Umbraco-CMS/src/Umbraco.Web.Common/ApplicationModels/VirtualPageApplicationModelProvider.cs

using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc.ApplicationModels;
using Umbraco.Cms.Core.Models.PublishedContent;
using Umbraco.Extensions;
using Umbraco.Web.Common.Controllers;

namespace Umbraco.Cms.Web.Common.ApplicationModels
{
    /// <summary>
    /// Applies the <see cref="VirtualPageConvention"/> to any action on a controller that is <see cref="IVirtualPageController"/>
    /// </summary>
    public class VirtualPageApplicationModelProvider : IApplicationModelProvider
    {
        private readonly List<IActionModelConvention> _actionModelConventions = new List<IActionModelConvention>()
        {
            new VirtualPageConvention()
        };

        /// <inheritdoc />
        /// <summary>
        /// Will execute after <see cref="DefaultApplicationModelProvider"/>
        /// </summary>
        public int Order => 0;

        /// <inheritdoc />
        public void OnProvidersExecuted(ApplicationModelProviderContext context) { }

        /// <inheritdoc />
        public void OnProvidersExecuting(ApplicationModelProviderContext context)
        {
            foreach (ControllerModel controller in context.Result.Controllers)
            {
                if (!IsVirtualPageController(controller))
                {
                    continue;
                }

                foreach (ActionModel action in controller.Actions.ToList())
                {
                    if (action.ActionName == nameof(IVirtualPageController.FindContent)
                        && action.ActionMethod.ReturnType == typeof(IPublishedContent))
                    {
                        // this is not an action, it's just the implementation of IVirtualPageController
                        controller.Actions.Remove(action);
                    }
                    else
                    {
                        foreach (IActionModelConvention convention in _actionModelConventions)
                        {
                            convention.Apply(action);
                        }
                    }
                }
            }
        }

        private bool IsVirtualPageController(ControllerModel controller)
            => controller.ControllerType.Implements<IVirtualPageController>();
    }
}