SkinControlLoader.cs :  » Bloggers » SubText » Subtext » Framework » UI » Skinning » C# / CSharp Open Source

#region Disclaimer/Info

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#endregion

using System;
using System.Diagnostics;
using System.Web;
using System.Web.UI;
using Subtext.Framework.Configuration;
using Subtext.Framework.Properties;

namespace Subtext.Framework.UI.Skinning{
    public class SkinControlLoader : ISkinControlLoader
    {
        const string ControlLocationFormat = "~/Skins/{0}/Controls/{1}.ascx";
        const string SystemFolderName = "_System";
        const string ErrorControlName = "Error";

        public SkinControlLoader(IContainerControl container, SkinConfig skin)
        {
            Container = container;
            Skin = skin;
        }

        protected IContainerControl Container
        {
            get; 
            private set;
        }

        protected SkinConfig Skin
        {
            get;
            private set;
        }

        public Control LoadControl(string controlName)
        {
            var control = LoadControlFromSkin(controlName);
            if(control != null && control.ID != null)
            {
                control.ID = control.ID.Replace('.', '_');
            }
            return control;
        }

        Control LoadControlFromSkin(string controlName)
        {
            var result = GetLoadControlResult(Skin.TemplateFolder, controlName);
            if(result.SkinControl != null)
            {
                return result.SkinControl;
            }

            // short circuit for this specific exception.
            if(result.Exception is HttpParseException)
            {
                return GetErrorControl(new SkinControlLoadException(Resources.SkinControlLoadException_Message, result.ControlPath, result.Exception));
            }
            
            // Fallback
            var fallBack = GetLoadControlResult(SystemFolderName, controlName);
            if(fallBack.SkinControl != null)
            {
                return fallBack.SkinControl;
            }

            // Need to return the original control path and exception.
            return GetErrorControl(new SkinControlLoadException(Resources.SkinControlLoadException_Message, result.ControlPath, result.Exception));
        }

        private Control GetErrorControl(SkinControlLoadException exception)
        {
            var result = GetLoadControlResult(SystemFolderName, ErrorControlName);
            Debug.Assert(result != null, "The result should never be null");
            var control = result.SkinControl;
            if(control == null)
            {
                throw new InvalidOperationException("The system Error skin control is missing. Did you delete it by mistake? It should be located at '" + result.ControlPath + "'");
            }
            
            var errorControl = result.SkinControl as IErrorControl;
            if(errorControl != null)
            {
                errorControl.Exception = exception;
            }
            return control;
        }

        private SkinControlLoadResult GetLoadControlResult(string folderName, string controlName)
        {
            string controlPath = string.Format(ControlLocationFormat, folderName, controlName);
            try
            {
                var control = Container.LoadControl(controlPath);
                return new SkinControlLoadResult(controlPath, control, null);
            }
            catch(Exception e)
            {
                return new SkinControlLoadResult(controlPath, null, e);
            }
        }
    }
}