using System.IO.Ports;
using System.Text;
using System.Text.RegularExpressions;

namespace Housing.Services;

public sealed class SerialScpiClient : IScpiClient
{
    private readonly SerialPort _serialPort;

    public string PortName => _serialPort.PortName;

    public SerialScpiClient(string portName, int baudRate, int timeoutMilliseconds, IEnumerable<string>? idnMatches = null)
    {
        var resolvedPortName = ResolvePortName(portName, baudRate, timeoutMilliseconds, idnMatches);

        _serialPort = CreateSerialPort(resolvedPortName, baudRate, timeoutMilliseconds);
        _serialPort.Open();
        _serialPort.DiscardInBuffer();
        _serialPort.DiscardOutBuffer();
    }

    public Task SendAsync(string command)
    {
        return Task.Run(() => _serialPort.Write(command.Trim() + "\n"));
    }

    public Task<string> QueryAsync(string command)
    {
        return Task.Run(() =>
        {
            _serialPort.DiscardInBuffer();
            _serialPort.Write(command.Trim() + "\n");
            return _serialPort.ReadLine().Trim();
        });
    }

    private static SerialPort CreateSerialPort(string portName, int baudRate, int timeoutMilliseconds)
    {
        return new SerialPort(portName, baudRate)
        {
            Encoding = Encoding.ASCII,
            NewLine = "\n",
            ReadTimeout = timeoutMilliseconds,
            WriteTimeout = timeoutMilliseconds,
            DtrEnable = true,
            RtsEnable = true
        };
    }

    private static string ResolvePortName(string portName, int baudRate, int timeoutMilliseconds, IEnumerable<string>? idnMatches)
    {
        if (!IsAutoPort(portName))
        {
            return portName.Trim();
        }

        var portNames = SerialPort.GetPortNames()
            .OrderBy(GetPortNumber)
            .ThenBy(candidate => candidate, StringComparer.OrdinalIgnoreCase)
            .ToArray();

        if (portNames.Length == 0)
        {
            throw new InvalidOperationException("사용 가능한 장비 COM 포트를 찾을 수 없습니다.");
        }

        var tokens = NormalizeIdnMatches(idnMatches);
        if (tokens.Length == 0 && portNames.Length == 1)
        {
            return portNames[0];
        }

        foreach (var candidate in portNames)
        {
            if (MatchesIdn(candidate, baudRate, timeoutMilliseconds, tokens))
            {
                return candidate;
            }
        }

        throw new InvalidOperationException($"SCPI 장비 자동 포트 검색 실패. 확인한 포트: {string.Join(", ", portNames)}");
    }

    private static bool IsAutoPort(string portName)
    {
        return string.IsNullOrWhiteSpace(portName) ||
               string.Equals(portName.Trim(), "Auto", StringComparison.OrdinalIgnoreCase);
    }

    private static int GetPortNumber(string portName)
    {
        var match = Regex.Match(portName, @"\d+");
        return match.Success && int.TryParse(match.Value, out var number)
            ? number
            : int.MaxValue;
    }

    private static string[] NormalizeIdnMatches(IEnumerable<string>? idnMatches)
    {
        return idnMatches?
            .SelectMany(value => value.Split(',', ';'))
            .Select(value => value.Trim())
            .Where(value => !string.IsNullOrWhiteSpace(value))
            .ToArray() ?? Array.Empty<string>();
    }

    private static bool MatchesIdn(string portName, int baudRate, int timeoutMilliseconds, string[] idnMatches)
    {
        try
        {
            using var probe = CreateSerialPort(portName, baudRate, timeoutMilliseconds);
            probe.Open();
            probe.DiscardInBuffer();
            probe.DiscardOutBuffer();
            probe.Write("*IDN?\n");
            var idn = probe.ReadLine().Trim();

            return idnMatches.Length == 0 ||
                   idnMatches.Any(token => idn.Contains(token, StringComparison.OrdinalIgnoreCase));
        }
        catch
        {
            return false;
        }
    }

    public void Dispose()
    {
        _serialPort.Dispose();
    }
}