using System;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;

namespace ASTM_D7896_Tester.Services
{
    /// <summary>
    /// 基于 LAN (TCP/IP) 的 TH1963 数字多用表通信服务
    /// 支持 SCPI 命令，实现高速批量采集
    /// </summary>
    public class Th1963LanService : IDisposable
    {
        private TcpClient _tcpClient;
        private NetworkStream _stream;
        private bool _disposed = false;

        /// <summary>
        /// 接收缓冲区大小（字节），建议至少 1MB 以支持大量数据
        /// </summary>
        public int ReceiveBufferSize { get; set; } = 2 * 1024 * 1024; // 2 MB

        /// <summary>
        /// 连接超时（毫秒）
        /// </summary>
        public int ConnectTimeoutMs { get; set; } = 3000;

        /// <summary>
        /// 读写超时（毫秒）
        /// </summary>
        public int ReadWriteTimeoutMs { get; set; } = 5000;

        /// <summary>
        /// 连接到 TH1963
        /// </summary>
        /// <param name="ipAddress">仪器 IP 地址，如 "192.168.1.241"</param>
        /// <param name="port">端口号，默认 45454</param>
        public async Task ConnectAsync(string ipAddress, int port = 45454)
        {
            if (_tcpClient != null && _tcpClient.Connected)
                return;

            _tcpClient = new TcpClient();
            _tcpClient.ReceiveBufferSize = ReceiveBufferSize;
            _tcpClient.SendBufferSize = ReceiveBufferSize;

            var connectTask = _tcpClient.ConnectAsync(ipAddress, port);
            if (await Task.WhenAny(connectTask, Task.Delay(ConnectTimeoutMs)) != connectTask)
                throw new TimeoutException($"连接 TH1963 ({ipAddress}:{port}) 超时");

            _stream = _tcpClient.GetStream();
            _stream.ReadTimeout = ReadWriteTimeoutMs;
            _stream.WriteTimeout = ReadWriteTimeoutMs;
        }

        /// <summary>
        /// 发送 SCPI 命令并等待响应（适用于查询类命令）
        /// </summary>
        public async Task<string> QueryAsync(string command)
        {
            EnsureConnected();
            byte[] cmdBytes = Encoding.ASCII.GetBytes(command + "\n");
            await _stream.WriteAsync(cmdBytes, 0, cmdBytes.Length);

            // 读取响应，直到换行符
            var responseBuilder = new StringBuilder();
            byte[] buffer = new byte[4096];
            int bytesRead;
            while (true)
            {
                bytesRead = await _stream.ReadAsync(buffer, 0, buffer.Length);
                if (bytesRead == 0) break;
                string chunk = Encoding.ASCII.GetString(buffer, 0, bytesRead);
                responseBuilder.Append(chunk);
                if (chunk.Contains("\n")) break;
            }
            return responseBuilder.ToString().Trim();
        }

        /// <summary>
        /// 发送命令但不等待响应（适用于设置类命令）
        /// </summary>
        public async Task SendCommandAsync(string command)
        {
            EnsureConnected();
            byte[] cmdBytes = Encoding.ASCII.GetBytes(command + "\n");
            await _stream.WriteAsync(cmdBytes, 0, cmdBytes.Length);
        }

        /// <summary>
        /// 配置为高速直流电压测量（用于批量采集）
        /// 设置：0.02 PLC（≈400μs积分时间），自动量程，关闭自动归零
        /// </summary>
        public async Task ConfigureForHighSpeedDcvAsync()
        {
            await SendCommandAsync("CONF:VOLT:DC AUTO");
            await SendCommandAsync("VOLT:DC:NPLC 0.02");      // 最快速度
            await SendCommandAsync("VOLT:DC:ZERO:AUTO OFF"); // 提高速度
            await SendCommandAsync("TRIG:SOUR EXT");         // 外部触发（与PLC同步）
            await SendCommandAsync("TRIG:DEL:AUTO OFF");
            await SendCommandAsync("TRIG:DEL 0");
        }

        /// <summary>
        /// 批量采集指定数量的电压值（使用外部触发，需等待硬件触发信号）
        /// 调用前必须已执行 ConfigureForHighSpeedDcvAsync 和 SAMP:COUN
        /// </summary>
        /// <param name="sampleCount">采样点数（最大 5000）</param>
        /// <returns>电压数组（单位：伏特）</returns>
        public async Task<double[]> AcquireBatchAsync(int sampleCount)
        {
            // 预置采样点数
            await SendCommandAsync($"SAMP:COUN {sampleCount}");
            // 进入等待触发状态
            await SendCommandAsync("INIT");

            // 等待采集完成（估算：sampleCount / 1000 秒 + 稳定时间）
            int waitMs = (int)(sampleCount / 1000.0 * 1000) + 200;
            await Task.Delay(waitMs);

            // 取回数据
            string response = await QueryAsync("FETCh?");
            string[] parts = response.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
            double[] values = new double[parts.Length];
            for (int i = 0; i < parts.Length; i++)
            {
                if (!double.TryParse(parts[i], System.Globalization.NumberStyles.Float,
                        System.Globalization.CultureInfo.InvariantCulture, out values[i]))
                    throw new Exception($"解析电压值失败: {parts[i]}");
            }
            if (values.Length != sampleCount)
                throw new Exception($"期望 {sampleCount} 个点，实际收到 {values.Length}");

            return values;
        }

        /// <summary>
        /// 单次读取当前电压（非批量，用于实时监控）
        /// </summary>
        public async Task<double> ReadVoltageAsync()
        {
            string resp = await QueryAsync("MEAS:VOLT:DC?");
            if (double.TryParse(resp, System.Globalization.NumberStyles.Float,
                    System.Globalization.CultureInfo.InvariantCulture, out double value))
                return value;
            throw new Exception($"电压读数无效: {resp}");
        }

        /// <summary>
        /// 复位仪器
        /// </summary>
        public async Task ResetAsync() => await SendCommandAsync("*RST");

        /// <summary>
        /// 查询仪器标识
        /// </summary>
        public async Task<string> IdentifyAsync() => await QueryAsync("*IDN?");

        private void EnsureConnected()
        {
            if (_tcpClient == null || !_tcpClient.Connected)
                throw new InvalidOperationException("未连接到 TH1963，请先调用 ConnectAsync");
        }

        // 实现 IDisposable
        public void Dispose()
        {
            if (!_disposed)
            {
                _stream?.Close();
                _tcpClient?.Close();
                _stream?.Dispose();
                _tcpClient?.Dispose();
                _disposed = true;
            }
        }
    }
}