using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.Threading;
using System.Threading.Tasks;
using NewLife.Collections;
using NewLife.Data;
using NewLife.Log;
using NewLife.Model;
using NewLife.Threading;
#if !NET4
using TaskEx = System.Threading.Tasks.Task;
#endif

namespace NewLife.Net
{
    /// <summary>网络服务器。可同时支持多个Socket服务器，同时支持IPv4和IPv6，同时支持Tcp和Udp</summary>
    /// <remarks>
    /// 网络服务器模型，所有网络应用服务器可以通过继承该类实现。
    /// 该类仅实现了业务应用对网络流的操作，与具体网络协议无关。
    /// 
    /// 收到请求<see cref="Server_NewSession"/>后，会建立<see cref="CreateSession"/>会话，并加入到会话集合<see cref="Sessions"/>中，然后启动<see cref="Start"/>会话处理；
    /// 
    /// 快速用法：
    /// 指定端口后直接<see cref="Start"/>，NetServer将同时监听Tcp/Udp和IPv4/IPv6（会检查是否支持）四个端口。
    /// 
    /// 简单用法：
    /// 重载方法<see cref="EnsureCreateServer"/>来创建一个SocketServer并赋值给<see cref="Server"/>属性，<see cref="EnsureCreateServer"/>将会在<see cref="OnStart"/>时首先被调用。
    /// 
    /// 标准用法：
    /// 使用<see cref="AttachServer"/>方法向网络服务器添加Socket服务，其中第一个将作为默认Socket服务<see cref="Server"/>。
    /// 如果Socket服务集合<see cref="Servers"/>为空，将依据地址<see cref="Local"/>、端口<see cref="Port"/>、地址族<see cref="AddressFamily"/>、协议<see cref="ProtocolType"/>创建默认Socket服务。
    /// 如果地址族<see cref="AddressFamily"/>指定为IPv4和IPv6以外的值，将同时创建IPv4和IPv6两个Socket服务；
    /// 如果协议<see cref="ProtocolType"/>指定为Tcp和Udp以外的值，将同时创建Tcp和Udp两个Socket服务；
    /// 默认情况下，地址族<see cref="AddressFamily"/>和协议<see cref="ProtocolType"/>都是其它值，所以一共将会创建四个Socket服务（Tcp、Tcpv6、Udp、Udpv6）。
    /// </remarks>
    public class NetServer : DisposeBase, IServer
    {
        #region 属性
        /// <summary>服务名</summary>
        public String Name { get; set; }

        private NetUri _Local = new NetUri();
        /// <summary>本地结点</summary>
        public NetUri Local
        {
            get => _Local;
            set
            {
                _Local = value;
                if (AddressFamily <= AddressFamily.Unspecified) AddressFamily = value.Address.AddressFamily;
            }
        }

        /// <summary>端口</summary>
        public Int32 Port { get => _Local.Port; set => _Local.Port = value; }

        /// <summary>协议类型</summary>
        public NetType ProtocolType { get => _Local.Type; set => _Local.Type = value; }

        /// <summary>寻址方案</summary>
        public AddressFamily AddressFamily { get; set; }

        /// <summary>服务器集合</summary>
        public IList<ISocketServer> Servers { get; private set; }

        /// <summary>服务器。返回服务器集合中的第一个服务器</summary>
        public ISocketServer Server
        {
            get
            {
                var ss = Servers;
                if (ss.Count <= 0) EnsureCreateServer();

                return ss.Count > 0 ? ss[0] : null;
            }
            set { if (!Servers.Contains(value)) Servers.Insert(0, value); }
        }

        /// <summary>是否活动</summary>
        public Boolean Active => Servers.Count > 0 && Server != null && Server.Active;

        /// <summary>会话超时时间。默认0秒，使用SocketServer默认值</summary>
        /// <remarks>
        /// 对于每一个会话连接，如果超过该时间仍然没有收到任何数据，则断开会话连接。
        /// </remarks>
        public Int32 SessionTimeout { get; set; }

        /// <summary>管道</summary>
        public IPipeline Pipeline { get; set; }

        /// <summary>使用会话集合，允许遍历会话。默认true</summary>
        public Boolean UseSession { get; set; } = true;

        /// <summary>SSL协议。默认None，服务端Default，客户端不启用</summary>
        public SslProtocols SslProtocol { get; set; } = SslProtocols.None;

        /// <summary>SSL证书。服务端使用</summary>
        /// <remarks>var cert = new X509Certificate2("file", "pass");</remarks>
        public X509Certificate Certificate { get; set; }

        /// <summary>会话统计</summary>
        public ICounter StatSession { get; set; }

        /// <summary>发送统计</summary>
        public ICounter StatSend { get; set; }

        /// <summary>接收统计</summary>
        public ICounter StatReceive { get; set; }

        /// <summary>显示统计信息的周期。默认600秒，0表示不显示统计信息</summary>
        public Int32 StatPeriod { get; set; } = 600;

        /// <summary>是否输出发送日志。默认false</summary>
        public Boolean LogSend { get; set; }

        /// <summary>是否输出接收日志。默认false</summary>
        public Boolean LogReceive { get; set; }

        /// <summary>用户会话数据</summary>
        public IDictionary<String, Object> Items { get; set; } = new NullableDictionary<String, Object>();

        /// <summary>获取/设置 用户会话数据</summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public virtual Object this[String key] { get => Items[key]; set => Items[key] = value; }
        #endregion

        #region 构造
        /// <summary>实例化一个网络服务器</summary>
        public NetServer()
        {
            Name = GetType().Name.TrimEnd("Server");

            Servers = new List<ISocketServer>();

            StatSession = new PerfCounter();
            StatSend = new PerfCounter();
            StatReceive = new PerfCounter();

            if (Setting.Current.Debug) Log = XTrace.Log;
        }

        /// <summary>通过指定监听地址和端口实例化一个网络服务器</summary>
        /// <param name="port"></param>
        public NetServer(Int32 port) : this(IPAddress.Any, port) { }

        /// <summary>通过指定监听地址和端口实例化一个网络服务器</summary>
        /// <param name="address"></param>
        /// <param name="port"></param>
        public NetServer(IPAddress address, Int32 port) : this(address, port, NetType.Unknown) { }

        /// <summary>通过指定监听地址和端口，还有协议，实例化一个网络服务器，默认支持Tcp协议和Udp协议</summary>
        /// <param name="address"></param>
        /// <param name="port"></param>
        /// <param name="protocolType"></param>
        public NetServer(IPAddress address, Int32 port, NetType protocolType) : this()
        {
            Local.Address = address;
            Port = port;
            Local.Type = protocolType;
        }

        /// <summary>已重载。释放会话集合等资源</summary>
        /// <param name="disposing"></param>
        protected override void Dispose(Boolean disposing)
        {
            base.Dispose(disposing);

            if (Active) Stop(GetType().Name + (disposing ? "Dispose" : "GC"));

            // 释放托管资源
            if (disposing)
            {
                var sessions = _Sessions;
                if (sessions != null)
                {
                    _Sessions = null;

                    WriteLog("准备释放网络会话{0}个！", sessions.Count);
                    foreach (var item in sessions.Values.ToArray())
                    {
                        item.Dispose();
                    }
                    sessions.Clear();
                }

                var severs = Servers;
                if (severs != null)
                {
                    WriteLog("准备释放服务{0}个！", severs.Count);
                    foreach (var item in severs)
                    {
                        item.Dispose();
                    }
                    severs.Clear();
                }
            }
        }
        #endregion

        #region 创建
        /// <summary>添加Socket服务器</summary>
        /// <param name="server"></param>
        /// <returns>添加是否成功</returns>
        public virtual Boolean AttachServer(ISocketServer server)
        {
            if (Servers.Contains(server)) return false;

            server.Name = String.Format("{0}{1}{2}", Name, server.Local.IsTcp ? "Tcp" : "Udp", server.Local.Address.IsIPv4() ? "" : "6");
            // 内部服务器日志更多是为了方便网络库调试，而网络服务器日志用于应用开发
            if (SocketLog != null) server.Log = SocketLog;
            server.NewSession += Server_NewSession;

            if (SessionTimeout > 0) server.SessionTimeout = SessionTimeout;
            if (Pipeline != null) server.Pipeline = Pipeline;

            server.StatSession = StatSession;
            server.StatSend = StatSend;
            server.StatReceive = StatReceive;

            server.LogSend = LogSend;
            server.LogReceive = LogReceive;

            server.Error += OnError;

            if (server is TcpServer ts)
            {
                ts.SslProtocol = SslProtocol;
                ts.Certificate = Certificate;
            }

            Servers.Add(server);

            return true;
        }

        /// <summary>同时添加指定端口的IPv4和IPv6服务器，如果协议不是指定的Tcp或Udp，则同时添加Tcp和Udp服务器</summary>
        /// <param name="address"></param>
        /// <param name="port"></param>
        /// <param name="protocol"></param>
        /// <param name="family"></param>
        /// <returns></returns>
        public virtual Int32 AddServer(IPAddress address, Int32 port, NetType protocol = NetType.Unknown, AddressFamily family = AddressFamily.Unspecified)
        {
            var list = CreateServer(address, port, protocol, family);
            var count = 0;
            foreach (var item in list)
            {
                AttachServer(item);

                count++;
            }
            return count;
        }

        /// <summary>确保建立服务器</summary>
        public virtual void EnsureCreateServer()
        {
            if (Servers.Count <= 0)
            {
                var list = CreateServer(Local.Address, Port, Local.Type, AddressFamily);
                foreach (var item in list)
                {
                    AttachServer(item);
                }
            }
        }

        /// <summary>添加处理器</summary>
        /// <typeparam name="THandler"></typeparam>
        public void Add<THandler>() where THandler : IHandler, new()
        {
            if (Pipeline == null) Pipeline = new Pipeline();

            Pipeline.AddLast(new THandler());
        }

        /// <summary>添加处理器</summary>
        /// <param name="handler">处理器</param>
        public void Add(IHandler handler)
        {
            if (Pipeline == null) Pipeline = new Pipeline();

            Pipeline.AddLast(handler);
        }
        #endregion

        #region 方法
        /// <summary>开始服务</summary>
        public void Start()
        {
            //if (Active) throw new InvalidOperationException("服务已经开始！");
            if (Active) return;

            OnStart();

            if (Server == null)
            {
                WriteLog("没有可用Socket服务器！");

                return;
            }

            Local.Type = Server.Local.Type;

            WriteLog("准备就绪！");
        }

        /// <summary>开始时调用的方法</summary>
        protected virtual void OnStart()
        {
            EnsureCreateServer();

            if (Servers.Count == 0) throw new Exception("全部端口监听失败！");

            WriteLog("准备开始监听{0}个服务器", Servers.Count);

            foreach (var item in Servers)
            {
                //if (item.Port > 0) WriteLog("开始监听 {0}", item);
                item.Start();

                // 如果是随机端口，反写回来，并且修改其它服务器的端口
                if (Port == 0)
                {
                    Port = item.Port;

                    foreach (var elm in Servers)
                    {
                        if (elm != item && elm.Port == 0) elm.Port = Port;
                    }
                }
                /*if (item.Port <= 0)*/
                WriteLog("开始监听 {0}", item);
            }

            if (StatPeriod > 0) _Timer = new TimerX(ShowStat, null, 10_000, StatPeriod * 1000);
        }

        /// <summary>停止服务</summary>
        /// <param name="reason">关闭原因。便于日志分析</param>
        public void Stop(String reason)
        {
            //if (!Active) throw new InvalidOperationException("服务没有开始！");
            //if (!Active) return;

            _Timer.TryDispose();

            var ss = Servers.Where(e => e.Active).ToArray();
            if (ss == null || ss.Length == 0) return;

            WriteLog("准备停止监听{0}个服务器 {1}", ss.Length, reason);

            if (reason.IsNullOrEmpty()) reason = GetType().Name + "Stop";
            foreach (var item in ss)
            {
                WriteLog("停止监听 {0}", item);
                item.Stop(reason);
            }

            OnStop();

            WriteLog("已停止！");
        }

        /// <summary>停止时调用的方法</summary>
        protected virtual void OnStop() { }
        #endregion

        #region 业务
        /// <summary>新会话，对于TCP是新连接，对于UDP是新客户端</summary>
        public event EventHandler<NetSessionEventArgs> NewSession;

        /// <summary>某个会话的数据到达。sender是ISocketSession</summary>
        public event EventHandler<ReceivedEventArgs> Received;

        ///// <summary>消息到达事件</summary>
        //public event EventHandler<MessageEventArgs> MessageReceived;

        /// <summary>接受连接时，对于Udp是收到数据时（同时触发OnReceived）。</summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void Server_NewSession(Object sender, SessionEventArgs e)
        {
            var session = e.Session;

            var ns = OnNewSession(session);

            NewSession?.Invoke(sender, new NetSessionEventArgs { Session = ns });
        }

        private Int32 sessionID = 0;
        /// <summary>收到连接时，建立会话，并挂接数据接收和错误处理事件</summary>
        /// <param name="session"></param>
        protected virtual INetSession OnNewSession(ISocketSession session)
        {
            Interlocked.Increment(ref _SessionCount);
            session.OnDisposed += (s, e2) => Interlocked.Decrement(ref _SessionCount);
            if (_SessionCount > MaxSessionCount) MaxSessionCount = _SessionCount;

            var ns = CreateSession(session);
            // sessionID变大后，可能达到最大值，然后变为-1，再变为0，所以不用担心
            //ns.ID = ++sessionID;
            // 网络会话改为原子操作，避免多线程冲突
            if (ns is NetSession) (ns as NetSession).ID = Interlocked.Increment(ref sessionID);
            ns.Host = this;
            ns.Server = session.Server;
            ns.Session = session;
            if (ns is NetSession ns2) ns2.Log = SessionLog ?? Log;

            if (UseSession) AddSession(ns);

            ns.Received += OnReceived;

            // 开始会话处理
            ns.Start();

            return ns;
        }

        /// <summary>收到数据时</summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void OnReceived(Object sender, ReceivedEventArgs e)
        {
            var session = sender as INetSession;

            OnReceive(session, e.Packet);

            Received?.Invoke(sender, e);
        }

        /// <summary>收到数据时，最原始的数据处理，但不影响会话内部的数据处理</summary>
        /// <param name="session"></param>
        /// <param name="pk"></param>
        protected virtual void OnReceive(INetSession session, Packet pk) { }

        /// <summary>错误发生/断开连接时。sender是ISocketSession</summary>
        public event EventHandler<ExceptionEventArgs> Error;

        /// <summary>触发异常</summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected virtual void OnError(Object sender, ExceptionEventArgs e)
        {
            if (Log.Enable) Log.Error("{0} Error {1}", sender, e.Exception);

            Error?.Invoke(sender, e);
        }
        #endregion

        #region 会话
        private ConcurrentDictionary<Int32, INetSession> _Sessions = new ConcurrentDictionary<Int32, INetSession>();
        /// <summary>会话集合。用自增的数字ID作为标识，业务应用自己维持ID与业务主键的对应关系。</summary>
        public IDictionary<Int32, INetSession> Sessions => _Sessions;

        private Int32 _SessionCount;
        /// <summary>会话数</summary>
        public Int32 SessionCount { get => _SessionCount; set => _SessionCount = value; }

        /// <summary>最高会话数</summary>
        public Int32 MaxSessionCount { get; private set; }

        /// <summary>添加会话。子类可以在添加会话前对会话进行一些处理</summary>
        /// <param name="session"></param>
        protected virtual void AddSession(INetSession session)
        {
            if (session.Host == null) session.Host = this;
            session.OnDisposed += (s, e) =>
            {
                var id = (s as INetSession).ID;
                if (id > 0) _Sessions.Remove(id);
            };
            _Sessions.TryAdd(session.ID, session);
        }

        /// <summary>创建会话</summary>
        /// <param name="session"></param>
        /// <returns></returns>
        protected virtual INetSession CreateSession(ISocketSession session)
        {
            var ns = new NetSession();
            (ns as INetSession).Host = this;
            ns.Server = session.Server;
            ns.Session = session;

            return ns;
        }

        /// <summary>根据会话ID查找会话</summary>
        /// <param name="sessionid"></param>
        /// <returns></returns>
        public INetSession GetSession(Int32 sessionid)
        {
            if (sessionid == 0) return null;

            if (!Sessions.TryGetValue(sessionid, out var ns)) return null;
            return ns;
        }
        #endregion

        #region 群发
        /// <summary>异步群发</summary>
        /// <param name="buffer"></param>
        /// <returns></returns>
        public virtual Task<Int32> SendAllAsync(Byte[] buffer)
        {
            if (!UseSession) throw new ArgumentOutOfRangeException(nameof(UseSession), true, "群发需要使用会话集合");

            var ts = new List<Task>();
            foreach (var item in Sessions)
            {
                ts.Add(TaskEx.Run(() => item.Value.Send(buffer)));
            }

            return TaskEx.WhenAll(ts).ContinueWith(t => Sessions.Count);
        }
        #endregion

        #region 创建Tcp/Udp、IPv4/IPv6服务
        /// <summary>创建Tcp/Udp、IPv4/IPv6服务</summary>
        /// <param name="address"></param>
        /// <param name="port"></param>
        /// <param name="protocol"></param>
        /// <param name="family"></param>
        /// <returns></returns>
        protected static ISocketServer[] CreateServer(IPAddress address, Int32 port, NetType protocol, AddressFamily family)
        {
            switch (protocol)
            {
                case NetType.Tcp:
                    return CreateServer<TcpServer>(address, port, family);
                case NetType.Http:
                case NetType.WebSocket:
                    var ss = CreateServer<TcpServer>(address, port, family);
                    foreach (TcpServer item in ss)
                    {
                        item.EnableHttp = true;
                    }
                    return ss;
                case NetType.Udp:
                    return CreateServer<UdpServer>(address, port, family);
                case NetType.Unknown:
                default:
                    var list = new List<ISocketServer>();

                    // 其它未知协议，同时用Tcp和Udp
                    list.AddRange(CreateServer<TcpServer>(address, port, family));
                    list.AddRange(CreateServer<UdpServer>(address, port, family));

                    return list.ToArray();
            }
        }

        static ISocketServer[] CreateServer<TServer>(IPAddress address, Int32 port, AddressFamily family) where TServer : ISocketServer, new()
        {
            var list = new List<ISocketServer>();
            switch (family)
            {
                case AddressFamily.InterNetwork:
                case AddressFamily.InterNetworkV6:
                    var addr = address.GetRightAny(family);
                    if (addr != null)
                    {
                        var svr = new TServer();
                        svr.Local.Address = addr;
                        svr.Port = port;
                        //svr.AddressFamily = family;

                        // 协议端口不能是已经被占用
                        if (!svr.Local.CheckPort()) list.Add(svr);
                    }
                    break;
                default:
                    // 其它情况表示同时支持IPv4和IPv6
                    // 兼容Linux
                    //if (Socket.OSSupportsIPv4)
                    list.AddRange(CreateServer<TServer>(address, port, AddressFamily.InterNetwork));
                    if (Socket.OSSupportsIPv6) list.AddRange(CreateServer<TServer>(address, port, AddressFamily.InterNetworkV6));
                    break;
            }

            return list.ToArray();
        }
        #endregion

        #region 统计
        private TimerX _Timer;
        private String _Last;

        private void ShowStat(Object state)
        {
            var msg = GetStat();
            if (msg.IsNullOrEmpty() || msg == _Last) return;
            _Last = msg;

            WriteLog(msg);
        }

        /// <summary>获取统计信息</summary>
        /// <returns></returns>
        public String GetStat()
        {
            var sb = Pool.StringBuilder.Get();
            if (MaxSessionCount > 0) sb.AppendFormat("在线：{0:n0}/{1:n0} ", SessionCount, MaxSessionCount);
            if (StatSend.Value > 0) sb.AppendFormat("发送：{0} ", StatSend);
            if (StatReceive.Value > 0) sb.AppendFormat("接收：{0} ", StatReceive);
            //if (StatSession.Value > 0) sb.AppendFormat("会话：{0} ", StatSession);

            return sb.Put(true);
        }
        #endregion

        #region 日志
        /// <summary>日志提供者</summary>
        public ILog Log { get; set; } = Logger.Null;

        /// <summary>用于内部Socket服务器的日志提供者</summary>
        public ILog SocketLog { get; set; }

        /// <summary>用于网络会话的日志提供者</summary>
        public ILog SessionLog { get; set; }

        private String _LogPrefix;
        /// <summary>日志前缀</summary>
        public virtual String LogPrefix
        {
            get
            {
                if (_LogPrefix == null) _LogPrefix = Name;
                return _LogPrefix;
            }
            set => _LogPrefix = value;
        }

        /// <summary>写日志</summary>
        /// <param name="format"></param>
        /// <param name="args"></param>
        public virtual void WriteLog(String format, params Object[] args)
        {
            if (!LogPrefix.EndsWith(" ") && !format.StartsWith(" ")) format = " " + format;
            Log.Info(LogPrefix + format, args);
        }

        /// <summary>输出错误日志</summary>
        /// <param name="format"></param>
        /// <param name="args"></param>
        public virtual void WriteError(String format, params Object[] args) => Log.Error(LogPrefix + format, args);
        #endregion

        #region 辅助
        /// <summary>已重载。</summary>
        /// <returns></returns>
        public override String ToString()
        {
            var servers = Servers;
            if (servers == null || servers.Count < 1) return Name;

            if (servers.Count == 1) return Name + " " + servers[0].ToString();

            var sb = Pool.StringBuilder.Get();
            foreach (var item in servers)
            {
                if (sb.Length > 0) sb.Append(" ");
                sb.Append(item);
            }
            return Name + " " + sb.Put(true);
        }
        #endregion
    }

    /// <summary>网络服务器</summary>
    /// <typeparam name="TSession"></typeparam>
    public class NetServer<TSession> : NetServer where TSession : class, INetSession, new()
    {
        /// <summary>创建会话</summary>
        /// <param name="session"></param>
        /// <returns></returns>
        protected override INetSession CreateSession(ISocketSession session)
        {
            var ns = new TSession
            {
                Host = this,
                Server = session.Server,
                Session = session
            };

            return ns;
        }

        /// <summary>获取指定标识的会话</summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public new TSession GetSession(Int32 id)
        {
            if (id <= 0) return null;

            return base.GetSession(id) as TSession;
        }
    }
}