using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ChatRoomServer.Main.Room
{
	using System.Collections.Concurrent;
	using ChatRoomServer.Main.Entities;

	class RoomContainer
	{
		ConcurrentDictionary<ChatSession, RoomSessionContext> _contexts = new ConcurrentDictionary<ChatSession, RoomSessionContext>();
		ConcurrentDictionary<string, HashSet<ChatSession>> _users = new ConcurrentDictionary<string, HashSet<ChatSession>>();

		public RoomContainer(string id)
		{
			Id = id;
		}

		private void Session_RequireSendMessage(object sender, RequireSendMessageEventArgs e)
		{
			var enumerator = _contexts.GetEnumerator();
			while (enumerator.MoveNext())
			{
				if (!e.ExcludeSender || sender != enumerator.Current.Key)
					enumerator.Current.Key.TrySend(e.MessageItem);
			}
		}

		public void Add(ChatSession session)
		{
			var ctx = _contexts.GetOrAdd(session, new RoomSessionContext());
			var list = _users.GetOrAdd(session.UserName, _ => new HashSet<ChatSession>());
			list.Add(session);

			session.RoomContainer = this;

			var count = _contexts.Count;
			var enumerator = _contexts.GetEnumerator();

			var data = count + "\t" + session.UserName + "\t" + session.NickName;
			var msg = new MessageItem(SystemMessageType.UserEnter, content: data);
			while (enumerator.MoveNext())
			{
				if (enumerator.Current.Key != session)
					enumerator.Current.Key.TrySend(msg);
			}
			session.TrySend(msg);

			//add event listener
			session.RequireSendMessage += Session_RequireSendMessage;
		}

		/// <summary>
		/// 判断指定的用户是否在线
		/// </summary>
		/// <param name="user"></param>
		/// <returns></returns>
		public bool IsUserInRoom(string user)
		{
			return _users.ContainsKey(user);
		}

		public void Remove(ChatSession session)
		{
			RoomSessionContext context;
			if (!_contexts.TryRemove(session, out context))
				return;

			HashSet<ChatSession> sessions;
			if (_users.TryGetValue(session.UserName, out sessions))
			{
				lock (sessions)
				{
					if (sessions.Contains(session))
						sessions.Remove(session);

					if (sessions.Count == 0)
						_users.TryRemove(session.UserName, out sessions);
				}
			}


			var count = _contexts.Count;
			var enumerator = _contexts.GetEnumerator();
			var data = count + "\t" + session.UserName + "\t" + session.NickName;
			var msg = new MessageItem(SystemMessageType.UserExit, content: data);
			while (enumerator.MoveNext())
			{
				enumerator.Current.Key.TrySend(msg);
			}

			//remove event listener
			session.RequireSendMessage -= Session_RequireSendMessage;
		}

		/// <summary>
		/// 获得或设置房间ID
		/// </summary>
		public string Id { get; private set; }

		/// <summary>
		/// 获得会话数
		/// </summary>
		public int SessionCount => _contexts.Count;
	}
}