feat(core): add password hashing and token generation interfaces

src/FiscalOS.API/Login/Response.cs

@@ -1,3 +1,16 @@
 namespace FiscalOS.API.Login;
 
-internal sealed record Response(string AccessToken);
+internal sealed record Response
+{
+  public string AccessToken { get; init; }
+
+  private Response(string accessToken)
+  {
+    AccessToken = accessToken;
+  }
+
+  public static Response From(string accessToken)
+  {
+    return new(accessToken);
+  }
+}

src/FiscalOS.Core/Authentication/IPasswordHasher.cs

@@ -0,0 +1,7 @@
+namespace FiscalOS.Core.Authentication;
+
+public interface IPasswordHasher
+{
+  string Hash(string password);
+  bool Verify(string providedPassword, string hashedPassword);
+}

src/FiscalOS.Core/Authentication/ITokenGenerator.cs

@@ -0,0 +1,7 @@
+namespace FiscalOS.Core.Authentication;
+
+public interface ITokenGenerator
+{
+  string GenerateAccessToken(User user);
+  RefreshToken GenerateRefreshToken(User user);
+}

src/FiscalOS.Infra/Data/AppDbContext.cs

@@ -23,7 +23,7 @@ public sealed class AppDbContext(IOptions<AppDbContextOptions> ctxOptions) : DbC
     var connectionString = $"{DataSourceKey}{dbPath}";
 
     optionsBuilder.UseSqlite(connectionString)
-      .AddInterceptors(new TimestampInterceptor());
+      .AddInterceptors(TimestampInterceptor.New());
   }
 
   protected override void OnModelCreating(ModelBuilder modelBuilder)

src/FiscalOS.Infra/Data/TimestampInterceptor.cs

@@ -4,6 +4,15 @@ namespace FiscalOS.Infra.Data;
 
 internal sealed class TimestampInterceptor : SaveChangesInterceptor
 {
+  private TimestampInterceptor()
+  {
+  }
+
+  public static TimestampInterceptor New()
+  {
+    return new();
+  }
+
   public override InterceptionResult<int> SavingChanges(DbContextEventData eventData, InterceptionResult<int> result)
   {
     UpdateEntities(eventData.Context);

tests/FiscalOS.Infra.Tests/Assertions/JwtTokenAssertions.cs

@@ -0,0 +1,45 @@
+namespace FiscalOS.Infra.Tests.Assertions;
+
+internal static class JwtTokenAssertionExtensions
+{
+  public static AndConstraint<string> HaveClaim(
+    this StringAssertions assertions,
+    string claimType
+  )
+  {
+    var handler = new JwtSecurityTokenHandler();
+    var jwtToken = handler.ReadJwtToken(assertions.Subject);
+
+    var claim = jwtToken.Claims.FirstOrDefault(c => c.Type == claimType);
+
+    assertions.CurrentAssertionChain
+      .ForCondition(claim is not null)
+      .FailWith($"Expected JWT token to have claim '{claimType}', but it was not found.");
+
+    return new AndConstraint<string>(assertions.Subject);
+  }
+
+  public static AndConstraint<string> HaveClaimWithValue(
+    this StringAssertions assertions,
+    string claimType,
+    string expectedValue
+  )
+  {
+    var handler = new JwtSecurityTokenHandler();
+    var jwtToken = handler.ReadJwtToken(assertions.Subject);
+
+    var claim = jwtToken.Claims.FirstOrDefault(c => c.Type == claimType);
+
+    assertions.CurrentAssertionChain
+      .ForCondition(claim is not null)
+      .FailWith($"Expected JWT token to have claim '{claimType}', but it was not found.");
+
+    assertions.CurrentAssertionChain
+      .ForCondition(claim!.Value == expectedValue)
+      .FailWith(
+        $"Expected JWT token claim '{claimType}' to have value '{expectedValue}', but found '{claim.Value}'."
+      );
+
+    return new AndConstraint<string>(assertions.Subject);
+  }
+}

tests/FiscalOS.Infra.Tests/Unit/TokenGeneratorTests.cs

@@ -0,0 +1,78 @@
+using System.Globalization;
+using System.Security.Cryptography;
+
+namespace FiscalOS.Infra.Tests.Unit;
+
+public class TokenGeneratorTests
+{
+  private readonly Mock<IOptions<JwtOptions>> _mockJwtOptions = new();
+  private readonly Mock<TimeProvider> _mockTimeProvider = new();
+  private readonly TokenGenerator _sut;
+
+  public TokenGeneratorTests()
+  {
+    _sut = TokenGenerator.From(
+      _mockTimeProvider.Object,
+      _mockJwtOptions.Object
+    );
+  }
+
+  [Fact]
+  public void GenerateAccessToken_WhenCalled_ItShouldReturnValidJwtToken()
+  {
+    var user = User.From("testuser", "hashedpassword");
+
+    var madeUp256BitSecret = RandomNumberGenerator.GetBytes(32);
+
+    var jwtOptions = new JwtOptions
+    {
+      Secret = Convert.ToBase64String(madeUp256BitSecret),
+      Issuer = "TestIssuer",
+      Audience = "TestAudience",
+      ExpiryInMinutes = 60,
+    };
+
+    _mockJwtOptions
+      .SetupGet(static x => x.Value)
+      .Returns(jwtOptions);
+
+    var now = DateTimeOffset.UtcNow;
+
+    _mockTimeProvider
+      .Setup(static x => x.GetUtcNow())
+      .Returns(now);
+
+    var token = _sut.GenerateAccessToken(user);
+
+    token.Should().HaveClaimWithValue(JwtRegisteredClaimNames.Sub, user.Id.ToString());
+    token.Should().HaveClaim(JwtRegisteredClaimNames.Jti);
+    token.Should().HaveClaimWithValue(JwtRegisteredClaimNames.Iss, jwtOptions.Issuer);
+    token.Should().HaveClaimWithValue(JwtRegisteredClaimNames.Aud, jwtOptions.Audience);
+    token.Should().HaveClaimWithValue(
+      JwtRegisteredClaimNames.Exp,
+      new DateTimeOffset(
+        now.AddMinutes(jwtOptions.ExpiryInMinutes).UtcDateTime
+      )
+      .ToUnixTimeSeconds()
+      .ToString(CultureInfo.InvariantCulture)
+    );
+  }
+
+  [Fact]
+  public void GenerateRefreshToken_WhenCalled_ItShouldReturnRefreshTokenWithCorrectProperties()
+  {
+    var user = User.From("testuser", "hashedpassword");
+
+    var now = DateTimeOffset.UtcNow;
+
+    _mockTimeProvider
+      .Setup(static x => x.GetUtcNow())
+      .Returns(now);
+
+    var refreshToken = _sut.GenerateRefreshToken(user);
+
+    refreshToken.UserId.Should().Be(user.Id);
+    refreshToken.ExpiresAt.Should().Be(now.AddHours(12));
+    refreshToken.Token.Should().NotBeNullOrEmpty();
+  }
+}