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

import '../providers/auth_provider.dart';
import '../providers/notifications_provider.dart';
import '../providers/profile_provider.dart';

class AppScaffold extends ConsumerWidget {
  const AppScaffold({super.key, required this.child});

  final Widget child;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final profileAsync = ref.watch(currentProfileProvider);
    final role = profileAsync.maybeWhen(
      data: (profile) => profile?.role ?? 'standard',
      orElse: () => 'standard',
    );
    final displayName = profileAsync.maybeWhen(
      data: (profile) {
        final name = profile?.fullName.trim() ?? '';
        return name.isNotEmpty ? name : 'User';
      },
      orElse: () => 'User',
    );

    final isStandard = role == 'standard';
    final location = GoRouterState.of(context).uri.toString();
    final sections = _buildSections(role);

    final width = MediaQuery.of(context).size.width;
    final showRail = !isStandard && width >= 860;
    final isExtended = !isStandard && width >= 1120;
    final showDrawer = !isStandard && !showRail;

    return Scaffold(
      appBar: AppBar(
        title: Row(
          children: [
            const Icon(Icons.memory),
            const SizedBox(width: 8),
            Text('TasQ'),
          ],
        ),
        actions: [
          if (isStandard)
            PopupMenuButton<int>(
              tooltip: 'Account',
              onSelected: (value) {
                if (value == 0) {
                  ref.read(authControllerProvider).signOut();
                }
              },
              itemBuilder: (context) => const [
                PopupMenuItem(value: 0, child: Text('Sign out')),
              ],
              child: Padding(
                padding: const EdgeInsets.symmetric(horizontal: 12),
                child: Row(
                  children: [
                    const Icon(Icons.account_circle),
                    const SizedBox(width: 8),
                    Text(displayName),
                    const SizedBox(width: 4),
                    const Icon(Icons.expand_more),
                  ],
                ),
              ),
            )
          else
            IconButton(
              tooltip: 'Sign out',
              onPressed: () => ref.read(authControllerProvider).signOut(),
              icon: const Icon(Icons.logout),
            ),
          const _NotificationBell(),
        ],
      ),
      drawer: showDrawer
          ? Drawer(
              child: AppSideNav(
                sections: sections,
                location: location,
                extended: true,
                displayName: displayName,
                onLogout: () => ref.read(authControllerProvider).signOut(),
              ),
            )
          : null,
      bottomNavigationBar: isStandard
          ? AppBottomNav(location: location, items: _standardNavItems())
          : null,
      body: Row(
        children: [
          if (showRail)
            AppSideNav(
              sections: sections,
              location: location,
              extended: isExtended,
              displayName: displayName,
              onLogout: () => ref.read(authControllerProvider).signOut(),
            ),
          Expanded(child: _ShellBackground(child: child)),
        ],
      ),
    );
  }
}

class AppSideNav extends StatelessWidget {
  const AppSideNav({
    super.key,
    required this.sections,
    required this.location,
    required this.extended,
    required this.displayName,
    required this.onLogout,
  });

  final List<NavSection> sections;
  final String location;
  final bool extended;
  final String displayName;
  final VoidCallback onLogout;

  @override
  Widget build(BuildContext context) {
    final width = extended ? 240.0 : 72.0;
    return Container(
      width: width,
      decoration: BoxDecoration(
        color: Theme.of(context).colorScheme.surface,
        border: Border(
          right: BorderSide(
            color: Theme.of(context).colorScheme.outlineVariant,
          ),
        ),
      ),
      child: ListView(
        padding: const EdgeInsets.symmetric(vertical: 12),
        children: [
          Padding(
            padding: EdgeInsets.symmetric(
              horizontal: extended ? 16 : 12,
              vertical: 8,
            ),
            child: Row(
              children: [
                Image.asset(
                  'assets/tasq_ico.png',
                  width: 28,
                  height: 28,
                  fit: BoxFit.contain,
                ),
                if (extended) ...[
                  const SizedBox(width: 12),
                  Expanded(
                    child: Text(
                      displayName,
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                      style: Theme.of(context).textTheme.titleSmall?.copyWith(
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  ),
                ],
              ],
            ),
          ),
          const SizedBox(height: 4),
          for (final section in sections) ...[
            if (section.label != null && extended)
              Padding(
                padding: const EdgeInsets.fromLTRB(16, 12, 16, 8),
                child: Text(
                  section.label!,
                  style: Theme.of(context).textTheme.labelMedium?.copyWith(
                    color: Theme.of(context).colorScheme.onSurfaceVariant,
                    letterSpacing: 0.4,
                  ),
                ),
              ),
            for (final item in section.items)
              _NavTile(
                item: item,
                selected: _isSelected(location, item.route),
                extended: extended,
                onLogout: onLogout,
              ),
          ],
        ],
      ),
    );
  }
}

class AppBottomNav extends StatelessWidget {
  const AppBottomNav({super.key, required this.location, required this.items});

  final String location;
  final List<NavItem> items;

  @override
  Widget build(BuildContext context) {
    final index = _currentIndex(location, items);
    return NavigationBar(
      selectedIndex: index,
      onDestinationSelected: (value) {
        final target = items[value].route;
        if (target.isNotEmpty) {
          context.go(target);
        }
      },
      destinations: [
        for (final item in items)
          NavigationDestination(
            icon: Icon(item.icon),
            selectedIcon: Icon(item.selectedIcon ?? item.icon),
            label: item.label,
          ),
      ],
    );
  }
}

class _NavTile extends StatelessWidget {
  const _NavTile({
    required this.item,
    required this.selected,
    required this.extended,
    required this.onLogout,
  });

  final NavItem item;
  final bool selected;
  final bool extended;
  final VoidCallback onLogout;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final iconColor = selected ? colorScheme.primary : colorScheme.onSurface;
    final background = selected
        ? colorScheme.primaryContainer.withValues(alpha: 0.6)
        : Colors.transparent;

    final content = Container(
      margin: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
      decoration: BoxDecoration(
        color: background,
        borderRadius: BorderRadius.circular(12),
      ),
      child: ListTile(
        leading: Icon(item.icon, color: iconColor),
        title: extended ? Text(item.label) : null,
        onTap: () => item.onTap(context, onLogout: onLogout),
        dense: true,
        visualDensity: VisualDensity.compact,
      ),
    );

    if (extended) {
      return content;
    }

    return Tooltip(message: item.label, child: content);
  }
}

class _NotificationBell extends ConsumerWidget {
  const _NotificationBell();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final unreadCount = ref.watch(unreadNotificationsCountProvider);
    return IconButton(
      tooltip: 'Notifications',
      onPressed: () => context.go('/notifications'),
      icon: Stack(
        clipBehavior: Clip.none,
        children: [
          const Icon(Icons.notifications),
          if (unreadCount > 0)
            const Positioned(
              right: -2,
              top: -2,
              child: Icon(Icons.circle, size: 10, color: Colors.red),
            ),
        ],
      ),
    );
  }
}

class _ShellBackground extends StatelessWidget {
  const _ShellBackground({required this.child});

  final Widget child;

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: Alignment.topLeft,
          end: Alignment.bottomRight,
          colors: [
            Theme.of(context).colorScheme.surface,
            Theme.of(context).colorScheme.surfaceContainerLowest,
          ],
        ),
      ),
      child: child,
    );
  }
}

class NavItem {
  NavItem({
    required this.label,
    required this.route,
    required this.icon,
    this.selectedIcon,
    this.isLogout = false,
  });

  final String label;
  final String route;
  final IconData icon;
  final IconData? selectedIcon;
  final bool isLogout;

  void onTap(BuildContext context, {VoidCallback? onLogout}) {
    if (isLogout) {
      onLogout?.call();
      return;
    }
    if (route.isNotEmpty) {
      context.go(route);
    }
  }
}

class NavSection {
  NavSection({this.label, required this.items});

  final String? label;
  final List<NavItem> items;
}

List<NavSection> _buildSections(String role) {
  final mainItems = [
    NavItem(
      label: 'Dashboard',
      route: '/dashboard',
      icon: Icons.grid_view,
      selectedIcon: Icons.grid_view_rounded,
    ),
    NavItem(
      label: 'Tickets',
      route: '/tickets',
      icon: Icons.support_agent_outlined,
      selectedIcon: Icons.support_agent,
    ),
    NavItem(
      label: 'Tasks',
      route: '/tasks',
      icon: Icons.task_outlined,
      selectedIcon: Icons.task,
    ),
    NavItem(
      label: 'Events',
      route: '/events',
      icon: Icons.event_outlined,
      selectedIcon: Icons.event,
    ),
    NavItem(
      label: 'Announcement',
      route: '/announcements',
      icon: Icons.campaign_outlined,
      selectedIcon: Icons.campaign,
    ),
    NavItem(
      label: 'Workforce',
      route: '/workforce',
      icon: Icons.groups_outlined,
      selectedIcon: Icons.groups,
    ),
    NavItem(
      label: 'Reports',
      route: '/reports',
      icon: Icons.analytics_outlined,
      selectedIcon: Icons.analytics,
    ),
  ];

  if (role == 'admin') {
    return [
      NavSection(label: 'Operations', items: mainItems),
      NavSection(
        label: 'Settings',
        items: [
          NavItem(
            label: 'User Management',
            route: '/settings/users',
            icon: Icons.admin_panel_settings_outlined,
            selectedIcon: Icons.admin_panel_settings,
          ),
          NavItem(
            label: 'Office Management',
            route: '/settings/offices',
            icon: Icons.apartment_outlined,
            selectedIcon: Icons.apartment,
          ),
          NavItem(
            label: 'Logout',
            route: '',
            icon: Icons.logout,
            isLogout: true,
          ),
        ],
      ),
    ];
  }

  return [NavSection(label: 'Operations', items: mainItems)];
}

List<NavItem> _standardNavItems() {
  return [
    NavItem(
      label: 'Dashboard',
      route: '/dashboard',
      icon: Icons.grid_view,
      selectedIcon: Icons.grid_view_rounded,
    ),
    NavItem(
      label: 'Tickets',
      route: '/tickets',
      icon: Icons.support_agent_outlined,
      selectedIcon: Icons.support_agent,
    ),
    NavItem(
      label: 'Tasks',
      route: '/tasks',
      icon: Icons.task_outlined,
      selectedIcon: Icons.task,
    ),
    NavItem(
      label: 'Events',
      route: '/events',
      icon: Icons.event_outlined,
      selectedIcon: Icons.event,
    ),
  ];
}

bool _isSelected(String location, String route) {
  if (route.isEmpty) return false;
  if (location == route) return true;
  return location.startsWith('$route/');
}

int _currentIndex(String location, List<NavItem> items) {
  final index = items.indexWhere((item) => _isSelected(location, item.route));
  return index == -1 ? 0 : index;
}