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

class _Destination {
  const _Destination(this.path, this.icon, this.selectedIcon, this.label);
  final String path;
  final IconData icon;
  final IconData selectedIcon;
  final String label;
}

const _destinations = [
  _Destination('/', Icons.dashboard_outlined, Icons.dashboard, 'Обзор'),
  _Destination('/accounts', Icons.account_balance_outlined, Icons.account_balance, 'Счета'),
  _Destination('/portfolio', Icons.pie_chart_outline, Icons.pie_chart, 'Портфель'),
  _Destination('/events', Icons.event_note_outlined, Icons.event_note, 'События'),
  _Destination('/cashflow', Icons.swap_horiz_outlined, Icons.swap_horiz, 'Потоки'),
  _Destination('/categories', Icons.category_outlined, Icons.category, 'Категории'),
  _Destination(
      '/transactions', Icons.receipt_long_outlined, Icons.receipt_long, 'Операции'),
  _Destination('/rules', Icons.rule_folder_outlined, Icons.rule_folder, 'Правила'),
  _Destination('/sync', Icons.sync_outlined, Icons.sync, 'Синк'),
  _Destination('/settings', Icons.settings_outlined, Icons.settings, 'Настройки'),
];

/// Breakpoints per the plan: bottom bar under 600, collapsed rail 600–1200,
/// extended rail at 1200 and above.
const _narrowBreakpoint = 600.0;
const _wideBreakpoint = 1200.0;

/// Adaptive navigation shell around the current route: a bottom
/// [NavigationBar] on narrow surfaces, a [NavigationRail] (collapsed or
/// extended) otherwise.
class AppShell extends StatelessWidget {
  const AppShell({required this.location, required this.child, super.key});

  final String location;
  final Widget child;

  int get _selectedIndex {
    // longest prefix wins, so /portfolio/instrument/311 keeps Портфель selected
    var best = -1;
    for (var i = 0; i < _destinations.length; i++) {
      final path = _destinations[i].path;
      final matches = path == '/' ? location == '/' : location.startsWith(path);
      if (matches && (best == -1 || path.length > _destinations[best].path.length)) best = i;
    }
    return best == -1 ? 0 : best;
  }

  void _onSelect(BuildContext context, int index) {
    if (index != _selectedIndex) context.go(_destinations[index].path);
  }

  @override
  Widget build(BuildContext context) {
    final width = MediaQuery.sizeOf(context).width;

    if (width < _narrowBreakpoint) {
      return Scaffold(
        body: SafeArea(child: child),
        bottomNavigationBar: NavigationBar(
          selectedIndex: _selectedIndex,
          onDestinationSelected: (i) => _onSelect(context, i),
          destinations: [
            for (final d in _destinations)
              NavigationDestination(
                icon: Icon(d.icon),
                selectedIcon: Icon(d.selectedIcon),
                label: d.label,
              ),
          ],
        ),
      );
    }

    final extended = width >= _wideBreakpoint;
    return Scaffold(
      body: Row(
        children: [
          NavigationRail(
            extended: extended,
            minExtendedWidth: 220,
            selectedIndex: _selectedIndex,
            onDestinationSelected: (i) => _onSelect(context, i),
            labelType: extended ? NavigationRailLabelType.none : NavigationRailLabelType.selected,
            destinations: [
              for (final d in _destinations)
                NavigationRailDestination(
                  icon: Icon(d.icon),
                  selectedIcon: Icon(d.selectedIcon),
                  label: Text(d.label),
                ),
            ],
          ),
          const VerticalDivider(width: 1),
          Expanded(child: SafeArea(child: child)),
        ],
      ),
    );
  }
}