Envelope/mobile/lib/views/authentication/login.dart

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';
import '/utils/encryption/crypto_utils.dart';
import '/utils/encryption/aes_helper.dart';
import '/utils/storage/encryption_keys.dart';
import '/utils/storage/session_cookie.dart';

class LoginResponse {
  final String status;
  final String message;
  final String asymmetricPublicKey;
  final String asymmetricPrivateKey;
  final String userId;
  final String username;

  const LoginResponse({
    required this.status,
    required this.message,
    required this.asymmetricPublicKey,
    required this.asymmetricPrivateKey,
    required this.userId,
    required this.username,
  });

  factory LoginResponse.fromJson(Map<String, dynamic> json) {
    return LoginResponse(
        status: json['status'],
        message: json['message'],
        asymmetricPublicKey: json['asymmetric_public_key'],
        asymmetricPrivateKey: json['asymmetric_private_key'],
        userId: json['user_id'],
        username: json['username'],
    );
  }
}

Future<LoginResponse> login(context, String username, String password) async {
  final resp = await http.post(
      Uri.parse('${dotenv.env["SERVER_URL"]}api/v1/login'),
      headers: <String, String>{
        'Content-Type': 'application/json; charset=UTF-8',
      },
      body: jsonEncode(<String, String>{
        'username': username,
        'password': password,
      }),
  );

  if (resp.statusCode != 200) {
    throw Exception(resp.body);
  }

  String? rawCookie = resp.headers['set-cookie'];
  if (rawCookie != null) {
    int index = rawCookie.indexOf(';');
    setSessionCookie((index == -1) ? rawCookie : rawCookie.substring(0, index));
  }

  LoginResponse response = LoginResponse.fromJson(jsonDecode(resp.body));

  var rsaPrivPem = AesHelper.aesDecrypt(password, base64.decode(response.asymmetricPrivateKey));

  var rsaPriv = CryptoUtils.rsaPrivateKeyFromPem(rsaPrivPem);
  setPrivateKey(rsaPriv);

  final preferences = await SharedPreferences.getInstance();
  preferences.setBool('islogin', true);
  preferences.setString('userId', response.userId);
  preferences.setString('username', response.username);
  preferences.setString('asymmetricPublicKey', response.asymmetricPublicKey);

  return response;
}

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        backgroundColor: Colors.cyan,
        appBar: AppBar(
            title: null,
            automaticallyImplyLeading: true,
            //`true` if you want Flutter to automatically add Back Button when needed,
            //or `false` if you want to force your own back button every where
            leading: IconButton(icon: const Icon(Icons.arrow_back),
                onPressed:() => {
                  Navigator.pop(context)
                }
            )
        ),
        body: const SafeArea(
            child: LoginWidget(),
        ),
    );
  }
}

class LoginWidget extends StatefulWidget {
  const LoginWidget({Key? key}) : super(key: key);

  @override
  State<LoginWidget> createState() => _LoginWidgetState();
}

class _LoginWidgetState extends State<LoginWidget> {
  final _formKey = GlobalKey<FormState>();

  TextEditingController usernameController = TextEditingController();
  TextEditingController passwordController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    const TextStyle _inputTextStyle = TextStyle(fontSize: 18, color: Colors.black);

    final ButtonStyle _buttonStyle = ElevatedButton.styleFrom(
        primary: Colors.white,
        onPrimary: Colors.cyan,
        minimumSize: const Size.fromHeight(50),
        padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 10),
        textStyle: const TextStyle(
            fontSize: 20,
            fontWeight: FontWeight.bold,
            color: Colors.red,
        ),
    );

    return Center(
        child: Form(
            key: _formKey,
            child: Center(
                child: Padding(
                    padding: const EdgeInsets.all(15),
                    child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        crossAxisAlignment: CrossAxisAlignment.center,
                        children: [
                          const Text('Login', style: TextStyle(fontSize: 35, color: Colors.white),),
                          const SizedBox(height: 30),
                          TextFormField(
                              controller: usernameController,
                              decoration: const InputDecoration(
                                  hintText: 'Username',
                              ),
                              style: _inputTextStyle,
                              // The validator receives the text that the user has entered.
                              validator: (value) {
                                if (value == null || value.isEmpty) {
                                  return 'Create a username';
                                }
                                return null;
                              },
                          ),
                          const SizedBox(height: 5),
                          TextFormField(
                              controller: passwordController,
                              obscureText: true,
                              enableSuggestions: false,
                              autocorrect: false,
                              decoration: const InputDecoration(
                                  hintText: 'Password',
                              ),
                              style: _inputTextStyle,
                              // The validator receives the text that the user has entered.
                              validator: (value) {
                                if (value == null || value.isEmpty) {
                                  return 'Enter a password';
                                }
                                return null;
                              },
                          ),
                          const SizedBox(height: 5),
                          ElevatedButton(
                              style: _buttonStyle,
                              onPressed: () {
                                if (_formKey.currentState!.validate()) {
                                  ScaffoldMessenger.of(context).showSnackBar(
                                      const SnackBar(content: Text('Processing Data')),
                                  );

                                  login(
                                      context,
                                      usernameController.text,
                                      passwordController.text,
                                  ).then((value) {
                                    Navigator.
                                        pushNamedAndRemoveUntil(
                                            context,
                                            '/home',
                                            ModalRoute.withName('/home'),
                                        );
                                  }).catchError((error) {
                                    print(error); // TODO: Show error on interface
                                  });
                                }
                              },
                              child: const Text('Submit'),
                          ),
                      ],
                  )
              )
          )
      )
    );
  }
}