GoRouter - Declarative Navigation

# pubspec.yaml
dependencies:
  go_router: ^12.0.0

final router = GoRouter(
  initialLocation: '/',
  routes: [
    GoRoute(
      path: '/',
      builder: (context, state) => HomeScreen(),
    ),
    GoRoute(
      path: '/profile',
      builder: (context, state) => ProfileScreen(),
    ),
    GoRoute(
      path: '/settings',
      builder: (context, state) => SettingsScreen(),
    ),
  ],
);

MaterialApp.router(
  routerConfig: router,
)

context.go('/profile');

context.push('/profile');

context.pop();

context.replace('/home');

1. context.go('/b')
   Stack: [/a]  ──▶  Stack: [/b]         (Thay thế hoàn toàn stack cũ nếu cần)

2. context.push('/b')
   Stack: [/a]  ──▶  Stack: [/a, /b]     (Thêm vào đỉnh stack)

3. context.replace('/b')
   Stack: [/a]  ──▶  Stack: [/b]         (Thay thế route hiện tại)

GoRoute(
  path: '/user/:id',
  builder: (context, state) {
    final userId = state.pathParameters['id']!;
    return UserScreen(userId: userId);
  },
),
 
// Navigate
context.go('/user/123');

GoRoute(
  path: '/search',
  builder: (context, state) {
    final query = state.uri.queryParameters['q'] ?? '';
    return SearchScreen(query: query);
  },
),
 
// Navigate
context.go('/search?q=flutter');

// Navigate với extra
context.go('/product', extra: Product(id: 1, name: 'iPhone'));
 
// Nhận trong route
GoRoute(
  path: '/product',
  builder: (context, state) {
    final product = state.extra as Product;
    return ProductScreen(product: product);
  },
),

GoRoute(
  path: '/shop',
  builder: (context, state) => ShopScreen(),
  routes: [
    GoRoute(
      path: 'products',  // /shop/products
      builder: (context, state) => ProductsScreen(),
      routes: [
        GoRoute(
          path: ':id',  // /shop/products/123
          builder: (context, state) {
            final id = state.pathParameters['id']!;
            return ProductDetailScreen(id: id);
          },
        ),
      ],
    ),
    GoRoute(
      path: 'cart',  // /shop/cart
      builder: (context, state) => CartScreen(),
    ),
  ],
),

final router = GoRouter(
  redirect: (context, state) {
    final isLoggedIn = authService.isLoggedIn;
    final isLoggingIn = state.matchedLocation == '/login';
 
    if (!isLoggedIn && !isLoggingIn) {
      return '/login';  // Redirect to login
    }
    if (isLoggedIn && isLoggingIn) {
      return '/';  // Redirect to home
    }
    return null;  // No redirect
  },
  routes: [...],
);

ShellRoute(
  builder: (context, state, child) {
    return Scaffold(
      body: child,
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
          BottomNavigationBarItem(icon: Icon(Icons.search), label: 'Search'),
          BottomNavigationBarItem(icon: Icon(Icons.person), label: 'Profile'),
        ],
        currentIndex: _calculateSelectedIndex(state),
        onTap: (index) => _onItemTapped(index, context),
      ),
    );
  },
  routes: [
    GoRoute(path: '/', builder: (_, __) => HomeScreen()),
    GoRoute(path: '/search', builder: (_, __) => SearchScreen()),
    GoRoute(path: '/profile', builder: (_, __) => ProfileScreen()),
  ],
),

final router = GoRouter(
  errorBuilder: (context, state) {
    return Scaffold(
      body: Center(
        child: Text('Page not found: ${state.uri}'),
      ),
    );
  },
  routes: [...],
);

class AppRouter {
  static final router = GoRouter(
    initialLocation: '/',
    redirect: _guard,
    errorBuilder: (context, state) => NotFoundScreen(),
    routes: [
      GoRoute(
        path: '/login',
        builder: (context, state) => LoginScreen(),
      ),
      ShellRoute(
        builder: (context, state, child) => MainShell(child: child),
        routes: [
          GoRoute(
            path: '/',
            builder: (context, state) => HomeScreen(),
          ),
          GoRoute(
            path: '/products',
            builder: (context, state) => ProductsScreen(),
            routes: [
              GoRoute(
                path: ':id',
                builder: (context, state) {
                  final id = state.pathParameters['id']!;
                  return ProductDetailScreen(id: id);
                },
              ),
            ],
          ),
          GoRoute(
            path: '/profile',
            builder: (context, state) => ProfileScreen(),
          ),
        ],
      ),
    ],
  );
 
  static String? _guard(BuildContext context, GoRouterState state) {
    final isLoggedIn = context.read<AuthProvider>().isLoggedIn;
    if (!isLoggedIn && state.matchedLocation != '/login') {
      return '/login';
    }
    return null;
  }
}
 
// main.dart
void main() {
  runApp(
    MaterialApp.router(
      routerConfig: AppRouter.router,
    ),
  );
}