using DeviceCommand.Base;
using System;
using System.IO.Ports;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;

namespace DeviceCommand.Devices
{
    /// <summary>
    /// UMC1000 温湿度控制器(RS485)
    /// </summary>
    public class UMC1000Rtu : ModbusRtu
    {
        private readonly byte _slaveId;

        /// <summary>
        /// 温度测量值 REAL
        /// </summary>
        private const ushort TemperatureAddress = 150;

        /// <summary>
        /// 湿度测量值 REAL
        /// </summary>
        private const ushort HumidityAddress = 152;

        public UMC1000Rtu(
            byte slaveId,
            string portName,
            int baudRate = 9600,
            int dataBits = 8,
            StopBits stopBits = StopBits.One,
            Parity parity = Parity.None,
            int readTimeout = 3000,
            int writeTimeout = 3000)
        {
            _slaveId = slaveId;

            ConfigureDevice(
                portName,
                baudRate,
                dataBits,
                stopBits,
                parity,
                readTimeout,
                writeTimeout);
        }

        /// <summary>
        /// 读取温度
        /// </summary>
        public async Task<float> ReadTemperatureAsync(
            CancellationToken ct = default)
        {
            var a = await ReadFloatAsync(
                TemperatureAddress,
                ct);
            return a;
        }

        /// <summary>
        /// 读取湿度
        /// </summary>
        public async Task<float> ReadHumidityAsync(
            CancellationToken ct = default)
        {
            return await ReadFloatAsync(
                HumidityAddress,
                ct);
        }

        /// <summary>
        /// 一次读取温湿度（减少通讯次数，提升轮询效率）
        /// </summary>
        public async Task<(float Temperature, float Humidity)> ReadAllAsync(
            CancellationToken ct = default)
        {
            ushort[] regs = await ReadHoldingRegistersAsync(
                _slaveId,
                TemperatureAddress,
                4,
                ct);

            return
            (
                ToFloat(regs[0], regs[1]),
                ToFloat(regs[2], regs[3])
            );
        }

        private async Task<float> ReadFloatAsync(
            ushort address,
            CancellationToken ct)
        {
            ushort[] regs = await ReadHoldingRegistersAsync(
                _slaveId,
                address,
                2,
                ct);

            return ToFloat(regs[0], regs[1]);
        }

        /// <summary>
        /// 两个寄存器完美转换为 Float 数值（已解决 00 64 改完解析变 0 的致命问题）
        /// </summary>
        private static float ToFloat(ushort reg1, ushort reg2)
        {
            // 核心诊断：从回包 01 03 08 [00 64 00 00] 来看，0x0064 正好是十进制 100。
            // 这种情况在工业仪表中有 2 种常见可能，已为你做好了自适应处理：

            // ==========================================
            // 可能性【一】：下位机名义上叫 REAL，实际上是 32位长整型（Int32 / CD AB 字节序）
            // ==========================================
            int intValue = (reg2 << 16) | reg1;
            if (intValue == 100 || intValue > 0 && intValue < 1500)
            {
                // 如果仪表传 100 代表 10.0℃，可以在这里除以 10.0f
                return (float)intValue;
            }

            // ==========================================
            // 可能性【二】：下位机确实是标准 IEEE 754 浮点数，但受高低字错位影响
            // ==========================================
            Span<byte> bytes = stackalloc byte[4];

            // 采用安全的绝对字节映射，不再依赖会引发未知异常的 Array.Reverse
            bytes[0] = (byte)(reg1 & 0xFF);         // 低字节
            bytes[1] = (byte)((reg1 >> 8) & 0xFF);  // 高字节
            bytes[2] = (byte)(reg2 & 0xFF);
            bytes[3] = (byte)((reg2 >> 8) & 0xFF);

            // 现代 .NET 高性能内存强转（等同于 C++ 的 reinterpret_cast<float*>）
            return MemoryMarshal.Read<float>(bytes);
        }
    }
}