import 'package:flutter/material.dart';

import '../../core/theme/app_theme.dart';
import '../../screens/feed/feed_screen.dart';
import '../../screens/profile/mine_screen.dart';

/// 首页壳：底部 Tab（首页/分类/发布/消息/我的），02-技术文档信息架构
/// 首页 Tab 为 Feed 播放页，我的页已接入，其余 Tab 随迭代接入；IndexedStack 保活各 Tab 状态
class HomeShell extends StatefulWidget {
  const HomeShell({super.key});

  @override
  State<HomeShell> createState() => _HomeShellState();
}

class _HomeShellState extends State<HomeShell> {
  int _index = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: IndexedStack(
        index: _index,
        children: const [
          FeedScreen(),
          _TabPlaceholder('分类'),
          _TabPlaceholder('发布'),
          _TabPlaceholder('消息'),
          MineScreen(),
        ],
      ),
      bottomNavigationBar: NavigationBar(
        backgroundColor: AppColors.surface,
        indicatorColor: AppColors.primary.withValues(alpha: 0.2),
        selectedIndex: _index,
        onDestinationSelected: (i) => setState(() => _index = i),
        destinations: const [
          NavigationDestination(
            icon: Icon(Icons.home_outlined),
            selectedIcon: Icon(Icons.home, color: AppColors.primary),
            label: '首页',
          ),
          NavigationDestination(
            icon: Icon(Icons.grid_view_outlined),
            label: '分类',
          ),
          NavigationDestination(
            icon: Icon(Icons.add_box_outlined),
            label: '发布',
          ),
          NavigationDestination(
            icon: Icon(Icons.notifications_none),
            label: '消息',
          ),
          NavigationDestination(
            icon: Icon(Icons.person_outline),
            label: '我的',
          ),
        ],
      ),
    );
  }
}

/// Tab 占位（迭代期）
class _TabPlaceholder extends StatelessWidget {
  const _TabPlaceholder(this.title);

  final String title;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Text(
        '$title（随迭代接入）',
        style: const TextStyle(color: AppColors.textSecondary, fontSize: 15),
      ),
    );
  }
}