// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// ignore_for_file: public_member_api_docs

import 'dart:async';

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

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final LocalAuthentication auth = LocalAuthentication();
  _SupportState _supportState = _SupportState.unknown;
  bool? _canCheckBiometrics;
  List<BiometricType>? _availableBiometrics;
  String _authorized = 'Not Authorized';
  bool _isAuthenticating = false;

  @override
  void initState() {
    super.initState();
    auth.isDeviceSupported().then(
          (isSupported) => setState(() => _supportState = isSupported
              ? _SupportState.supported
              : _SupportState.unsupported),
        );
  }

  Future<void> _checkBiometrics() async {
    late bool canCheckBiometrics;
    try {
      canCheckBiometrics = await auth.canCheckBiometrics;
    } on PlatformException catch (e) {
      canCheckBiometrics = false;
      print(e);
    }
    if (!mounted) return;

    setState(() {
      _canCheckBiometrics = canCheckBiometrics;
    });
  }

  Future<void> _getAvailableBiometrics() async {
    late List<BiometricType> availableBiometrics;
    try {
      availableBiometrics = await auth.getAvailableBiometrics();
    } on PlatformException catch (e) {
      availableBiometrics = <BiometricType>[];
      print(e);
    }
    if (!mounted) return;

    setState(() {
      _availableBiometrics = availableBiometrics;
    });
  }

  Future<void> _authenticate() async {
    bool authenticated = false;
    try {
      setState(() {
        _isAuthenticating = true;
        _authorized = 'Authenticating';
      });
      authenticated = await auth.authenticate(
          localizedReason: 'Let OS determine authentication method',
          useErrorDialogs: true,
          stickyAuth: true);
      setState(() {
        _isAuthenticating = false;
        _authorized = 'Authenticating';
      });
    } on PlatformException catch (e) {
      print(e);
      setState(() {
        _isAuthenticating = false;
        _authorized = "Error - ${e.message}";
      });
      return;
    }
    if (!mounted) return;

    setState(
        () => _authorized = authenticated ? 'Authorized' : 'Not Authorized');
  }

  Future<void> _authenticateWithBiometrics() async {
    bool authenticated = false;
    try {
      setState(() {
        _isAuthenticating = true;
        _authorized = 'Authenticating';
      });
      authenticated = await auth.authenticate(
          localizedReason:
              'Scan your fingerprint (or face or whatever) to authenticate',
          useErrorDialogs: true,
          stickyAuth: true,
          biometricOnly: true);
      setState(() {
        _isAuthenticating = false;
        _authorized = 'Authenticating';
      });
    } on PlatformException catch (e) {
      print(e);
      setState(() {
        _isAuthenticating = false;
        _authorized = "Error - ${e.message}";
      });
      return;
    }
    if (!mounted) return;

    final String message = authenticated ? 'Authorized' : 'Not Authorized';
    setState(() {
      _authorized = message;
    });
  }

  void _cancelAuthentication() async {
    await auth.stopAuthentication();
    setState(() => _isAuthenticating = false);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Plugin example app'),
        ),
        body: ListView(
          padding: const EdgeInsets.only(top: 30),
          children: [
            Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                if (_supportState == _SupportState.unknown)
                  CircularProgressIndicator()
                else if (_supportState == _SupportState.supported)
                  Text("This device is supported")
                else
                  Text("This device is not supported"),
                Divider(height: 100),
                Text('Can check biometrics: $_canCheckBiometrics\n'),
                ElevatedButton(
                  child: const Text('Check biometrics'),
                  onPressed: _checkBiometrics,
                ),
                Divider(height: 100),
                Text('Available biometrics: $_availableBiometrics\n'),
                ElevatedButton(
                  child: const Text('Get available biometrics'),
                  onPressed: _getAvailableBiometrics,
                ),
                Divider(height: 100),
                Text('Current State: $_authorized\n'),
                (_isAuthenticating)
                    ? ElevatedButton(
                        onPressed: _cancelAuthentication,
                        child: Row(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            Text("Cancel Authentication"),
                            Icon(Icons.cancel),
                          ],
                        ),
                      )
                    : Column(
                        children: [
                          ElevatedButton(
                            child: Row(
                              mainAxisSize: MainAxisSize.min,
                              children: [
                                Text('Authenticate'),
                                Icon(Icons.perm_device_information),
                              ],
                            ),
                            onPressed: _authenticate,
                          ),
                          ElevatedButton(
                            child: Row(
                              mainAxisSize: MainAxisSize.min,
                              children: [
                                Text(_isAuthenticating
                                    ? 'Cancel'
                                    : 'Authenticate: biometrics only'),
                                Icon(Icons.fingerprint),
                              ],
                            ),
                            onPressed: _authenticateWithBiometrics,
                          ),
                        ],
                      ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

enum _SupportState {
  unknown,
  supported,
  unsupported,
}