password_protection_overlay.dart

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

const String _appPassword = 'flutterweb';

class PasswordProtectionOverlay extends StatefulWidget {
  const PasswordProtectionOverlay({super.key});

  @override
  State<PasswordProtectionOverlay> createState() =>
      _PasswordProtectionOverlayState();
}

class _PasswordProtectionOverlayState extends State<PasswordProtectionOverlay> {
  bool? _authenticated;
  bool _invalidPasslock = false;
  late final TextEditingController _passwordController;

  @override
  void initState() {
    super.initState();
    _passwordController = TextEditingController();
    _checkPasslock();
  }

  @override
  void dispose() {
    super.dispose();
    _passwordController.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (_authenticated == null) {
      return const Scaffold(
        body: Center(child: CircularProgressIndicator.adaptive()),
      );
    }

    if (_authenticated!) {
      return const SizedBox.shrink();
    }

    return Scaffold(
      body: Center(
        child: SizedBox(
          width: 320.0,
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              const Text(
                'Enter password to continue',
                style: TextStyle(fontSize: 20),
              ),
              const SizedBox(height: 32.0),
              TextField(
                controller: _passwordController,
                onSubmitted: (_) {
                  _submitPasslock();
                },
                decoration: const InputDecoration(
                  border: OutlineInputBorder(),
                  labelText: 'Password',
                  suffixIcon: Icon(Icons.lock),
                ),
              ),
              const SizedBox(height: 32.0),
              FilledButton(
                style: ButtonStyle(
                  backgroundColor: WidgetStateProperty.all<Color>(
                    _invalidPasslock ? Colors.red : Colors.blue,
                  ),
                ),
                onPressed: () {
                  _submitPasslock();
                },
                child: Text(
                  _invalidPasslock ? 'Wrong Password' : 'Submit',
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Future<void> _checkPasslock() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();
    final String? cached = prefs.getString('password');
    final bool valid = cached == _appPassword;
    setState(() {
      _authenticated = valid;
    });
  }

  void _submitPasslock() async {
    if (_passwordController.text == _appPassword) {
      setState(() {
        _authenticated = true;
      });
      final SharedPreferences prefs = await SharedPreferences.getInstance();
      await prefs.setString('password', _appPassword);
    } else {
      setState(() {
        _invalidPasslock = true;
      });
      await Future.delayed(const Duration(milliseconds: 500));
      setState(() {
        _invalidPasslock = false;
      });
    }
  }
}