gui-cs.Terminal.Gui/Terminal.Gui/ConsoleDrivers/NetDriver.cs

//
// NetDriver.cs: The System.Console-based .NET driver, works on Windows and Unix, but is not particularly efficient.
//

using System.Diagnostics;
using System.Runtime.InteropServices;
using static Terminal.Gui.ConsoleDrivers.ConsoleKeyMapping;
using static Terminal.Gui.NetEvents;

namespace Terminal.Gui;

internal class NetWinVTConsole
{
    private const uint DISABLE_NEWLINE_AUTO_RETURN = 8;
    private const uint ENABLE_ECHO_INPUT = 4;
    private const uint ENABLE_EXTENDED_FLAGS = 128;
    private const uint ENABLE_INSERT_MODE = 32;
    private const uint ENABLE_LINE_INPUT = 2;
    private const uint ENABLE_LVB_GRID_WORLDWIDE = 10;
    private const uint ENABLE_MOUSE_INPUT = 16;

    // Input modes.
    private const uint ENABLE_PROCESSED_INPUT = 1;

    // Output modes.
    private const uint ENABLE_PROCESSED_OUTPUT = 1;
    private const uint ENABLE_QUICK_EDIT_MODE = 64;
    private const uint ENABLE_VIRTUAL_TERMINAL_INPUT = 512;
    private const uint ENABLE_VIRTUAL_TERMINAL_PROCESSING = 4;
    private const uint ENABLE_WINDOW_INPUT = 8;
    private const uint ENABLE_WRAP_AT_EOL_OUTPUT = 2;
    private const int STD_ERROR_HANDLE = -12;
    private const int STD_INPUT_HANDLE = -10;
    private const int STD_OUTPUT_HANDLE = -11;

    private readonly nint _errorHandle;
    private readonly nint _inputHandle;
    private readonly uint _originalErrorConsoleMode;
    private readonly uint _originalInputConsoleMode;
    private readonly uint _originalOutputConsoleMode;
    private readonly nint _outputHandle;

    public NetWinVTConsole ()
    {
        _inputHandle = GetStdHandle (STD_INPUT_HANDLE);

        if (!GetConsoleMode (_inputHandle, out uint mode))
        {
            throw new ApplicationException ($"Failed to get input console mode, error code: {GetLastError ()}.");
        }

        _originalInputConsoleMode = mode;

        if ((mode & ENABLE_VIRTUAL_TERMINAL_INPUT) < ENABLE_VIRTUAL_TERMINAL_INPUT)
        {
            mode |= ENABLE_VIRTUAL_TERMINAL_INPUT;

            if (!SetConsoleMode (_inputHandle, mode))
            {
                throw new ApplicationException ($"Failed to set input console mode, error code: {GetLastError ()}.");
            }
        }

        _outputHandle = GetStdHandle (STD_OUTPUT_HANDLE);

        if (!GetConsoleMode (_outputHandle, out mode))
        {
            throw new ApplicationException ($"Failed to get output console mode, error code: {GetLastError ()}.");
        }

        _originalOutputConsoleMode = mode;

        if ((mode & (ENABLE_VIRTUAL_TERMINAL_PROCESSING | DISABLE_NEWLINE_AUTO_RETURN)) < DISABLE_NEWLINE_AUTO_RETURN)
        {
            mode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING | DISABLE_NEWLINE_AUTO_RETURN;

            if (!SetConsoleMode (_outputHandle, mode))
            {
                throw new ApplicationException ($"Failed to set output console mode, error code: {GetLastError ()}.");
            }
        }

        _errorHandle = GetStdHandle (STD_ERROR_HANDLE);

        if (!GetConsoleMode (_errorHandle, out mode))
        {
            throw new ApplicationException ($"Failed to get error console mode, error code: {GetLastError ()}.");
        }

        _originalErrorConsoleMode = mode;

        if ((mode & DISABLE_NEWLINE_AUTO_RETURN) < DISABLE_NEWLINE_AUTO_RETURN)
        {
            mode |= DISABLE_NEWLINE_AUTO_RETURN;

            if (!SetConsoleMode (_errorHandle, mode))
            {
                throw new ApplicationException ($"Failed to set error console mode, error code: {GetLastError ()}.");
            }
        }
    }

    public void Cleanup ()
    {
        if (!SetConsoleMode (_inputHandle, _originalInputConsoleMode))
        {
            throw new ApplicationException ($"Failed to restore input console mode, error code: {GetLastError ()}.");
        }

        if (!SetConsoleMode (_outputHandle, _originalOutputConsoleMode))
        {
            throw new ApplicationException ($"Failed to restore output console mode, error code: {GetLastError ()}.");
        }

        if (!SetConsoleMode (_errorHandle, _originalErrorConsoleMode))
        {
            throw new ApplicationException ($"Failed to restore error console mode, error code: {GetLastError ()}.");
        }
    }

    [DllImport ("kernel32.dll")]
    private static extern bool GetConsoleMode (nint hConsoleHandle, out uint lpMode);

    [DllImport ("kernel32.dll")]
    private static extern uint GetLastError ();

    [DllImport ("kernel32.dll", SetLastError = true)]
    private static extern nint GetStdHandle (int nStdHandle);

    [DllImport ("kernel32.dll")]
    private static extern bool SetConsoleMode (nint hConsoleHandle, uint dwMode);
}

internal class NetEvents : IDisposable
{
    private readonly ManualResetEventSlim _inputReady = new (false);
    private CancellationTokenSource _inputReadyCancellationTokenSource;
    private readonly ManualResetEventSlim _waitForStart = new (false);

    //CancellationTokenSource _waitForStartCancellationTokenSource;
    private readonly ManualResetEventSlim _winChange = new (false);
    private readonly Queue<InputResult?> _inputQueue = new ();
    private readonly ConsoleDriver _consoleDriver;
    private ConsoleKeyInfo [] _cki;
    private bool _isEscSeq;
#if PROCESS_REQUEST
    bool _neededProcessRequest;
#endif
    public EscSeqRequests EscSeqRequests { get; } = new ();

    public NetEvents (ConsoleDriver consoleDriver)
    {
        _consoleDriver = consoleDriver ?? throw new ArgumentNullException (nameof (consoleDriver));
        _inputReadyCancellationTokenSource = new CancellationTokenSource ();

        Task.Run (ProcessInputQueue, _inputReadyCancellationTokenSource.Token);

        Task.Run (CheckWindowSizeChange, _inputReadyCancellationTokenSource.Token);
    }

    public InputResult? DequeueInput ()
    {
        while (_inputReadyCancellationTokenSource is { Token.IsCancellationRequested: false })
        {
            _waitForStart.Set ();
            _winChange.Set ();

            try
            {
                if (!_inputReadyCancellationTokenSource.Token.IsCancellationRequested)
                {
                    if (_inputQueue.Count == 0)
                    {
                        _inputReady.Wait (_inputReadyCancellationTokenSource.Token);
                    }
                }
            }
            catch (OperationCanceledException)
            {
                return null;
            }
            finally
            {
                _inputReady.Reset ();
            }

#if PROCESS_REQUEST
            _neededProcessRequest = false;
#endif
            if (_inputQueue.Count > 0)
            {
                return _inputQueue.Dequeue ();
            }
        }

        return null;
    }

    private static ConsoleKeyInfo ReadConsoleKeyInfo (CancellationToken cancellationToken, bool intercept = true)
    {
        // The Console.KeyAvailable must only be used if
        // the console is reading an Ansi escape sequence
        // Task.Delay must only be used on limited situations
        // and not for the entire application execution, which
        // case need to use async Task to really awaiting,
        // like the CheckWindowSizeChange is using
        try
        {
            return Console.ReadKey (intercept);
        }
        catch (InvalidOperationException) { }

        cancellationToken.ThrowIfCancellationRequested ();

        return default (ConsoleKeyInfo);
    }

    private void ProcessInputQueue ()
    {
        while (!_inputReadyCancellationTokenSource.Token.IsCancellationRequested)
        {
            try
            {
                _waitForStart.Wait (_inputReadyCancellationTokenSource.Token);
            }
            catch (OperationCanceledException)
            {
                return;
            }

            _waitForStart.Reset ();

            if (_inputQueue.Count == 0)
            {
                ConsoleKey key = 0;
                ConsoleModifiers mod = 0;
                ConsoleKeyInfo newConsoleKeyInfo = default;

                while (true)
                {
                    if (_inputReadyCancellationTokenSource.Token.IsCancellationRequested)
                    {
                        return;
                    }

                    ConsoleKeyInfo consoleKeyInfo;

                    try
                    {
                        consoleKeyInfo = ReadConsoleKeyInfo (_inputReadyCancellationTokenSource.Token);
                    }
                    catch (OperationCanceledException)
                    {
                        return;
                    }

                    if ((consoleKeyInfo.KeyChar == (char)KeyCode.Esc && !_isEscSeq)
                        || (consoleKeyInfo.KeyChar != (char)KeyCode.Esc && _isEscSeq))
                    {
                        if (_cki is null && consoleKeyInfo.KeyChar != (char)KeyCode.Esc && _isEscSeq)
                        {
                            _cki = EscSeqUtils.ResizeArray (
                                                            new ConsoleKeyInfo (
                                                                                (char)KeyCode.Esc,
                                                                                0,
                                                                                false,
                                                                                false,
                                                                                false
                                                                               ),
                                                            _cki
                                                           );
                        }

                        _isEscSeq = true;
                        newConsoleKeyInfo = consoleKeyInfo;
                        _cki = EscSeqUtils.ResizeArray (consoleKeyInfo, _cki);

                        if (Console.KeyAvailable)
                        {
                            continue;
                        }

                        ProcessRequestResponse (ref newConsoleKeyInfo, ref key, _cki, ref mod);
                        _cki = null;
                        _isEscSeq = false;

                        break;
                    }

                    if (consoleKeyInfo.KeyChar == (char)KeyCode.Esc && _isEscSeq && _cki is { })
                    {
                        ProcessRequestResponse (ref newConsoleKeyInfo, ref key, _cki, ref mod);
                        _cki = null;

                        if (Console.KeyAvailable)
                        {
                            _cki = EscSeqUtils.ResizeArray (consoleKeyInfo, _cki);
                        }
                        else
                        {
                            ProcessMapConsoleKeyInfo (consoleKeyInfo);
                        }

                        break;
                    }

                    if (consoleKeyInfo != default (ConsoleKeyInfo))
                    {
                        ProcessMapConsoleKeyInfo (consoleKeyInfo);
                    }

                    break;
                }
            }

            _inputReady.Set ();
        }

        void ProcessMapConsoleKeyInfo (ConsoleKeyInfo consoleKeyInfo)
        {
            _inputQueue.Enqueue (
                                 new InputResult
                                 {
                                     EventType = EventType.Key, ConsoleKeyInfo = EscSeqUtils.MapConsoleKeyInfo (consoleKeyInfo)
                                 }
                                );
            _isEscSeq = false;
        }
    }

    private async Task CheckWindowSizeChange ()
    {
        while (true)
        {
            if (_inputReadyCancellationTokenSource.IsCancellationRequested)
            {
                return;
            }

            try
            {
                _winChange.Wait (_inputReadyCancellationTokenSource.Token);
                _winChange.Reset ();

                await RequestWindowSize (_inputReadyCancellationTokenSource.Token);
            }
            catch (OperationCanceledException)
            {
                return;
            }

            _inputReady.Set ();
        }

        async Task RequestWindowSize (CancellationToken cancellationToken)
        {
            while (!cancellationToken.IsCancellationRequested)
            {
                // Wait for a while then check if screen has changed sizes
                await Task.Delay (500, cancellationToken);

                int buffHeight, buffWidth;

                if (((NetDriver)_consoleDriver).IsWinPlatform)
                {
                    buffHeight = Math.Max (Console.BufferHeight, 0);
                    buffWidth = Math.Max (Console.BufferWidth, 0);
                }
                else
                {
                    buffHeight = _consoleDriver.Rows;
                    buffWidth = _consoleDriver.Cols;
                }

                if (EnqueueWindowSizeEvent (
                                            Math.Max (Console.WindowHeight, 0),
                                            Math.Max (Console.WindowWidth, 0),
                                            buffHeight,
                                            buffWidth
                                           ))
                {
                    return;
                }
            }

            cancellationToken.ThrowIfCancellationRequested ();
        }
    }

    /// <summary>Enqueue a window size event if the window size has changed.</summary>
    /// <param name="winHeight"></param>
    /// <param name="winWidth"></param>
    /// <param name="buffHeight"></param>
    /// <param name="buffWidth"></param>
    /// <returns></returns>
    private bool EnqueueWindowSizeEvent (int winHeight, int winWidth, int buffHeight, int buffWidth)
    {
        if (winWidth == _consoleDriver.Cols && winHeight == _consoleDriver.Rows)
        {
            return false;
        }

        int w = Math.Max (winWidth, 0);
        int h = Math.Max (winHeight, 0);

        _inputQueue.Enqueue (
                             new InputResult
                             {
                                 EventType = EventType.WindowSize, WindowSizeEvent = new WindowSizeEvent { Size = new (w, h) }
                             }
                            );

        return true;
    }

    // Process a CSI sequence received by the driver (key pressed, mouse event, or request/response event)
    private void ProcessRequestResponse (
        ref ConsoleKeyInfo newConsoleKeyInfo,
        ref ConsoleKey key,
        ConsoleKeyInfo [] cki,
        ref ConsoleModifiers mod
    )
    {
        // isMouse is true if it's CSI<, false otherwise
        EscSeqUtils.DecodeEscSeq (
                                  EscSeqRequests,
                                  ref newConsoleKeyInfo,
                                  ref key,
                                  cki,
                                  ref mod,
                                  out string c1Control,
                                  out string code,
                                  out string [] values,
                                  out string terminating,
                                  out bool isMouse,
                                  out List<MouseFlags> mouseFlags,
                                  out Point pos,
                                  out bool isReq,
                                  (f, p) => HandleMouseEvent (MapMouseFlags (f), p)
                                 );

        if (isMouse)
        {
            foreach (MouseFlags mf in mouseFlags)
            {
                HandleMouseEvent (MapMouseFlags (mf), pos);
            }

            return;
        }

        if (isReq)
        {
            HandleRequestResponseEvent (c1Control, code, values, terminating);

            return;
        }

        HandleKeyboardEvent (newConsoleKeyInfo);
    }

    private MouseButtonState MapMouseFlags (MouseFlags mouseFlags)
    {
        MouseButtonState mbs = default;

        foreach (object flag in Enum.GetValues (mouseFlags.GetType ()))
        {
            if (mouseFlags.HasFlag ((MouseFlags)flag))
            {
                switch (flag)
                {
                    case MouseFlags.Button1Pressed:
                        mbs |= MouseButtonState.Button1Pressed;

                        break;
                    case MouseFlags.Button1Released:
                        mbs |= MouseButtonState.Button1Released;

                        break;
                    case MouseFlags.Button1Clicked:
                        mbs |= MouseButtonState.Button1Clicked;

                        break;
                    case MouseFlags.Button1DoubleClicked:
                        mbs |= MouseButtonState.Button1DoubleClicked;

                        break;
                    case MouseFlags.Button1TripleClicked:
                        mbs |= MouseButtonState.Button1TripleClicked;

                        break;
                    case MouseFlags.Button2Pressed:
                        mbs |= MouseButtonState.Button2Pressed;

                        break;
                    case MouseFlags.Button2Released:
                        mbs |= MouseButtonState.Button2Released;

                        break;
                    case MouseFlags.Button2Clicked:
                        mbs |= MouseButtonState.Button2Clicked;

                        break;
                    case MouseFlags.Button2DoubleClicked:
                        mbs |= MouseButtonState.Button2DoubleClicked;

                        break;
                    case MouseFlags.Button2TripleClicked:
                        mbs |= MouseButtonState.Button2TripleClicked;

                        break;
                    case MouseFlags.Button3Pressed:
                        mbs |= MouseButtonState.Button3Pressed;

                        break;
                    case MouseFlags.Button3Released:
                        mbs |= MouseButtonState.Button3Released;

                        break;
                    case MouseFlags.Button3Clicked:
                        mbs |= MouseButtonState.Button3Clicked;

                        break;
                    case MouseFlags.Button3DoubleClicked:
                        mbs |= MouseButtonState.Button3DoubleClicked;

                        break;
                    case MouseFlags.Button3TripleClicked:
                        mbs |= MouseButtonState.Button3TripleClicked;

                        break;
                    case MouseFlags.WheeledUp:
                        mbs |= MouseButtonState.ButtonWheeledUp;

                        break;
                    case MouseFlags.WheeledDown:
                        mbs |= MouseButtonState.ButtonWheeledDown;

                        break;
                    case MouseFlags.WheeledLeft:
                        mbs |= MouseButtonState.ButtonWheeledLeft;

                        break;
                    case MouseFlags.WheeledRight:
                        mbs |= MouseButtonState.ButtonWheeledRight;

                        break;
                    case MouseFlags.Button4Pressed:
                        mbs |= MouseButtonState.Button4Pressed;

                        break;
                    case MouseFlags.Button4Released:
                        mbs |= MouseButtonState.Button4Released;

                        break;
                    case MouseFlags.Button4Clicked:
                        mbs |= MouseButtonState.Button4Clicked;

                        break;
                    case MouseFlags.Button4DoubleClicked:
                        mbs |= MouseButtonState.Button4DoubleClicked;

                        break;
                    case MouseFlags.Button4TripleClicked:
                        mbs |= MouseButtonState.Button4TripleClicked;

                        break;
                    case MouseFlags.ButtonShift:
                        mbs |= MouseButtonState.ButtonShift;

                        break;
                    case MouseFlags.ButtonCtrl:
                        mbs |= MouseButtonState.ButtonCtrl;

                        break;
                    case MouseFlags.ButtonAlt:
                        mbs |= MouseButtonState.ButtonAlt;

                        break;
                    case MouseFlags.ReportMousePosition:
                        mbs |= MouseButtonState.ReportMousePosition;

                        break;
                    case MouseFlags.AllEvents:
                        mbs |= MouseButtonState.AllEvents;

                        break;
                }
            }
        }

        return mbs;
    }

    private Point _lastCursorPosition;

    private void HandleRequestResponseEvent (string c1Control, string code, string [] values, string terminating)
    {
        switch (terminating)
        {
            // BUGBUG: I can't find where we send a request for cursor position (ESC[?6n), so I'm not sure if this is needed.
            case EscSeqUtils.CSI_RequestCursorPositionReport_Terminator:
                var point = new Point { X = int.Parse (values [1]) - 1, Y = int.Parse (values [0]) - 1 };

                if (_lastCursorPosition.Y != point.Y)
                {
                    _lastCursorPosition = point;
                    var eventType = EventType.WindowPosition;
                    var winPositionEv = new WindowPositionEvent { CursorPosition = point };

                    _inputQueue.Enqueue (
                                         new InputResult { EventType = eventType, WindowPositionEvent = winPositionEv }
                                        );
                }
                else
                {
                    return;
                }

                break;

            case EscSeqUtils.CSI_ReportTerminalSizeInChars_Terminator:
                switch (values [0])
                {
                    case EscSeqUtils.CSI_ReportTerminalSizeInChars_ResponseValue:
                        EnqueueWindowSizeEvent (
                                                Math.Max (int.Parse (values [1]), 0),
                                                Math.Max (int.Parse (values [2]), 0),
                                                Math.Max (int.Parse (values [1]), 0),
                                                Math.Max (int.Parse (values [2]), 0)
                                               );

                        break;
                    default:
                        EnqueueRequestResponseEvent (c1Control, code, values, terminating);

                        break;
                }

                break;
            default:
                EnqueueRequestResponseEvent (c1Control, code, values, terminating);

                break;
        }

        _inputReady.Set ();
    }

    private void EnqueueRequestResponseEvent (string c1Control, string code, string [] values, string terminating)
    {
        var eventType = EventType.RequestResponse;
        var requestRespEv = new RequestResponseEvent { ResultTuple = (c1Control, code, values, terminating) };

        _inputQueue.Enqueue (
                             new InputResult { EventType = eventType, RequestResponseEvent = requestRespEv }
                            );
    }

    private void HandleMouseEvent (MouseButtonState buttonState, Point pos)
    {
        var mouseEvent = new MouseEvent { Position = pos, ButtonState = buttonState };

        _inputQueue.Enqueue (
                             new InputResult { EventType = EventType.Mouse, MouseEvent = mouseEvent }
                            );

        _inputReady.Set ();
    }

    public enum EventType
    {
        Key = 1,
        Mouse = 2,
        WindowSize = 3,
        WindowPosition = 4,
        RequestResponse = 5
    }

    [Flags]
    public enum MouseButtonState
    {
        Button1Pressed = 0x1,
        Button1Released = 0x2,
        Button1Clicked = 0x4,
        Button1DoubleClicked = 0x8,
        Button1TripleClicked = 0x10,
        Button2Pressed = 0x20,
        Button2Released = 0x40,
        Button2Clicked = 0x80,
        Button2DoubleClicked = 0x100,
        Button2TripleClicked = 0x200,
        Button3Pressed = 0x400,
        Button3Released = 0x800,
        Button3Clicked = 0x1000,
        Button3DoubleClicked = 0x2000,
        Button3TripleClicked = 0x4000,
        ButtonWheeledUp = 0x8000,
        ButtonWheeledDown = 0x10000,
        ButtonWheeledLeft = 0x20000,
        ButtonWheeledRight = 0x40000,
        Button4Pressed = 0x80000,
        Button4Released = 0x100000,
        Button4Clicked = 0x200000,
        Button4DoubleClicked = 0x400000,
        Button4TripleClicked = 0x800000,
        ButtonShift = 0x1000000,
        ButtonCtrl = 0x2000000,
        ButtonAlt = 0x4000000,
        ReportMousePosition = 0x8000000,
        AllEvents = -1
    }

    public struct MouseEvent
    {
        public Point Position;
        public MouseButtonState ButtonState;
    }

    public struct WindowSizeEvent
    {
        public Size Size;
    }

    public struct WindowPositionEvent
    {
        public int Top;
        public int Left;
        public Point CursorPosition;
    }

    public struct RequestResponseEvent
    {
        public (string c1Control, string code, string [] values, string terminating) ResultTuple;
    }

    public struct InputResult
    {
        public EventType EventType;
        public ConsoleKeyInfo ConsoleKeyInfo;
        public MouseEvent MouseEvent;
        public WindowSizeEvent WindowSizeEvent;
        public WindowPositionEvent WindowPositionEvent;
        public RequestResponseEvent RequestResponseEvent;

        public readonly override string ToString ()
        {
            return EventType switch
                   {
                       EventType.Key => ToString (ConsoleKeyInfo),
                       EventType.Mouse => MouseEvent.ToString (),

                       //EventType.WindowSize => WindowSize.ToString (),
                       //EventType.RequestResponse => RequestResponse.ToString (),
                       _ => "Unknown event type: " + EventType
                   };
        }

        /// <summary>Prints a ConsoleKeyInfoEx structure</summary>
        /// <param name="cki"></param>
        /// <returns></returns>
        public readonly string ToString (ConsoleKeyInfo cki)
        {
            var ke = new Key ((KeyCode)cki.KeyChar);
            var sb = new StringBuilder ();
            sb.Append ($"Key: {(KeyCode)cki.Key} ({cki.Key})");
            sb.Append ((cki.Modifiers & ConsoleModifiers.Shift) != 0 ? " | Shift" : string.Empty);
            sb.Append ((cki.Modifiers & ConsoleModifiers.Control) != 0 ? " | Control" : string.Empty);
            sb.Append ((cki.Modifiers & ConsoleModifiers.Alt) != 0 ? " | Alt" : string.Empty);
            sb.Append ($", KeyChar: {ke.AsRune.MakePrintable ()} ({(uint)cki.KeyChar}) ");
            string s = sb.ToString ().TrimEnd (',').TrimEnd (' ');

            return $"[ConsoleKeyInfo({s})]";
        }
    }

    private void HandleKeyboardEvent (ConsoleKeyInfo cki)
    {
        var inputResult = new InputResult { EventType = EventType.Key, ConsoleKeyInfo = cki };

        _inputQueue.Enqueue (inputResult);
    }

    public void Dispose ()
    {
        _inputReadyCancellationTokenSource?.Cancel ();
        _inputReadyCancellationTokenSource?.Dispose ();
        _inputReadyCancellationTokenSource = null;

        try
        {
            // throws away any typeahead that has been typed by
            // the user and has not yet been read by the program.
            while (Console.KeyAvailable)
            {
                Console.ReadKey (true);
            }
        }
        catch (InvalidOperationException)
        {
            // Ignore - Console input has already been closed
        }
    }
}

internal class NetDriver : ConsoleDriver
{
    private const int COLOR_BLACK = 30;
    private const int COLOR_BLUE = 34;
    private const int COLOR_BRIGHT_BLACK = 90;
    private const int COLOR_BRIGHT_BLUE = 94;
    private const int COLOR_BRIGHT_CYAN = 96;
    private const int COLOR_BRIGHT_GREEN = 92;
    private const int COLOR_BRIGHT_MAGENTA = 95;
    private const int COLOR_BRIGHT_RED = 91;
    private const int COLOR_BRIGHT_WHITE = 97;
    private const int COLOR_BRIGHT_YELLOW = 93;
    private const int COLOR_CYAN = 36;
    private const int COLOR_GREEN = 32;
    private const int COLOR_MAGENTA = 35;
    private const int COLOR_RED = 31;
    private const int COLOR_WHITE = 37;
    private const int COLOR_YELLOW = 33;
    private NetMainLoop _mainLoopDriver;
    public bool IsWinPlatform { get; private set; }
    public NetWinVTConsole NetWinConsole { get; private set; }

    public override bool SupportsTrueColor => Environment.OSVersion.Platform == PlatformID.Unix
                                              || (IsWinPlatform && Environment.OSVersion.Version.Build >= 14931);

    public override void Refresh ()
    {
        UpdateScreen ();
        UpdateCursor ();
    }

    public override void SendKeys (char keyChar, ConsoleKey key, bool shift, bool alt, bool control)
    {
        var input = new InputResult
        {
            EventType = EventType.Key, ConsoleKeyInfo = new ConsoleKeyInfo (keyChar, key, shift, alt, control)
        };

        try
        {
            ProcessInput (input);
        }
        catch (OverflowException)
        { }
    }

    public override void Suspend ()
    {
        if (Environment.OSVersion.Platform != PlatformID.Unix)
        {
            return;
        }

        StopReportingMouseMoves ();

        if (!RunningUnitTests)
        {
            Console.ResetColor ();
            Console.Clear ();
            Platform.Suspend ();
            Application.Refresh ();
        }

        StartReportingMouseMoves ();
    }

    public override void UpdateScreen ()
    {
        if (RunningUnitTests
            || _winSizeChanging
            || Console.WindowHeight < 1
            || Contents.Length != Rows * Cols
            || Rows != Console.WindowHeight)
        {
            return;
        }

        var top = 0;
        var left = 0;
        int rows = Rows;
        int cols = Cols;
        var output = new StringBuilder ();
        Attribute? redrawAttr = null;
        int lastCol = -1;

        CursorVisibility? savedVisibitity = _cachedCursorVisibility;
        SetCursorVisibility (CursorVisibility.Invisible);

        for (int row = top; row < rows; row++)
        {
            if (Console.WindowHeight < 1)
            {
                return;
            }

            if (!_dirtyLines [row])
            {
                continue;
            }

            if (!SetCursorPosition (0, row))
            {
                return;
            }

            _dirtyLines [row] = false;
            output.Clear ();

            for (int col = left; col < cols; col++)
            {
                lastCol = -1;
                var outputWidth = 0;

                for (; col < cols; col++)
                {
                    if (!Contents [row, col].IsDirty)
                    {
                        if (output.Length > 0)
                        {
                            WriteToConsole (output, ref lastCol, row, ref outputWidth);
                        }
                        else if (lastCol == -1)
                        {
                            lastCol = col;
                        }

                        if (lastCol + 1 < cols)
                        {
                            lastCol++;
                        }

                        continue;
                    }

                    if (lastCol == -1)
                    {
                        lastCol = col;
                    }

                    Attribute attr = Contents [row, col].Attribute.Value;

                    // Performance: Only send the escape sequence if the attribute has changed.
                    if (attr != redrawAttr)
                    {
                        redrawAttr = attr;

                        if (Force16Colors)
                        {
                            output.Append (
                                           EscSeqUtils.CSI_SetGraphicsRendition (
                                                                                 MapColors (
                                                                                            (ConsoleColor)attr.Background.GetClosestNamedColor (),
                                                                                            false
                                                                                           ),
                                                                                 MapColors ((ConsoleColor)attr.Foreground.GetClosestNamedColor ())
                                                                                )
                                          );
                        }
                        else
                        {
                            output.Append (
                                           EscSeqUtils.CSI_SetForegroundColorRGB (
                                                                                  attr.Foreground.R,
                                                                                  attr.Foreground.G,
                                                                                  attr.Foreground.B
                                                                                 )
                                          );

                            output.Append (
                                           EscSeqUtils.CSI_SetBackgroundColorRGB (
                                                                                  attr.Background.R,
                                                                                  attr.Background.G,
                                                                                  attr.Background.B
                                                                                 )
                                          );
                        }
                    }

                    outputWidth++;
                    Rune rune = Contents [row, col].Rune;
                    output.Append (rune);

                    if (Contents [row, col].CombiningMarks.Count > 0)
                    {
                        // AtlasEngine does not support NON-NORMALIZED combining marks in a way
                        // compatible with the driver architecture. Any CMs (except in the first col)
                        // are correctly combined with the base char, but are ALSO treated as 1 column
                        // width codepoints E.g. `echo "[e`u{0301}`u{0301}]"` will output `[é  ]`.
                        // 
                        // For now, we just ignore the list of CMs.
                        //foreach (var combMark in Contents [row, col].CombiningMarks) {
                        //	output.Append (combMark);
                        //}
                        // WriteToConsole (output, ref lastCol, row, ref outputWidth);
                    }
                    else if (rune.IsSurrogatePair () && rune.GetColumns () < 2)
                    {
                        WriteToConsole (output, ref lastCol, row, ref outputWidth);
                        SetCursorPosition (col - 1, row);
                    }

                    Contents [row, col].IsDirty = false;
                }
            }

            if (output.Length > 0)
            {
                SetCursorPosition (lastCol, row);
                Console.Write (output);
            }
        }

        SetCursorPosition (0, 0);

        _cachedCursorVisibility = savedVisibitity;

        void WriteToConsole (StringBuilder output, ref int lastCol, int row, ref int outputWidth)
        {
            SetCursorPosition (lastCol, row);
            Console.Write (output);
            output.Clear ();
            lastCol += outputWidth;
            outputWidth = 0;
        }
    }

    internal override void End ()
    {
        if (IsWinPlatform)
        {
            NetWinConsole?.Cleanup ();
        }

        StopReportingMouseMoves ();

        if (!RunningUnitTests)
        {
            Console.ResetColor ();

            //Disable alternative screen buffer.
            Console.Out.Write (EscSeqUtils.CSI_RestoreCursorAndRestoreAltBufferWithBackscroll);

            //Set cursor key to cursor.
            Console.Out.Write (EscSeqUtils.CSI_ShowCursor);
            Console.Out.Close ();
        }
    }

    internal override MainLoop Init ()
    {
        PlatformID p = Environment.OSVersion.Platform;

        if (p == PlatformID.Win32NT || p == PlatformID.Win32S || p == PlatformID.Win32Windows)
        {
            IsWinPlatform = true;

            try
            {
                NetWinConsole = new NetWinVTConsole ();
            }
            catch (ApplicationException)
            {
                // Likely running as a unit test, or in a non-interactive session.
            }
        }

        if (IsWinPlatform)
        {
            Clipboard = new WindowsClipboard ();
        }
        else if (RuntimeInformation.IsOSPlatform (OSPlatform.OSX))
        {
            Clipboard = new MacOSXClipboard ();
        }
        else
        {
            if (CursesDriver.Is_WSL_Platform ())
            {
                Clipboard = new WSLClipboard ();
            }
            else
            {
                Clipboard = new CursesClipboard ();
            }
        }

        if (!RunningUnitTests)
        {
            Console.TreatControlCAsInput = true;

            Cols = Console.WindowWidth;
            Rows = Console.WindowHeight;

            //Enable alternative screen buffer.
            Console.Out.Write (EscSeqUtils.CSI_SaveCursorAndActivateAltBufferNoBackscroll);

            //Set cursor key to application.
            Console.Out.Write (EscSeqUtils.CSI_HideCursor);
        }
        else
        {
            // We are being run in an environment that does not support a console
            // such as a unit test, or a pipe.
            Cols = 80;
            Rows = 24;
        }

        ResizeScreen ();
        ClearContents ();
        CurrentAttribute = new Attribute (Color.White, Color.Black);

        StartReportingMouseMoves ();

        _mainLoopDriver = new NetMainLoop (this);
        _mainLoopDriver.ProcessInput = ProcessInput;

        return new MainLoop (_mainLoopDriver);
    }

    private void ProcessInput (InputResult inputEvent)
    {
        switch (inputEvent.EventType)
        {
            case EventType.Key:
                ConsoleKeyInfo consoleKeyInfo = inputEvent.ConsoleKeyInfo;

                //if (consoleKeyInfo.Key == ConsoleKey.Packet) {
                //	consoleKeyInfo = FromVKPacketToKConsoleKeyInfo (consoleKeyInfo);
                //}

                //Debug.WriteLine ($"event: {inputEvent}");

                KeyCode map = MapKey (consoleKeyInfo);

                if (map == KeyCode.Null)
                {
                    break;
                }

                OnKeyDown (new Key (map));
                OnKeyUp (new Key (map));

                break;
            case EventType.Mouse:
                MouseEvent me = ToDriverMouse (inputEvent.MouseEvent);
                //Debug.WriteLine ($"NetDriver: ({me.X},{me.Y}) - {me.Flags}");
                OnMouseEvent (me);

                break;
            case EventType.WindowSize:
                _winSizeChanging = true;
                Top = 0;
                Left = 0;
                Cols = inputEvent.WindowSizeEvent.Size.Width;
                Rows = Math.Max (inputEvent.WindowSizeEvent.Size.Height, 0);
                ;
                ResizeScreen ();
                ClearContents ();
                _winSizeChanging = false;
                OnSizeChanged (new SizeChangedEventArgs (new (Cols, Rows)));

                break;
            case EventType.RequestResponse:
                break;
            case EventType.WindowPosition:
                break;
            default:
                throw new ArgumentOutOfRangeException ();
        }
    }

    #region Size and Position Handling

    private volatile bool _winSizeChanging;

    private void SetWindowPosition (int col, int row)
    {
        if (!RunningUnitTests)
        {
            Top = Console.WindowTop;
            Left = Console.WindowLeft;
        }
        else
        {
            Top = row;
            Left = col;
        }
    }

    public virtual void ResizeScreen ()
    {
        // Not supported on Unix.
        if (IsWinPlatform)
        {
            // Can raise an exception while is still resizing.
            try
            {
#pragma warning disable CA1416
                if (Console.WindowHeight > 0)
                {
                    Console.CursorTop = 0;
                    Console.CursorLeft = 0;
                    Console.WindowTop = 0;
                    Console.WindowLeft = 0;

                    if (Console.WindowHeight > Rows)
                    {
                        Console.SetWindowSize (Cols, Rows);
                    }

                    Console.SetBufferSize (Cols, Rows);
                }
#pragma warning restore CA1416
            }
            // INTENT: Why are these eating the exceptions?
            // Comments would be good here.
            catch (IOException)
            {
                // CONCURRENCY: Unsynchronized access to Clip is not safe.
                Clip = new (0, 0, Cols, Rows);
            }
            catch (ArgumentOutOfRangeException)
            {
                // CONCURRENCY: Unsynchronized access to Clip is not safe.
                Clip = new (0, 0, Cols, Rows);
            }
        }
        else
        {
            Console.Out.Write (EscSeqUtils.CSI_SetTerminalWindowSize (Rows, Cols));
        }

        // CONCURRENCY: Unsynchronized access to Clip is not safe.
        Clip = new (0, 0, Cols, Rows);
    }

    #endregion

    #region Color Handling

    // Cache the list of ConsoleColor values.
    private static readonly HashSet<int> ConsoleColorValues = new (
                                                                   Enum.GetValues (typeof (ConsoleColor))
                                                                       .OfType<ConsoleColor> ()
                                                                       .Select (c => (int)c)
                                                                  );

    // Dictionary for mapping ConsoleColor values to the values used by System.Net.Console.
    private static readonly Dictionary<ConsoleColor, int> colorMap = new ()
    {
        { ConsoleColor.Black, COLOR_BLACK },
        { ConsoleColor.DarkBlue, COLOR_BLUE },
        { ConsoleColor.DarkGreen, COLOR_GREEN },
        { ConsoleColor.DarkCyan, COLOR_CYAN },
        { ConsoleColor.DarkRed, COLOR_RED },
        { ConsoleColor.DarkMagenta, COLOR_MAGENTA },
        { ConsoleColor.DarkYellow, COLOR_YELLOW },
        { ConsoleColor.Gray, COLOR_WHITE },
        { ConsoleColor.DarkGray, COLOR_BRIGHT_BLACK },
        { ConsoleColor.Blue, COLOR_BRIGHT_BLUE },
        { ConsoleColor.Green, COLOR_BRIGHT_GREEN },
        { ConsoleColor.Cyan, COLOR_BRIGHT_CYAN },
        { ConsoleColor.Red, COLOR_BRIGHT_RED },
        { ConsoleColor.Magenta, COLOR_BRIGHT_MAGENTA },
        { ConsoleColor.Yellow, COLOR_BRIGHT_YELLOW },
        { ConsoleColor.White, COLOR_BRIGHT_WHITE }
    };

    // Map a ConsoleColor to a platform dependent value.
    private int MapColors (ConsoleColor color, bool isForeground = true)
    {
        return colorMap.TryGetValue (color, out int colorValue) ? colorValue + (isForeground ? 0 : 10) : 0;
    }

    ///// <remarks>
    ///// In the NetDriver, colors are encoded as an int. 
    ///// However, the foreground color is stored in the most significant 16 bits, 
    ///// and the background color is stored in the least significant 16 bits.
    ///// </remarks>
    //public override Attribute MakeColor (Color foreground, Color background)
    //{
    //	// Encode the colors into the int value.
    //	return new Attribute (
    //		platformColor: ((((int)foreground.ColorName) & 0xffff) << 16) | (((int)background.ColorName) & 0xffff),
    //		foreground: foreground,
    //		background: background
    //	);
    //}

    #endregion

    #region Cursor Handling

    private bool SetCursorPosition (int col, int row)
    {
        if (IsWinPlatform)
        {
            // Could happens that the windows is still resizing and the col is bigger than Console.WindowWidth.
            try
            {
                Console.SetCursorPosition (col, row);

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        // + 1 is needed because non-Windows is based on 1 instead of 0 and
        // Console.CursorTop/CursorLeft isn't reliable.
        Console.Out.Write (EscSeqUtils.CSI_SetCursorPosition (row + 1, col + 1));

        return true;
    }

    private CursorVisibility? _cachedCursorVisibility;

    public override void UpdateCursor ()
    {
        EnsureCursorVisibility ();

        if (Col >= 0 && Col < Cols && Row >= 0 && Row <= Rows)
        {
            SetCursorPosition (Col, Row);
            SetWindowPosition (0, Row);
        }
    }

    public override bool GetCursorVisibility (out CursorVisibility visibility)
    {
        visibility = _cachedCursorVisibility ?? CursorVisibility.Default;

        return visibility == CursorVisibility.Default;
    }

    public override bool SetCursorVisibility (CursorVisibility visibility)
    {
        _cachedCursorVisibility = visibility;

        bool isVisible = RunningUnitTests
                             ? visibility == CursorVisibility.Default
                             : Console.CursorVisible = visibility == CursorVisibility.Default;
        Console.Out.Write (isVisible ? EscSeqUtils.CSI_ShowCursor : EscSeqUtils.CSI_HideCursor);

        return isVisible;
    }

    public override bool EnsureCursorVisibility ()
    {
        if (!(Col >= 0 && Row >= 0 && Col < Cols && Row < Rows))
        {
            GetCursorVisibility (out CursorVisibility cursorVisibility);
            _cachedCursorVisibility = cursorVisibility;
            SetCursorVisibility (CursorVisibility.Invisible);

            return false;
        }

        SetCursorVisibility (_cachedCursorVisibility ?? CursorVisibility.Default);

        return _cachedCursorVisibility == CursorVisibility.Default;
    }

    #endregion

    #region Mouse Handling

    public void StartReportingMouseMoves ()
    {
        if (!RunningUnitTests)
        {
            Console.Out.Write (EscSeqUtils.CSI_EnableMouseEvents);
        }
    }

    public void StopReportingMouseMoves ()
    {
        if (!RunningUnitTests)
        {
            Console.Out.Write (EscSeqUtils.CSI_DisableMouseEvents);
        }
    }

    private MouseEvent ToDriverMouse (NetEvents.MouseEvent me)
    {
       //System.Diagnostics.Debug.WriteLine ($"X: {me.Position.X}; Y: {me.Position.Y}; ButtonState: {me.ButtonState}");

        MouseFlags mouseFlag = 0;

        if ((me.ButtonState & MouseButtonState.Button1Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button1Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button1Released) != 0)
        {
            mouseFlag |= MouseFlags.Button1Released;
        }

        if ((me.ButtonState & MouseButtonState.Button1Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button1Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button1DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button1DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button1TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button1TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button2Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button2Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button2Released) != 0)
        {
            mouseFlag |= MouseFlags.Button2Released;
        }

        if ((me.ButtonState & MouseButtonState.Button2Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button2Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button2DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button2DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button2TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button2TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button3Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button3Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button3Released) != 0)
        {
            mouseFlag |= MouseFlags.Button3Released;
        }

        if ((me.ButtonState & MouseButtonState.Button3Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button3Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button3DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button3DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button3TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button3TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledUp) != 0)
        {
            mouseFlag |= MouseFlags.WheeledUp;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledDown) != 0)
        {
            mouseFlag |= MouseFlags.WheeledDown;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledLeft) != 0)
        {
            mouseFlag |= MouseFlags.WheeledLeft;
        }

        if ((me.ButtonState & MouseButtonState.ButtonWheeledRight) != 0)
        {
            mouseFlag |= MouseFlags.WheeledRight;
        }

        if ((me.ButtonState & MouseButtonState.Button4Pressed) != 0)
        {
            mouseFlag |= MouseFlags.Button4Pressed;
        }

        if ((me.ButtonState & MouseButtonState.Button4Released) != 0)
        {
            mouseFlag |= MouseFlags.Button4Released;
        }

        if ((me.ButtonState & MouseButtonState.Button4Clicked) != 0)
        {
            mouseFlag |= MouseFlags.Button4Clicked;
        }

        if ((me.ButtonState & MouseButtonState.Button4DoubleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button4DoubleClicked;
        }

        if ((me.ButtonState & MouseButtonState.Button4TripleClicked) != 0)
        {
            mouseFlag |= MouseFlags.Button4TripleClicked;
        }

        if ((me.ButtonState & MouseButtonState.ReportMousePosition) != 0)
        {
            mouseFlag |= MouseFlags.ReportMousePosition;
        }

        if ((me.ButtonState & MouseButtonState.ButtonShift) != 0)
        {
            mouseFlag |= MouseFlags.ButtonShift;
        }

        if ((me.ButtonState & MouseButtonState.ButtonCtrl) != 0)
        {
            mouseFlag |= MouseFlags.ButtonCtrl;
        }

        if ((me.ButtonState & MouseButtonState.ButtonAlt) != 0)
        {
            mouseFlag |= MouseFlags.ButtonAlt;
        }

        return new MouseEvent { Position = me.Position, Flags = mouseFlag };
    }

    #endregion Mouse Handling

    #region Keyboard Handling

    private ConsoleKeyInfo FromVKPacketToKConsoleKeyInfo (ConsoleKeyInfo consoleKeyInfo)
    {
        if (consoleKeyInfo.Key != ConsoleKey.Packet)
        {
            return consoleKeyInfo;
        }

        ConsoleModifiers mod = consoleKeyInfo.Modifiers;
        bool shift = (mod & ConsoleModifiers.Shift) != 0;
        bool alt = (mod & ConsoleModifiers.Alt) != 0;
        bool control = (mod & ConsoleModifiers.Control) != 0;

        ConsoleKeyInfo cKeyInfo = DecodeVKPacketToKConsoleKeyInfo (consoleKeyInfo);

        return new ConsoleKeyInfo (cKeyInfo.KeyChar, cKeyInfo.Key, shift, alt, control);
    }

    private KeyCode MapKey (ConsoleKeyInfo keyInfo)
    {
        switch (keyInfo.Key)
        {
            case ConsoleKey.OemPeriod:
            case ConsoleKey.OemComma:
            case ConsoleKey.OemPlus:
            case ConsoleKey.OemMinus:
            case ConsoleKey.Packet:
            case ConsoleKey.Oem1:
            case ConsoleKey.Oem2:
            case ConsoleKey.Oem3:
            case ConsoleKey.Oem4:
            case ConsoleKey.Oem5:
            case ConsoleKey.Oem6:
            case ConsoleKey.Oem7:
            case ConsoleKey.Oem8:
            case ConsoleKey.Oem102:
                if (keyInfo.KeyChar == 0)
                {
                    // If the keyChar is 0, keyInfo.Key value is not a printable character. 

                    return KeyCode.Null; // MapToKeyCodeModifiers (keyInfo.Modifiers, KeyCode)keyInfo.Key);
                }

                if (keyInfo.Modifiers != ConsoleModifiers.Shift)
                {
                    // If Shift wasn't down we don't need to do anything but return the keyInfo.KeyChar
                    return MapToKeyCodeModifiers (keyInfo.Modifiers, (KeyCode)keyInfo.KeyChar);
                }

                // Strip off Shift - We got here because they KeyChar from Windows is the shifted char (e.g. "Ç")
                // and passing on Shift would be redundant.
                return MapToKeyCodeModifiers (keyInfo.Modifiers & ~ConsoleModifiers.Shift, (KeyCode)keyInfo.KeyChar);
        }

        // Handle control keys whose VK codes match the related ASCII value (those below ASCII 33) like ESC
        if (keyInfo.Key != ConsoleKey.None && Enum.IsDefined (typeof (KeyCode), (uint)keyInfo.Key))
        {
            if (keyInfo.Modifiers.HasFlag(ConsoleModifiers.Control) && keyInfo.Key == ConsoleKey.I)
            {
                return KeyCode.Tab;
            }

            return MapToKeyCodeModifiers (keyInfo.Modifiers, (KeyCode)((uint)keyInfo.Key));
        }

        // Handle control keys (e.g. CursorUp)
        if (keyInfo.Key != ConsoleKey.None
            && Enum.IsDefined (typeof (KeyCode), (uint)keyInfo.Key + (uint)KeyCode.MaxCodePoint))
        {
            return MapToKeyCodeModifiers (keyInfo.Modifiers, (KeyCode)((uint)keyInfo.Key + (uint)KeyCode.MaxCodePoint));
        }

        if (((ConsoleKey)keyInfo.KeyChar) is >= ConsoleKey.A and <= ConsoleKey.Z)
        {
            // Shifted
            keyInfo = new ConsoleKeyInfo (
                                          keyInfo.KeyChar,
                                          (ConsoleKey)keyInfo.KeyChar,
                                          true,
                                          keyInfo.Modifiers.HasFlag (ConsoleModifiers.Alt),
                                          keyInfo.Modifiers.HasFlag (ConsoleModifiers.Control));
        }

        if ((ConsoleKey)keyInfo.KeyChar - 32 is >= ConsoleKey.A and <= ConsoleKey.Z)
        {
            // Unshifted
            keyInfo = new ConsoleKeyInfo (
                                          keyInfo.KeyChar,
                                          (ConsoleKey)(keyInfo.KeyChar - 32),
                                          false,
                                          keyInfo.Modifiers.HasFlag (ConsoleModifiers.Alt),
                                          keyInfo.Modifiers.HasFlag (ConsoleModifiers.Control));
        }

        if (keyInfo.Key is >= ConsoleKey.A and <= ConsoleKey.Z )
        {
            if (keyInfo.Modifiers.HasFlag (ConsoleModifiers.Alt)
                || keyInfo.Modifiers.HasFlag (ConsoleModifiers.Control))
            {
                // NetDriver doesn't support Shift-Ctrl/Shift-Alt combos
                return MapToKeyCodeModifiers (keyInfo.Modifiers & ~ConsoleModifiers.Shift, (KeyCode)keyInfo.Key);
            }

            if (keyInfo.Modifiers == ConsoleModifiers.Shift)
            {
                // If ShiftMask is on  add the ShiftMask
                if (char.IsUpper (keyInfo.KeyChar))
                {
                    return (KeyCode)keyInfo.Key | KeyCode.ShiftMask;
                }
            }

            return (KeyCode)keyInfo.Key;
        }


        return MapToKeyCodeModifiers (keyInfo.Modifiers, (KeyCode)((uint)keyInfo.KeyChar));
    }

    #endregion Keyboard Handling
}

/// <summary>
///     Mainloop intended to be used with the .NET System.Console API, and can be used on Windows and Unix, it is
///     cross platform but lacks things like file descriptor monitoring.
/// </summary>
/// <remarks>This implementation is used for NetDriver.</remarks>
internal class NetMainLoop : IMainLoopDriver
{
    internal NetEvents _netEvents;

    /// <summary>Invoked when a Key is pressed.</summary>
    internal Action<InputResult> ProcessInput;

    private readonly ManualResetEventSlim _eventReady = new (false);
    private readonly CancellationTokenSource _inputHandlerTokenSource = new ();
    private readonly Queue<InputResult?> _resultQueue = new ();
    private readonly ManualResetEventSlim _waitForProbe = new (false);
    private CancellationTokenSource _eventReadyTokenSource = new ();
    private MainLoop _mainLoop;

    /// <summary>Initializes the class with the console driver.</summary>
    /// <remarks>Passing a consoleDriver is provided to capture windows resizing.</remarks>
    /// <param name="consoleDriver">The console driver used by this Net main loop.</param>
    /// <exception cref="ArgumentNullException"></exception>
    public NetMainLoop (ConsoleDriver consoleDriver = null)
    {
        if (consoleDriver is null)
        {
            throw new ArgumentNullException (nameof (consoleDriver));
        }

        _netEvents = new NetEvents (consoleDriver);
    }

    void IMainLoopDriver.Setup (MainLoop mainLoop)
    {
        _mainLoop = mainLoop;
        Task.Run (NetInputHandler, _inputHandlerTokenSource.Token);
    }

    void IMainLoopDriver.Wakeup () { _eventReady.Set (); }

    bool IMainLoopDriver.EventsPending ()
    {
        _waitForProbe.Set ();

        if (_mainLoop.CheckTimersAndIdleHandlers (out int waitTimeout))
        {
            return true;
        }

        try
        {
            if (!_eventReadyTokenSource.IsCancellationRequested)
            {
                // Note: ManualResetEventSlim.Wait will wait indefinitely if the timeout is -1. The timeout is -1 when there
                // are no timers, but there IS an idle handler waiting.
                _eventReady.Wait (waitTimeout, _eventReadyTokenSource.Token);
            }
        }
        catch (OperationCanceledException)
        {
            return true;
        }
        finally
        {
            _eventReady.Reset ();
        }

        if (!_eventReadyTokenSource.IsCancellationRequested)
        {
            return _resultQueue.Count > 0 || _mainLoop.CheckTimersAndIdleHandlers (out _);
        }

        _eventReadyTokenSource.Dispose ();
        _eventReadyTokenSource = new CancellationTokenSource ();

        return true;
    }

    void IMainLoopDriver.Iteration ()
    {
        while (_resultQueue.Count > 0)
        {
            ProcessInput?.Invoke (_resultQueue.Dequeue ().Value);
        }
    }

    void IMainLoopDriver.TearDown ()
    {
        _inputHandlerTokenSource?.Cancel ();
        _inputHandlerTokenSource?.Dispose ();
        _eventReadyTokenSource?.Cancel ();
        _eventReadyTokenSource?.Dispose ();

        _eventReady?.Dispose ();

        _resultQueue?.Clear ();
        _waitForProbe?.Dispose ();
        _netEvents?.Dispose ();
        _netEvents = null;

        _mainLoop = null;
    }

    private void NetInputHandler ()
    {
        while (_mainLoop is { })
        {
            try
            {
                if (!_inputHandlerTokenSource.IsCancellationRequested)
                {
                    _waitForProbe.Wait (_inputHandlerTokenSource.Token);
                }
            }
            catch (OperationCanceledException)
            {
                return;
            }
            finally
            {
                if (_waitForProbe.IsSet)
                {
                    _waitForProbe.Reset ();
                }
            }

            if (_inputHandlerTokenSource.IsCancellationRequested)
            {
                return;
            }

            if (_resultQueue.Count == 0)
            {
                _resultQueue.Enqueue (_netEvents.DequeueInput ());
            }

            try
            {
                while (_resultQueue.Peek () is null)
                {
                    _resultQueue.Dequeue ();
                }

                if (_resultQueue.Count > 0)
                {
                    _eventReady.Set ();
                }
            }
            catch (InvalidOperationException)
            {
                // Ignore
            }
        }
    }
}