using System.Net.Sockets;
using System.Text;
using System.Text.Json;
using System.IO;

namespace WIDESEAWCS_Tasks.SocketServer
{
    public partial class TcpSocketServer
    {
        /// <summary>
        /// Òì²½´¦ÀíÓëÒÑÁ¬½ÓµÄTCP¿Í»§¶ËµÄͨÐÅ£¬´¦Àí»úÆ÷ÈËÆðÖØ»ú»á»°ÖеĴ«ÈëÏûÏ¢ºÍ¿Í»§¶Ë״̬¸üС£
        /// </summary>
        /// <remarks>´Ë·½·¨¹ÜÀí¿Í»§¶ËÁ¬½ÓµÄÉúÃüÖÜÆÚ£¬°üÀ¨¶ÁÈ¡ÏûÏ¢¡¢¸üпͻ§¶Ë״̬ºÍµ÷ÓÃÏà¹Øʼþ¡£
        /// µ±´¦Àí½áÊøʱ£¬¿Í»§¶ËºÍÏà¹ØµÄÍøÂç×ÊÔ´½«±»ÊÍ·Å¡£Èç¹ûÆôÓÃÐÄÌø»ò¿ÕÏг¬Ê±Ñ¡Ï
        /// ½«Ó¦ÓöîÍâµÄÈ¡ÏûÂß¼­¡£Ê¼þµ÷ÓÃÆÚ¼äµÄÒì³£½«±»²¶»ñ²¢ÒÖÖÆ£¬ÒÔÈ·±£»á»°´¦ÀíµÄ³°ôÐÔ¡£</remarks>
        /// <param name="client">±íʾҪ´¦ÀíµÄÔ¶³ÌÁ¬½ÓµÄTCP¿Í»§¶Ë¡£·½·¨Íê³Éºó½«ÊͷŴ˶ÔÏó¡£</param>
        /// <param name="clientId">ÒÑÁ¬½Ó¿Í»§¶ËµÄΨһ±êʶ·û¡£ÓÃÓÚÔÚÕû¸ö»á»°Öиú×ٺ͸üпͻ§¶Ë״̬¡£</param>
        /// <param name="cancellationToken">¿ÉÓÃÓÚÈ¡Ïû¿Í»§¶Ë´¦Àí²Ù×÷µÄÈ¡ÏûÁîÅÆ¡£Èç¹ûÇëÇóÈ¡Ïû£¬·½·¨½«Á¢¼´ÖÕÖ¹´¦Àí¡£</param>
        /// <param name="robotCrane">±íʾÓë¿Í»§¶Ë¹ØÁªµÄ»úÆ÷ÈËÆðÖØ»úµÄµ±Ç°×´Ì¬¶ÔÏó¡£ÓÃÓÚΪÏûÏ¢´¦ÀíºÍʼþµ÷ÓÃÌṩÉÏÏÂÎÄ¡£</param>
        /// <returns>±íʾ´¦Àí¿Í»§¶ËÁ¬½ÓµÄÒì²½²Ù×÷µÄÈÎÎñ¡£µ±¿Í»§¶Ë¶Ï¿ªÁ¬½Ó»òÇëÇóÈ¡ÏûʱÈÎÎñÍê³É¡£</returns>
        public async Task HandleClientAsync(TcpClient client, string clientId, CancellationToken cancellationToken, RobotSocketState robotCrane)
        {
            using (client)
            using (NetworkStream networkStream = client.GetStream())
            using (StreamReader reader = new(networkStream, _textEncoding, false, 1024, true))
            using (StreamWriter writer = new(networkStream, _textEncoding, 1024, true) { AutoFlush = true })
            {
                CancellationTokenSource? localCts = null;
                if (_options.EnableHeartbeat || _options.IdleTimeoutSeconds > 0)
                {
                    localCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
                }

                try
                {
                    while (!cancellationToken.IsCancellationRequested && client.Connected)
                    {
                        string? message;
                        try
                        {
                            var ct = localCts?.Token ?? cancellationToken;
                            message = await ReceiveFullMessageAsync(networkStream, _textEncoding, ct);
                            //message = await reader.ReadLineAsync().WaitAsync(ct);
                        }
                        catch (OperationCanceledException)
                        {
                            break;
                        }

                        if (message == null)
                        {
                            break;
                        }

                        UpdateClientStatus(clientId, message);

                        string messageLower = message.ToLowerInvariant();

                        if (TryHandleRegister(messageLower, message, clientId, networkStream, cancellationToken))
                        {
                            continue;
                        }

                        if (MessageReceived != null)
                        {
                            try
                            {
                                // ÅжÏÊÇ·ñΪ JSON ¸ñʽ
                                bool isJsonFormat = TryParseJsonSilent(message);
                                _ = MessageReceived.Invoke(message, isJsonFormat, client, robotCrane);
                            }
                            catch { }
                        }
                    }
                }
                finally
                {
                    try { localCts?.Cancel(); localCts?.Dispose(); } catch { }
                    RemoveClient(clientId);
                    try { _ = RobotReceived.Invoke(clientId); } catch { }
                }
            }
        }

        /// <summary>
        /// ³¢ÊÔ´¦ÀíÀ´×Ô¿Í»§¶ËµÄÉ豸ע²áÇëÇó¡£·µ»ØÒ»¸öֵָʾ¸ÃÏûÏ¢ÊÇ·ñ±»×÷Ϊע²áÇëÇó´¦Àí¡£
        /// </summary>
        /// <remarks>Èç¹ûÏûÏ¢ÊÇÓÐЧµÄ×¢²áÇëÇóÇÒ°üº¬·Ç¿ÕµÄÉ豸±êʶ·û£¬
        /// Ôò½«É豸°ó¶¨µ½¿Í»§¶Ë²¢·¢ËÍÈ·ÈÏÐÅÏ¢¡£´Ë·½·¨²»»áÒòÎÞЧÏûÏ¢¶øÅ׳öÒì³££»
        /// Ëü½ö·µ»Ø false¡£</remarks>
        /// <param name="messageLower">¿Í»§¶ËÏûÏ¢µÄСд°æ±¾£¬ÓÃÓÚÅжÏÏûÏ¢ÊÇ·ñΪע²áÇëÇó¡£</param>
        /// <param name="message">°üº¬×¢²áÃüÁîºÍÉ豸±êʶ·ûµÄԭʼ¿Í»§¶ËÏûÏ¢¡£</param>
        /// <param name="clientId">·¢ËÍ×¢²áÇëÇóµÄ¿Í»§¶ËµÄΨһ±êʶ·û¡£</param>
        /// <param name="client">Óë¿Í»§¶ËͨÐŵÄTCP¿Í»§¶ËÁ¬½Ó¡£</param>
        /// <param name="cancellationToken">¿ÉÓÃÓÚÈ¡Ïû×¢²á²Ù×÷µÄÈ¡ÏûÁîÅÆ¡£</param>
        /// <returns>Èç¹ûÏûÏ¢±»Ê¶±ð²¢×÷Ϊע²áÇëÇó´¦Àí£¬Ôò·µ»Ø true£»·ñÔò·µ»Ø false¡£</returns>
        private bool TryHandleRegister(string messageLower, string message, string clientId, NetworkStream networkStream, CancellationToken cancellationToken)
        {
            if (!messageLower.StartsWith("register,"))
            {
                return false;
            }

            string deviceId = message.Substring("register,".Length).Trim();
            if (!string.IsNullOrEmpty(deviceId))
            {
                lock (_syncRoot)
                {
                    _deviceBindings[deviceId] = clientId;
                }

                _ = WriteToClientAsync(clientId, networkStream, $"Registered,{deviceId}", cancellationToken);
            }

            return true;
        }

        /// <summary>
        /// ¸üпͻ§¶Ë״̬
        /// </summary>
        /// <param name="clientId"></param>
        /// <param name="message"></param>
        private void UpdateClientStatus(string clientId, string message)
        {
            lock (_syncRoot)
            {
                _clientLastActive[clientId] = DateTime.Now;

                if (!_clientEncodings.ContainsKey(clientId))
                {
                    if (_options.AutoDetectEncoding && _autoDetectedGb2312 != null)
                    {
                        bool isUtf8 = TryParseJsonSilent(message) || IsLikelyUtf8(_textEncoding.GetBytes(message));
                        _clientEncodings[clientId] = isUtf8 ? _textEncoding : _autoDetectedGb2312;
                    }
                    else
                    {
                        _clientEncodings[clientId] = _textEncoding;
                    }
                }
            }
        }

        /// <summary>
        /// дÈëÏûÏ¢µ½¿Í»§¶Ë
        /// </summary>
        /// <param name="clientId"></param>
        /// <param name="networkStream"></param>
        /// <param name="message"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        private async Task WriteToClientAsync(string clientId, NetworkStream networkStream, string message, CancellationToken cancellationToken)
        {
            SemaphoreSlim? sem = null;
            Encoding? enc = null;
            lock (_syncRoot)
            {
                _clientLocks.TryGetValue(clientId, out sem);
                _clientEncodings.TryGetValue(clientId, out enc);
            }

            enc ??= _textEncoding;

            if (sem != null) await sem.WaitAsync(cancellationToken);
            try
            {
                var framedMessage = BuildFramedMessage(message);
                var data = enc.GetBytes(framedMessage);
                await networkStream.WriteAsync(data, 0, data.Length, cancellationToken);
            }
            finally
            {
                if (sem != null) sem.Release();
            }
        }

        /// <summary>
        /// Ìí¼ÓÏûϢ֡ͷβ
        /// </summary>
        /// <param name="message"></param>
        /// <returns></returns>
        private string BuildFramedMessage(string message)
        {
            var header = _options.MessageHeader ?? string.Empty;
            var footer = _options.MessageFooter ?? string.Empty;
            return header + (message ?? string.Empty) + footer;
        }

        /// <summary>
        /// JSON¸ñʽ³¢ÊÔ½âÎö£¨¾²Ä¬Ê§°Ü£©
        /// </summary>
        /// <param name="message"></param>
        /// <returns></returns>
        private static bool TryParseJsonSilent(string message)
        {
            if (string.IsNullOrWhiteSpace(message)) return false;
            char c = message.TrimStart()[0];
            if (c != '{' && c != '[') return false;
            try { JsonDocument.Parse(message); return true; } catch { return false; }
        }

        /// <summary>
        /// utf-8 ¿ÉÄÜÐÔ¼ì²â
        /// </summary>
        /// <param name="data"></param>
        /// <returns></returns>
        private static bool IsLikelyUtf8(byte[] data)
        {
            int i = 0;
            while (i < data.Length)
            {
                byte b = data[i];
                if (b <= 0x7F) { i++; continue; }
                if (b >= 0xC2 && b <= 0xDF)
                {
                    if (i + 1 >= data.Length) return false;
                    if ((data[i + 1] & 0xC0) != 0x80) return false;
                    i += 2; continue;
                }
                if (b >= 0xE0 && b <= 0xEF)
                {
                    if (i + 2 >= data.Length) return false;
                    if ((data[i + 1] & 0xC0) != 0x80 || (data[i + 2] & 0xC0) != 0x80) return false;
                    i += 3; continue;
                }
                if (b >= 0xF0 && b <= 0xF4)
                {
                    if (i + 3 >= data.Length) return false;
                    if ((data[i + 1] & 0xC0) != 0x80 || (data[i + 2] & 0xC0) != 0x80 || (data[i + 3] & 0xC0) != 0x80) return false;
                    i += 4; continue;
                }
                return false;
            }
            return true;
        }

        /// <summary>
        /// ¶ÁÈ¡ÍêÕûÏûÏ¢
        /// </summary>
        /// <param name="networkStream">×Ö½ÚÁ÷</param>
        /// <param name="encoding">±àÂë¸ñʽ</param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        private async Task<string?> ReceiveFullMessageAsync(NetworkStream networkStream, Encoding encoding, CancellationToken cancellationToken)
        {
            var header = _options.MessageHeader ?? string.Empty;
            var footer = _options.MessageFooter ?? string.Empty;

            var buffer = new byte[1024];
            var builder = new StringBuilder();

            while (true)
            {
                int bytesRead = await networkStream.ReadAsync(buffer.AsMemory(0, buffer.Length), cancellationToken);
                if (bytesRead <= 0)
                {
                    if (builder.Length == 0) return null;
                    return string.IsNullOrEmpty(header) && string.IsNullOrEmpty(footer) ? builder.ToString() : null;
                }

                builder.Append(encoding.GetString(buffer, 0, bytesRead));

                if (string.IsNullOrEmpty(header) && string.IsNullOrEmpty(footer))
                {
                    if (!networkStream.DataAvailable)
                    {
                        break;
                    }
                    continue;
                }

                var data = builder.ToString();
                var headerIndex = string.IsNullOrEmpty(header) ? 0 : data.IndexOf(header, StringComparison.Ordinal);
                if (headerIndex < 0)
                {
                    continue;
                }

                var startIndex = headerIndex + header.Length;
                var footerIndex = string.IsNullOrEmpty(footer) ? data.Length : data.IndexOf(footer, startIndex, StringComparison.Ordinal);
                if (footerIndex >= 0)
                {
                    return data.Substring(startIndex, footerIndex - startIndex);
                }
            }

            return builder.ToString();
        }
    }
}