init project setup of the backend with dart and go as well as the frontend with nextjs

backend_dart/lib/application/usecases/register_user.dart

@@ -0,0 +1,19 @@
+import 'package:backend_dart/domain/entities/user.dart';
+import 'package:backend_dart/domain/repositories/user_repository.dart';
+
+class RegisterUserUseCase {
+  final UserRepository userRepository;
+
+  RegisterUserUseCase(this.userRepository);
+
+  Future<void> execute(String name, String email, String password) async {
+    final user = User(
+      id: 'generated-id', // Eine Methode zur ID-Erzeugung einfügen
+      name: name,
+      email: email,
+      password: password, // In der Realität: Passwörter hashen
+    );
+
+    await userRepository.create(user);
+  }
+}

backend_dart/lib/backend_dart.dart

@@ -0,0 +1,3 @@
+int calculate() {
+  return 6 * 7;
+}

backend_dart/lib/domain/entities/user.dart

@@ -0,0 +1,13 @@
+class User {
+  final String id;
+  final String name;
+  final String email;
+  final String password;
+
+  User({
+    required this.id,
+    required this.name,
+    required this.email,
+    required this.password,
+  });
+}

backend_dart/lib/domain/repositories/user_repository.dart

@@ -0,0 +1,7 @@
+import 'package:backend_dart/domain/entities/user.dart';
+
+abstract class UserRepository {
+  Future<void> create(User user);
+  Future<User?> findByEmail(String email);
+  Future<User?> findById(String id);
+}

backend_dart/lib/infrastructure/config/config.dart

@@ -0,0 +1,20 @@
+import 'dart:io';
+import 'package:yaml/yaml.dart';
+
+class Config {
+  final String databaseUrl;
+  final String port;
+
+  Config({required this.databaseUrl, required this.port});
+
+  static Future<Config> load() async {
+    final file = File('config.yaml');
+    final content = await file.readAsString();
+    final config = loadYaml(content);
+
+    return Config(
+      databaseUrl: config['database']['url'],
+      port: config['server']['port'],
+    );
+  }
+}

backend_dart/lib/infrastructure/persistence/postgres_user_repository.dart

@@ -0,0 +1,60 @@
+import 'package:backend_dart/domain/entities/user.dart';
+import 'package:backend_dart/domain/repositories/user_repository.dart';
+import 'package:postgres/postgres.dart';
+
+class PostgresUserRepository implements UserRepository {
+  final PostgreSQLConnection connection;
+
+  PostgresUserRepository(this.connection);
+
+  @override
+  Future<void> create(User user) async {
+    await connection.query(
+      'INSERT INTO users (id, name, email, password) VALUES (@id, @name, @mail, @pwd)',
+      substitutionValues: {
+        'id': user.id,
+        'name': user.name,
+        'mail': user.email,
+        'pwd': user.password,
+      },
+    );
+  }
+
+  @override
+  Future<User?> findByEmail(String email) async {
+    final results = await connection.query(
+      'SELECT id, name, email, password FROM users WHERE email = @mail',
+      substitutionValues: {'mail': email},
+    );
+
+    if (results.isNotEmpty) {
+      final row = results.first;
+      return User(
+        id: row[0],
+        name: row[1],
+        email: row[2],
+        password: row[3],
+      );
+    }
+    return null;
+  }
+
+  @override
+  Future<User?> findById(String id) async {
+    final results = await connection.query(
+      'SELECT id, name, email, password FROM users WHERE id = @id',
+      substitutionValues: {'id': id},
+    );
+
+    if (results.isNotEmpty) {
+      final row = results.first;
+      return User(
+        id: row[0],
+        name: row[1],
+        email: row[2],
+        password: row[3],
+      );
+    }
+    return null;
+  }
+}

backend_dart/lib/interfaces/http/server.dart

@@ -0,0 +1,21 @@
+import 'dart:io';
+
+import 'package:backend_dart/infrastructure/config/config.dart';
+
+class Server {
+  final Config config;
+
+  Server(this.config);
+
+  Future<void> start() async {
+    final server =
+        await HttpServer.bind(InternetAddress.anyIPv4, int.parse(config.port));
+    print('Listening on port ${config.port}');
+
+    await for (HttpRequest request in server) {
+      request.response
+        ..write('Welcome to ActaTempus!')
+        ..close();
+    }
+  }
+}