using System;
using System.Collections.Generic;

namespace DMX2
{

	public struct EventData
	{
		public string id;
		public byte value;
	}

	public interface IEventProvider
	{
		string MenuName{ get; }
		ICollection<string>  GetEventList();		
		bool Bind (string eventId);
		void Unbind (string eventId);
		Gtk.Menu GetProviderSubMenu( EventManager.EventMenuData state, Gtk.ButtonPressEventHandler handler );
		void ProcessEvents(EventManagerCallback callback);
	}

	public interface IEventTarget
	{
		bool FireEvent(EventData data);
	}

	public delegate void EventManagerCallback(EventData data);
	public delegate void EventManagerMenuCallBack(object state, string eventId);


	public class EventManager
	{
		static public object StateKey = new object();
		static public object EventIdKey = new object();

		class eventBinding
		{
			List<IEventTarget> targets=new List<IEventTarget>();
			public void AddTarget(IEventTarget target)
			{
				if(!targets.Contains(target))
					targets.Add(target);
			}
			public void RemoveTarget(IEventTarget target)
			{
				targets.Remove(target);
			}
			public ICollection<IEventTarget> Targets {
				get {
					return targets;
				}
			}
		}

		Dictionary<string,eventBinding> bindings = new Dictionary<string,eventBinding>();
		List<IEventProvider> providers = new List<IEventProvider>();

		public EventManager ()
		{

		}

		public void RegisterProvider (IEventProvider prov)
		{
			providers.Add (prov);


		}

		public class EventMenuData {
			public EventManagerMenuCallBack CallBack;
			public object state;
		}

		public Gtk.Menu GetMenu (object state, EventManagerMenuCallBack callback)
		{
			Gtk.Menu menu = new Gtk.Menu ();
			EventMenuData evd = new EventMenuData();
			evd.CallBack = callback;
			evd.state = state;

			Gtk.ButtonPressEventHandler handler = new Gtk.ButtonPressEventHandler (HandleButtonPressEvent);

			foreach (IEventProvider prov in providers) {
				Gtk.MenuItem provitem = new Gtk.MenuItem(prov.MenuName);
				provitem.Submenu = prov.GetProviderSubMenu(evd, handler);
				menu.Add(provitem);
			}

			return menu;

		}

		void HandleButtonPressEvent (object o, Gtk.ButtonPressEventArgs args)
		{
			Gtk.MenuItem item = o as Gtk.MenuItem;
			EventMenuData evd = item.Data[EventManager.StateKey] as EventMenuData;
			string id = item.Data[EventManager.EventIdKey] as string;
			evd.CallBack(evd.state,id);
		}

		public void ProcessEvents ()
		{
			foreach (IEventProvider prov in providers) {
				prov.ProcessEvents(new EventManagerCallback(EventCallBack));
			}
		}

		public void UnregisterProvider (IEventProvider prov)
		{
			providers.Remove(prov);
		}

		public bool Bind (string eventId, IEventTarget target)
		{
			if(!bindings.ContainsKey(eventId)) 
				bindings.Add (eventId,new eventBinding());
			bindings[eventId].AddTarget(target);
			foreach (IEventProvider prov in providers) {
				if(prov.Bind(eventId)) return true;
			}
			return false;
		}


		public void Unbind (string eventId, IEventTarget target)
		{
			if (!bindings.ContainsKey (eventId))
				return;
			bindings [eventId].RemoveTarget (target);
			if (bindings [eventId].Targets.Count == 0) {
				bindings.Remove(eventId);
			foreach (IEventProvider prov in providers) {
				prov.Unbind(eventId);
				}			
			}
		}


		public void EventCallBack (EventData data)
		{
			if (bindings.ContainsKey (data.id)) {
				foreach (IEventTarget target in bindings[data.id].Targets) {
					target.FireEvent(data);
				}
			}			
		}
	}
}