Foxchat.NET/Foxchat.Identity/Middleware/AuthorizationMiddleware.cs

using Foxchat.Core;
using Foxchat.Identity.Database;
using NodaTime;

namespace Foxchat.Identity.Middleware;

public class AuthorizationMiddleware(
    IdentityContext db,
    IClock clock
) : IMiddleware
{
    public async Task InvokeAsync(HttpContext ctx, RequestDelegate next)
    {
        var endpoint = ctx.GetEndpoint();
        var attribute = endpoint?.Metadata.GetMetadata<AuthorizeAttribute>();

        if (attribute == null)
        {
            await next(ctx);
            return;
        }

        var token = ctx.GetToken();
        if (token == null || token.Expires > clock.GetCurrentInstant())
            throw new ApiError.Unauthorized("This endpoint requires an authenticated user.");
        if (attribute.Scopes.Length > 0 && attribute.Scopes.Except(token.Scopes).Any())
            throw new ApiError.Forbidden("This endpoint requires ungranted scopes.", attribute.Scopes.Except(token.Scopes));

        await next(ctx);
    }
}

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class AuthorizeAttribute(params string[] scopes) : Attribute
{
    public readonly string[] Scopes = scopes;
}