Refactor user management: Extract IUserService and UserService, consolidate user registration, authentication, and profile management. Fix memory leaks in ApiClient, enhance connection management, and improve error handling in AuthController and UsersController. Update IRC command handling to utilize IUserService for user operations.

src/EchoHub.Core/Contracts/IChatService.cs

@@ -25,9 +25,6 @@ public interface IChatService
     Task BroadcastMessageAsync(string channelName, MessageDto message);
     Task BroadcastChannelUpdatedAsync(ChannelDto channel, string? channelName = null);
 
-    // Query operations (used by IRC gateway for WHOIS, AUTH)
-    Task<UserProfileDto?> GetUserProfileAsync(string username);
+    // Query operations (used by IRC gateway for WHOIS)
     Task<List<string>> GetChannelsForUserAsync(string username);
-    Task<(Guid UserId, string Username)?> AuthenticateUserAsync(string username, string password);
-    Task<(Guid UserId, string Username)?> RegisterUserAsync(string username, string password);
 }

src/EchoHub.Core/Contracts/IUserService.cs

@@ -0,0 +1,13 @@
+using EchoHub.Core.DTOs;
+
+namespace EchoHub.Core.Contracts;
+
+public interface IUserService
+{
+    Task<UserOperationResult> RegisterUserAsync(string username, string password, string? displayName = null);
+    Task<UserOperationResult> AuthenticateUserAsync(string username, string password);
+    Task<UserProfileDto?> GetUserProfileAsync(string username);
+    Task<UserProfileDto?> GetUserByIdAsync(Guid userId);
+    Task<UserOperationResult> UpdateProfileAsync(Guid userId, string? displayName, string? bio, string? nicknameColor);
+    Task<UserOperationResult> SetAvatarAsync(Guid userId, string asciiArt);
+}

src/EchoHub.Core/DTOs/CommonDtos.cs

@@ -24,3 +24,20 @@ public record ChannelOperationResult(ChannelDto? Channel, ChannelError? Error, s
     public static ChannelOperationResult Success(ChannelDto channel) => new(channel, null, null);
     public static ChannelOperationResult Fail(ChannelError error, string message) => new(null, error, message);
 }
+
+public enum UserError
+{
+    ValidationFailed,
+    AlreadyExists,
+    NotFound,
+    InvalidCredentials,
+    Banned
+}
+
+public record UserOperationResult(UserProfileDto? User, UserError? Error, string? ErrorMessage)
+{
+    public bool IsSuccess => Error is null;
+
+    public static UserOperationResult Success(UserProfileDto user) => new(user, null, null);
+    public static UserOperationResult Fail(UserError error, string message) => new(null, error, message);
+}