Add initial implementation of API, database, and user management components.

MikrocopApi/Services/AuthService.cs

@@ -0,0 +1,40 @@
+using MikrocopApi.Dtos;
+using MikrocopApi.Exceptions;
+using MikrocopApi.Mappers;
+using MikrocopDb.Repositories;
+
+namespace MikrocopApi.Services;
+
+public sealed class AuthService : IAuthService
+{
+    private readonly IUserRepository _userRepository;
+    private readonly IPasswordHashingService _passwordHashingService;
+    private readonly IJwtTokenService _jwtTokenService;
+
+    public AuthService(
+        IUserRepository userRepository,
+        IPasswordHashingService passwordHashingService,
+        IJwtTokenService jwtTokenService)
+    {
+        _userRepository = userRepository;
+        _passwordHashingService = passwordHashingService;
+        _jwtTokenService = jwtTokenService;
+    }
+
+    public async Task<LoginResponseDto> LoginAsync(LoginRequestDto request, CancellationToken cancellationToken = default)
+    {
+        var user = await _userRepository.GetByUserNameAsync(request.UserName, cancellationToken);
+        if (user is null)
+        {
+            throw new UnauthorizedException("Invalid username or password.");
+        }
+
+        var isValid = _passwordHashingService.VerifyPassword(request.Password, user.PasswordHash, user.PasswordSalt);
+        if (!isValid)
+        {
+            throw new UnauthorizedException("Invalid username or password.");
+        }
+
+        return _jwtTokenService.Generate(user).ToDto();
+    }
+}