/MVCForum.Core/Events/EventManager.cs

using System;

using System.IO;

using System.Linq;

using System.Reflection;

using MVCForum.Domain.Interfaces.API;

using MVCForum.Domain.Interfaces.Events;

using MVCForum.Domain.Interfaces.Services;

using MVCForum.Utilities;



namespace MVCForum.Domain.Events

{

    public sealed class EventManager : IEventManager

    {

        private const string InterfaceTargetName =@"MVCForum.Domain.Interfaces.Events.IEventHandler";



        public EventHandler<BadgeEventArgs> BeforeBadgeAwarded;

        public EventHandler<VoteEventArgs> BeforeVoteMade;

        public EventHandler<MarkedAsSolutionEventArgs> BeforeMarkedAsSolution;

        public EventHandler<PostMadeEventArgs> BeforePostMade;

        public EventHandler<RegisterUserEventArgs> BeforeRegisterUser;

        public EventHandler<UpdateProfileEventArgs> BeforeUpdateProfile;



        public EventHandler<BadgeEventArgs> AfterBadgeAwarded;

        public EventHandler<VoteEventArgs> AfterVoteMade;

        public EventHandler<MarkedAsSolutionEventArgs> AfterMarkedAsSolution;

        public EventHandler<PostMadeEventArgs> AfterPostMade;

        public EventHandler<RegisterUserEventArgs> AfterRegisterUser;

        public EventHandler<UpdateProfileEventArgs> AfterUpdateProfile;



        private static volatile EventManager _instance;

        private static readonly object SyncRoot = new Object();



        public ILoggingService Logger { get; set; }



        /// <summary>

        /// Constructor - hidden

        /// </summary>

        private EventManager()

        {

        }



        /// <summary>

        /// Callback used when comparing objects to see if they implement an interface

        /// </summary>

        /// <param name="typeObj"></param>

        /// <param name="criteriaObj"></param>

        /// <returns></returns>

        private static bool InterfaceFilter(Type typeObj, Object criteriaObj)

        {

            return typeObj.ToString() == criteriaObj.ToString();

        }



        /// <summary>

        /// Singleton instance

        /// </summary>

        public static EventManager Instance

        {

            get

            {

                if (_instance == null)

                {

                    lock (SyncRoot)

                    {

                        if (_instance == null)

                        {

                            _instance = new EventManager();

                        }

                    }

                }



                return _instance;

            }

        }



        /// <summary>

        /// Use reflection to get all event handling classes. Call this ONCE.

        /// </summary>

        public void Initialize(ILoggingService loggingService)

        {

            Logger = loggingService;



            var interfaceFilter = new TypeFilter(InterfaceFilter);



            var path = AppDomain.CurrentDomain.RelativeSearchPath;



            // Get all the dlls

            var di = new DirectoryInfo(path);

            foreach (var file in di.GetFiles("*.dll"))

            {

                if (file.Name.ToLower().StartsWith("ecmascript"))

                {

                    continue;

                }



                Assembly nextAssembly;

                try

                {

                    nextAssembly = Assembly.LoadFrom(file.FullName);

                }

                catch (BadImageFormatException)

                {

                    // Not an assembly ignore

                    continue;

                }



                if (nextAssembly.FullName.StartsWith("System") || nextAssembly.FullName.StartsWith("Microsoft"))

                {

                    // Skip microsoft assemblies

                    continue;

                }



                try

                {

                    foreach (var type in nextAssembly.GetTypes())

                    {

                        if (type.IsInterface)

                        {

                            continue;

                        }



                        var myInterfaces = type.FindInterfaces(interfaceFilter, InterfaceTargetName);

                        if (myInterfaces.Length <= 0)

                        {

                            // Not a match

                            continue;

                        }



                        var ctor = type.GetConstructors().First();

                        var createdActivator = ReflectionUtilities.GetActivator<IEventHandler>(ctor);



                        // Create an instance:

                        var instance = createdActivator();



                        instance.RegisterHandlers(this);

                    }

                }

                catch (ReflectionTypeLoadException rtle)

                {

                    var msg =

                        string.Format(

                            "Unable to load assembly. Probably not an event assembly. In file named '{0}', loader exception was: '{1}':'{2}'.",

                            file.Name, rtle.LoaderExceptions[0].GetType(), rtle.LoaderExceptions[0].Message);

                    LogError(msg);

                }

                catch (Exception ex)

                {

                    LogError(string.Format("Error reflecting over event handlers: {0}", ex.Message));

                }

            }

        }



        /// <summary>

        /// Log errors

        /// </summary>

        /// <param name="msg"></param>

        public void LogError(string msg)

        {

            if (Logger != null)

            {

                Logger.Error(msg);

            }

        }

        #region Event triggers



        public void FireAfterBadgeAwarded(object sender, BadgeEventArgs eventArgs)

        {

            var handler = AfterBadgeAwarded;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireBeforeBadgeAwarded(object sender, BadgeEventArgs eventArgs)

        {

            var handler = BeforeBadgeAwarded;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireBeforeVoteMade(object sender, VoteEventArgs eventArgs)

        {

            var handler = BeforeVoteMade;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireBeforeMarkedAsSolution(object sender, MarkedAsSolutionEventArgs eventArgs)

        {

            var handler = BeforeMarkedAsSolution;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireBeforePostMade(object sender, PostMadeEventArgs eventArgs)

        {

            var handler = BeforePostMade;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireBeforeRegisterUser(object sender, RegisterUserEventArgs eventArgs)

        {

            var handler = BeforeRegisterUser;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireBeforeProfileUpdated(object sender, UpdateProfileEventArgs eventArgs)

        {

            var handler = BeforeUpdateProfile;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireAfterVoteMade(object sender, VoteEventArgs eventArgs)

        {

            var handler = AfterVoteMade;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireAfterMarkedAsSolution(object sender, MarkedAsSolutionEventArgs eventArgs)

        {

            var handler = AfterMarkedAsSolution;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireAfterPostMade(object sender, PostMadeEventArgs eventArgs)

        {

            var handler = AfterPostMade;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireAfterRegisterUser(object sender, RegisterUserEventArgs eventArgs)

        {

            var handler = AfterRegisterUser;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }



        public void FireAfterProfileUpdated(object sender, UpdateProfileEventArgs eventArgs)

        {

            var handler = AfterUpdateProfile;



            if (handler != null)

            {

                handler(this, eventArgs);

            }

        }





        #endregion



        public IMVCForumAPI API { get; set; }

    }

}