/MVC/src/SystemWebMvc/Mvc/MvcHandler.cs

namespace System.Web.Mvc {

    using System;

    using System.Diagnostics.CodeAnalysis;

    using System.Globalization;

    using System.Reflection;

    using System.Web;

    using System.Web.Mvc.Resources;

    using System.Web.Routing;

    using System.Web.SessionState;



    [SuppressMessage("Microsoft.Security", "CA2112:SecuredTypesShouldNotExposeFields", Justification = "There's nothing secret about the value of this field.")]

    public class MvcHandler : IHttpHandler, IRequiresSessionState {

        private ControllerBuilder _controllerBuilder;

        private static string MvcVersion = GetMvcVersionString();



        public static readonly string MvcVersionHeaderName = "X-AspNetMvc-Version";



        public MvcHandler(RequestContext requestContext) {

            if (requestContext == null) {

                throw new ArgumentNullException("requestContext");

            }

            RequestContext = requestContext;

        }



        protected virtual bool IsReusable {

            get {

                return false;

            }

        }



        internal ControllerBuilder ControllerBuilder {

            get {

                if (_controllerBuilder == null) {

                    _controllerBuilder = ControllerBuilder.Current;

                }

                return _controllerBuilder;

            }

            set {

                _controllerBuilder = value;

            }

        }



        public static bool DisableMvcResponseHeader {

            get;

            set;

        }



        public RequestContext RequestContext {

            get;

            private set;

        }



        protected internal virtual void AddVersionHeader(HttpContextBase httpContext) {

            if (!DisableMvcResponseHeader) {

                httpContext.Response.AppendHeader(MvcVersionHeaderName, MvcVersion);

            }

        }



        private static string GetMvcVersionString() {

            // DevDiv 216459:

            // This code originally used Assembly.GetName(), but that requires FileIOPermission, which isn't granted in

            // medium trust. However, Assembly.FullName *is* accessible in medium trust.

            return new AssemblyName(typeof(MvcHandler).Assembly.FullName).Version.ToString(2);

        }



        protected virtual void ProcessRequest(HttpContext httpContext) {

            HttpContextBase iHttpContext = new HttpContextWrapper(httpContext);

            ProcessRequest(iHttpContext);

        }



        protected internal virtual void ProcessRequest(HttpContextBase httpContext) {

            AddVersionHeader(httpContext);



            // Get the controller type

            string controllerName = RequestContext.RouteData.GetRequiredString("controller");



            // Instantiate the controller and call Execute

            IControllerFactory factory = ControllerBuilder.GetControllerFactory();

            IController controller = factory.CreateController(RequestContext, controllerName);

            if (controller == null) {

                throw new InvalidOperationException(

                    String.Format(

                        CultureInfo.CurrentUICulture,

                        MvcResources.ControllerBuilder_FactoryReturnedNull,

                        factory.GetType(),

                        controllerName));

            }

            try {

                controller.Execute(RequestContext);

            }

            finally {

                factory.ReleaseController(controller);

            }

        }



        #region IHttpHandler Members

        bool IHttpHandler.IsReusable {

            get {

                return IsReusable;

            }

        }



        void IHttpHandler.ProcessRequest(HttpContext httpContext) {

            ProcessRequest(httpContext);

        }

        #endregion

    }

}