namespace ErvProtocol
{
    // StatusRecord → STATUS(0x81) 134B payload. StatusDecoder 의 역(逆).
    // ERV(메인보드/시뮬레이터) 측이 STATUS 를 송신할 때 사용. PC_ERV_Protocol.md 4장.
    public static class StatusEncoder
    {
        static void W16(byte[] p, int off, int v)   // 빅엔디안
        {
            p[off] = (byte)((v >> 8) & 0xFF);
            p[off + 1] = (byte)(v & 0xFF);
        }

        // StatusRecord → 134B payload
        public static byte[] Encode(StatusRecord s)
        {
            var p = new byte[StatusDecoder.STATUS_LEN];

            // 글로벌 0~16
            p[0] = s.Power;
            p[1] = s.RunMode;
            p[2] = s.AutoState;
            p[3] = s.FanMode;
            p[4] = s.SubMode;
            p[5] = s.Hood;
            p[6] = s.HystPreset;
            W16(p, 7, s.HystPm25);
            W16(p, 9, s.HystPm10);
            W16(p, 11, s.HystVoc);
            W16(p, 13, s.HystCo2);
            W16(p, 15, s.ErrorCode);

            // 각실 17~ (14B x 4)
            const int baseOff = 17;
            for (int r = 0; r < 4; r++)
            {
                int o = baseOff + r * 14;
                var room = s.Rooms[r];
                p[o + 0] = room.Damper;
                W16(p, o + 1, room.Pm25);
                W16(p, o + 3, room.Pm10);
                W16(p, o + 5, room.Voc);
                W16(p, o + 7, room.Co2);
                p[o + 9] = room.AirQuality;
                p[o + 10] = room.LedDim;
                W16(p, o + 11, room.LoadScore);
                p[o + 13] = room.FinalVolume;
            }

            // ERV 리셋 (offset 73)
            p[73] = s.Reset;

            // 풍량 VSP (offset 74~, 9엔트리 × u16 SA·EA)
            const int vspOff = 74;
            for (int i = 0; i < 9; i++)
            {
                int o = vspOff + i * 4;
                W16(p, o, s.Vsp[i].Sa);
                W16(p, o + 2, s.Vsp[i].Ea);
            }

            // 히스테리시스 프리셋 테이블 (offset 110~, 3프리셋 × PM2.5/PM10/VOC/CO2 u16)
            const int hystOff = 110;
            for (int i = 0; i < 3; i++)
            {
                int o = hystOff + i * 8;
                W16(p, o, s.HystTable[i].Pm25);
                W16(p, o + 2, s.HystTable[i].Pm10);
                W16(p, o + 4, s.HystTable[i].Voc);
                W16(p, o + 6, s.HystTable[i].Co2);
            }

            // 모드별 오염단계 임계표 (offset 134~, 3프리셋 × [CO2,PM2.5,PM10,VOC] × L1~L4)
            for (int i = 0; i < 3; i++)
            {
                int o = StatusDecoder.THR_OFF + i * 32;
                for (int k = 0; k < 4; k++) W16(p, o + 0 + k * 2,  s.ThrTable[i].Co2[k]);
                for (int k = 0; k < 4; k++) W16(p, o + 8 + k * 2,  s.ThrTable[i].Pm25[k]);
                for (int k = 0; k < 4; k++) W16(p, o + 16 + k * 2, s.ThrTable[i].Pm10[k]);
                for (int k = 0; k < 4; k++) W16(p, o + 24 + k * 2, s.ThrTable[i].Voc[k]);
            }

            // 각실 온도/습도 (offset 230~, 4실 × [Temp, Humi])
            for (int r = 0; r < 4; r++)
            {
                int o = StatusDecoder.TEMPHUMI_OFF + r * 2;
                p[o + 0] = s.Rooms[r].Temp;
                p[o + 1] = s.Rooms[r].Humi;
            }

            // (꺼짐)예약 잔여초 (offset 238, u16)
            W16(p, StatusDecoder.RESERVE_OFF, s.ReserveRemainSec);

            return p;
        }

        // STATUS(0x81) 완성 프레임 (CRC 포함)
        public static byte[] BuildStatusFrame(StatusRecord s) => CtrlFrame.Build(StatusDecoder.STATUS, Encode(s));

        // ACK(0x82) 프레임 : [echoCmd][result(0 OK/1 ERR)]
        public static byte[] BuildAckFrame(byte echoCmd, byte result) => CtrlFrame.Build(StatusDecoder.ACK, echoCmd, result);
    }
}