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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    final dispatcher = BackDispatcher();
    return MaterialApp.router(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      // routerConfig: router,
      routerDelegate: router.routerDelegate,
      routeInformationProvider: router.routeInformationProvider,
      routeInformationParser: router.routeInformationParser,
      backButtonDispatcher: dispatcher,
    );
  }
}

class BackDispatcher extends RootBackButtonDispatcher {
  @override
  Future<bool> didPopRoute() async {
    if (modalStack.isNotEmpty) {
      debugPrint('popping modal');
      Navigator.of(navKey.currentContext!).pop();
      return true;
    }

    return super.didPopRoute();
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('home page'),
      ),
      body: Center(
        child: IconButton(
          onPressed: () => context.go('/home/second'),
          icon: const Icon(Icons.link),
        ),
      ),
    );
  }
}

class SecondPage extends StatelessWidget {
  const SecondPage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('second page'),
      ),
      body: Center(
        child: IconButton(
          onPressed: () {
            showModalBottomSheet(
              context: context,
              useRootNavigator: true,
              builder: (context) {
                return Container(
                  width: 100,
                  height: 100,
                  color: Colors.red,
                );
              },
            );
          },
          icon: const Icon(Icons.slideshow),
        ),
      ),
    );
  }
}

class Layout extends StatelessWidget {
  const Layout(
    this.shell, {
    super.key,
  });

  final StatefulNavigationShell shell;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Expanded(child: shell),
        Container(
          height: 10,
          color: Colors.blueGrey,
        ),
      ],
    );
  }
}

final modalStack = <Route>[];

class MyObserver extends RouteObserver {
  @override
  void didPush(Route route, Route? previousRoute) {
    if (previousRoute == null) return;
    debugPrint('!!! didPush ${route.runtimeType}');
    modalStack.add(route);
    super.didPush(route, previousRoute);
  }

  @override
  void didPop(Route route, Route? previousRoute) {
    debugPrint('!!! didPop ${route.runtimeType}');
    modalStack.removeLast();
    super.didPop(route, previousRoute);
  }
}

final navKey = GlobalKey<NavigatorState>();
GoRouter router = GoRouter(
  debugLogDiagnostics: true,
  observers: [MyObserver()],
  initialLocation: '/home',
  navigatorKey: navKey,
  routes: [
    GoRoute(
      path: '/',
      redirect: (_, state) {
        return state.fullPath == '/' ? '/home' : null;
      },
      routes: [
        StatefulShellRoute.indexedStack(
          builder: (context, state, shell) => Layout(shell),
          branches: [
            StatefulShellBranch(
              routes: [
                GoRoute(
                  path: 'home',
                  builder: (context, _) => const MyHomePage(),
                  routes: [
                    GoRoute(
                      path: 'second',
                      builder: (context, _) => const SecondPage(),
                    ),
                  ],
                ),
              ],
            ),
          ],
        ),
      ],
    ),
  ],
);