// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

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

// This scenario demonstrates a simple two-page app.
//
// The first route '/' is mapped to Page1Screen, and the second route '/page2'
// is mapped to Page2Screen. To navigate between pages, press the buttons on the
// pages.
//
// The onPress callbacks use context.go() to navigate to another page. This is
// equivalent to entering url to the browser url bar directly.

void main() => runApp(App());

/// The main app.
class App extends StatelessWidget {
  /// Creates an [App].
  App({Key? key}) : super(key: key);

  /// The title of the app.
  static const String title = 'GoRouter Example: Declarative Routes';

  @override
  Widget build(BuildContext context) => MaterialApp.router(
        routeInformationProvider: _router.routeInformationProvider,
        routeInformationParser: _router.routeInformationParser,
        routerDelegate: _router.routerDelegate,
        title: title,
      );

  final GoRouter _router = GoRouter(
    routes: <GoRoute>[
      GoRoute(
        path: '/',
        builder: (BuildContext context, GoRouterState state) =>
            const Page1Screen(),
        routes: <GoRoute>[
          GoRoute(
            path: 'page2',
            builder: (BuildContext context, GoRouterState state) =>
                const Page2Screen(),
          ),
        ],
      ),
    ],
  );
}

/// The screen of the first page.
class Page1Screen extends StatelessWidget {
  /// Creates a [Page1Screen].
  const Page1Screen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(title: const Text(App.title)),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              ElevatedButton(
                onPressed: () => context.go('/page2'),
                child: const Text('Go to page 2'),
              ),
            ],
          ),
        ),
      );
}

/// The screen of the second page.
class Page2Screen extends StatelessWidget {
  /// Creates a [Page2Screen].
  const Page2Screen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(title: const Text(App.title)),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              ElevatedButton(
                onPressed: () => context.go('/'),
                child: const Text('Go back to home page'),
              ),
            ],
          ),
        ),
      );
}