import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:shadcn_ui/shadcn_ui.dart';

import '../theme/app_icons.dart';

class TabShell extends StatefulWidget {
  const TabShell({super.key, required this.child, required this.location});

  final Widget child;
  final String location;

  @override
  State<TabShell> createState() => _TabShellState();
}

class _TabShellState extends State<TabShell> {
  static const double _compactHeaderThreshold = 34;

  bool _showCompactHeader = false;

  static const _tabs = ['/assets', '/market', '/news', '/profile'];

  int get _index =>
      _tabs.indexWhere((t) => widget.location.startsWith(t)).clamp(0, 3);

  @override
  void didUpdateWidget(covariant TabShell oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.location != widget.location && _showCompactHeader) {
      _showCompactHeader = false;
    }
  }

  @override
  Widget build(BuildContext context) {
    final cs = ShadTheme.of(context).colorScheme;
    final header = _headerForPath(widget.location);
    final canPop = GoRouter.of(context).canPop();

    return Scaffold(
      backgroundColor: cs.background,
      resizeToAvoidBottomInset: false,
      appBar: AppBar(
        backgroundColor: cs.background,
        surfaceTintColor: Colors.transparent,
        elevation: 0,
        scrolledUnderElevation: 0,
        centerTitle: true,
        toolbarHeight: 32,
        leading: canPop
            ? IconButton(
                onPressed: () => context.pop(),
                icon: const Icon(Icons.chevron_left, size: 20),
              )
            : null,
        title: AnimatedOpacity(
          opacity: _showCompactHeader ? 1 : 0,
          duration: const Duration(milliseconds: 160),
          curve: Curves.easeOut,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text(
                header.title,
                textAlign: TextAlign.center,
                style: TextStyle(
                  fontSize: 15,
                  fontWeight: FontWeight.w700,
                  color: cs.foreground,
                  height: 1.1,
                  letterSpacing: 0,
                ),
              ),
              if (header.subtitle != null) ...[
                const SizedBox(height: 2),
                Text(
                  header.subtitle!,
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                  textAlign: TextAlign.center,
                  style: TextStyle(
                    fontSize: 11,
                    fontWeight: FontWeight.w400,
                    color: cs.mutedForeground,
                    height: 1.1,
                    letterSpacing: 0,
                  ),
                ),
              ],
            ],
          ),
        ),
      ),
      body: ColoredBox(
        color: cs.background,
        child: NotificationListener<ScrollNotification>(
          onNotification: _handleScrollNotification,
          child: Stack(children: [Positioned.fill(child: widget.child)]),
        ),
      ),
      bottomNavigationBar: DecoratedBox(
        decoration: BoxDecoration(
          color: Colors.white,
          border: Border(top: BorderSide(color: cs.border, width: 1)),
        ),
        child: SafeArea(
          top: false,
          child: SizedBox(
            height: 62,
            child: Row(
              children: [
                for (var i = 0; i < _tabs.length; i++)
                  Expanded(
                    child: _TabButton(
                      icon: i == _index ? _filledIcons[i] : _outlineIcons[i],
                      label: _labels[i],
                      selected: i == _index,
                      onTap: () => context.go(_tabs[i]),
                    ),
                  ),
              ],
            ),
          ),
        ),
      ),
    );
  }

  bool _handleScrollNotification(ScrollNotification notification) {
    if (notification.metrics.axis != Axis.vertical) {
      return false;
    }
    final next = notification.metrics.pixels > _compactHeaderThreshold;
    if (next != _showCompactHeader && mounted) {
      setState(() => _showCompactHeader = next);
    }
    return false;
  }
}

class _TabButton extends StatelessWidget {
  const _TabButton({
    required this.icon,
    required this.label,
    required this.selected,
    required this.onTap,
  });

  final IconData icon;
  final String label;
  final bool selected;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final cs = ShadTheme.of(context).colorScheme;
    final color = selected ? cs.primary : cs.mutedForeground;
    return InkWell(
      onTap: onTap,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          if (selected)
            Container(
              width: 22,
              height: 2.5,
              margin: const EdgeInsets.only(bottom: 6),
              decoration: BoxDecoration(
                color: cs.primary,
                borderRadius: const BorderRadius.vertical(
                  bottom: Radius.circular(3),
                ),
              ),
            )
          else
            const SizedBox(height: 8.5),
          Icon(icon, size: 22, color: color),
          const SizedBox(height: 4),
          Text(
            label,
            style: TextStyle(
              fontSize: 11,
              fontWeight: selected ? FontWeight.w600 : FontWeight.w400,
              color: color,
              letterSpacing: 0,
            ),
          ),
        ],
      ),
    );
  }
}

const _filledIcons = [
  AppIcons.assetsFill,
  AppIcons.marketFill,
  AppIcons.newsFill,
  AppIcons.meFill,
];

const _outlineIcons = [
  AppIcons.assetsLine,
  AppIcons.marketLine,
  AppIcons.newsLine,
  AppIcons.meLine,
];

const _labels = ['资产', '行情', '资讯', '我的'];

_ShellHeader _headerForPath(String path) {
  return switch (path) {
    '/market' => const _ShellHeader('行情', ''),
    '/news' => const _ShellHeader('资讯', ''),
    '/profile' => const _ShellHeader('我的'),
    _ => const _ShellHeader('金值', ''),
  };
}

class _ShellHeader {
  const _ShellHeader(this.title, [this.subtitle]);

  final String title;
  final String? subtitle;
}