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

import '../../features/auth/presentation/controllers/dev_auth_bypass.dart';

/// Adaptive application shell.
///
/// * Desktop / tablet (>= 1024 dp): a seven-destination [NavigationRail]
///   (Medication, Nutrition, Exercise, Meal Plan, Recipes, Pantry,
///   Settings) with `labelType` set to `all`; the rail is wrapped in a
///   scrollable constrained to the available height so compact vertical
///   windows never overflow.
/// * Mobile: the four core daily actions live in the bottom
///   [NavigationBar]; secondary destinations (Exercise, Recipes, Settings)
///   are routed through an adaptive drawer opened from the "More" tab.
class AdaptiveHomeScaffold extends ConsumerWidget {
  final Widget child;

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

  /// Key for the mobile scaffold so the "More" bottom-bar tab can open the
  /// secondary-destinations drawer (the build context cannot reach a
  /// Scaffold constructed in the same method via [Scaffold.of]).
  ///
  /// Static: the shell is a singleton route scaffold.
  static final GlobalKey<ScaffoldState> _mobileScaffoldKey =
      GlobalKey<ScaffoldState>();

  /// Desktop rail destinations in navigation order.
  static const _railDestinations = [
    NavigationRailDestination(
      icon: Icon(Icons.medication_liquid_outlined),
      selectedIcon: Icon(Icons.medication_liquid),
      label: Text('Medication'),
    ),
    NavigationRailDestination(
      icon: Icon(Icons.restaurant_outlined),
      selectedIcon: Icon(Icons.restaurant),
      label: Text('Nutrition'),
    ),
    NavigationRailDestination(
      icon: Icon(Icons.fitness_center_outlined),
      selectedIcon: Icon(Icons.fitness_center),
      label: Text('Exercise'),
    ),
    NavigationRailDestination(
      icon: Icon(Icons.calendar_month_outlined),
      selectedIcon: Icon(Icons.calendar_month),
      label: Text('Meal Plan'),
    ),
    NavigationRailDestination(
      icon: Icon(Icons.menu_book_outlined),
      selectedIcon: Icon(Icons.menu_book),
      label: Text('Recipes'),
    ),
    NavigationRailDestination(
      icon: Icon(Icons.inventory_2_outlined),
      selectedIcon: Icon(Icons.inventory_2),
      label: Text('Pantry'),
    ),
    NavigationRailDestination(
      icon: Icon(Icons.settings_outlined),
      selectedIcon: Icon(Icons.settings),
      label: Text('Settings'),
    ),
  ];

  /// Maps a location to its desktop rail index (0..6); secondary routes
  /// that share a rail slot resolve to that slot.
  int _railIndexFor(String location) {
    if (location.startsWith('/medication')) return 0;
    if (location.startsWith('/nutrition')) return 1;
    if (location.startsWith('/exercise')) return 2;
    if (location.startsWith('/meal-planner')) return 3;
    if (location.startsWith('/recipes')) return 4;
    if (location.startsWith('/pantry')) return 5;
    if (location.startsWith('/settings')) return 6;
    return 0;
  }

  /// Maps a location to its bottom-bar index; secondary destinations
  /// (exercise / recipes / settings) highlight the "More" tab.
  int _bottomIndexFor(String location) {
    if (location.startsWith('/medication')) return 0;
    if (location.startsWith('/nutrition')) return 1;
    if (location.startsWith('/meal-planner')) return 2;
    if (location.startsWith('/pantry')) return 3;
    return 4; // exercise, recipes, settings -> More
  }

  void _onRailSelected(int index, BuildContext context) {
    switch (index) {
      case 0:
        context.go('/medication');
        break;
      case 1:
        context.go('/nutrition');
        break;
      case 2:
        context.go('/exercise');
        break;
      case 3:
        context.go('/meal-planner');
        break;
      case 4:
        context.go('/recipes');
        break;
      case 5:
        context.go('/pantry');
        break;
      case 6:
        context.go('/settings');
        break;
    }
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final width = MediaQuery.of(context).size.width;
    final isDesktop = width >= 1024;
    final location = GoRouterState.of(context).uri.toString();
    // Visual marker while the debug auth bypass is active, so a review
    // session can never be mistaken for a signed-in one.
    final showDevBanner = kDebugMode && ref.watch(devAuthBypassProvider);

    if (isDesktop) {
      return Scaffold(
        body: Column(
          children: [
            if (showDevBanner) const _DevAccessBanner(),
            Expanded(
              child: Row(
                children: [
                  // Wrap the rail in a height-constrained scroll view so a
                  // compact vertical window (or browser zoom) scrolls the
                  // destinations instead of overflowing the render flex.
                  LayoutBuilder(
                    builder: (context, constraints) => SingleChildScrollView(
                      child: ConstrainedBox(
                        constraints:
                            BoxConstraints(minHeight: constraints.maxHeight),
                        child: IntrinsicHeight(
                          child: NavigationRail(
                            selectedIndex: _railIndexFor(location),
                            onDestinationSelected: (idx) =>
                                _onRailSelected(idx, context),
                            labelType: NavigationRailLabelType.all,
                            destinations: _railDestinations,
                          ),
                        ),
                      ),
                    ),
                  ),
                  const VerticalDivider(thickness: 1, width: 1),
                  Expanded(child: child),
                ],
              ),
            ),
          ],
        ),
      );
    }

    final selectedIndex = _bottomIndexFor(location);

    return Scaffold(
      key: _mobileScaffoldKey,
      body: Column(
        children: [
          if (showDevBanner) const _DevAccessBanner(),
          Expanded(child: child),
        ],
      ),
      drawer: const _SecondaryDestinationsDrawer(),
      bottomNavigationBar: NavigationBar(
        selectedIndex: selectedIndex,
        onDestinationSelected: (index) {
          if (index == 4) {
            // "More": open the drawer with secondary destinations.
            _mobileScaffoldKey.currentState?.openDrawer();
            return;
          }
          switch (index) {
            case 0:
              context.go('/medication');
              break;
            case 1:
              context.go('/nutrition');
              break;
            case 2:
              context.go('/meal-planner');
              break;
            case 3:
              context.go('/pantry');
              break;
          }
        },
        destinations: const [
          NavigationDestination(
            icon: Icon(Icons.medication_liquid_outlined),
            selectedIcon: Icon(Icons.medication_liquid),
            label: 'Meds',
          ),
          NavigationDestination(
            icon: Icon(Icons.restaurant_outlined),
            selectedIcon: Icon(Icons.restaurant),
            label: 'Food',
          ),
          NavigationDestination(
            icon: Icon(Icons.calendar_month_outlined),
            selectedIcon: Icon(Icons.calendar_month),
            label: 'Plan',
          ),
          NavigationDestination(
            icon: Icon(Icons.inventory_2_outlined),
            selectedIcon: Icon(Icons.inventory_2),
            label: 'Pantry',
          ),
          NavigationDestination(
            icon: Icon(Icons.more_horiz),
            selectedIcon: Icon(Icons.more_horiz),
            label: 'More',
          ),
        ],
      ),
    );
  }
}

/// Mobile drawer holding the secondary destinations that do not fit the
/// four-slot bottom bar (Exercise, Recipes, Settings).
class _SecondaryDestinationsDrawer extends StatelessWidget {
  const _SecondaryDestinationsDrawer();

  @override
  Widget build(BuildContext context) {
    final location = GoRouterState.of(context).uri.toString();

    return Drawer(
      child: SafeArea(
        child: ListView(
          padding: EdgeInsets.zero,
          children: [
            Padding(
              padding: const EdgeInsets.all(16),
              child: Text(
                'More',
                style: Theme.of(context)
                    .textTheme
                    .titleMedium
                    ?.copyWith(fontWeight: FontWeight.bold),
              ),
            ),
            const Divider(height: 1),
            ListTile(
              leading: const Icon(Icons.fitness_center_outlined),
              title: const Text('Exercise'),
              selected: location.startsWith('/exercise'),
              onTap: () {
                Navigator.of(context).pop();
                context.go('/exercise');
              },
            ),
            ListTile(
              leading: const Icon(Icons.menu_book_outlined),
              title: const Text('Recipes'),
              selected: location.startsWith('/recipes'),
              onTap: () {
                Navigator.of(context).pop();
                context.go('/recipes');
              },
            ),
            ListTile(
              leading: const Icon(Icons.settings_outlined),
              title: const Text('Settings'),
              selected: location.startsWith('/settings'),
              onTap: () {
                Navigator.of(context).pop();
                context.go('/settings');
              },
            ),
          ],
        ),
      ),
    );
  }
}

/// Slim status strip shown while the development auth bypass is active.
class _DevAccessBanner extends StatelessWidget {
  const _DevAccessBanner();

  @override
  Widget build(BuildContext context) {
    return Material(
      color: Colors.orange,
      child: SafeArea(
        bottom: false,
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 6),
          child: Row(
            children: [
              const Icon(Icons.bug_report_outlined,
                  size: 16, color: Colors.white),
              const SizedBox(width: 8),
              Expanded(
                child: Text(
                  'Development mode - not signed in',
                  style: Theme.of(context).textTheme.labelMedium?.copyWith(
                        color: Colors.white,
                      ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}