//---------------------------------------------------------------------------
//
// <copyright file="WeakEventManagerT.cs" company="Microsoft">
//    Copyright (C) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// Description: Generic weak event manager.
//
//---------------------------------------------------------------------------
using System;
using System.Reflection;
using MS.Internal.WindowsBase;
 
namespace System.Windows
{
    public class WeakEventManager<TEventSource, TEventArgs> : WeakEventManager
        where TEventArgs : EventArgs
    {
        #region Constructors
 
        //
        //  Constructors
        //
 
        private WeakEventManager(string eventName)
        {
            _eventName = eventName;
            _eventInfo = typeof(TEventSource).GetEvent(_eventName);
 
            if (_eventInfo == null)
                throw new ArgumentException(SR.Get(SRID.EventNotFound, typeof(TEventSource).FullName, eventName));
 
            _handler = Delegate.CreateDelegate(_eventInfo.EventHandlerType, this, DeliverEventMethodInfo);
        }
 
        #endregion Constructors
 
        #region Public Methods
 
        //
        //  Public Methods
        //
 
        /// <summary>
        /// Add a handler for the given source's event.
        /// </summary>
        public static void AddHandler(TEventSource source, string eventName, EventHandler<TEventArgs> handler)
        {
            if (handler == null)
                throw new ArgumentNullException("handler");
 
            CurrentManager(eventName).ProtectedAddHandler(source, handler);
        }
 
        /// <summary>
        /// Remove a handler for the given source's event.
        /// </summary>
        public static void RemoveHandler(TEventSource source, string eventName, EventHandler<TEventArgs> handler)
        {
            if (handler == null)
                throw new ArgumentNullException("handler");
 
            CurrentManager(eventName).ProtectedRemoveHandler(source, handler);
        }
 
        #endregion Public Methods
 
        #region Protected Methods
 
        //
        //  Protected Methods
        //
 
        /// <summary>
        /// Return a new list to hold listeners to the event.
        /// </summary>
        protected override ListenerList NewListenerList()
        {
            return new ListenerList<TEventArgs>();
        }
 
        /// <summary>
        /// Listen to the given source for the event.
        /// </summary>
        protected override void StartListening(object source)
        {
            _eventInfo.AddEventHandler(source, _handler);
        }
 
        /// <summary>
        /// Stop listening to the given source for the event.
        /// </summary>
        protected override void StopListening(object source)
        {
            _eventInfo.RemoveEventHandler(source, _handler);
        }
 
        #endregion Protected Methods
 
        #region Private Properties
 
        //
        //  Private Properties
        //
 
        // get the event manager for the current thread
        private static WeakEventManager<TEventSource, TEventArgs> CurrentManager(string eventName)
        {
            Type managerType = typeof(WeakEventManager<TEventSource, TEventArgs>);
            WeakEventManager<TEventSource, TEventArgs> manager = (WeakEventManager<TEventSource, TEventArgs>)GetCurrentManager(typeof(TEventSource), eventName);
 
            // at first use, create and register a new manager
            if (manager == null)
            {
                manager = new WeakEventManager<TEventSource, TEventArgs>(eventName);
                SetCurrentManager(typeof(TEventSource), eventName, manager);
            }
 
            return manager;
        }
 
        #endregion Private Properties
 
        #region Private Data
 
        Delegate _handler;
        string _eventName;
        EventInfo _eventInfo;
 
        #endregion Private Data
    }
}