using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace OpenSEMI.Core.Publisher
{
	public class Publisher : IPublisher
	{
		internal class Handler
		{
			public Delegate Action
			{
				get;
				set;
			}

			public WeakReference Sender
			{
				get;
				set;
			}

			public Type Type
			{
				get;
				set;
			}
		}

		internal List<Handler> _handlers = new List<Handler>();

		internal object _locker = new object();

		public void Publish<T>(T data = default(T))
		{
			List<Handler> list = default(List<Handler>);
			lock (_locker)
			{
				list = new List<Handler>(_handlers.Count);
				List<Handler> list2 = new List<Handler>(_handlers.Count);
				foreach (Handler handler in _handlers)
				{
					if (!handler.Sender.IsAlive)
					{
						list2.Add(handler);
					}
					else if (handler.Type.GetTypeInfo().IsAssignableFrom(typeof(T).GetTypeInfo()))
					{
						list.Add(handler);
					}
				}
				foreach (Handler item in list2)
				{
					_handlers.Remove(item);
				}
			}
			foreach (Handler item2 in list)
			{
				((Action<T>)item2.Action)(data);
			}
		}

		public void Subscribe<T>(Action<T> pHandler)
		{
			Subscribe(this, pHandler);
		}

		public void Subscribe<T>(object subscriber, Action<T> pHandler)
		{
			Handler handler = new Handler();
			handler.Action = pHandler;
			handler.Sender = new WeakReference(subscriber);
			handler.Type = typeof(T);
			Handler item = handler;
			lock (_locker)
			{
				_handlers.Add(item);
			}
		}

		public void Unsubscribe()
		{
			Unsubscribe(this);
		}

		public void Unsubscribe(object subscriber)
		{
			lock (_locker)
			{
				IEnumerable<Handler> source = from a in _handlers
				where !a.Sender.IsAlive || a.Sender.Target.Equals(subscriber)
				select a;
				foreach (Handler item in source.ToList())
				{
					_handlers.Remove(item);
				}
			}
		}

		public void Unsubscribe<T>()
		{
			Unsubscribe((object)this, (Action<T>)null);
		}

		public void Unsubscribe<T>(Action<T> pHandler)
		{
			Unsubscribe(this, pHandler);
		}

		public void Unsubscribe<T>(object subscriber, Action<T> pHandler = null)
		{
			lock (_locker)
			{
				IEnumerable<Handler> source = from a in _handlers
				where !a.Sender.IsAlive || (a.Sender.Target.Equals(subscriber) && a.Type == typeof(T))
				select a;
				if (pHandler != null)
				{
					source = from a in source
					where a.Action.Equals(pHandler)
					select a;
				}
				foreach (Handler item in source.ToList())
				{
					_handlers.Remove(item);
				}
			}
		}
	}
}