feat: moderation API

Foxnouns.Backend/Middleware/LimitMiddleware.cs

@@ -0,0 +1,64 @@
+// Copyright (C) 2023-present sam/u1f320 (vulpine.solutions)
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+using Foxnouns.Backend.Database.Models;
+
+namespace Foxnouns.Backend.Middleware;
+
+public class LimitMiddleware : IMiddleware
+{
+    public async Task InvokeAsync(HttpContext ctx, RequestDelegate next)
+    {
+        Endpoint? endpoint = ctx.GetEndpoint();
+        LimitAttribute? attribute = endpoint?.Metadata.GetMetadata<LimitAttribute>();
+
+        if (attribute == null)
+        {
+            await next(ctx);
+            return;
+        }
+
+        Token? token = ctx.GetToken();
+        if (
+            token?.User.Deleted == true
+            && (!attribute.UsableBySuspendedUsers || token.User.DeletedBy == null)
+        )
+        {
+            throw new ApiError.Forbidden("Deleted users cannot access this endpoint.");
+        }
+
+        if (attribute.RequireAdmin && token?.User.Role != UserRole.Admin)
+        {
+            throw new ApiError.Forbidden("This endpoint can only be used by admins.");
+        }
+
+        if (
+            attribute.RequireModerator
+            && token?.User.Role is not (UserRole.Admin or UserRole.Moderator)
+        )
+        {
+            throw new ApiError.Forbidden("This endpoint can only be used by moderators.");
+        }
+
+        await next(ctx);
+    }
+}
+
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
+public class LimitAttribute : Attribute
+{
+    public bool UsableBySuspendedUsers { get; init; }
+    public bool RequireAdmin { get; init; }
+    public bool RequireModerator { get; init; }
+}