starting a gym app here i need to utilize dart full-stack mode any tips, i have coupled the main parts of the app into a single file the home code, admin code, router code and services

gym.dart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'screens/home_screen.dart';
import 'screens/services_screen.dart';
import 'screens/shop_screen.dart';
import 'screens/contact_screen.dart';
import 'screens/admin_screen.dart';
import 'widgets/volt_nav_bar.dart';

void main() {
  runApp(const ProviderScope(child: VoltApp()));
}

class VoltApp extends ConsumerWidget {
  const VoltApp({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final themeMode = ref.watch(themeModeProvider);
    final router = ref.watch(routerProvider);

    return MaterialApp.router(
      title: 'Volt Kinetic',
      debugShowCheckedModeBanner: false,
      theme: VoltTheme.lightTheme,
      darkTheme: VoltTheme.darkTheme,
      themeMode: themeMode,
      routerConfig: router,
    );
  }
}


final routerProvider = Provider<GoRouter>((ref) {
  return GoRouter(
    initialLocation: '/',
    routes: [
      ShellRoute(
        builder: (context, state, child) {
          return MainScaffold(state: state, child: child);
        },
        routes: [
          GoRoute(path: '/', builder: (context, state) => const HomeScreen()),
          GoRoute(
            path: '/services',
            builder: (context, state) => const ServicesScreen(),
          ),
          GoRoute(
            path: '/shop',
            builder: (context, state) => const ShopScreen(),
          ),
          GoRoute(
            path: '/contact',
            builder: (context, state) => const ContactScreen(),
          ),
          GoRoute(
            path: '/admin',
            builder: (context, state) => const AdminScreen(),
          ),
        ],
      ),
    ],
  );
});

class MainScaffold extends StatelessWidget {
  final Widget child;
  final GoRouterState state;
  const MainScaffold({super.key, required this.child, required this.state});

  @override
  Widget build(BuildContext context) {
    // Determine active index safely from state.matchedLocation
    final String location = state.matchedLocation;
    int activeIndex = 0;
    if (location.startsWith('/services')) {
      activeIndex = 1;
    } else if (location.startsWith('/shop')) {
      activeIndex = 2;
    } else if (location.startsWith('/contact')) {
      activeIndex = 3;
    } else if (location.startsWith('/admin')) {
      activeIndex = 4;
    }

    return Scaffold(
      backgroundColor: Colors.black, // Ensure we have a base color
      body: child,
      // Using a Stack to place the Nav Bar to ensure it doesn't displace the body
      // and allows for proper 'floating' aesthetic requested earlier.
      bottomNavigationBar: SizedBox(
        height: 110, // Explicit height for bottomNavigationBar area
        child: VoltNavBar(
          activeIndex: activeIndex,
          onIndexChanged: (index) {
            switch (index) {
              case 0:
                context.go('/');
                break;
              case 1:
                context.go('/services');
                break;
              case 2:
                context.go('/shop');
                break;
              case 3:
                context.go('/contact');
                break;
              case 4:
                context.go('/admin');
                break;
            }
          },
        ),
      ),
    );
  }
}

class ApiService {
  static const String baseUrl = 'http://127.0.0.1:5000/api';

  static Future<List<dynamic>> getServices() async {
    final response = await http.get(Uri.parse('$baseUrl/services'));
    if (response.statusCode == 200) {
      return json.decode(response.body);
    }
    throw Exception('Failed to load services');
  }

  static Future<List<dynamic>> getProducts() async {
    final response = await http.get(Uri.parse('$baseUrl/products'));
    if (response.statusCode == 200) {
      return json.decode(response.body);
    }
    throw Exception('Failed to load products');
  }

  static Future<void> submitInquiry(Map<String, String> data) async {
    final response = await http.post(
      Uri.parse('$baseUrl/inquiries'),
      headers: {'Content-Type': 'application/json'},
      body: json.encode(data),
    );
    if (response.statusCode != 201) {
      throw Exception('Failed to submit inquiry');
    }
  }

  // Admin methods
  static Future<void> addService(Map<String, dynamic> data) async {
    await http.post(
      Uri.parse('$baseUrl/admin/services'),
      headers: {'Content-Type': 'application/json'},
      body: json.encode(data),
    );
  }

  static Future<void> updateService(int id, Map<String, dynamic> data) async {
    await http.put(
      Uri.parse('$baseUrl/admin/services/$id'),
      headers: {'Content-Type': 'application/json'},
      body: json.encode(data),
    );
  }

  static Future<void> deleteService(int id) async {
    await http.delete(Uri.parse('$baseUrl/admin/services/$id'));
  }

  static Future<void> addProduct(Map<String, dynamic> data) async {
    await http.post(
      Uri.parse('$baseUrl/admin/products'),
      headers: {'Content-Type': 'application/json'},
      body: json.encode(data),
    );
  }

  static Future<void> updateProduct(int id, Map<String, dynamic> data) async {
    await http.put(
      Uri.parse('$baseUrl/admin/products/$id'),
      headers: {'Content-Type': 'application/json'},
      body: json.encode(data),
    );
  }

  static Future<void> deleteProduct(int id) async {
    await http.delete(Uri.parse('$baseUrl/admin/products/$id'));
  }
}


class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen>
    with SingleTickerProviderStateMixin {
  late AnimationController _pulseController;
  List<dynamic>? _services;
  bool _isLoading = true;

  @override
  void initState() {
    super.initState();
    _pulseController = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 4),
    )..repeat(reverse: true);
    _loadData();
  }

  Future<void> _loadData() async {
    try {
      final services = await ApiService.getServices();
      if (mounted) {
        setState(() {
          _services = services;
          _isLoading = false;
        });
      }
    } catch (e) {
      if (mounted) {
        setState(() {
          _services = _getStaticData();
          _isLoading = false;
        });
      }
    }
  }

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

  @override
  Widget build(BuildContext context) {
    final scale = VoltResponsive.scale(context);
    final isMobile = VoltResponsive.isMobile(context);
    final screenWidth = MediaQuery.of(context).size.width;

    double sidePadding = isMobile ? 24.0 : 60.0;
    if (screenWidth > 1400) {
      sidePadding = (screenWidth - 1400) / 2 + 60.0;
    }

    return Scaffold(
      body: CustomScrollView(
        physics: const BouncingScrollPhysics(),
        slivers: [
          _buildSliverAppBar(scale, isMobile ? 24.0 : 60.0),
          SliverToBoxAdapter(
            child: Padding(
              padding: EdgeInsets.symmetric(horizontal: sidePadding),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: AnimationConfiguration.toStaggeredList(
                  duration: const Duration(milliseconds: 800),
                  childAnimationBuilder: (widget) => SlideAnimation(
                    verticalOffset: 50.0,
                    curve: Curves.easeOutQuart,
                    child: FadeInAnimation(child: widget),
                  ),
                  children: [
                    const SizedBox(height: 60),
                    _buildHeroText(context, scale, isMobile),
                    const SizedBox(height: 80),
                    _isLoading
                        ? const Center(
                            child: CircularProgressIndicator(
                              color: VoltColors.primaryFixedDim,
                            ),
                          )
                        : _buildFeaturedServices(context, scale, isMobile),
                    const SizedBox(height: 160),
                  ],
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildSliverAppBar(double scale, double sidePadding) {
    return SliverAppBar(
      expandedHeight: 120.0 * scale,
      backgroundColor: Theme.of(context).scaffoldBackgroundColor,
      toolbarHeight: 80,
      title: const VoltLogo(scale: 1.1),
      pinned: true,
      flexibleSpace: FlexibleSpaceBar(
        background: Container(
          decoration: BoxDecoration(
            gradient: RadialGradient(
              center: Alignment.topLeft,
              radius: 1.5,
              colors: [
                VoltColors.primaryFixedDim.withValues(alpha: 0.05),
                Colors.transparent,
              ],
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildHeroText(BuildContext context, double scale, bool isMobile) {
    final theme = Theme.of(context);
    final displayStyle = theme.textTheme.displayLarge;
    final fontSize = (isMobile ? 48.0 : 72.0) * scale;
    final onSurface = theme.colorScheme.onSurface;

    return Stack(
      clipBehavior: Clip.none,
      children: [
        Positioned(
          right: -40,
          top: -100,
          child: Opacity(
            opacity: 0.25,
            child: Image.asset(
              'assets/images/home.png',
              width: 350 * scale,
              height: 500 * scale,
              fit: BoxFit.contain,
              errorBuilder: (_, _, _) => const SizedBox(),
            ),
          ),
        ),
        Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              'THE',
              style: displayStyle?.copyWith(
                color: onSurface,
                fontSize: fontSize,
                letterSpacing: -2,
              ),
            ),
            ShaderMask(
              shaderCallback: (b) => VoltColors.primaryGradient.createShader(b),
              child: Text(
                'ELECTRIC',
                style: displayStyle?.copyWith(
                  fontSize: fontSize,
                  color: Colors.white,
                  letterSpacing: -2,
                ),
              ),
            ),
            Text(
              'PULSE.',
              style: displayStyle?.copyWith(
                color: onSurface,
                fontSize: fontSize,
                letterSpacing: -2,
              ),
            ),
            const SizedBox(height: 24),
            SizedBox(
              width: (isMobile ? 300.0 : 450.0) * scale,
              child: Text(
                'HIGH INTENSITY MEETS HIGH SOPHISTICATION. EXPERIENCE THE NEW STANDARD OF MOTION.',
                style: theme.textTheme.bodyLarge?.copyWith(
                  height: 1.6,
                  color: onSurface.withValues(alpha: 0.7),
                  fontSize: (isMobile ? 15.0 : 18.0) * scale,
                ),
              ),
            ),
          ],
        ),
      ],
    );
  }

  Widget _buildFeaturedServices(
    BuildContext context,
    double scale,
    bool isMobile,
  ) {
    final services = _services!;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const VoltSectionHeader(title: 'SERVICES', actionText: 'EXPLORE ALL'),
        const SizedBox(height: 32),
        SizedBox(
          height: 300 * scale,
          child: ListView.builder(
            scrollDirection: Axis.horizontal,
            physics: const BouncingScrollPhysics(),
            itemCount: services.length,
            itemBuilder: (context, index) {
              return Padding(
                padding: const EdgeInsets.only(right: 24.0),
                child: VoltServiceCard(
                  title: services[index]['title'],
                  category: services[index]['category'],
                  description: services[index]['description'],
                  imageUrl: services[index]['image_url'],
                  scale: isMobile ? 1.0 : 0.85,
                ),
              );
            },
          ),
        ),
      ],
    );
  }

  List<dynamic> _getStaticData() {
    return [
      {'title': 'HYPER TROPHY', 'category': 'STRENGTH'},
      {'title': 'OXYGEN METRICS', 'category': 'CARDIO'},
      {'title': 'NEURAL FLEX', 'category': 'YOGA'},
    ];
  }
}


class AdminScreen extends StatefulWidget {
  const AdminScreen({super.key});

  @override
  State<AdminScreen> createState() => _AdminScreenState();
}

class _AdminScreenState extends State<AdminScreen> {
  final _titleController = TextEditingController();
  final _descController = TextEditingController();
  final _priceController = TextEditingController();
  bool _isService = true;
  bool _isSubmitting = false;

  void _addItem() async {
    if (_titleController.text.isEmpty) return;
    
    setState(() => _isSubmitting = true);
    final Map<String, dynamic> data = {
      'title': _titleController.text,
      'description': _descController.text,
    };

    try {
      if (_isService) {
        data['category'] = 'STRENGTH';
        await ApiService.addService(data);
      } else {
        data['price'] = double.tryParse(_priceController.text) ?? 0.0;
        await ApiService.addProduct(data);
      }

      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Operational Objective Complete')),
      );
      _titleController.clear();
      _descController.clear();
      _priceController.clear();
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Sync Error.')),
      );
    } finally {
      if (mounted) setState(() => _isSubmitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final scale = VoltResponsive.scale(context);
    final sidePadding = VoltResponsive.isMobile(context) ? 24.0 : 40.0;

    return Scaffold(
      backgroundColor: VoltColors.surface,
      body: CustomScrollView(
        physics: const BouncingScrollPhysics(),
        slivers: [
          _buildSliverAppBar(scale, sidePadding),
          SliverToBoxAdapter(
            child: Center(
              child: ConstrainedBox(
                constraints: const BoxConstraints(maxWidth: 1000),
                child: Padding(
                  padding: EdgeInsets.symmetric(horizontal: sidePadding, vertical: 40 * scale),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      _buildStats(scale),
                      const SizedBox(height: 48),
                      _buildControlPanel(scale),
                      const SizedBox(height: 160), // Nav spacer
                    ],
                  ),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildSliverAppBar(double scale, double sidePadding) {
    return SliverAppBar(
      expandedHeight: 180.0 * scale,
      backgroundColor: VoltColors.surface,
      title: const VoltLogo(scale: 1.1),
      pinned: true,
      flexibleSpace: FlexibleSpaceBar(
        background: Padding(
          padding: EdgeInsets.only(bottom: 40 * scale, left: sidePadding),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.end,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                'SYSTEM ADMIN',
                style: VoltTheme.darkTheme.textTheme.displayMedium?.copyWith(
                  fontSize: 38 * scale,
                  letterSpacing: -1,
                ),
              ),
              Text(
                'INFRASTRUCTURE MANAGEMENT',
                style: VoltTheme.darkTheme.textTheme.labelMedium?.copyWith(
                  color: VoltColors.primaryFixedDim,
                  fontSize: 12 * scale,
                  letterSpacing: 4,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildStats(double scale) {
    return Column(
      children: [
        VoltActionCard(
          title: 'SYSTEM STATUS',
          subtitle: 'OPERATIONAL - SYNCED',
          icon: Icons.check_circle_outline,
          scale: scale * 0.9,
        ),
        const SizedBox(height: 16),
        VoltActionCard(
          title: 'DATABASE NODES',
          subtitle: 'FLASK API ACTIVE @ PORT 5000',
          icon: Icons.storage_outlined,
          scale: scale * 0.9,
        ),
      ],
    );
  }

  Widget _buildControlPanel(double scale) {
    return Container(
      padding: EdgeInsets.all(32 * scale),
      decoration: BoxDecoration(
        color: VoltColors.surfaceContainerLow,
        borderRadius: BorderRadius.circular(30),
        border: Border.all(color: VoltColors.surfaceContainerHighest),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          _buildTypeToggle(scale),
          const SizedBox(height: 40),
          _buildField('OBJECTIVE NAME (TITLE)', _titleController, scale),
          const SizedBox(height: 24),
          _buildField('INTEL (DESCRIPTION)', _descController, scale, maxLines: 4),
          if (!_isService) ...[
            const SizedBox(height: 24),
            _buildField('VALUATION (PRICE)', _priceController, scale, isNum: true),
          ],
          const SizedBox(height: 48),
          _buildActionButton(scale),
        ],
      ),
    );
  }

  Widget _buildTypeToggle(double scale) {
    return Container(
      height: 54 * scale,
      decoration: BoxDecoration(color: VoltColors.surfaceContainerLow, borderRadius: BorderRadius.circular(27 * scale)),
      child: Row(
        children: [
          _buildToggle('SERVICE', _isService, () => setState(() => _isService = true), scale),
          _buildToggle('PRODUCT', !_isService, () => setState(() => _isService = false), scale),
        ],
      ),
    );
  }

  Widget _buildToggle(String label, bool active, VoidCallback onTap, double scale) {
    return Expanded(
      child: GestureDetector(
        onTap: onTap,
        child: AnimatedContainer(
          duration: const Duration(milliseconds: 300),
          alignment: Alignment.center,
          decoration: BoxDecoration(color: active ? VoltColors.primaryFixedDim : Colors.transparent, borderRadius: BorderRadius.circular(27 * scale)),
          child: Text(label, style: VoltTheme.darkTheme.textTheme.labelMedium?.copyWith(color: active ? Colors.black : VoltColors.onSurfaceVariant, fontWeight: FontWeight.bold, fontSize: 13 * scale)),
        ),
      ),
    );
  }

  Widget _buildField(String label, TextEditingController controller, double scale, {int maxLines = 1, bool isNum = false}) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(label, style: VoltTheme.darkTheme.textTheme.labelMedium?.copyWith(color: VoltColors.onSurfaceVariant, fontSize: 11 * scale, letterSpacing: 2)),
        const SizedBox(height: 12),
        TextField(
          controller: controller,
          maxLines: maxLines,
          keyboardType: isNum ? const TextInputType.numberWithOptions(decimal: true) : TextInputType.text,
          style: VoltTheme.darkTheme.textTheme.bodyLarge?.copyWith(fontSize: 17 * scale),
          decoration: InputDecoration(
            filled: true,
            fillColor: VoltColors.surfaceContainerHigh.withValues(alpha: 0.5),
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(16 * scale), borderSide: BorderSide.none),
          ),
        ),
      ],
    );
  }

  Widget _buildActionButton(double scale) {
    return InkWell(
      onTap: _isSubmitting ? null : _addItem,
      child: AnimatedContainer(
        duration: const Duration(milliseconds: 300),
        height: 64 * scale,
        decoration: BoxDecoration(gradient: _isSubmitting ? null : VoltColors.primaryGradient, color: _isSubmitting ? VoltColors.surfaceContainerLow : null, borderRadius: BorderRadius.circular(32 * scale)),
        child: Center(child: _isSubmitting ? const CircularProgressIndicator(color: Colors.black) : Text('SYNC SYSTEM DATA', style: VoltTheme.darkTheme.textTheme.labelMedium?.copyWith(color: Colors.black, fontSize: 15 * scale, fontWeight: FontWeight.bold))),
      ),
    );
  }
}