using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO.Ports;
using System.Security;
using System.Text;
using System.Threading;
using Microsoft.Win32;

namespace OpenHardwareMonitor.Hardware.Controller.Heatmaster;

internal class HeatmasterGroup : IGroup
{
    private readonly List<Heatmaster> _hardware = new();
    private readonly StringBuilder _report = new();

    public HeatmasterGroup(ISettings settings)
    {
        // No implementation for Heatmaster on Unix systems
        if (OperatingSystemHelper.IsUnix)
            return;

        string[] portNames = GetRegistryPortNames();
        for (int i = 0; i < portNames.Length; i++)
        {
            bool isValid = false;
            try
            {
                using SerialPort serialPort = new(portNames[i], 38400, Parity.None, 8, StopBits.One);
                serialPort.NewLine = ((char)0x0D).ToString();
                _report.Append("Port Name: ");
                _report.AppendLine(portNames[i]);
                try
                {
                    serialPort.Open();
                }
                catch (UnauthorizedAccessException)
                {
                    _report.AppendLine("Exception: Access Denied");
                }

                if (serialPort.IsOpen)
                {
                    serialPort.DiscardInBuffer();
                    serialPort.DiscardOutBuffer();
                    serialPort.Write(new byte[] { 0xAA }, 0, 1);

                    int j = 0;
                    while (serialPort.BytesToRead == 0 && j < 10)
                    {
                        Thread.Sleep(20);
                        j++;
                    }

                    if (serialPort.BytesToRead > 0)
                    {
                        bool flag = false;
                        while (serialPort.BytesToRead > 0 && !flag)
                        {
                            flag |= serialPort.ReadByte() == 0xAA;
                        }

                        if (flag)
                        {
                            serialPort.WriteLine("[0:0]RH");
                            try
                            {
                                int k = 0;
                                int revision = 0;
                                while (k < 5)
                                {
                                    string line = ReadLine(serialPort, 100);
                                    if (line.StartsWith("-[0:0]RH:", StringComparison.Ordinal))
                                    {
                                        revision = int.Parse(line.Substring(9), CultureInfo.InvariantCulture);
                                        break;
                                    }

                                    k++;
                                }

                                isValid = revision == 770;
                                if (!isValid)
                                {
                                    _report.Append("Status: Wrong Hardware Revision " + revision.ToString(CultureInfo.InvariantCulture));
                                }
                            }
                            catch (TimeoutException)
                            {
                                _report.AppendLine("Status: Timeout Reading Revision");
                            }
                        }
                        else
                        {
                            _report.AppendLine("Status: Wrong Startflag");
                        }
                    }
                    else
                    {
                        _report.AppendLine("Status: No Response");
                    }

                    serialPort.DiscardInBuffer();
                }
                else
                {
                    _report.AppendLine("Status: Port not Open");
                }
            }
            catch (Exception e)
            {
                _report.AppendLine(e.ToString());
            }

            if (isValid)
            {
                _report.AppendLine("Status: OK");
                _hardware.Add(new Heatmaster(portNames[i], settings));
            }

            _report.AppendLine();
        }
    }

    public IReadOnlyList<IHardware> Hardware => _hardware;

    public string GetReport()
    {
        if (_report.Length > 0)
        {
            StringBuilder r = new();
            r.AppendLine("Serial Port Heatmaster");
            r.AppendLine();
            r.Append(_report);
            r.AppendLine();
            return r.ToString();
        }

        return null;
    }

    public void Close()
    {
        foreach (Heatmaster heatmaster in _hardware)
            heatmaster.Close();
    }

    private static string ReadLine(SerialPort port, int timeout)
    {
        int i = 0;
        StringBuilder builder = new();
        while (i < timeout)
        {
            while (port.BytesToRead > 0)
            {
                byte b = (byte)port.ReadByte();
                switch (b)
                {
                    case 0xAA: return ((char)b).ToString();
                    case 0x0D: return builder.ToString();
                    default:
                        builder.Append((char)b);
                        break;
                }
            }

            i++;
            Thread.Sleep(1);
        }

        throw new TimeoutException();
    }

    private static string[] GetRegistryPortNames()
    {
        List<string> result = new();
        string[] paths = { string.Empty, "&MI_00" };
        try
        {
            foreach (string path in paths)
            {
                RegistryKey key = Registry.LocalMachine.OpenSubKey(@"SYSTEM\CurrentControlSet\Enum\USB\VID_10C4&PID_EA60" + path);
                if (key != null)
                {
                    foreach (string subKeyName in key.GetSubKeyNames())
                    {
                        RegistryKey subKey = key.OpenSubKey(subKeyName + "\\" + "Device Parameters");
                        if (subKey?.GetValue("PortName") is string name && !result.Contains(name))
                            result.Add(name);
                    }
                }
            }
        }
        catch (SecurityException)
        { }

        return result.ToArray();
    }
}
