using System;
using System.IO.Ports;
using System.Threading;
using System.Threading.Tasks;

namespace HoodSimulator
{
    // 후드메인(Slave) 시뮬레이터 프로토콜
    //  규격 : Protocol/HOOD/주신전자_protocol_hood_전열교환기_Rev1.3_20241125.xlsx
    //  - 9바이트 고정, 115200 8N1, 폴링주기 100~500ms, 응답 50ms 이내
    //  - CS = Preamble~CS직전(byte0~7) 전체 XOR
    //  Master(전열교환기) → Slave(후드) : AA 21 ID MODE FAN 연동EN 연동운전중 ERROR CS
    //  Slave(후드) → Master(전열교환기) : AA 11 ID FANSTATUS LIGHTSTATUS 00 연동CMD ERROR CS
    //  시뮬레이터는 Slave 역할 — 마스터 폴 수신 시 현재 후드 상태로 응답.
    public class HoodProtocol : IDisposable
    {
        public const byte PREAMBLE  = 0xAA;
        public const byte MS_MASTER = 0x21;
        public const byte MS_SLAVE  = 0x11;
        public const byte HOOD_ID   = 0x01;
        public const int  FRAME_LEN = 9;

        SerialPort? _port;
        CancellationTokenSource? _cts;
        readonly object _lock = new();
        bool _disposed;
        bool _responding;

        // ---- 후드 상태 (UI 제어) ----
        public bool PowerOn;       // 전원 on/off
        public byte FanStage;      // 풍량 0(꺼짐)~5
        public bool Light;         // 조명 on/off
        public byte ErrorCode;     // ERROR : 0 정상 / 1 FAN 에러 / 2 기타 에러

        public event Action<byte, byte, byte, byte>? MasterPacketReceived;  // mode, fan, en, run
        public event Action<byte[]>? ResponseSent;                          // 송신한 9바이트 응답
        public event Action<string>? LogMessage;
        public event Action<bool>? ConnectionChanged;

        public bool IsConnected => _port?.IsOpen == true;
        public bool IsResponding => _responding;

        public static byte Xor(byte[] d, int start, int len)
        {
            byte x = 0;
            for (int i = 0; i < len; i++) x ^= d[start + i];
            return x;
        }

        public string[] GetAvailablePorts() => SerialPort.GetPortNames();

        public bool Connect(string portName)
        {
            try
            {
                Disconnect();
                _port = new SerialPort(portName)
                {
                    BaudRate = 115200, DataBits = 8,
                    StopBits = StopBits.One, Parity = Parity.None,
                    ReadTimeout = 100, WriteTimeout = 500
                };
                _port.Open();
                Log($"[연결] {portName} (115200, 8N1)");
                ConnectionChanged?.Invoke(true);
                return true;
            }
            catch (Exception ex)
            {
                Log($"[오류] 연결 실패: {ex.Message}");
                ConnectionChanged?.Invoke(false);
                return false;
            }
        }

        public void Disconnect()
        {
            StopResponding();
            try { if (_port?.IsOpen == true) { _port.Close(); Log("[연결 해제]"); } } catch { }
            _port?.Dispose();
            _port = null;
            ConnectionChanged?.Invoke(false);
        }

        public void StartResponding()
        {
            StopResponding();
            _responding = true;
            _cts = new CancellationTokenSource();
            var token = _cts.Token;

            Task.Run(() =>
            {
                while (!token.IsCancellationRequested)
                {
                    try
                    {
                        if (_port?.IsOpen != true) { Thread.Sleep(50); continue; }
                        if (_port.BytesToRead < 1) { Thread.Sleep(3); continue; }

                        byte b = (byte)_port.ReadByte();
                        if (b != PREAMBLE) continue;

                        byte[] rx = new byte[FRAME_LEN];
                        rx[0] = PREAMBLE;
                        int total = 1, remain = FRAME_LEN - 1, retries = 100;
                        while (remain > 0 && retries-- > 0)
                        {
                            if (_port.BytesToRead > 0)
                            { int r = _port.Read(rx, total, remain); total += r; remain -= r; }
                            else Thread.Sleep(2);
                        }
                        if (total < FRAME_LEN) continue;

                        // 마스터 프레임만 처리
                        if (rx[1] != MS_MASTER) continue;
                        if (rx[2] != HOOD_ID) continue;
                        byte cs = Xor(rx, 0, 8);
                        if (cs != rx[8]) { Log($"[CS오류] 수신:0x{rx[8]:X2} 계산:0x{cs:X2} {BitConverter.ToString(rx)}"); continue; }

                        byte mode = rx[3], fan = rx[4], en = rx[5], run = rx[6];
                        Log($"[RX] {BitConverter.ToString(rx)}  MODE={mode} FAN={fan} 연동EN={en} 연동운전={run}");
                        MasterPacketReceived?.Invoke(mode, fan, en, run);

                        // 응답 전송 (현재 후드 상태)
                        byte[] tx = BuildResponse();
                        lock (_lock) { _port?.Write(tx, 0, tx.Length); }
                        Log($"[TX 응답] {BitConverter.ToString(tx)}");
                        ResponseSent?.Invoke(tx);
                    }
                    catch (TimeoutException) { }
                    catch (OperationCanceledException) { break; }
                    catch (Exception ex)
                    {
                        if (!token.IsCancellationRequested) Log($"[오류] {ex.Message}");
                        Thread.Sleep(100);
                    }
                }
            }, token);
            Log("[통신 시작] 마스터 응답 모드");
        }

        public void StopResponding()
        {
            _responding = false;
            _cts?.Cancel();
            _cts?.Dispose();
            _cts = null;
        }

        public byte[] BuildResponse()
        {
            byte fanStatus   = PowerOn ? FanStage : (byte)0;          // 후드 FAN STATUS 0~5
            byte lightStatus = (byte)((PowerOn && Light) ? 1 : 0);    // 후드 LIGHT STATUS
            byte cmd         = (byte)(PowerOn ? 1 : 0);               // 연동 CMD : 0 꺼짐 / 1 켜짐

            byte[] p = new byte[FRAME_LEN];
            p[0] = PREAMBLE;
            p[1] = MS_SLAVE;
            p[2] = HOOD_ID;
            p[3] = fanStatus;
            p[4] = lightStatus;
            p[5] = 0x00;
            p[6] = cmd;
            p[7] = ErrorCode;             // ERROR : 0 정상 / 1 FAN / 2 기타
            p[8] = Xor(p, 0, 8);          // CS
            return p;
        }

        void Log(string msg) => LogMessage?.Invoke($"[{DateTime.Now:HH:mm:ss.fff}] {msg}");

        public void Dispose()
        {
            if (_disposed) return;
            _disposed = true;
            Disconnect();
            GC.SuppressFinalize(this);
        }
    }
}