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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: TextButton(
          child: Text('Start biometric auth'),
          onPressed: () async {
            final LocalAuthentication localAuth = LocalAuthentication();
            final bool canCheckBiometrics = await localAuth.canCheckBiometrics;

            if (canCheckBiometrics) {
              final List<BiometricType> availableBiometrics =
                  await localAuth.getAvailableBiometrics();
              if (availableBiometrics.length > 0) {
                print('Waiting for biometric authentication.');

                bool isAuthenticated;
                try {
                  isAuthenticated = await localAuth.authenticate(
                      localizedReason: ''
                      // localizedReason: I18n.of(context).login_biometricAuthMsg,
                      );
                } catch (e) {
                  print(e);
                  return;
                }
                if (isAuthenticated) {
                  print('Authenticated!!');
                } else {
                  print('Authentication failed!!');
                }
              }
            } else {
              print('Cannot check biometrics');
            }
          },
        ),
      ),
    );
  }
}