/trunk/src/AjaxSnippets/Snippet.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Text;

using System.Reflection;

using System.Web.UI.HtmlControls;

using System.IO;

using System.Text.RegularExpressions;



namespace AjaxSnippets

{

    /// <summary>

    /// Base class for snippets

    /// </summary>

    public abstract class Snippet : UserControl

    {

        /// <summary>

        /// TODO: this does not work currently, need to somehow flip this to true if

        /// there are child controls of SnippetCallback

        /// </summary>

        private bool _ContainsCallbacks = false;

        private ScriptManager GetScriptManager()

        {

            return (ScriptManager)Parent.FindControl("ScriptManager");

        }



        protected override void Render(HtmlTextWriter writer)

        {

            // Render the contents in <snippet> tag that we can use as a marker

            // to strip out the noise that ASP.NET creates which we will not be

            // making any use of

            if (IsOnSnippetPage) writer.Write("<snippet>");





            // Wrap up the snippet in a div with the ClientID of this control

            writer.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID);

            writer.RenderBeginTag(HtmlTextWriterTag.Div);



            base.Render(writer);



            if (IsOnSnippetPage)

            {

                RenderCssIncludes(writer);





                // HACK: Use reflection to get at ScriptRegistration from ScriptManager

                // this holds all the script includes and script blocks ready 

                // to be pumped out to the browser

                ScriptManager sm = GetScriptManager();

                List<RegisteredScript> scriptBlocks = null;

                List<RegisteredScript> scriptStartupBlocks = null;

                if (sm != null)

                {

                    object scriptRegistrations = sm.GetType().GetProperty("ScriptRegistration", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(sm, null);

                    scriptBlocks = (List<RegisteredScript>)scriptRegistrations.GetType().GetProperty("ScriptBlocks").GetValue(scriptRegistrations, null);

                    scriptStartupBlocks = (List<RegisteredScript>)scriptRegistrations.GetType().GetProperty("ScriptStartupBlocks").GetValue(scriptRegistrations, null);

                }



                RenderScriptIncludes(writer, scriptBlocks);



                //Make sure we have SnippetManager script registered

                RenderSnippetManagerCheckScript(writer);



                if (scriptStartupBlocks != null)

                {

                    // Try to remove this component if its already been created in a previous request

                    RenderComponentRemovalScripts(writer, scriptStartupBlocks);



                    #region TODO: May have to enumerate descriptors and manually set them up

                    //foreach (RegisteredScript startupScript in scriptStartupBlocks)

                    //{

                    //    if (startupScript.Control is IScriptControl)

                    //    {

                    //        IScriptControl scriptControl = (IScriptControl)startupScript.Control;



                    //        IEnumerable<ScriptDescriptor> descriptors = scriptControl.GetScriptDescriptors();



                    //        IEnumerator<ScriptDescriptor> descEnumerator = descriptors.GetEnumerator();

                    //        while (descEnumerator.MoveNext())

                    //        {

                    //            ScriptDescriptor descriptor = descEnumerator.Current;

                    //        }

                    //    }

                    //}

                    #endregion



                    foreach (RegisteredScript startupScript in scriptStartupBlocks)

                    {

                        writer.AddAttribute(HtmlTextWriterAttribute.Type, "text/javascript");

                        writer.AddAttribute("language", "javascript");

                        writer.RenderBeginTag(HtmlTextWriterTag.Script);

                        // HACK: Lets replace this and have snippet manager deal with it

                        writer.Write(startupScript.Script.Replace("Sys.Application.add_init", "AjaxSnippets.SnippetManager.stackFunction"));

                        writer.RenderEndTag();

                    }

                }

            }



            if (IsOnSnippetPage) RenderInvokeSnippetRenderedScript(writer);



            writer.RenderEndTag();



            if (IsOnSnippetPage) writer.Write("</snippet>");

        }



        /// <summary>

        /// TODO: Refactor this to RenderHtmlLinks, attributes for rel and type can be pulled from HtmlLink

        /// </summary>

        /// <param name="writer"></param>

        private void RenderCssIncludes(HtmlTextWriter writer)

        {

            if (this.Page.Header != null)

            {

                foreach (Control control in this.Page.Header.Controls)

                {

                    // we expect AJAX Framework scripts to be already rendered since SnippetManager needs it in the hosting page

                    if (control is HtmlLink)

                    {

                        HtmlLink link = (HtmlLink)control;

                        writer.AddAttribute(HtmlTextWriterAttribute.Type, "text/javascript");

                        writer.AddAttribute("language", "javascript");

                        writer.RenderBeginTag(HtmlTextWriterTag.Script);

                        writer.Write("AjaxSnippets.SnippetManager.loadCss('" + link.Href + "');");

                        writer.RenderEndTag();

                    }

                }

            }

        }





        private void RenderScriptIncludes(HtmlTextWriter writer, List<RegisteredScript> includes)

        {

            if (includes != null)

            {

                foreach (RegisteredScript include in includes)

                {

                    // we expect AJAX Framework scripts to be already rendered since SnippetManager needs it in the hosting page

                    if (!(include.Control is ScriptManager))

                    {

                        writer.AddAttribute(HtmlTextWriterAttribute.Type, "text/javascript");

                        writer.AddAttribute("language", "javascript");

                        writer.RenderBeginTag(HtmlTextWriterTag.Script);

                        writer.Write("AjaxSnippets.SnippetManager.loadScript('" + include.Url + "');");

                        writer.RenderEndTag();

                    }

                }

            }     

        }



        private void RenderComponentRemovalScripts(HtmlTextWriter writer, List<RegisteredScript> scriptStartupBlocks)

        {

            foreach (RegisteredScript startupScript in scriptStartupBlocks)

            {

                writer.AddAttribute(HtmlTextWriterAttribute.Type, "text/javascript");

                writer.AddAttribute("language", "javascript");

                writer.RenderBeginTag(HtmlTextWriterTag.Script);

                writer.Write("AjaxSnippets.SnippetManager.removeComponent('" + startupScript.Control.ClientID + "');");

                writer.RenderEndTag();

            }

        }



        /// <summary>

        /// Renders a script that alerts the user that they need to add the SnippetManager

        /// </summary>

        /// <param name="writer"></param>

        private void RenderSnippetManagerCheckScript(HtmlTextWriter writer)

        {

            if (_ContainsCallbacks)

            {

                writer.AddAttribute(HtmlTextWriterAttribute.Type, "text/javascript");

                writer.AddAttribute("language", "javascript");

                writer.RenderBeginTag(HtmlTextWriterTag.Script);

                writer.Write("if($find('SnippetManager') === null) { alert('The SnippetManager control must be added to the page'); }\n");

                writer.RenderEndTag();

            }

        }



        /// <summary>

        /// Renders a client script block that invokes a client snippetRendered() function if it exists

        /// 

        /// TODO: Might remove this feature, evaluate if this is actually needed

        /// </summary>

        private void RenderInvokeSnippetRenderedScript(HtmlTextWriter writer)

        {

            // Invoke the client-side snippetRendered method if any

            writer.AddAttribute(HtmlTextWriterAttribute.Type, "text/javascript");

            writer.AddAttribute("language", "javascript");

            writer.RenderBeginTag(HtmlTextWriterTag.Script);

            writer.Write("if(typeof(snippetRendered) !== 'undefined') { snippetRendered('" + this.ID + "') }\n");

            writer.RenderEndTag();

        }



        public bool IsOnSnippetPage

        {

            get

            {

                return (this.Page is SnippetPage);

            }

        }

        public override string ToString()

        {

            if (!IsOnSnippetPage)

                return base.ToString();



            string result = null;



            try

            {

                StringWriter writer = new StringWriter();

                HttpContext.Current.Server.Execute(Page, writer, false);

                Regex regEx = new Regex(@"(?<=<snippet>)(.*)(?=</snippet>)", RegexOptions.Singleline);

                result = regEx.Match(writer.ToString()).Value;

            }

            catch (Exception ex)

            {

                throw ex.GetBaseException();

            }

            

            

            return result;

        }



        /// <summary>

        /// Create a snippet of the given type from the given file

        /// </summary>

        /// <typeparam name="SnippetType">The Type of the snippet</typeparam>

        /// <param name="snippetId">a naming container</param>

        /// <param name="virtualPath">The virtual path to the ascx file of this snippet</param>

        /// <returns></returns>

        public static SnippetType Create<SnippetType>(string snippetId, string virtualPath) where SnippetType : Snippet

        {

            SnippetPage holder = new SnippetPage();

            // HACK: Add a HtmlHead, AjaxControlToolkit controls use this to register CSS

            holder.GetType().BaseType.GetField("_header", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic).SetValue(holder, new HtmlHead());



            HtmlForm form = new HtmlForm();

            holder.Controls.Add(form);



            ScriptManager scriptManager = new ScriptManager();

            scriptManager.ID = "ScriptManager";

            form.Controls.Add(scriptManager);



            Snippet snippetControl = (Snippet)holder.LoadControl(virtualPath);

            snippetControl.ID = snippetId;

            form.Controls.Add(snippetControl);

            return (SnippetType)snippetControl;

        }



        public class SnippetPage : Page{}

    }

}