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

class AppShell extends StatefulWidget {
  final Widget child;

  const AppShell({super.key, required this.child});

  @override
  State<AppShell> createState() => _AppShellState();
}

class _AppShellState extends State<AppShell> {
  static const double _railBreakpoint = 800; // tablet and up
  bool _railExtended = true; // start "open" on tablet/desktop
  final FocusNode _contentFocus = FocusNode(debugLabel: 'contentFocus');

  @override
  void dispose() {
    _contentFocus.dispose();
    super.dispose();
  }

  // --- NAV ITEMS -------------------------------------------------------------

  final _items =
      const <
        ({IconData icon, IconData? selectedIcon, String label, String route})
      >[
        (
          icon: Icons.dashboard_outlined,
          selectedIcon: Icons.dashboard,
          label: 'Dashboard',
          route: '/home',
        ),
        (
          icon: Icons.account_balance_wallet_outlined,
          selectedIcon: Icons.account_balance_wallet,
          label: 'Budgets',
          route: '/budget',
        ),
        (
          icon: Icons.inventory_2_outlined,
          selectedIcon: Icons.inventory_2,
          label: 'Inventar',
          route: '/inventory',
        ),
        (
          icon: Icons.bar_chart_outlined,
          selectedIcon: Icons.bar_chart,
          label: 'Reports',
          route: '/reports',
        ),
        (
        icon: Icons.settings,
        selectedIcon: Icons.settings_outlined,
        label: 'Settings',
        route: '/settings',
        ),
      ];

  int _indexForPath(String p) {
    for (var i = 0; i < _items.length; i++) {
      if (p.startsWith(_items[i].route)) return i;
    }
    return 0;
  }

  void _goForIndex(BuildContext ctx, int i) => ctx.go(_items[i].route);

  @override
  Widget build(BuildContext context) {
    final width = MediaQuery.of(context).size.width;
    final isRail = width >= _railBreakpoint;
    final currentPath = GoRouterState.of(context).matchedLocation;

    // keep focus on right/content pane on wide layouts
    if (isRail) {
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (mounted && !_contentFocus.hasFocus) _contentFocus.requestFocus();
      });
    }

    final appBar = AppBar(
      title: _LogoHeader(),
      leading: isRail
          ? null
          : Builder(
              builder: (ctx) => IconButton(
                icon: const Icon(Icons.menu),
                onPressed: () => Scaffold.of(ctx).openDrawer(),
                tooltip: 'Menü',
              ),
            ),
      actions: [
        IconButton(
          tooltip: 'Benachrichtigungen',
          onPressed: () {},
          icon: const Icon(Icons.notifications_none),
        ),
        IconButton(
          tooltip: 'Benutzer-Einstellungen',
          onPressed: () => context.push('/settings'),
          icon: const Icon(Icons.account_circle_outlined),
        ),
      ],
    );

    if (!isRail) {
      // ------------------- MOBILE: Drawer -------------------
      final selectedIndex = _indexForPath(currentPath);
      return Scaffold(
        appBar: appBar,
        drawer: _AppDrawer(items: _items, selectedIndex: selectedIndex),
        body: SafeArea(child: widget.child),
      );
    }

    // ------------------- TABLET/DESKTOP: NavigationRail -------------------
    final selected = _indexForPath(currentPath);
    final scheme = Theme.of(context).colorScheme;

    return Scaffold(
      appBar: appBar,
      body: Row(
        children: [
          NavigationRailTheme(
            data: NavigationRailThemeData(
              groupAlignment: -1.0,
              // align to top
              useIndicator: true,
              indicatorColor: scheme.secondaryContainer,
              // background for selected "button"
              indicatorShape: const StadiumBorder(),
              selectedIconTheme: IconThemeData(
                color: scheme.onSecondaryContainer,
              ),
              selectedLabelTextStyle: TextStyle(
                color: scheme.onSecondaryContainer,
                fontWeight: FontWeight.w600,
              ),
            ),
            child: NavigationRail(
              extended: _railExtended,
              selectedIndex: selected,
              onDestinationSelected: (i) => _goForIndex(context, i),
              // leading: const Padding(
              //   padding: EdgeInsets.only(top: 8),
              //   child: _LogoHeader(),
              // ),
              destinations: [
                for (final it in _items)
                  NavigationRailDestination(
                    icon: Icon(it.icon),
                    selectedIcon: Icon(it.selectedIcon ?? it.icon),
                    label: Text(it.label),
                  ),
              ],
              trailingAtBottom: true,
              trailing: Column(
                children: [
                  const SizedBox(height: 8),
                  const Divider(height: 1),
                  // toggle lives at the very bottom so layout doesn't jump
                  IconButton(
                    tooltip: _railExtended
                        ? 'Leiste verkleinern'
                        : 'Leiste erweitern',
                    onPressed: () =>
                        setState(() => _railExtended = !_railExtended),
                    icon: Icon(
                      _railExtended
                          ? Icons.keyboard_double_arrow_left
                          : Icons.keyboard_double_arrow_right,
                    ),
                  ),
                ],
              ),
            ),
          ),
          const VerticalDivider(width: 1),
          Expanded(
            child: SafeArea(
              child: Focus(
                focusNode: _contentFocus,
                autofocus: true,
                child: widget.child,
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class _AppDrawer extends StatelessWidget {
  final List<
    ({IconData icon, IconData? selectedIcon, String label, String route})
  >
  items;
  final int selectedIndex;

  const _AppDrawer({required this.items, required this.selectedIndex});

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;

    return Drawer(
      child: SafeArea(
        child: ListTileTheme(
          selectedColor: scheme.onSecondaryContainer,
          selectedTileColor: scheme.secondaryContainer,
          child: ListView(
            padding: const EdgeInsets.symmetric(vertical: 8),
            children: [
              const _LogoHeader(),
              const Divider(),
              for (var i = 0; i < items.length; i++)
                ListTile(
                  selected: i == selectedIndex,
                  leading: Icon(
                    i == selectedIndex
                        ? (items[i].selectedIcon ?? items[i].icon)
                        : items[i].icon,
                  ),
                  title: Text(items[i].label),
                  onTap: () {
                    Navigator.of(context).maybePop();
                    context.go(items[i].route);
                  },
                ),
              const Divider(),
              ListTile(
                leading: const Icon(Icons.settings_outlined),
                title: const Text('Einstellungen'),
                onTap: () {
                  Navigator.of(context).maybePop();
                  context.go('/settings');
                },
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _LogoHeader extends StatelessWidget {
  const _LogoHeader();

  @override
  Widget build(BuildContext context) {
    return const Padding(
      padding: EdgeInsets.all(16),
      child: Row(
        children: [
          Icon(Icons.account_balance_wallet, size: 28),
          SizedBox(width: 8),
        ],
      ),
    );
  }
}