// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.

using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Security.Principal;
using System.Text;
using System.Web.Mvc.Async;
using System.Web.Mvc.Properties;
using System.Web.Profile;
using System.Web.Routing;

namespace System.Web.Mvc
{
    [SuppressMessage("Microsoft.Maintainability", "CA1506:AvoidExcessiveClassCoupling", Justification = "Class complexity dictated by public surface area")]
    public abstract class Controller : ControllerBase, IActionFilter, IAuthorizationFilter, IDisposable, IExceptionFilter, IResultFilter, IAsyncController, IAsyncManagerContainer
    {
        private static readonly object _executeTag = new object();
        private static readonly object _executeCoreTag = new object();

        private readonly AsyncManager _asyncManager = new AsyncManager();
        private IActionInvoker _actionInvoker;
        private ModelBinderDictionary _binders;
        private RouteCollection _routeCollection;
        private ITempDataProvider _tempDataProvider;
        private ViewEngineCollection _viewEngineCollection;

        private IDependencyResolver _resolver;

        // By default, use the global resolver with caching. 
        // Or we can override to supply this instance with its own cache.
        internal IDependencyResolver Resolver
        {
            get { return _resolver ?? DependencyResolver.CurrentCache; }
            set { _resolver = value; }
        }

        public AsyncManager AsyncManager
        {
            get { return _asyncManager; }
        }

        /// <summary>
        /// This is for backwards compat. MVC 4.0 starts allowing Controller to support asynchronous patterns.
        /// This means ExecuteCore doesn't get called on derived classes. Derived classes can override this
        /// flag and set to true if they still need ExecuteCore to be called.
        /// </summary>
        protected virtual bool DisableAsyncSupport
        {
            get { return false; }
        }

        public IActionInvoker ActionInvoker
        {
            get
            {
                if (_actionInvoker == null)
                {
                    _actionInvoker = CreateActionInvoker();
                }
                return _actionInvoker;
            }
            set { _actionInvoker = value; }
        }

        [SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "Property is settable so that the dictionary can be provided for unit testing purposes.")]
        protected internal ModelBinderDictionary Binders
        {
            get
            {
                if (_binders == null)
                {
                    _binders = ModelBinders.Binders;
                }
                return _binders;
            }
            set { _binders = value; }
        }

        public HttpContextBase HttpContext
        {
            get { return ControllerContext == null ? null : ControllerContext.HttpContext; }
        }

        public ModelStateDictionary ModelState
        {
            get { return ViewData.ModelState; }
        }

        public ProfileBase Profile
        {
            get { return HttpContext == null ? null : HttpContext.Profile; }
        }

        public HttpRequestBase Request
        {
            get { return HttpContext == null ? null : HttpContext.Request; }
        }

        public HttpResponseBase Response
        {
            get { return HttpContext == null ? null : HttpContext.Response; }
        }

        internal RouteCollection RouteCollection
        {
            get
            {
                if (_routeCollection == null)
                {
                    _routeCollection = RouteTable.Routes;
                }
                return _routeCollection;
            }
            set { _routeCollection = value; }
        }

        public RouteData RouteData
        {
            get { return ControllerContext == null ? null : ControllerContext.RouteData; }
        }

        public HttpServerUtilityBase Server
        {
            get { return HttpContext == null ? null : HttpContext.Server; }
        }

        public HttpSessionStateBase Session
        {
            get { return HttpContext == null ? null : HttpContext.Session; }
        }

        public ITempDataProvider TempDataProvider
        {
            get
            {
                if (_tempDataProvider == null)
                {
                    _tempDataProvider = CreateTempDataProvider();
                }
                return _tempDataProvider;
            }
            set { _tempDataProvider = value; }
        }

        public UrlHelper Url { get; set; }

        public IPrincipal User
        {
            get { return HttpContext == null ? null : HttpContext.User; }
        }

        [SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly", Justification = "This entire type is meant to be mutable.")]
        public ViewEngineCollection ViewEngineCollection
        {
            get { return _viewEngineCollection ?? ViewEngines.Engines; }
            set { _viewEngineCollection = value; }
        }

        [SuppressMessage("Microsoft.Naming", "CA1719:ParameterNamesShouldNotMatchMemberNames", MessageId = "0#", Justification = "'Content' refers to ContentResult type; 'content' refers to ContentResult.Content property.")]
        protected internal ContentResult Content(string content)
        {
            return Content(content, null /* contentType */);
        }

        [SuppressMessage("Microsoft.Naming", "CA1719:ParameterNamesShouldNotMatchMemberNames", MessageId = "0#", Justification = "'Content' refers to ContentResult type; 'content' refers to ContentResult.Content property.")]
        protected internal ContentResult Content(string content, string contentType)
        {
            return Content(content, contentType, null /* contentEncoding */);
        }

        [SuppressMessage("Microsoft.Naming", "CA1719:ParameterNamesShouldNotMatchMemberNames", MessageId = "0#", Justification = "'Content' refers to ContentResult type; 'content' refers to ContentResult.Content property.")]
        protected internal virtual ContentResult Content(string content, string contentType, Encoding contentEncoding)
        {
            return new ContentResult
            {
                Content = content,
                ContentType = contentType,
                ContentEncoding = contentEncoding
            };
        }

        protected virtual IActionInvoker CreateActionInvoker()
        {
            // Controller supports asynchronous operations by default. 
            return Resolver.GetService<IAsyncActionInvoker>() ?? Resolver.GetService<IActionInvoker>() ?? new AsyncControllerActionInvoker();
        }

        protected virtual ITempDataProvider CreateTempDataProvider()
        {
            return Resolver.GetService<ITempDataProvider>() ?? new SessionStateTempDataProvider();
        }

        // The default invoker will never match methods defined on the Controller type, so
        // the Dispose() method is not web-callable.  However, in general, since implicitly-
        // implemented interface methods are public, they are web-callable unless decorated with
        // [NonAction].
        public void Dispose()
        {
            Dispose(true /* disposing */);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
        }

        protected override void ExecuteCore()
        {
            // If code in this method needs to be updated, please also check the BeginExecuteCore() and
            // EndExecuteCore() methods of AsyncController to see if that code also must be updated.

            PossiblyLoadTempData();
            try
            {
                string actionName = RouteData.GetRequiredString("action");
                if (!ActionInvoker.InvokeAction(ControllerContext, actionName))
                {
                    HandleUnknownAction(actionName);
                }
            }
            finally
            {
                PossiblySaveTempData();
            }
        }

        protected internal FileContentResult File(byte[] fileContents, string contentType)
        {
            return File(fileContents, contentType, null /* fileDownloadName */);
        }

        protected internal virtual FileContentResult File(byte[] fileContents, string contentType, string fileDownloadName)
        {
            return new FileContentResult(fileContents, contentType) { FileDownloadName = fileDownloadName };
        }

        protected internal FileStreamResult File(Stream fileStream, string contentType)
        {
            return File(fileStream, contentType, null /* fileDownloadName */);
        }

        protected internal virtual FileStreamResult File(Stream fileStream, string contentType, string fileDownloadName)
        {
            return new FileStreamResult(fileStream, contentType) { FileDownloadName = fileDownloadName };
        }

        protected internal FilePathResult File(string fileName, string contentType)
        {
            return File(fileName, contentType, null /* fileDownloadName */);
        }

        protected internal virtual FilePathResult File(string fileName, string contentType, string fileDownloadName)
        {
            return new FilePathResult(fileName, contentType) { FileDownloadName = fileDownloadName };
        }

        protected virtual void HandleUnknownAction(string actionName)
        {
            throw new HttpException(404, String.Format(CultureInfo.CurrentCulture,
                                                       MvcResources.Controller_UnknownAction, actionName, GetType().FullName));
        }

        protected internal HttpNotFoundResult HttpNotFound()
        {
            return HttpNotFound(null);
        }

        protected internal virtual HttpNotFoundResult HttpNotFound(string statusDescription)
        {
            return new HttpNotFoundResult(statusDescription);
        }

        protected internal virtual JavaScriptResult JavaScript(string script)
        {
            return new JavaScriptResult { Script = script };
        }

        protected internal JsonResult Json(object data)
        {
            return Json(data, null /* contentType */, null /* contentEncoding */, JsonRequestBehavior.DenyGet);
        }

        protected internal JsonResult Json(object data, string contentType)
        {
            return Json(data, contentType, null /* contentEncoding */, JsonRequestBehavior.DenyGet);
        }

        protected internal virtual JsonResult Json(object data, string contentType, Encoding contentEncoding)
        {
            return Json(data, contentType, contentEncoding, JsonRequestBehavior.DenyGet);
        }

        protected internal JsonResult Json(object data, JsonRequestBehavior behavior)
        {
            return Json(data, null /* contentType */, null /* contentEncoding */, behavior);
        }

        protected internal JsonResult Json(object data, string contentType, JsonRequestBehavior behavior)
        {
            return Json(data, contentType, null /* contentEncoding */, behavior);
        }

        protected internal virtual JsonResult Json(object data, string contentType, Encoding contentEncoding, JsonRequestBehavior behavior)
        {
            return new JsonResult
            {
                Data = data,
                ContentType = contentType,
                ContentEncoding = contentEncoding,
                JsonRequestBehavior = behavior
            };
        }

        protected override void Initialize(RequestContext requestContext)
        {
            base.Initialize(requestContext);
            Url = new UrlHelper(requestContext);
        }

        protected virtual void OnActionExecuting(ActionExecutingContext filterContext)
        {
        }

        protected virtual void OnActionExecuted(ActionExecutedContext filterContext)
        {
        }

        protected virtual void OnAuthorization(AuthorizationContext filterContext)
        {
        }

        protected virtual void OnException(ExceptionContext filterContext)
        {
        }

        protected virtual void OnResultExecuted(ResultExecutedContext filterContext)
        {
        }

        protected virtual void OnResultExecuting(ResultExecutingContext filterContext)
        {
        }

        protected internal PartialViewResult PartialView()
        {
            return PartialView(null /* viewName */, null /* model */);
        }

        protected internal PartialViewResult PartialView(object model)
        {
            return PartialView(null /* viewName */, model);
        }

        protected internal PartialViewResult PartialView(string viewName)
        {
            return PartialView(viewName, null /* model */);
        }

        protected internal virtual PartialViewResult PartialView(string viewName, object model)
        {
            if (model != null)
            {
                ViewData.Model = model;
            }

            return new PartialViewResult
            {
                ViewName = viewName,
                ViewData = ViewData,
                TempData = TempData,
                ViewEngineCollection = ViewEngineCollection
            };
        }

        internal void PossiblyLoadTempData()
        {
            if (!ControllerContext.IsChildAction)
            {
                TempData.Load(ControllerContext, TempDataProvider);
            }
        }

        internal void PossiblySaveTempData()
        {
            if (!ControllerContext.IsChildAction)
            {
                TempData.Save(ControllerContext, TempDataProvider);
            }
        }

        [SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "0#", Justification = "Response.Redirect() takes its URI as a string parameter.")]
        protected internal virtual RedirectResult Redirect(string url)
        {
            if (String.IsNullOrEmpty(url))
            {
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "url");
            }

            return new RedirectResult(url);
        }

        [SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "0#", Justification = "Response.RedirectPermanent() takes its URI as a string parameter.")]
        protected internal virtual RedirectResult RedirectPermanent(string url)
        {
            if (String.IsNullOrEmpty(url))
            {
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "url");
            }

            return new RedirectResult(url, permanent: true);
        }

        protected internal RedirectToRouteResult RedirectToAction(string actionName)
        {
            return RedirectToAction(actionName, (RouteValueDictionary)null);
        }

        protected internal RedirectToRouteResult RedirectToAction(string actionName, object routeValues)
        {
            return RedirectToAction(actionName, new RouteValueDictionary(routeValues));
        }

        protected internal RedirectToRouteResult RedirectToAction(string actionName, RouteValueDictionary routeValues)
        {
            return RedirectToAction(actionName, null /* controllerName */, routeValues);
        }

        protected internal RedirectToRouteResult RedirectToAction(string actionName, string controllerName)
        {
            return RedirectToAction(actionName, controllerName, (RouteValueDictionary)null);
        }

        protected internal RedirectToRouteResult RedirectToAction(string actionName, string controllerName, object routeValues)
        {
            return RedirectToAction(actionName, controllerName, new RouteValueDictionary(routeValues));
        }

        protected internal virtual RedirectToRouteResult RedirectToAction(string actionName, string controllerName, RouteValueDictionary routeValues)
        {
            RouteValueDictionary mergedRouteValues;

            if (RouteData == null)
            {
                mergedRouteValues = RouteValuesHelpers.MergeRouteValues(actionName, controllerName, null, routeValues, includeImplicitMvcValues: true);
            }
            else
            {
                mergedRouteValues = RouteValuesHelpers.MergeRouteValues(actionName, controllerName, RouteData.Values, routeValues, includeImplicitMvcValues: true);
            }

            return new RedirectToRouteResult(mergedRouteValues);
        }

        protected internal RedirectToRouteResult RedirectToActionPermanent(string actionName)
        {
            return RedirectToActionPermanent(actionName, (RouteValueDictionary)null);
        }

        protected internal RedirectToRouteResult RedirectToActionPermanent(string actionName, object routeValues)
        {
            return RedirectToActionPermanent(actionName, new RouteValueDictionary(routeValues));
        }

        protected internal RedirectToRouteResult RedirectToActionPermanent(string actionName, RouteValueDictionary routeValues)
        {
            return RedirectToActionPermanent(actionName, null /* controllerName */, routeValues);
        }

        protected internal RedirectToRouteResult RedirectToActionPermanent(string actionName, string controllerName)
        {
            return RedirectToActionPermanent(actionName, controllerName, (RouteValueDictionary)null);
        }

        protected internal RedirectToRouteResult RedirectToActionPermanent(string actionName, string controllerName, object routeValues)
        {
            return RedirectToActionPermanent(actionName, controllerName, new RouteValueDictionary(routeValues));
        }

        protected internal virtual RedirectToRouteResult RedirectToActionPermanent(string actionName, string controllerName, RouteValueDictionary routeValues)
        {
            RouteValueDictionary implicitRouteValues = (RouteData != null) ? RouteData.Values : null;

            RouteValueDictionary mergedRouteValues =
                RouteValuesHelpers.MergeRouteValues(actionName, controllerName, implicitRouteValues, routeValues, includeImplicitMvcValues: true);

            return new RedirectToRouteResult(null, mergedRouteValues, permanent: true);
        }

        protected internal RedirectToRouteResult RedirectToRoute(object routeValues)
        {
            return RedirectToRoute(new RouteValueDictionary(routeValues));
        }

        protected internal RedirectToRouteResult RedirectToRoute(RouteValueDictionary routeValues)
        {
            return RedirectToRoute(null /* routeName */, routeValues);
        }

        protected internal RedirectToRouteResult RedirectToRoute(string routeName)
        {
            return RedirectToRoute(routeName, (RouteValueDictionary)null);
        }

        protected internal RedirectToRouteResult RedirectToRoute(string routeName, object routeValues)
        {
            return RedirectToRoute(routeName, new RouteValueDictionary(routeValues));
        }

        protected internal virtual RedirectToRouteResult RedirectToRoute(string routeName, RouteValueDictionary routeValues)
        {
            return new RedirectToRouteResult(routeName, RouteValuesHelpers.GetRouteValues(routeValues));
        }

        protected internal RedirectToRouteResult RedirectToRoutePermanent(object routeValues)
        {
            return RedirectToRoutePermanent(new RouteValueDictionary(routeValues));
        }

        protected internal RedirectToRouteResult RedirectToRoutePermanent(RouteValueDictionary routeValues)
        {
            return RedirectToRoutePermanent(null /* routeName */, routeValues);
        }

        protected internal RedirectToRouteResult RedirectToRoutePermanent(string routeName)
        {
            return RedirectToRoutePermanent(routeName, (RouteValueDictionary)null);
        }

        protected internal RedirectToRouteResult RedirectToRoutePermanent(string routeName, object routeValues)
        {
            return RedirectToRoutePermanent(routeName, new RouteValueDictionary(routeValues));
        }

        protected internal virtual RedirectToRouteResult RedirectToRoutePermanent(string routeName, RouteValueDictionary routeValues)
        {
            return new RedirectToRouteResult(routeName, RouteValuesHelpers.GetRouteValues(routeValues), permanent: true);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model) where TModel : class
        {
            return TryUpdateModel(model, null, null, null, ValueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string prefix) where TModel : class
        {
            return TryUpdateModel(model, prefix, null, null, ValueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string[] includeProperties) where TModel : class
        {
            return TryUpdateModel(model, null, includeProperties, null, ValueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string prefix, string[] includeProperties) where TModel : class
        {
            return TryUpdateModel(model, prefix, includeProperties, null, ValueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, string[] excludeProperties) where TModel : class
        {
            return TryUpdateModel(model, prefix, includeProperties, excludeProperties, ValueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, IValueProvider valueProvider) where TModel : class
        {
            return TryUpdateModel(model, null, null, null, valueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string prefix, IValueProvider valueProvider) where TModel : class
        {
            return TryUpdateModel(model, prefix, null, null, valueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string[] includeProperties, IValueProvider valueProvider) where TModel : class
        {
            return TryUpdateModel(model, null, includeProperties, null, valueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, IValueProvider valueProvider) where TModel : class
        {
            return TryUpdateModel(model, prefix, includeProperties, null, valueProvider);
        }

        protected internal bool TryUpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, string[] excludeProperties, IValueProvider valueProvider) where TModel : class
        {
            if (model == null)
            {
                throw new ArgumentNullException("model");
            }
            if (valueProvider == null)
            {
                throw new ArgumentNullException("valueProvider");
            }

            Predicate<string> propertyFilter = propertyName => BindAttribute.IsPropertyAllowed(propertyName, includeProperties, excludeProperties);
            IModelBinder binder = Binders.GetBinder(typeof(TModel));

            ModelBindingContext bindingContext = new ModelBindingContext()
            {
                ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => model, typeof(TModel)),
                ModelName = prefix,
                ModelState = ModelState,
                PropertyFilter = propertyFilter,
                ValueProvider = valueProvider
            };
            binder.BindModel(ControllerContext, bindingContext);
            return ModelState.IsValid;
        }

        protected internal bool TryValidateModel(object model)
        {
            return TryValidateModel(model, null /* prefix */);
        }

        protected internal bool TryValidateModel(object model, string prefix)
        {
            if (model == null)
            {
                throw new ArgumentNullException("model");
            }

            ModelMetadata metadata = ModelMetadataProviders.Current.GetMetadataForType(() => model, model.GetType());

            foreach (ModelValidationResult validationResult in ModelValidator.GetModelValidator(metadata, ControllerContext).Validate(null))
            {
                ModelState.AddModelError(DefaultModelBinder.CreateSubPropertyName(prefix, validationResult.MemberName), validationResult.Message);
            }

            return ModelState.IsValid;
        }

        protected internal void UpdateModel<TModel>(TModel model) where TModel : class
        {
            UpdateModel(model, null, null, null, ValueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string prefix) where TModel : class
        {
            UpdateModel(model, prefix, null, null, ValueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string[] includeProperties) where TModel : class
        {
            UpdateModel(model, null, includeProperties, null, ValueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string prefix, string[] includeProperties) where TModel : class
        {
            UpdateModel(model, prefix, includeProperties, null, ValueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, string[] excludeProperties) where TModel : class
        {
            UpdateModel(model, prefix, includeProperties, excludeProperties, ValueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, IValueProvider valueProvider) where TModel : class
        {
            UpdateModel(model, null, null, null, valueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string prefix, IValueProvider valueProvider) where TModel : class
        {
            UpdateModel(model, prefix, null, null, valueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string[] includeProperties, IValueProvider valueProvider) where TModel : class
        {
            UpdateModel(model, null, includeProperties, null, valueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, IValueProvider valueProvider) where TModel : class
        {
            UpdateModel(model, prefix, includeProperties, null, valueProvider);
        }

        protected internal void UpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, string[] excludeProperties, IValueProvider valueProvider) where TModel : class
        {
            bool success = TryUpdateModel(model, prefix, includeProperties, excludeProperties, valueProvider);
            if (!success)
            {
                string message = String.Format(CultureInfo.CurrentCulture, MvcResources.Controller_UpdateModel_UpdateUnsuccessful,
                                               typeof(TModel).FullName);
                throw new InvalidOperationException(message);
            }
        }

        protected internal void ValidateModel(object model)
        {
            ValidateModel(model, null /* prefix */);
        }

        protected internal void ValidateModel(object model, string prefix)
        {
            if (!TryValidateModel(model, prefix))
            {
                throw new InvalidOperationException(
                    String.Format(
                        CultureInfo.CurrentCulture,
                        MvcResources.Controller_Validate_ValidationFailed,
                        model.GetType().FullName));
            }
        }

        protected internal ViewResult View()
        {
            return View(viewName: null, masterName: null, model: null);
        }

        protected internal ViewResult View(object model)
        {
            return View(null /* viewName */, null /* masterName */, model);
        }

        protected internal ViewResult View(string viewName)
        {
            return View(viewName, masterName: null, model: null);
        }

        protected internal ViewResult View(string viewName, string masterName)
        {
            return View(viewName, masterName, null /* model */);
        }

        protected internal ViewResult View(string viewName, object model)
        {
            return View(viewName, null /* masterName */, model);
        }

        protected internal virtual ViewResult View(string viewName, string masterName, object model)
        {
            if (model != null)
            {
                ViewData.Model = model;
            }

            return new ViewResult
            {
                ViewName = viewName,
                MasterName = masterName,
                ViewData = ViewData,
                TempData = TempData,
                ViewEngineCollection = ViewEngineCollection
            };
        }

        [SuppressMessage("Microsoft.Naming", "CA1719:ParameterNamesShouldNotMatchMemberNames", MessageId = "0#", Justification = "The method name 'View' is a convenient shorthand for 'CreateViewResult'.")]
        protected internal ViewResult View(IView view)
        {
            return View(view, null /* model */);
        }

        [SuppressMessage("Microsoft.Naming", "CA1719:ParameterNamesShouldNotMatchMemberNames", MessageId = "0#", Justification = "The method name 'View' is a convenient shorthand for 'CreateViewResult'.")]
        protected internal virtual ViewResult View(IView view, object model)
        {
            if (model != null)
            {
                ViewData.Model = model;
            }

            return new ViewResult
            {
                View = view,
                ViewData = ViewData,
                TempData = TempData
            };
        }

        IAsyncResult IAsyncController.BeginExecute(RequestContext requestContext, AsyncCallback callback, object state)
        {
            return BeginExecute(requestContext, callback, state);
        }

        void IAsyncController.EndExecute(IAsyncResult asyncResult)
        {
            EndExecute(asyncResult);
        }

        protected virtual IAsyncResult BeginExecute(RequestContext requestContext, AsyncCallback callback, object state)
        {
            if (DisableAsyncSupport)
            {
                // For backwards compat, we can disallow async support and just chain to the sync Execute() function.
                Action action = () =>
                {
                    Execute(requestContext);
                };

                return AsyncResultWrapper.BeginSynchronous(callback, state, action, _executeTag);
            }
            else
            {
                if (requestContext == null)
                {
                    throw new ArgumentNullException("requestContext");
                }

                // Support Asynchronous behavior. 
                // Execute/ExecuteCore are no longer called.

                VerifyExecuteCalledOnce();
                Initialize(requestContext);
                return AsyncResultWrapper.Begin(callback, state, BeginExecuteCore, EndExecuteCore, _executeTag);
            }
        }

        protected virtual IAsyncResult BeginExecuteCore(AsyncCallback callback, object state)
        {
            // If code in this method needs to be updated, please also check the ExecuteCore() method
            // of Controller to see if that code also must be updated.
            PossiblyLoadTempData();
            try
            {
                string actionName = RouteData.GetRequiredString("action");
                IActionInvoker invoker = ActionInvoker;
                IAsyncActionInvoker asyncInvoker = invoker as IAsyncActionInvoker;
                if (asyncInvoker != null)
                {
                    // asynchronous invocation
                    BeginInvokeDelegate beginDelegate = delegate(AsyncCallback asyncCallback, object asyncState)
                    {
                        return asyncInvoker.BeginInvokeAction(ControllerContext, actionName, asyncCallback, asyncState);
                    };

                    EndInvokeDelegate endDelegate = delegate(IAsyncResult asyncResult)
                    {
                        if (!asyncInvoker.EndInvokeAction(asyncResult))
                        {
                            HandleUnknownAction(actionName);
                        }
                    };

                    return AsyncResultWrapper.Begin(callback, state, beginDelegate, endDelegate, _executeCoreTag);
                }
                else
                {
                    // synchronous invocation
                    Action action = () =>
                    {
                        if (!invoker.InvokeAction(ControllerContext, actionName))
                        {
                            HandleUnknownAction(actionName);
                        }
                    };
                    return AsyncResultWrapper.BeginSynchronous(callback, state, action, _executeCoreTag);
                }
            }
            catch
            {
                PossiblySaveTempData();
                throw;
            }
        }

        protected virtual void EndExecute(IAsyncResult asyncResult)
        {
            AsyncResultWrapper.End(asyncResult, _executeTag);
        }

        protected virtual void EndExecuteCore(IAsyncResult asyncResult)
        {
            // If code in this method needs to be updated, please also check the ExecuteCore() method
            // of Controller to see if that code also must be updated.

            try
            {
                AsyncResultWrapper.End(asyncResult, _executeCoreTag);
            }
            finally
            {
                PossiblySaveTempData();
            }
        }

        #region IActionFilter Members

        void IActionFilter.OnActionExecuting(ActionExecutingContext filterContext)
        {
            OnActionExecuting(filterContext);
        }

        void IActionFilter.OnActionExecuted(ActionExecutedContext filterContext)
        {
            OnActionExecuted(filterContext);
        }

        #endregion

        #region IAuthorizationFilter Members

        void IAuthorizationFilter.OnAuthorization(AuthorizationContext filterContext)
        {
            OnAuthorization(filterContext);
        }

        #endregion

        #region IExceptionFilter Members

        void IExceptionFilter.OnException(ExceptionContext filterContext)
        {
            OnException(filterContext);
        }

        #endregion

        #region IResultFilter Members

        void IResultFilter.OnResultExecuting(ResultExecutingContext filterContext)
        {
            OnResultExecuting(filterContext);
        }

        void IResultFilter.OnResultExecuted(ResultExecutedContext filterContext)
        {
            OnResultExecuted(filterContext);
        }

        #endregion
    }
}
