Added extendability to the sign-in / sync, the session validation and the frontend claims transfer calls

Moonlight.ApiServer/Interfaces/IUserAuthExtension.cs

@@ -0,0 +1,25 @@
+using System.Security.Claims;
+using Moonlight.ApiServer.Database.Entities;
+
+namespace Moonlight.ApiServer.Interfaces;
+
+public interface IUserAuthExtension
+{
+    /// <summary>
+    /// This function is called on every sign-in. It should be used to synchronize additional user data from the principal
+    /// or extend the claims saved in the user session
+    /// </summary>
+    /// <param name="user">The current user this method is called for</param>
+    /// <param name="principal">The principal after being processed by moonlight itself</param>
+    /// <returns>The result of the synchronisation. Returning false will immediately invalidate the sign-in and no other extensions will be called</returns>
+    public Task<bool> Sync(User user, ClaimsPrincipal principal);
+
+    /// <summary>
+    /// IMPORTANT: Please note that heavy operations should not occur in this method as it will be called for every request
+    /// of every user
+    /// </summary>
+    /// <param name="user">The current user this method is called for</param>
+    /// <param name="principal">The principal after being processed by moonlight itself</param>
+    /// <returns>The result of the validation. Returning false will immediately invalidate the users session and no other extensions will be called</returns>
+    public Task<bool> Validate(User user, ClaimsPrincipal principal);
+}