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

namespace Housing.Services;

public sealed class SerialBoardClient : IDisposable
{
    private readonly BoardHardwareSettings _settings;
    private readonly SerialPort _serialPort;

    public string PortName => _serialPort.PortName;

    public SerialBoardClient(BoardHardwareSettings settings)
    {
        _settings = settings;
        var portName = ResolvePortName(settings);

        _serialPort = CreateSerialPort(portName, _settings);
    }

    public void Open()
    {
        if (!_serialPort.IsOpen)
        {
            _serialPort.Open();
            _serialPort.DiscardInBuffer();
            _serialPort.DiscardOutBuffer();
        }
    }

    public Task<string> SendCommandAsync(string command, int timeoutMilliseconds, bool waitForEndToken)
    {
        return Task.Run(() => SendCommand(command, timeoutMilliseconds, waitForEndToken));
    }

    private static SerialPort CreateSerialPort(string portName, BoardHardwareSettings settings)
    {
        return new SerialPort(portName, settings.BaudRate)
        {
            Encoding = Encoding.ASCII,
            NewLine = "\r\n",
            ReadTimeout = settings.ReadTimeout,
            WriteTimeout = settings.ReadTimeout,
            DtrEnable = true,
            RtsEnable = true
        };
    }

    private static string ResolvePortName(BoardHardwareSettings settings)
    {
        if (!IsAutoPort(settings.PortName))
        {
            return settings.PortName.Trim();
        }

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

        foreach (var portName in portNames)
        {
            if (CanConnectBoard(portName, settings))
            {
                return portName;
            }
        }

        throw new InvalidOperationException($"보드 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 string[] GetOrderedPortNames()
    {
        return SerialPort.GetPortNames()
            .OrderBy(GetPortNumber)
            .ThenBy(portName => portName, StringComparer.OrdinalIgnoreCase)
            .ToArray();
    }

    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 bool CanConnectBoard(string portName, BoardHardwareSettings settings)
    {
        try
        {
            using var probe = CreateSerialPort(portName, settings);
            probe.Open();
            probe.DiscardInBuffer();
            probe.DiscardOutBuffer();

            if (string.IsNullOrWhiteSpace(settings.ConnectCommand))
            {
                return true;
            }

            probe.Write(settings.ConnectCommand.Trim() + "\r\n");
            var startedAt = DateTime.UtcNow;

            while ((DateTime.UtcNow - startedAt).TotalMilliseconds < settings.ReadTimeout)
            {
                try
                {
                    var line = probe.ReadLine();
                    if (IsSuccessLine(line))
                    {
                        return true;
                    }

                    if (!string.IsNullOrWhiteSpace(settings.EndToken) &&
                        line.Contains(settings.EndToken, StringComparison.OrdinalIgnoreCase))
                    {
                        return false;
                    }
                }
                catch (TimeoutException)
                {
                    return false;
                }
            }
        }
        catch
        {
            return false;
        }

        return false;
    }

    private static bool IsSuccessLine(string line)
    {
        return string.Equals(line.Trim(), "Success", StringComparison.OrdinalIgnoreCase);
    }

    private string SendCommand(string command, int timeoutMilliseconds, bool waitForEndToken)
    {
        if (string.IsNullOrWhiteSpace(command))
        {
            return string.Empty;
        }

        Open();
        _serialPort.ReadTimeout = Math.Max(500, timeoutMilliseconds);
        _serialPort.DiscardInBuffer();
        _serialPort.Write(command.Trim() + "\r\n");

        var startedAt = DateTime.UtcNow;
        var response = new StringBuilder();

        while ((DateTime.UtcNow - startedAt).TotalMilliseconds < timeoutMilliseconds)
        {
            try
            {
                var line = _serialPort.ReadLine();
                response.AppendLine(line);

                if (!waitForEndToken)
                {
                    break;
                }

                if (line.Contains(_settings.EndToken, StringComparison.OrdinalIgnoreCase))
                {
                    break;
                }
            }
            catch (TimeoutException)
            {
                break;
            }
        }

        return response.ToString();
    }

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