[FA-55] User Service backend initial setup

FictionArchive.Service.UserService/Services/UserManagementService.cs

@@ -1,4 +1,5 @@
 using FictionArchive.Service.UserService.Models.Database;
+using FictionArchive.Service.UserService.Services.AuthenticationClient;
 using Microsoft.EntityFrameworkCore;
 
 namespace FictionArchive.Service.UserService.Services;
@@ -7,37 +8,112 @@ public class UserManagementService
 {
     private readonly ILogger<UserManagementService> _logger;
     private readonly UserServiceDbContext _dbContext;
+    private readonly IAuthenticationServiceClient _authClient;
 
-    public UserManagementService(UserServiceDbContext dbContext, ILogger<UserManagementService> logger)
+    public UserManagementService(
+        UserServiceDbContext dbContext,
+        ILogger<UserManagementService> logger,
+        IAuthenticationServiceClient authClient)
     {
         _dbContext = dbContext;
         _logger = logger;
+        _authClient = authClient;
     }
 
-    public async Task<User> RegisterUser(string username, string email, string oAuthProviderId,
-        string? inviterOAuthProviderId)
+    /// <summary>
+    /// Invites a new user by creating them in Authentik, saving to the database, and sending a recovery email.
+    /// </summary>
+    /// <param name="inviter">The user sending the invite</param>
+    /// <param name="email">Email address of the invitee</param>
+    /// <param name="username">Username for the invitee</param>
+    /// <returns>The created user, or null if the invite failed</returns>
+    public async Task<User?> InviteUserAsync(User inviter, string email, string username)
     {
-        var newUser = new User();
-        User? inviter =
-            await _dbContext.Users.FirstOrDefaultAsync(user => user.OAuthProviderId == inviterOAuthProviderId);
-        if (inviter == null && inviterOAuthProviderId != null)
+        // Check if inviter has available invites
+        if (inviter.AvailableInvites <= 0)
         {
-            _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;
+            _logger.LogWarning("User {InviterId} has no available invites", inviter.Id);
+            return null;
         }
 
-        newUser.Username = username;
-        newUser.Email = email;
-        newUser.OAuthProviderId = oAuthProviderId;
+        // Check if email is already in use
+        var existingUser = await _dbContext.Users
+            .AsQueryable()
+            .FirstOrDefaultAsync(u => u.Email == email);
+
+        if (existingUser != null)
+        {
+            _logger.LogWarning("Email {Email} is already in use", email);
+            return null;
+        }
+
+        // Check if username is already in use
+        var existingUsername = await _dbContext.Users
+            .AsQueryable()
+            .FirstOrDefaultAsync(u => u.Username == username);
+
+        if (existingUsername != null)
+        {
+            _logger.LogWarning("Username {Username} is already in use", username);
+            return null;
+        }
+
+        // Create user in Authentik
+        var authentikUser = await _authClient.CreateUserAsync(username, email, username);
+        if (authentikUser == null)
+        {
+            _logger.LogError("Failed to create user {Username} in Authentik", username);
+            return null;
+        }
+
+        // Send recovery email via Authentik
+        var emailSent = await _authClient.SendRecoveryEmailAsync(authentikUser.Pk);
+        if (!emailSent)
+        {
+            _logger.LogWarning(
+                "User {Username} was created in Authentik but recovery email failed to send. Authentik pk: {Pk}",
+                username, authentikUser.Pk);
+            // Continue anyway - the user is created, admin can resend email manually
+        }
+
+        // Create user in local database
+        var newUser = new User
+        {
+            Username = username,
+            Email = email,
+            OAuthProviderId = authentikUser.Uid,
+            Disabled = false,
+            AvailableInvites = 0,
+            InviterId = inviter.Id
+        };
+
+        _dbContext.Users.Add(newUser);
+
+        // Decrement inviter's available invites
+        inviter.AvailableInvites--;
+
+        await _dbContext.SaveChangesAsync();
+
+        _logger.LogInformation(
+            "User {Username} was successfully invited by {InviterId}. New user id: {NewUserId}",
+            username, inviter.Id, newUser.Id);
 
-        _dbContext.Users.Add(newUser); // Add the new user to the DbContext
-        await _dbContext.SaveChangesAsync(); // Save changes to the database
-        
         return newUser;
     }
 
+    /// <summary>
+    /// Gets a user by their OAuth provider ID (Authentik UID).
+    /// </summary>
+    public async Task<User?> GetUserByOAuthProviderIdAsync(string oAuthProviderId)
+    {
+        return await _dbContext.Users
+            .AsQueryable()
+            .FirstOrDefaultAsync(u => u.OAuthProviderId == oAuthProviderId);
+    }
+
+    /// <summary>
+    /// Gets all users as a queryable for GraphQL.
+    /// </summary>
     public IQueryable<User> GetUsers()
     {
         return _dbContext.Users.AsQueryable();