Kentico 12 Custom MVC View Engine

using System;
using System.Web.Mvc;
using CMS.SiteProvider;

namespace Website.Infrastructure.ViewEngines
{
    public class MultiSiteViewEngine : RazorViewEngine
    {
        private bool _locationsSet;

        private void SetViewLocations(string themeName)
        {
            if (_locationsSet) return;

            ViewLocationFormats = new[]
            {
                $"~/Views/Themes/{themeName}/{{1}}/{{0}}.cshtml",
                $"~/Views/Themes/{themeName}/Shared/{{0}}.cshtml"
            };
            PartialViewLocationFormats = ViewLocationFormats;
            MasterLocationFormats = ViewLocationFormats;

            AreaViewLocationFormats = new[]
            {
                $"~/Areas/{{2}}/Views/Themes/{themeName}/{{1}}/{{0}}.cshtml",
                $"~/Areas/{{2}}/Views/Themes/{themeName}/Shared/{{0}}.cshtml"
            };
            AreaPartialViewLocationFormats = AreaViewLocationFormats;
            AreaMasterLocationFormats = AreaViewLocationFormats;

            _locationsSet = true;
        }

        public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName,
            string masterName, bool useCache)
        {
            SetViewLocations(SiteContext.CurrentSiteName);

            // If it's a Kentico view - return an empty result to
            // force MVC to drop through to Kentico's own ViewEngine
            if (IsKenticoEmbeddedView(viewName))
            {
                return new ViewEngineResult(ViewLocationFormats);
            }

            return base.FindView(controllerContext, viewName, masterName, useCache);

        }

        public override ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName,
            bool useCache)
        {
            SetViewLocations(SiteContext.CurrentSiteName);

            // If it's a Kentico view - return an empty result to
            // force MVC to drop through to Kentico's own ViewEngine
            if (IsKenticoEmbeddedView(partialViewName))
            {
                return new ViewEngineResult(PartialViewLocationFormats);
            }

            return base.FindPartialView(controllerContext, partialViewName, useCache);

        }
        private static bool IsKenticoEmbeddedView(string viewName)
        {
            return (viewName.StartsWith("~/", StringComparison.Ordinal))
                   && viewName.IndexOf("Kentico/", StringComparison.OrdinalIgnoreCase) >= 0;
        }
    }

}