import 'package:flutter/material.dart';
import '../../../core/constants/app_colors.dart';
import '../home/home_page.dart';
import '../market/market_page.dart';
import '../trade/trade_page.dart';
import '../asset/asset_page.dart';
import '../mine/mine_page.dart';

/// 主页面（包含底部导航）
class MainPage extends StatefulWidget {
  const MainPage({super.key});

  @override
  State<MainPage> createState() => _MainPageState();
}

class _MainPageState extends State<MainPage> {
  int _currentIndex = 0;

  final List<Widget> _pages = [
    const HomePage(),
    const MarketPage(),
    const TradePage(),
    const AssetPage(),
    const MinePage(),
  ];

  final List<_TabItem> _tabs = [
    _TabItem('首页', Icons.home_outlined, Icons.home),
    _TabItem('行情', Icons.show_chart_outlined, Icons.show_chart),
    _TabItem('交易', Icons.swap_horiz_outlined, Icons.swap_horiz),
    _TabItem('资产', Icons.account_balance_wallet_outlined, Icons.account_balance_wallet),
    _TabItem('我的', Icons.person_outline, Icons.person),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: IndexedStack(
        index: _currentIndex,
        children: _pages,
      ),
      bottomNavigationBar: _buildBottomNav(),
    );
  }

  Widget _buildBottomNav() {
    return Container(
      decoration: const BoxDecoration(
        color: AppColors.cardBackground,
        border: Border(top: BorderSide(color: AppColors.border)),
      ),
      child: SafeArea(
        child: Padding(
          padding: const EdgeInsets.symmetric(vertical: 8),
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: _tabs.asMap().entries.map((entry) {
              final index = entry.key;
              final tab = entry.value;
              final isSelected = index == _currentIndex;

              return GestureDetector(
                onTap: () => setState(() => _currentIndex = index),
                behavior: HitTestBehavior.opaque,
                child: Container(
                  padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Icon(
                        isSelected ? tab.selectedIcon : tab.icon,
                        color: isSelected ? AppColors.primary : AppColors.textSecondary,
                        size: 24,
                      ),
                      const SizedBox(height: 4),
                      Text(
                        tab.label,
                        style: TextStyle(
                          fontSize: 12,
                          color: isSelected ? AppColors.primary : AppColors.textSecondary,
                        ),
                      ),
                    ],
                  ),
                ),
              );
            }).toList(),
          ),
        ),
      ),
    );
  }
}

class _TabItem {
  final String label;
  final IconData icon;
  final IconData selectedIcon;

  _TabItem(this.label, this.icon, this.selectedIcon);
}

/// IndexedStack 用于保持页面状态
class IndexedStack extends StatefulWidget {
  final int index;
  final List<Widget> children;

  const IndexedStack({
    super.key,
    required this.index,
    required this.children,
  });

  @override
  State<IndexedStack> createState() => _IndexedStackState();
}

class _IndexedStackState extends State<IndexedStack> {
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: widget.children.asMap().entries.map((entry) {
        return Positioned.fill(
          child: Offstage(
            offstage: entry.key != widget.index,
            child: TickerMode(
              enabled: entry.key == widget.index,
              child: entry.value,
            ),
          ),
        );
      }).toList(),
    );
  }
}