Name input page

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: FutureBuilder(
        future: _getUserName(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Scaffold(
              body: Center(
                child: CircularProgressIndicator(),
              ),
            );
          } else {
            return snapshot.hasData ? ChatPage(snapshot.data) : HomePage();
          }
        },
      ),
    );
  }

  // Function to get the user name from Shared Preferences
  Future<String?> _getUserName() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return prefs.getString('user_name');
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final TextEditingController _nameController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('User Name Page'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            TextField(
              controller: _nameController,
              decoration: InputDecoration(
                labelText: 'Enter your name',
              ),
            ),
            SizedBox(height: 16.0),
            ElevatedButton(
              onPressed: () async {
                String name = _nameController.text.trim();
                if (name.isNotEmpty) {
                  await _saveUserName(name);
                  Navigator.pushReplacement(
                    context,
                    MaterialPageRoute(builder: (context) => ChatPage(name)),
                  );
                }
              },
              child: Text('Save'),
            ),
          ],
        ),
      ),
    );
  }

  // Function to save the user name in Shared Preferences
  Future<void> _saveUserName(String userName) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setString('user_name', userName);
  }
}

class ChatPage extends StatelessWidget {
  final String userName;

  ChatPage(this.userName);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Chat Page'),
      ),
      body: Center(
        child: Text('Welcome to the Chat, $userName!'),
      ),
    );
  }
}