A dynamic Rehosted Workflow Designer for WF 4

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using System.Configuration;
using System.Activities;
using System.Xaml;
using System.Activities.XamlIntegration;

namespace Selen.ActivityWorkflowType
{
    public class CompiledActivityLoader
    {
        public void LoadActivities(bool clear = true)
        {
            this.LoadActivities(ActivityPaths.FileName, ActivityPaths.DestFileName, clear);
        }

        public IDictionary<string, Type> GetExecutableActivities()
        {
            return this.GetAllCompiledActivities(Directory.GetFiles(ActivityPaths.DestFileName, "*.dll"));
        }

        public IDictionary<string, Type> GetAllCompiledActivities(string[] files)
        {
            var activities = new Dictionary<string, Type>();

            foreach (var item in files)
            {
                var fileName = Path.GetTempFileName();
                File.Copy(item, fileName, true);
                var asm = Assembly.LoadFrom(fileName);
                var toAdd = asm.GetType("DynamicActivities.CompiledActivity", false);

                if (toAdd != null ? typeof(ICompiledActivity).IsAssignableFrom(toAdd) : false)
                {
                    var instance = ((ICompiledActivity)Activator.CreateInstance(toAdd));
                    activities.Add(instance.ActivityName, toAdd);
                }
            }

            return activities;
        }

        public void LoadActivities(string fileName, string destFileName, bool clear = true)
        {
            if (!Directory.Exists(fileName))
            {
                Directory.CreateDirectory(fileName);
            }

            if (Directory.Exists(destFileName) && clear)
            {
                foreach (var item in Directory.EnumerateFiles(destFileName))
                {
                    File.Delete(item);
                }
            }
            else
            {
                Directory.CreateDirectory(destFileName);
            }

            foreach (var item in Directory.GetFiles(fileName, "*.dll"))
            {
                var copy = Path.GetTempFileName();
                File.Copy(item, copy, true);
                var asm = Assembly.LoadFrom(copy);
                File.Copy(item, Path.Combine(destFileName, asm.GetName().Name + ".dll"), true);
            }
        }
    }
}