/* ****************************************************************************
 *
 * Copyright (c) Microsoft Corporation. All rights reserved.
 *
 * This software is subject to the Microsoft Public License (Ms-PL). 
 * A copy of the license can be found in the license.htm file included 
 * in this distribution.
 *
 * You must not remove this notice, or any other, from this software.
 *
 * ***************************************************************************/

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
    }
}