using Common.Attributes;
using NModbus;
using NModbus.Serial;
using System;
using System.IO.Ports;
using System.Threading;
using System.Threading.Tasks;

namespace DeviceCommand.Flexible
{
    /// <summary>
    /// 灵活型 Modbus RTU 串口通信类（免实例化，每次调用临时创建串口连接）。
    /// 支持保持寄存器与线圈的读写操作，内部使用通信锁保证同一时刻只有一个事务在执行，
    /// 适用于偶发性、无需保持长连接的 Modbus RTU 设备读写场景。
    /// </summary>
    [ADPCommand]
    public static class FModbusRTU
    {
        // 通信锁：保证同一时刻只有一个 Modbus 事务在执行
        private static readonly SemaphoreSlim _commLock = new(1, 1);

        /// <summary>
        /// 创建串口实例并配置超时参数。
        /// </summary>
        private static SerialPort CreatePort(
            string portName,
            int baudRate,
            int dataBits,
            StopBits stopBits,
            Parity parity,
            int readTimeout,
            int writeTimeout)
        {
            return new SerialPort(portName, baudRate, parity, dataBits, stopBits)
            {
                ReadTimeout = readTimeout > 0 ? readTimeout : SerialPort.InfiniteTimeout,
                WriteTimeout = writeTimeout > 0 ? writeTimeout : SerialPort.InfiniteTimeout
            };
        }

        /// <summary>
        /// 基于指定串口创建 Modbus RTU 主站。
        /// </summary>
        private static IModbusMaster CreateMaster(SerialPort port)
        {
            return new ModbusFactory().CreateRtuMaster(port);
        }

        #region Holding Register

        /// <summary>
        /// 读取保持寄存器（功能码 03），返回指定数量的寄存器值数组。
        /// </summary>
        /// <param name="portName">串口名称，如 "COM1"</param>
        /// <param name="baudRate">波特率，如 9600、115200</param>
        /// <param name="slaveAddress">Modbus 从站站号 (1-247)</param>
        /// <param name="startAddress">起始寄存器地址</param>
        /// <param name="numberOfPoints">读取的寄存器数量</param>
        /// <param name="dataBits">数据位，默认 8</param>
        /// <param name="stopBits">停止位，默认 1 位</param>
        /// <param name="parity">校验位，默认无校验</param>
        /// <param name="readTimeout">读取超时时间（毫秒），默认 3000</param>
        /// <param name="writeTimeout">写入超时时间（毫秒），默认 3000</param>
        /// <param name="ct">异步取消令牌</param>
        /// <returns>读取到的寄存器值数组</returns>
        public static async Task<ushort[]> 读保持寄存器(
            string portName,
            int baudRate,
            byte slaveAddress,
            ushort startAddress,
            ushort numberOfPoints,
            int dataBits = 8,
            StopBits stopBits = StopBits.One,
            Parity parity = Parity.None,
            int readTimeout = 3000,
            int writeTimeout = 3000,
            CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                using var port = CreatePort(
                    portName, baudRate, dataBits, stopBits, parity, readTimeout, writeTimeout);

                port.Open();

                var master = CreateMaster(port);

                using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
                if (readTimeout > 0)
                    cts.CancelAfter(readTimeout);

                return await master
                    .ReadHoldingRegistersAsync(slaveAddress, startAddress, numberOfPoints)
                    .WaitAsync(TimeSpan.FromMilliseconds(readTimeout),cts.Token);
            }
            finally
            {
                _commLock.Release();
            }
        }

        /// <summary>
        /// 写入单个保持寄存器（功能码 06）。
        /// </summary>
        /// <param name="portName">串口名称，如 "COM1"</param>
        /// <param name="baudRate">波特率，如 9600、115200</param>
        /// <param name="slaveAddress">Modbus 从站站号 (1-247)</param>
        /// <param name="registerAddress">要写入的寄存器地址</param>
        /// <param name="value">要写入的寄存器值 (0-65535)</param>
        /// <param name="dataBits">数据位，默认 8</param>
        /// <param name="stopBits">停止位，默认 1 位</param>
        /// <param name="parity">校验位，默认无校验</param>
        /// <param name="readTimeout">读取超时时间（毫秒），默认 3000</param>
        /// <param name="writeTimeout">写入超时时间（毫秒），默认 3000</param>
        /// <param name="ct">异步取消令牌</param>
        public static async Task 写单个寄存器(
            string portName,
            int baudRate,
            byte slaveAddress,
            ushort registerAddress,
            ushort value,
            int dataBits = 8,
            StopBits stopBits = StopBits.One,
            Parity parity = Parity.None,
            int readTimeout = 3000,
            int writeTimeout = 3000,
            CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                using var port = CreatePort(
                    portName, baudRate, dataBits, stopBits, parity, readTimeout, writeTimeout);

                port.Open();

                var master = CreateMaster(port);

                using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
                if (writeTimeout > 0)
                    cts.CancelAfter(writeTimeout);

                await master
                    .WriteSingleRegisterAsync(slaveAddress, registerAddress, value)
                    .WaitAsync(TimeSpan.FromMilliseconds(writeTimeout),cts.Token);
            }
            finally
            {
                _commLock.Release();
            }
        }

        #endregion

        #region Coil

        /// <summary>
        /// 读取线圈状态（功能码 01），返回指定数量的线圈开关状态数组。
        /// </summary>
        /// <param name="portName">串口名称，如 "COM1"</param>
        /// <param name="baudRate">波特率，如 9600、115200</param>
        /// <param name="slaveAddress">Modbus 从站站号 (1-247)</param>
        /// <param name="startAddress">起始线圈地址</param>
        /// <param name="numberOfPoints">读取的线圈数量</param>
        /// <param name="dataBits">数据位，默认 8</param>
        /// <param name="stopBits">停止位，默认 1 位</param>
        /// <param name="parity">校验位，默认无校验</param>
        /// <param name="readTimeout">读取超时时间（毫秒），默认 3000</param>
        /// <param name="writeTimeout">写入超时时间（毫秒），默认 3000</param>
        /// <param name="ct">异步取消令牌</param>
        /// <returns>线圈状态数组，true 表示吸合/导通</returns>
        public static async Task<bool[]> 读线圈(
            string portName,
            int baudRate,
            byte slaveAddress,
            ushort startAddress,
            ushort numberOfPoints,
            int dataBits = 8,
            StopBits stopBits = StopBits.One,
            Parity parity = Parity.None,
            int readTimeout = 3000,
            int writeTimeout = 3000,
            CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                using var port = CreatePort(
                    portName, baudRate, dataBits, stopBits, parity, readTimeout, writeTimeout);

                port.Open();

                var master = CreateMaster(port);

                using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
                if (readTimeout > 0)
                    cts.CancelAfter(readTimeout);

                return await master
                    .ReadCoilsAsync(slaveAddress, startAddress, numberOfPoints)
                    .WaitAsync(TimeSpan.FromMilliseconds(readTimeout),cts.Token);
            }
            finally
            {
                _commLock.Release();
            }
        }

        /// <summary>
        /// 写入单个线圈（功能码 05），控制单个开关量输出。
        /// </summary>
        /// <param name="portName">串口名称，如 "COM1"</param>
        /// <param name="baudRate">波特率，如 9600、115200</param>
        /// <param name="slaveAddress">Modbus 从站站号 (1-247)</param>
        /// <param name="coilAddress">要写入的线圈地址</param>
        /// <param name="value">线圈状态（true: 吸合/导通, false: 断开）</param>
        /// <param name="dataBits">数据位，默认 8</param>
        /// <param name="stopBits">停止位，默认 1 位</param>
        /// <param name="parity">校验位，默认无校验</param>
        /// <param name="readTimeout">读取超时时间（毫秒），默认 3000</param>
        /// <param name="writeTimeout">写入超时时间（毫秒），默认 3000</param>
        /// <param name="ct">异步取消令牌</param>
        public static async Task 写单个线圈(
            string portName,
            int baudRate,
            byte slaveAddress,
            ushort coilAddress,
            bool value,
            int dataBits = 8,
            StopBits stopBits = StopBits.One,
            Parity parity = Parity.None,
            int readTimeout = 3000,
            int writeTimeout = 3000,
            CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                using var port = CreatePort(
                    portName, baudRate, dataBits, stopBits, parity, readTimeout, writeTimeout);

                port.Open();

                var master = CreateMaster(port);

                using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
                if (writeTimeout > 0)
                    cts.CancelAfter(writeTimeout);

                await master
                    .WriteSingleCoilAsync(slaveAddress, coilAddress, value)
                    .WaitAsync(TimeSpan.FromMilliseconds(writeTimeout), cts.Token);
            }
            finally
            {
                _commLock.Release();
            }
        }

        #endregion
    }
}