app-boilerplate/lib/ui/navigation/main_navigation_scaffold.dart

import 'package:flutter/material.dart';
import '../home/home_screen.dart';
import '../immich/immich_screen.dart';
import '../nostr_events/nostr_events_screen.dart';
import '../session/session_screen.dart';
import '../settings/settings_screen.dart';
import '../../core/service_locator.dart';

/// Main navigation scaffold with bottom navigation bar.
class MainNavigationScaffold extends StatefulWidget {
  const MainNavigationScaffold({super.key});

  @override
  State<MainNavigationScaffold> createState() => _MainNavigationScaffoldState();
}

class _MainNavigationScaffoldState extends State<MainNavigationScaffold> {
  int _currentIndex = 0;
  int _loginStateVersion = 0; // Increment when login state changes
  int? _pendingProtectedRoute; // Track if user was trying to access a protected route

  void _onItemTapped(int index) {
    setState(() {
      _currentIndex = index;
      // If accessing a protected route (Immich=1, Nostr=2) while not logged in, remember it
      final sessionService = ServiceLocator.instance.sessionService;
      if ((index == 1 || index == 2) && !(sessionService?.isLoggedIn ?? false)) {
        _pendingProtectedRoute = index;
      } else {
        _pendingProtectedRoute = null;
      }
    });
  }

  /// Callback to notify that login state may have changed
  void _onSessionStateChanged() {
    setState(() {
      _loginStateVersion++; // Force rebuild when login state changes
      
      // If user just logged in and was trying to access a protected route, navigate there
      final sessionService = ServiceLocator.instance.sessionService;
      if (sessionService?.isLoggedIn == true && _pendingProtectedRoute != null) {
        _currentIndex = _pendingProtectedRoute!;
        _pendingProtectedRoute = null;
      }
    });
  }

  Widget _buildScreen(int index) {
    final locator = ServiceLocator.instance;
    final sessionService = locator.sessionService;
    
    switch (index) {
      case 0:
        return const HomeScreen();
      case 1:
        // Check auth guard for Immich
        if (!(sessionService?.isLoggedIn ?? false)) {
          return _buildLoginRequiredScreen();
        }
        return const ImmichScreen();
      case 2:
        // Check auth guard for Nostr Events
        if (!(sessionService?.isLoggedIn ?? false)) {
          return _buildLoginRequiredScreen();
        }
        return const NostrEventsScreen();
      case 3:
        return SessionScreen(
          onSessionChanged: _onSessionStateChanged,
        );
      case 4:
        return const SettingsScreen();
      default:
        return const SizedBox();
    }
  }

  Widget _buildLoginRequiredScreen() {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(
              Icons.lock_outline,
              size: 64,
              color: Colors.grey,
            ),
            const SizedBox(height: 16),
            const Text(
              'Please login to access this feature',
              style: TextStyle(fontSize: 16),
            ),
            const SizedBox(height: 24),
            ElevatedButton(
              onPressed: () {
                setState(() {
                  _currentIndex = 3; // Navigate to Session tab
                });
              },
              child: const Text('Go to Login'),
            ),
          ],
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    // Use login state version to force IndexedStack rebuild when login changes
    return Scaffold(
      body: IndexedStack(
        key: ValueKey('nav_$_currentIndex\_v$_loginStateVersion'),
        index: _currentIndex,
        children: List.generate(5, (index) => _buildScreen(index)),
      ),
      bottomNavigationBar: BottomNavigationBar(
        type: BottomNavigationBarType.fixed,
        currentIndex: _currentIndex,
        onTap: _onItemTapped,
        items: const [
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.photo_library),
            label: 'Immich',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.cloud),
            label: 'Nostr',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.person),
            label: 'Session',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.settings),
            label: 'Settings',
          ),
        ],
      ),
    );
  }
}