[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);
+    }
+}

FictionArchive.Service.UserService/Services/UserManagementService.cs

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+using FictionArchive.Service.UserService.Models.Database;
+using Microsoft.EntityFrameworkCore;
+
+namespace FictionArchive.Service.UserService.Services;
+
+public class UserManagementService
+{
+    private readonly ILogger<UserManagementService> _logger;
+    private readonly UserServiceDbContext _dbContext;
+
+    public UserManagementService(UserServiceDbContext dbContext, ILogger<UserManagementService> logger)
+    {
+        _dbContext = dbContext;
+        _logger = logger;
+    }
+
+    public async Task<User> RegisterUser(string username, string email, string oAuthProviderId,
+        string? inviterOAuthProviderId)
+    {
+        var newUser = new User();
+        User? inviter =
+            await _dbContext.Users.FirstOrDefaultAsync(user => user.OAuthProviderId == inviterOAuthProviderId);
+        if (inviter == null && inviterOAuthProviderId != null)
+        {
+            _logger.LogCritical(
+                "A user with OAuthProviderId {OAuthProviderId} was marked as having inviter with OAuthProviderId {inviterOAuthProviderId}, but no user was found with that value.",
+                inviterOAuthProviderId, inviterOAuthProviderId);
+            newUser.Disabled = true;
+        }
+
+        newUser.Username = username;
+        newUser.Email = email;
+        newUser.OAuthProviderId = oAuthProviderId;
+
+        _dbContext.Users.Add(newUser); // Add the new user to the DbContext
+        await _dbContext.SaveChangesAsync(); // Save changes to the database
+        
+        return newUser;
+    }
+
+    public IQueryable<User> GetUsers()
+    {
+        return _dbContext.Users.AsQueryable();
+    }
+}

FictionArchive.Service.UserService/Services/UserServiceDbContext.cs

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+using FictionArchive.Service.Shared.Services.Database;
+using FictionArchive.Service.UserService.Models.Database;
+using Microsoft.EntityFrameworkCore;
+
+namespace FictionArchive.Service.UserService.Services;
+
+public class UserServiceDbContext : FictionArchiveDbContext
+{
+    public DbSet<User> Users { get; set; }
+    
+    public UserServiceDbContext(DbContextOptions options, ILogger<UserServiceDbContext> logger) : base(options, logger)
+    {
+    }
+}