Scans an ASP.NET WebApplication project to find UserControls and adds them to the web.config file

UserControlScanner.cs

/*
 * Hugo Bonacci
 * http://hugoware.net
 * 
 * UserControls in Web Application projects do not appear unless
 * you use the Register tag at the top of the page or add them and
 * their virtual path to the web.config file.
 * 
 * This code allows you to add the namespace of your UserControls
 * to the web.config file and it will automatically scan for any
 * new .ascx files and add them for you automatically.
 * 
 * Use this code as part of the Application_Start method in 
 * the Global.ascx. 
 * 
 * NOTE: This code causes a single redirect for the first request 
 * to the site if a change is found in the web.config
 * 
 */

using System;
using System.Collections.Generic;
using System.Configuration;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Security.Cryptography;
using System.Text;
using System.Web;
using System.Web.Configuration;
using System.Web.UI;
using System.Xml.Linq;
using System.Text.RegularExpressions;

namespace Web {

    /// <summary>
    /// Located existing UserControls and attaches them to the Web.config
    /// </summary>
    public class UserControlScanner {

        #region Constants

        private const string SCAN_FILE_TYPE = "*.ascx";

        #endregion

        #region Constructors

        /// <summary>
        /// Creates a new UserControl scanner that finds .ascx files
        /// and then attaches them to the web.config
        /// </summary>
        public UserControlScanner()
            : this("asp") {
        }

        /// <summary>
        /// Creates a new UserControl scanner that finds .ascx files
        /// and then attaches them to the web.config
        /// </summary>
        public UserControlScanner(string prefix) {
            this.DefaultTagPrefix = prefix;
            this._Root = HttpContext.Current.Server.MapPath("~/");
            this._Controls = new List<_UserControlDetail>();
            this._Types = new List<Type>();
        }

        #endregion

        #region Properties

        /// <summary>
        /// The tag prefix to use if the control doesn't have
        /// a matching namespace in the web.config file
        /// </summary>
        public string DefaultTagPrefix { get; set; }

        //scan details
        private string _Root;
        private List<_UserControlDetail> _Controls;
        private List<Type> _Types;

        #endregion

        #region Public Methods

        /// <summary>
        /// Scans for .ASCX files and updates the web.config
        /// folder with the new files
        /// </summary>
        public void ScanAndUpdate() {

            //find the types that inherit from UserControl
            this._FindUserControlTypes();

            //find the .ascx files
            this._ScanForAscxFiles();

            //assign types to the correct UserControls
            this._SyncTypes();

            //update the web.config for changes
            this._UpdateConfig();

        }

        /// <summary>
        /// Shuts down the current site and reloads it - This
        /// causes a redirect for the connecting user
        /// </summary>
        public void Reset() {

            //get the path to redirect to
            string url = HttpContext.Current.Request.Url.AbsolutePath;

            //then reset the system
            HttpRuntime.UnloadAppDomain();

            //and redirect the request to start over
            HttpContext.Current.Response.Redirect(url);

        }

        #endregion

        #region Private Methods

        //scans for ascx files to compare against
        private void _ScanForAscxFiles() {
            foreach (string path in Directory.GetFiles(this._Root, SCAN_FILE_TYPE, SearchOption.AllDirectories)) {
                this._Controls.Add(_UserControlDetail.Parse(path));
            }
        }

        //finds all of the matching user controls
        private void _FindUserControlTypes() {
            foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies()) {
                this._Types.AddRange(
                    assembly.GetTypes()
                        .Where(item => item.IsSubclassOf(typeof(UserControl))));
            }
        }

        //syncs all of the types to a matching value
        private void _SyncTypes() {

            //update the types
            foreach (_UserControlDetail detail in this._Controls) {
                detail.Type = this._Types.FirstOrDefault(item => item.FullName.Equals(detail.FullName));
            }

            //drop anything that is missing
            this._Controls.RemoveAll(item => item.Type == null);

        }

        //returns a list of existing controls found for the site
        private void _UpdateConfig() {

            //open the configuration section
            Configuration config = WebConfigurationManager.OpenWebConfiguration("~");

            //grab the details for the controls
            ConfigurationSection section = config.GetSection("system.web/pages");
            string content = section.SectionInformation.GetRawXml();

            //get the controls section
            XElement xml = XElement.Parse(content);

            //start by getting a hash of the starting setup
            string start = this._GetHash(xml.ToString());

            //make sure the controls node is available
            XElement controls = xml.Element("controls");
            if (controls == null) {
                controls = new XElement("controls");
                xml.Add(controls);
            }

            //reach each type to find tagPrefix names
            foreach (XElement element in controls.Elements()) {
                XAttribute @namespace = element.Attribute("namespace");
                XAttribute prefix = element.Attribute("tagPrefix");

                //check for a namespace value
                if (!(@namespace is XAttribute && prefix is XAttribute)) {
                    continue;
                }

                //update all of the correct elements
                foreach (_UserControlDetail detail in this._Controls) {
                    if (detail.Type.Namespace.Equals(@namespace.Value.Trim())) {
                        detail.Prefix = prefix.Value;
                    }
                }
            }

            //make sure all of the controls have a prefix
            foreach (_UserControlDetail control in this._Controls) {
                control.Prefix = string.IsNullOrEmpty(control.Prefix)
                    ? this.DefaultTagPrefix
                    : control.Prefix;
            }

            //next, remove any controls with paths 
            for (int i = controls.Elements().Count(); i-- > 0; ) {
                XElement element = controls.Elements().ElementAt(i);
                if (element.Attribute("src") is XAttribute) {
                    element.Remove();
                }
            }

            //then add back all of the new paths
            foreach (_UserControlDetail detail in this._Controls) {
                controls.Add(
                    new XElement("add",
                        new XAttribute("tagPrefix", detail.Prefix),
                        new XAttribute("tagName", detail.Type.Name),
                        new XAttribute("src", detail.VirtualPath)
                        ));
            }

            //check if anything changes
            string finish = this._GetHash(xml.ToString());
            if (start.Equals(finish)) { return; }

            //update the XML information
            section.SectionInformation.SetRawXml(xml.ToString());
            config.Save();

            //since this has changes, go ahead and reset
            this.Reset();

        }

        //creates a hash for comparing changes
        private string _GetHash(string content) {
            return Convert.ToBase64String(SHA256.Create().ComputeHash(Encoding.UTF8.GetBytes(content)));
        }

        #endregion

    }

    #region User Control Details

    //contains information about a user control and how
    //to map the control
    internal class _UserControlDetail {

        #region Static Constructors

        //prepares the UserControlDetail expressions
        static _UserControlDetail() {
            _UserControlDetail.RegexFindControlInformation = new Regex(@"^\s*<%@ Control.*%>", RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.IgnoreCase);
            _UserControlDetail.RegexFindControlInherit = new Regex(@"Inherits=""(?<inherit>[^""]+)""", RegexOptions.IgnoreCase);
        }

        #endregion

        #region Static Values

        private static Regex RegexFindControlInformation;
        private static Regex RegexFindControlInherit;

        #endregion

        #region Properties

        public string PhysicalPath;
        public string VirtualPath;
        public string FullName;
        public string Prefix;
        public Type Type;

        #endregion

        #region Static Creation

        //parses the values for a user control
        public static _UserControlDetail Parse(string path) {
            _UserControlDetail detail = new _UserControlDetail();
            detail.PhysicalPath = path;

            //get the virtual path
            string root = HttpContext.Current.Server.MapPath("~/");
            string file = detail.PhysicalPath.Replace(root, string.Empty);
            detail.VirtualPath = string.Concat("~/", file.Replace("\\", "/"));

            //determine the virtual path for this
            string content = File.ReadAllText(path);
            Match control = _UserControlDetail.RegexFindControlInformation.Match(content);
            if (!control.Success) { return null; }

            //find what class it inherits from
            Match inherit = _UserControlDetail.RegexFindControlInherit.Match(control.Value);
            if (!inherit.Success) { return null; }
            detail.FullName = inherit.Groups["inherit"].Value;

            //return the result to work with
            return detail;

        }

        #endregion

    }

    #endregion

}

Scans a WebApplication project for UserControls and creates matching instances in the web.config file.