MvcScriptHelper: Helps render multiple script blocks from multiple pages/layouts/partial views, in the expected order

MvcScriptHelper.cs

//-----------------------------------------------------------------------
// <copyright file="MvcScriptHelper.cs" company="The Swedish Post and Telecom Authority (PTS)">
//      Copyright (c) 2011, 2012 The Swedish Post and Telecom Authority (PTS)
//      Developed for PTS by Joel Purra <http://joelpurra.se/>
//      Released under the BSD license.
// </copyright>
//-----------------------------------------------------------------------
// https://gist.github.com/2398969

namespace JoelPurra.Web.Helpers
{
    using System;
    using System.Diagnostics.Contracts;
    using System.Linq;
    using System.Web;
    using System.Web.Mvc;
    using System.Web.WebPages;

    /// <summary>
    ///     Helps renders multiple script blocks from multiple pages, layouts, partial views in the expected order.
    /// </summary>
    public static class MvcScriptHelper
    {
        #region Constants and Fields

        private static int counter;

        #endregion

        #region Public Methods

        /// <summary>
        ///     Renders multiple script blocks from multiple partial views
        /// </summary>
        /// <remarks>
        ///     Inspiration from http://stackoverflow.com/questions/5433531/using-sections-in-editor-display-templates/5433722#5433722
        /// </remarks>
        /// <param name="htmlHelper"> </param>
        /// <returns> </returns>
        public static IHtmlString RenderScripts(this HtmlHelper htmlHelper)
        {
            Contract.Requires(htmlHelper != null);

            // Order the collection by the key in order to output scripts in the order they were added on each "execution level".
            // This is a hack due to the execution order of Razor pages
            // See http://mvcdev.com/differences-between-asp-net-razor-and-web-forms-view-engines/
            IOrderedEnumerable<object> scriptKeys =
                htmlHelper.ViewContext.HttpContext.Items.Keys.Cast<object>().Where(
                    key => key.GetType() == typeof(int[])).OrderBy(key => string.Join(", ", (int[])key));

            foreach (object key in scriptKeys)
            {
                Func<object, HelperResult> template =
                    htmlHelper.ViewContext.HttpContext.Items[key] as Func<object, HelperResult>;

                if (template != null)
                {
                    htmlHelper.ViewContext.Writer.Write(template(null));
                }
            }

            return MvcHtmlString.Empty;
        }

        /// <summary>
        ///     Adds script blocks to be executed in order called.
        /// </summary>
        /// <example>
        ///     <![CDATA[@Html.Script(
        ///     @&lt;script&gt;
        ///     //&lt;![CDATA[
        ///         alert("This is a script block!");
        ///     //]]&gt;
        ///     &lt;/script&gt;)
        /// ]]>
        /// </example>
        /// <remarks>
        ///     Inspiration from http://stackoverflow.com/questions/5433531/using-sections-in-editor-display-templates/5433722#5433722
        /// </remarks>
        /// <param name="htmlHelper"> </param>
        /// <param name="razorExecutionLevel"> </param>
        /// <param name="template"> One or more script blocks. Surround multiple blocks with the &lt;text&gt; tag. </param>
        /// <returns> </returns>
        public static MvcHtmlString Script(
            this HtmlHelper htmlHelper, RazorExecutionLevel razorExecutionLevel, Func<object, HelperResult> template)
        {
            Contract.Requires(htmlHelper != null);
            Contract.Requires(template != null);

            int razorExecutionLevelInt = (int)razorExecutionLevel;

            // TODO: Make a new ScriptKey class that is sortable
            int[] key = new[]
            {
                razorExecutionLevelInt, counter
            };

            htmlHelper.ViewContext.HttpContext.Items.Add(key, template);

            counter++;

            return MvcHtmlString.Empty;
        }

        public static MvcHtmlString ScriptInLayout(this HtmlHelper htmlHelper, Func<object, HelperResult> template)
        {
            Contract.Requires(htmlHelper != null);
            Contract.Requires(template != null);

            return htmlHelper.Script(RazorExecutionLevel.Layout, template);
        }

        public static MvcHtmlString ScriptInPage(this HtmlHelper htmlHelper, Func<object, HelperResult> template)
        {
            Contract.Requires(htmlHelper != null);
            Contract.Requires(template != null);

            return htmlHelper.Script(RazorExecutionLevel.Page, template);
        }

        public static MvcHtmlString ScriptInPartialView(this HtmlHelper htmlHelper, Func<object, HelperResult> template)
        {
            Contract.Requires(htmlHelper != null);
            Contract.Requires(template != null);

            return htmlHelper.Script(RazorExecutionLevel.PartialView, template);
        }

        #endregion
    }
}

RazorExecutionLevel.cs

//-----------------------------------------------------------------------
// <copyright file="RazorExecutionLevel.cs" company="The Swedish Post and Telecom Authority (PTS)">
//      Copyright (c) 2011, 2012 The Swedish Post and Telecom Authority (PTS)
//      Developed for PTS by Joel Purra <http://joelpurra.se/>
//      Released under the BSD license.
// </copyright>
//-----------------------------------------------------------------------
// https://gist.github.com/2398969

namespace JoelPurra.Web.Helpers
{
    public enum RazorExecutionLevel
    {
        Layout = 1,

        Page = 2,

        PartialView = 3
    }
}