using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using ClientList = System.Collections.Generic.List<LiveLogger4Log4Net.IL4NClient>;

namespace LiveLogger4Log4Net
{
	/// <summary>
	/// Helps to keep track of registration of the clients.
	/// </summary>
	public class RegistrationList
	{
		/// <summary>
		/// This is the list of the clients that wants to listen to all channels.
		/// </summary>
		private ClientList clientsThatListenToAllLoggers = new ClientList();

		/// <summary>
		/// some clients can ask only for some logger, so I keep a map that for each
		/// logger name stores all clients in a list.
		/// </summary>
		private Dictionary<String, ClientList> clients = new Dictionary<String, ClientList>();

		/// <summary>
		/// Add a client that will listen to all loggers.
		/// </summary>
		/// <param name="client"></param>
		public void Add(IL4NClient client)
		{
			clientsThatListenToAllLoggers.Add(client);
		}

		/// <summary>
		/// Add a client that will listen only to specific loggers
		/// </summary>
		/// <param name="client"></param>
		/// <param name="loggerList"></param>
		public void Add(IL4NClient client, IEnumerable<String> loggerList)
		{
			foreach (String loggerName in loggerList)
			{
				if (!clients.ContainsKey(loggerName))
				{
					clients.Add(loggerName, new ClientList());
				}
				clients[loggerName].Add(client);
			}
		}

		/// <summary>
		/// Add a client that will listen only to specific loggers
		/// </summary>
		/// <param name="client"></param>
		/// <param name="loggerList"></param>
		public void Add(IL4NClient client, params String[] loggerList)
		{
			Add(client, (IEnumerable<String>)loggerList);
		}

		#region Enumerators

		/// <summary>
		/// Enumerate through all listening channels 
		/// </summary>
		/// <returns></returns>
		public IEnumerable<IL4NClient> GetEnumerator(String loggerName)
		{
			foreach (IL4NClient client in clientsThatListenToAllLoggers.Union(
				clients.ContainsKey(loggerName) ? clients[loggerName] : Enumerable.Empty<IL4NClient>()))
				yield return client;
		}

		#endregion


		/// <summary>
		/// invoke the action for all registered clients, if some clients generates exception it remove the
		/// registration.
		/// </summary>
		/// <param name="action">The action to invoke for all the clients</param>
		/// <param name="loggerName">The name of the logger</param>
		public void InvokeOnAllClients(Action<IL4NClient> action, String loggerName)
		{
			ClientList unregisterClientList = null;
			foreach (IL4NClient client in this.GetEnumerator(loggerName))
			{
				try
				{
					action(client);
				}
				catch (Exception)
				{
					//client must be unregistered.
					if (unregisterClientList == null)
					{
						unregisterClientList = new ClientList();
					}
					unregisterClientList.Add(client);
				}
			}
			//now if I need to unregister some client i do it
			if (unregisterClientList != null)
			{
				unregisterClientList.ForEach(client =>
				{
					//Remove from the global list
					clientsThatListenToAllLoggers.Remove(client);
					//Remove from all the specific logger list.
					foreach (KeyValuePair<String, ClientList> el in clients)
					{
						el.Value.Remove(client);
					}
				});
			}
		}

	}
}