Untitled Page

import 'package:flutter/material.dart';

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

class NavigationAssignmentApp extends StatelessWidget {
  const NavigationAssignmentApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Navigation Methods',
      theme: ThemeData(primarySwatch: Colors.blue),
      // We set an initial route and named routes to demonstrate 'pushNamed'
      initialRoute: '/',
      routes: {
        '/': (context) => const Screen1(),
        '/screen4': (context) => const Screen4(),
      },
    );
  }
}

// --- SCREEN 1 (Home) ---
class Screen1 extends StatelessWidget {
  const Screen1({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Screen 1 (Root)')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Text('You are at the start of the stack.'),
            const SizedBox(height: 20),
            
            // 1. push
            ElevatedButton(
              onPressed: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => const Screen2()),
                );
              },
              child: const Text('1. Navigator.push() to Screen 2'),
            ),
            
            // 2. pushNamed
            ElevatedButton(
              onPressed: () {
                Navigator.pushNamed(context, '/screen4');
              },
              child: const Text('2. Navigator.pushNamed() to Screen 4'),
            ),
            
            // 3. maybePop
            ElevatedButton(
              onPressed: () async {
                bool didPop = await Navigator.maybePop(context);
                if (!didPop) {
                  // This will trigger because we are at the root route and can't pop further
                  ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(content: Text('maybePop: Can\'t pop the root route!')),
                  );
                }
              },
              style: ElevatedButton.styleFrom(backgroundColor: Colors.grey),
              child: const Text('3. Navigator.maybePop()'),
            ),
          ],
        ),
      ),
    );
  }
}

// --- SCREEN 2 ---
class Screen2 extends StatelessWidget {
  const Screen2({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Screen 2')),
      backgroundColor: Colors.lightGreen[100],
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            // 4. pop
            ElevatedButton(
              onPressed: () {
                Navigator.pop(context);
              },
              child: const Text('4. Navigator.pop() (Go Back)'),
            ),
            
            // 5. pushReplacement
            ElevatedButton(
              onPressed: () {
                // Replaces Screen 2 with Screen 3 in the stack
                Navigator.pushReplacement(
                  context,
                  MaterialPageRoute(builder: (context) => const Screen3()),
                );
              },
              child: const Text('5. Navigator.pushReplacement() to Screen 3'),
            ),
          ],
        ),
      ),
    );
  }
}

// --- SCREEN 3 ---
class Screen3 extends StatelessWidget {
  const Screen3({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Screen 3')),
      backgroundColor: Colors.orange[100],
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Text('Notice there is no back button to Screen 2\nbecause we used pushReplacement.'),
            const SizedBox(height: 20),
            
            // 6. pushAndRemoveUntil
            ElevatedButton(
              onPressed: () {
                // Pushes Screen 1 and removes all other screens in the stack (like a logout)
                Navigator.pushAndRemoveUntil(
                  context,
                  MaterialPageRoute(builder: (context) => const Screen1()),
                  (Route<dynamic> route) => false,
                );
              },
              child: const Text('6. pushAndRemoveUntil() (Reset to Screen 1)'),
            ),
            
            // 7. popUntil
            ElevatedButton(
              onPressed: () {
                // Pops everything on top until it finds the route named '/'
                Navigator.popUntil(context, ModalRoute.withName('/'));
              },
              child: const Text('7. Navigator.popUntil() (Back to Root)'),
            ),
          ],
        ),
      ),
    );
  }
}

// --- SCREEN 4 ---
class Screen4 extends StatelessWidget {
  const Screen4({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Screen 4 (Named Route)')),
      backgroundColor: Colors.purple[100],
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            Navigator.pop(context);
          },
          child: const Text('Navigator.pop() to return'),
        ),
      ),
    );
  }
}