Implemented user deletion service and IUserDeleteHandler for plugins to hook into

Moonlight.ApiServer/Http/Controllers/Admin/Users/UsersController.cs

@@ -2,11 +2,13 @@ using System.ComponentModel.DataAnnotations;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
 using MoonCore.Exceptions;
 using MoonCore.Extended.Abstractions;
 using MoonCore.Extended.Helpers;
 using MoonCore.Models;
 using Moonlight.ApiServer.Database.Entities;
+using Moonlight.ApiServer.Services;
 using Moonlight.Shared.Http.Requests.Admin.Users;
 using Moonlight.Shared.Http.Responses.Admin.Users;
 
@@ -166,7 +168,7 @@ public class UsersController : Controller
 
     [HttpDelete("{id}")]
     [Authorize(Policy = "permissions:admin.users.delete")]
-    public async Task Delete([FromRoute] int id)
+    public async Task Delete([FromRoute] int id, [FromQuery] bool force = false)
     {
         var user = await UserRepository
             .Get()
@@ -175,6 +177,16 @@ public class UsersController : Controller
         if (user == null)
             throw new HttpApiException("No user with that id found", 404);
 
-        await UserRepository.Remove(user);
+        var deletionService = HttpContext.RequestServices.GetRequiredService<UserDeletionService>();
+
+        if (!force)
+        {
+            var validationResult = await deletionService.Validate(user);
+
+            if (!validationResult.IsAllowed)
+                throw new HttpApiException($"Unable to delete user", 400, validationResult.Reason);
+        }
+
+        await deletionService.Delete(user, force);
     }
 }

Moonlight.ApiServer/Interfaces/IUserDeleteHandler.cs

@@ -0,0 +1,10 @@
+using Moonlight.ApiServer.Database.Entities;
+using Moonlight.ApiServer.Models;
+
+namespace Moonlight.ApiServer.Interfaces;
+
+public interface IUserDeleteHandler
+{
+    public Task<UserDeleteValidationResult> Validate(User user);
+    public Task Delete(User user, bool force);
+}

Moonlight.ApiServer/Models/UserDeleteValidateResult.cs

@@ -0,0 +1,27 @@
+namespace Moonlight.ApiServer.Models;
+
+public class UserDeleteValidationResult
+{
+    public bool IsAllowed { get; set; }
+    public string Reason { get; set; }
+
+    public static UserDeleteValidationResult Allow()
+    {
+        return new UserDeleteValidationResult()
+        {
+            IsAllowed = true
+        };
+    }
+
+    public static UserDeleteValidationResult Deny()
+        => Deny("No reason provided");
+
+    public static UserDeleteValidationResult Deny(string reason)
+    {
+        return new UserDeleteValidationResult()
+        {
+            IsAllowed = false,
+            Reason = reason
+        };
+    }
+}

Moonlight.ApiServer/Services/UserService.cs

@@ -0,0 +1,42 @@
+using MoonCore.Extended.Abstractions;
+using Moonlight.ApiServer.Database.Entities;
+using Moonlight.ApiServer.Interfaces;
+using Moonlight.ApiServer.Models;
+
+namespace Moonlight.ApiServer.Services;
+
+public class UserDeletionService
+{
+    private readonly IUserDeleteHandler[] Handlers;
+    private readonly DatabaseRepository<User> UserRepository;
+
+    public UserDeletionService(
+        IEnumerable<IUserDeleteHandler> handlers,
+        DatabaseRepository<User> userRepository
+    )
+    {
+        UserRepository = userRepository;
+        Handlers = handlers.ToArray();
+    }
+
+    public async Task<UserDeleteValidationResult> Validate(User user)
+    {
+        foreach (var handler in Handlers)
+        {
+            var result = await handler.Validate(user);
+
+            if (!result.IsAllowed)
+                return result;
+        }
+
+        return UserDeleteValidationResult.Allow();
+    }
+
+    public async Task Delete(User user, bool force)
+    {
+        foreach (var handler in Handlers)
+            await Delete(user, force);
+
+        await UserRepository.Remove(user);
+    }
+}

Moonlight.ApiServer/Startup/Startup.Auth.cs

@@ -6,6 +6,7 @@ using MoonCore.Extended.JwtInvalidation;
 using MoonCore.Permissions;
 using Moonlight.ApiServer.Implementations;
 using Moonlight.ApiServer.Interfaces;
+using Moonlight.ApiServer.Services;
 
 namespace Moonlight.ApiServer.Startup;
 
@@ -47,6 +48,8 @@ public partial class Startup
         if (Configuration.Authentication.EnableLocalOAuth2)
             WebApplicationBuilder.Services.AddScoped<IOAuth2Provider, LocalOAuth2Provider>();
 
+        WebApplicationBuilder.Services.AddScoped<UserDeletionService>();
+
         return Task.CompletedTask;
     }