Add user avatar and profile feature, consolidate Auth and UserManagement features (#257)

web/backend/Features/Features.Users/Commands/Authentication/RefreshToken/RefreshTokenHandler.cs

@@ -0,0 +1,31 @@
+using Features.Auth.Dtos;
+using Features.Auth.Services;
+using MediatR;
+
+namespace Features.Auth.Commands.Authentication.RefreshToken;
+
+/// <summary>
+///     Handles <see cref="RefreshTokenCommand" /> by validating the refresh token and issuing a new
+///     access/refresh token pair.
+/// </summary>
+public class RefreshTokenHandler(ITokenService tokenService)
+    : IRequestHandler<RefreshTokenCommand, LoginPayload>
+{
+    /// <exception cref="Domain.Exceptions.UnauthorizedException">
+    ///     Thrown when the refresh token is invalid or expired, or when the user account it refers to no
+    ///     longer exists.
+    /// </exception>
+    public async Task<LoginPayload> Handle(
+        RefreshTokenCommand request,
+        CancellationToken cancellationToken
+    )
+    {
+        RefreshTokenResult result = await tokenService.RefreshTokenAsync(request.RefreshToken);
+        return new LoginPayload(
+            result.UserId,
+            result.Username,
+            result.RefreshToken,
+            result.AccessToken
+        );
+    }
+}