[FA-10] Adds user service and authentication service

FictionArchive.Service.UserService/Services/EventHandlers/AuthUserAddedEventHandler.cs

@@ -0,0 +1,23 @@
+using FictionArchive.Service.Shared.Services.EventBus;
+using FictionArchive.Service.UserService.Models.IntegrationEvents;
+using FictionArchive.Service.UserService.Models.Database;
+using Microsoft.EntityFrameworkCore; // Add this line to include the UserModel
+
+namespace FictionArchive.Service.UserService.Services.EventHandlers;
+
+public class AuthUserAddedEventHandler : IIntegrationEventHandler<AuthUserAddedEvent>
+{
+    private readonly UserManagementService _userManagementService;
+    private readonly ILogger<AuthUserAddedEventHandler> _logger;
+
+    public AuthUserAddedEventHandler(UserServiceDbContext dbContext, ILogger<AuthUserAddedEventHandler> logger, UserManagementService userManagementService)
+    {
+        _logger = logger;
+        _userManagementService = userManagementService;
+    }
+
+    public async Task Handle(AuthUserAddedEvent @event)
+    {
+        await _userManagementService.RegisterUser(@event.EventUserUsername, @event.EventUserEmail, @event.OAuthProviderId, @event.InviterOAuthProviderId);
+    }
+}