写操作后首页/统计的数据失效能立即重取，
    // 用户切回时看到的就是最新数据。
    const pages = [
      HomePage(),
      AddPage(),
      StatisticsPage(),
      MinePage(),
    ];
    return Scaffold(
      body: IndexedStack(index: _index, children: pages),
      bottomNavigationBar: NavigationBar(
        selectedIndex: _index,
        onDestinationSelected: (i) => setState(() => _index = i),
        backgroundColor: Colors.white,
        indicatorColor: const Color(0x33C8956E),
        destinations: const [
          NavigationDestination(icon: Icon(Icons.home_outlined), selectedIcon: Icon(Icons.home), label: '首页'),
          NavigationDestination(icon: Icon(Icons.add_circle_outline), selectedIcon: Icon(Icons.add_circle), label: '记账'),
          NavigationDestination(icon: Icon(Icons.bar_chart_outlined), selectedIcon: Icon(Icons.bar_chart), label: '统计'),
          NavigationDestination(icon: Icon(Icons.person_outline), selectedIcon: Icon(Icons.person), label: '我的'),
        ],
      ),
    );
  }
}