using System;
using ERVSimulator.Model;

namespace ERVSimulator.Protocol
{
    // 룸콘 프로토콜 (UART2/SC0)
    // 패킷: AA | Cmd | D[2..12] | XOR_SUM[13] | EE  (15 byte)
    // 펌웨어 [My_RJ2.c] rx_roomcon_check() + roomcon_parsing()
    public class RoomConProtocol
    {
        public const byte HEADER = 0xAA;
        public const byte TAIL   = 0xEE;
        public const int PACKET_LEN = 15;

        // Cmd (Rx_roomcon232_buffer[1])
        public const byte CMD_NORMAL   = 0x00;  // 상태 폴링
        public const byte CMD_EVENT    = 0x01;  // 모드/팬 변경 이벤트
        public const byte CMD_RESTART1 = 0x02;  // 환기단 preset 요청
        public const byte CMD_RESTART2 = 0x12;  // bypass/air preset 요청
        public const byte CMD_VSP      = 0x03;  // 테스트모드 진입
        public const byte CMD_EXIT     = 0x04;  // 테스트모드 종료
        public const byte CMD_HOOD_INFO = 0x0A; // ERV→룸콘 후드 연동 통지 (힘펠 V3.7 RX_DATA_HOOD_INFO)

        readonly SerialChannel _ch;
        readonly ErvState _state;
        readonly DamperSequencer _seq;
        readonly System.Windows.Threading.Dispatcher _dispatcher;

        readonly byte[] _rx = new byte[PACKET_LEN];
        int _rxPos;
        bool _hoodLinkReported;   // 마지막으로 룸콘에 통지한 후드 연동 상태(변화 시에만 0x0A 송신)
        DateTime _lastByte = DateTime.MinValue;
        static readonly TimeSpan FrameGap = TimeSpan.FromMilliseconds(50);

        public event Action<string>? PacketReceived;
        public event Action<string>? PacketSent;

        public RoomConProtocol(SerialChannel ch, ErvState state, DamperSequencer seq,
                               System.Windows.Threading.Dispatcher dispatcher)
        {
            _ch = ch; _state = state; _seq = seq; _dispatcher = dispatcher;
            _ch.ByteReceived += OnByte;
        }

        void OnByte(byte b)
        {
            var now = DateTime.UtcNow;
            if (now - _lastByte > FrameGap) _rxPos = 0;
            _lastByte = now;

            // 펌웨어와 동일한 byte 파서 (My_RJ2.c:37)
            if (_rxPos == 0)
            {
                if (b != HEADER) return;
                _rx[_rxPos++] = b;
                return;
            }
            if (_rxPos >= 1 && _rxPos <= 12)
            {
                _rx[_rxPos++] = b;
                return;
            }
            if (_rxPos == 13)
            {
                byte cksum = ChecksumHelper.Xor(_rx, 0, 13);
                if (cksum != b) { _rxPos = 0; return; }
                _rx[_rxPos++] = b;
                return;
            }
            if (_rxPos == 14)
            {
                _rxPos = 0;
                if (b != TAIL) return;
                byte[] copy = (byte[])_rx.Clone();
                _dispatcher.BeginInvoke(new Action(() => HandlePacket(copy)));
            }
        }

        void HandlePacket(byte[] p)
        {
            PacketReceived?.Invoke($"RoomCon RX: {HexFormat.Bytes(p, 14)} EE");

            byte cmd = p[1];
            switch (cmd)
            {
                case CMD_EVENT:    HandleEvent(p); break;
                case CMD_NORMAL:   HandleNormal(p); break;
                case CMD_RESTART1: HandleRestart1(); break;
                case CMD_RESTART2: HandleRestart2(); break;
                case CMD_VSP:      HandleVsp(p); break;
                case CMD_EXIT:     HandleExit(); break;
                default:
                    PacketReceived?.Invoke($"  (unknown RoomCon cmd 0x{cmd:X2})");
                    break;
            }
        }

        // [My_RJ2.c:387] RX_DATA_MODE_EVENT - 운전 모드/팬 변경
        void HandleEvent(byte[] p)
        {
            byte runMode = p[2];
            byte fanMode = p[3];
            _state.RunMode = (RunMode)runMode;
            _state.SetRunMode = (RunMode)runMode;
            _state.FanMode = fanMode;
            _state.SetFanMode = fanMode;
            // VENT && fan=0 ⇒ Power OFF 진입
            _state.PowerOn = !(runMode == 0 && fanMode == 0);

            // 예약 (룸콘 EVENT [10]=flag / [11]=시 / [12]=분). HOMENET STATUS(reserve)로도 전달 → 대시보드 반영
            if (p[10] == 1)
            {
                int hours = p[11];
                _state.ReserveHours = hours;                          // 0이면 해제
                _state.ReserveRemainSec = hours * 3600 + p[12] * 60;  // 카운트다운/전원OFF는 ReserveTick(1s) 처리
            }

            _seq.NotifyCommandChanged();

            // 응답: AA 01 RunMode FanMode 00 misc... XOR EE  (펌웨어 [My_RJ2.c:489])
            var tx = NewPacket();
            tx[1] = 0x01;
            tx[2] = runMode;
            tx[3] = fanMode;
            tx[5] = 0; // Heater/UV/Kijer
            tx[7] = _state.ErrorCode; // ErrorCode (E02/E07/E09/E10/COLD 비트맵)
            tx[8] = 0; // Out_Temperature sign
            tx[9] = 20 + 25; // Out_Temperature = 25
            tx[10] = 20 + 22; // In_Temperature = 22
            FinalizeAndSend(tx);
        }

        // [My_RJ2.c:327] RX_DATA_MODE_NORMAL - 상태 폴링 응답
        void HandleNormal(byte[] p)
        {
            // 후드 연동 상태가 바뀌면 HOOD_INFO(0x0A)로 통지 (힘펠 V3.7, 펌웨어 Hood_info_command).
            // HoodStatus = 연동운전중(후드 가동 → 메이크업 에어). 후드 OFF로 ERV 복귀 시 0x80(OFF) 전송.
            if (_state.HoodStatus != _hoodLinkReported)
            {
                _hoodLinkReported = _state.HoodStatus;
                var hi = NewPacket();
                hi[1] = CMD_HOOD_INFO;
                hi[2] = _state.HoodStatus ? (byte)RunMode.Ventilation : (byte)_state.SetRunMode;  // 연동 시 환기
                hi[3] = _state.HoodStatus ? (byte)1 : _state.SetFanMode;
                hi[6] = _state.HoodStatus ? (byte)0x81 : (byte)0x80;   // 후드 연동 ON / OFF
                FinalizeAndSend(hi);
                return;
            }

            var tx = NewPacket();
            tx[1] = 0x07; // COMMAND_CONTROLL
            tx[2] = (byte)_state.SetRunMode;
            tx[3] = _state.SetFanMode;
            tx[4] = 0;    // Auto_Mode
            tx[5] = 0;
            tx[7] = _state.ErrorCode; // ErrorCode 도 동봉
            FinalizeAndSend(tx);
        }

        // [My_RJ2.c:522] RX_DATA_MODE_RESTART1 - 환기 1~4단 preset
        void HandleRestart1()
        {
            var tx = NewPacket();
            tx[1] = 0x02;
            tx[4] = 0x10;
            tx[5]  = (byte)_state.FanSAPreset_Vent[1]; tx[6]  = (byte)_state.FanEAPreset_Vent[1];
            tx[7]  = (byte)_state.FanSAPreset_Vent[2]; tx[8]  = (byte)_state.FanEAPreset_Vent[2];
            tx[9]  = (byte)_state.FanSAPreset_Vent[3]; tx[10] = (byte)_state.FanEAPreset_Vent[3];
            tx[11] = (byte)_state.FanSAPreset_Vent[4]; tx[12] = (byte)_state.FanEAPreset_Vent[4];
            FinalizeAndSend(tx);
        }

        // [My_RJ2.c:556] RX_DATA_MODE_RESTART2 - bypass/air preset
        void HandleRestart2()
        {
            var tx = NewPacket();
            tx[1] = 0x12;
            tx[4] = 0x10;
            tx[5] = (byte)_state.FanSAPreset_Bypass[1]; tx[6] = (byte)_state.FanEAPreset_Bypass[1];
            tx[7] = (byte)_state.FanSAPreset_Air[1];
            tx[8] = (byte)_state.FanSAPreset_Air[2];
            tx[9] = (byte)_state.FanSAPreset_Air[3];
            tx[10] = (byte)_state.FanSAPreset_Air[4];
            FinalizeAndSend(tx);
        }

        // [My_RJ2.c:579] RX_DATA_MODE_VSP - 테스트 모드 진입 (preset 갱신)
        void HandleVsp(byte[] p)
        {
            // 본 시뮬레이터에선 RX만 기록, preset 변경은 생략
            PacketReceived?.Invoke($"  VSP select={p[3]} sa={p[4]} ea={p[5]}");
        }

        void HandleExit()
        {
            PacketReceived?.Invoke("  VSP exit");
        }

        byte[] NewPacket()
        {
            var tx = new byte[PACKET_LEN];
            tx[0] = HEADER;
            return tx;
        }

        void FinalizeAndSend(byte[] tx)
        {
            tx[13] = ChecksumHelper.Xor(tx, 0, 13);
            tx[14] = TAIL;
            if (_ch.Send(tx, PACKET_LEN))
                PacketSent?.Invoke($"RoomCon TX: {HexFormat.Bytes(tx, 15)}");
        }
    }
}