PluginService

using System;
using System.IO;
using System.Reflection;

namespace ManagedScanDesktop
{
    /// <summary>
    /// Summary description for PluginServices.
    /// </summary>
    public class PluginManagment//
    {
        private Types.AvailablePlugins colAvailablePlugins = new Types.AvailablePlugins();

        /// <summary>
        /// A Collection of all Plugins Found and Loaded by the FindPlugins() Method
        /// </summary>
        public Types.AvailablePlugins AvailablePlugins
        {
            get { return colAvailablePlugins; }
            set { colAvailablePlugins = value; }
        }

        /// <summary>
        /// Searches the passed Path for Plugins
        /// </summary>
        /// <param name="Path">Directory to search for Plugins in</param>
        public void FindPlugins(string Path)
        {
            //First empty the collection, we're reloading them all
            colAvailablePlugins.Clear();

            //Go through all the files in the plugin directory
            foreach (String fileOn in Directory.GetFiles(Path))
            {
                FileInfo file = new FileInfo(fileOn);

                //Preliminary check, must be .dll
                if (file.Extension.Equals(".dll") || file.Extension.Equals(".Dll"))
                {
                    //Add the 'plugin'
                    this.AddPlugin(fileOn);
                }
            }
        }

        /// <summary>
        /// Unloads and Closes all AvailablePlugins
        /// </summary>
        public void ClosePlugins()
        {
            foreach (Types.AvailablePlugin pluginOn in colAvailablePlugins)
            {
                //Close all plugin instances
                //We call the plugins Dispose sub first incase it has to do
                //Its own cleanup stuff
                //pluginOn.Instance.Dispose();

                //After we give the plugin a chance to tidy up, get rid of it
                //pluginOn.Instance = null;
            }

            //Finally, clear our collection of available plugins
            colAvailablePlugins.Clear();
        }

        private void AddPlugin(String FileName)
        {
            //Create a new assembly from the plugin file we're adding..
            Assembly pluginAssembly = Assembly.LoadFrom(FileName);
            Version assemblyVersion = pluginAssembly.GetName().Version;

            //Next we'll loop through all the Types found in the assembly
            foreach (Type pluginType in pluginAssembly.GetTypes())
            {
                if (pluginType.IsPublic) //Only look at public types
                {
                    if (!pluginType.IsAbstract)  //Only look at non-abstract types
                    {
                        //Gets a type object of the interface we need the plugins to match
                        //Type typeInterface = pluginType.GetInterface("InvuInterface.IInvuInterface", true);

                        //Make sure the interface we want to use actually exists
                        //if (typeInterface != null)
                        //{
                        //    //Make sure the assembly version matches the current lowes minimum

                        //    //Create a new available plugin since the type implements the IPlugin interface
                        //    Types.AvailablePlugin newPlugin = new Types.AvailablePlugin();

                        //    //Set the filename where we found it
                        //    newPlugin.AssemblyPath = FileName;

                        //    //Create a new instance and store the instance in the collection for later use
                        //    //We could change this later on to not load an instance.. we have 2 options
                        //    //1- Make one instance, and use it whenever we need it.. it's always there
                        //    //2- Don't make an instance, and instead make an instance whenever we use it, then close it
                        //    //For now we'll just make an instance of all the plugins
                        //    //newPlugin.Instance = (InvuInterface.IInvuInterface)Activator.CreateInstance(pluginAssembly.GetType(pluginType.ToString()));

                        //    //Add the new plugin to our collection here
                        //    this.colAvailablePlugins.Add(newPlugin);

                        //    //cleanup a bit
                        //    newPlugin = null;

                        //}

                        //typeInterface = null; //Mr. Clean //Mr. These are managed resources
                    }
                }
            }

            pluginAssembly = null; //more cleanup
        }
    }

    namespace Types
    {
        /// <summary>
        /// Collection for AvailablePlugin Type
        /// </summary>
        public class AvailablePlugins : System.Collections.CollectionBase
        {
            //A Simple Home-brew class to hold some info about our Available Plugins

            /// <summary>
            /// Add a Plugin to the collection of Available plugins
            /// </summary>
            /// <param name="pluginToAdd">The Plugin to Add</param>
            public void Add(Types.AvailablePlugin pluginToAdd)
            {
                this.List.Add(pluginToAdd);
            }

            /// <summary>
            /// Remove a Plugin to the collection of Available plugins
            /// </summary>
            /// <param name="pluginToRemove">The Plugin to Remove</param>
            public void Remove(Types.AvailablePlugin pluginToRemove)
            {
                this.List.Remove(pluginToRemove);
            }

            /// <summary>
            /// Finds a plugin in the available Plugins
            /// </summary>
            /// <param name="pluginNameOrPath">The name or File path of the plugin to find</param>
            /// <returns>Available Plugin, or null if the plugin is not found</returns>
            public Types.AvailablePlugin Find(string pluginNameOrPath)
            {
                Types.AvailablePlugin toReturn = null;

                //Loop through all the plugins
                foreach (Types.AvailablePlugin pluginOn in this.List)
                {
                    //Find the one with the matching name or filename
                    if (pluginOn.AssemblyPath.Equals(pluginNameOrPath))
                    {
                        toReturn = pluginOn;
                        break;
                    }
                }
                return toReturn;
            }

            public Types.AvailablePlugin Get(int index)
            {
                if (index > this.List.Count)
                {
                    return null;
                }
                else
                {
                    return (Types.AvailablePlugin)this.List[index];
                }
            }
        }

        /// <summary>
        /// Data Class for Available Plugin.  Holds and instance of the loaded Plugin, as well as the Plugin's Assembly Path
        /// </summary>
        public class AvailablePlugin
        {
            //This is the actual AvailablePlugin object..
            //Holds an instance of the plugin to access
            //ALso holds assembly path... not really necessary
            //private InvuInterface.IInvuInterface myInstance = null;
            private string myAssemblyPath = "";

            //public InvuInterface.IInvuInterface Instance
            //{
            //    get { return myInstance; }
            //    set { myInstance = value; }
            //}
            public string AssemblyPath
            {
                get { return myAssemblyPath; }
                set { myAssemblyPath = value; }
            }
        }
    }
}