using Remotely.Desktop.Core.Enums;
using Remotely.Desktop.Core.Interfaces;
using Remotely.Desktop.Core.Services;
using Remotely.Shared.Utilities;
using Remotely.Shared.Win32;
using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using static Remotely.Shared.Win32.User32;

namespace Remotely.Desktop.Win.Services
{
    public class KeyboardMouseInputWin : IKeyboardMouseInput
    {
        private volatile bool inputBlocked;

        private CancellationTokenSource CancelTokenSource { get; set; }

        private ConcurrentQueue<Action> InputActions { get; } = new ConcurrentQueue<Action>();

        public Tuple<double, double> GetAbsolutePercentFromRelativePercent(double percentX, double percentY, IScreenCapturer capturer)
        {
            var absoluteX = (capturer.CurrentScreenBounds.Width * percentX) + capturer.CurrentScreenBounds.Left - capturer.GetVirtualScreenBounds().Left;
            var absoluteY = (capturer.CurrentScreenBounds.Height * percentY) + capturer.CurrentScreenBounds.Top - capturer.GetVirtualScreenBounds().Top;
            return new Tuple<double, double>(absoluteX / capturer.GetVirtualScreenBounds().Width, absoluteY / capturer.GetVirtualScreenBounds().Height);
        }

        public Tuple<double, double> GetAbsolutePointFromRelativePercent(double percentX, double percentY, IScreenCapturer capturer)
        {
            var absoluteX = (capturer.CurrentScreenBounds.Width * percentX) + capturer.CurrentScreenBounds.Left;
            var absoluteY = (capturer.CurrentScreenBounds.Height * percentY) + capturer.CurrentScreenBounds.Top;
            return new Tuple<double, double>(absoluteX, absoluteY);
        }

        public void Init()
        {
            App.Current.Dispatcher.Invoke(() =>
            {
                App.Current.Exit -= App_Exit;
                App.Current.Exit += App_Exit;
            });

            StartInputProcessingThread();
        }

        public void SendKeyDown(string key)
        {
            TryOnInputDesktop(() =>
            {
                var keyCode = ConvertJavaScriptKeyToVirtualKey(key);
                var union = new InputUnion()
                {
                    ki = new KEYBDINPUT()
                    {
                        wVk = keyCode,
                        wScan = (ScanCodeShort)MapVirtualKeyEx((uint)keyCode, VkMapType.MAPVK_VK_TO_VSC, GetKeyboardLayout()),
                        time = 0,
                        dwExtraInfo = GetMessageExtraInfo()
                    }
                };
                var input = new INPUT() { type = InputType.KEYBOARD, U = union };
                SendInput(1, new INPUT[] { input }, INPUT.Size);
            });
        }

        public void SendKeyUp(string key)
        {
            TryOnInputDesktop(() =>
            {
                var keyCode = ConvertJavaScriptKeyToVirtualKey(key);
                var union = new InputUnion()
                {
                    ki = new KEYBDINPUT()
                    {
                        wVk = keyCode,
                        wScan = (ScanCodeShort)MapVirtualKeyEx((uint)keyCode, VkMapType.MAPVK_VK_TO_VSC, GetKeyboardLayout()),
                        time = 0,
                        dwFlags = KEYEVENTF.KEYUP,
                        dwExtraInfo = GetMessageExtraInfo()
                    }
                };
                var input = new INPUT() { type = InputType.KEYBOARD, U = union };
                SendInput(1, new INPUT[] { input }, INPUT.Size);
            });
        }

        public void SendMouseButtonAction(int button, ButtonAction buttonAction, double percentX, double percentY, Viewer viewer)
        {
            TryOnInputDesktop(() =>
            {
                MOUSEEVENTF mouseEvent;
                switch (button)
                {
                    case 0:
                        switch (buttonAction)
                        {
                            case ButtonAction.Down:
                                mouseEvent = MOUSEEVENTF.LEFTDOWN;
                                break;
                            case ButtonAction.Up:
                                mouseEvent = MOUSEEVENTF.LEFTUP;
                                break;
                            default:
                                return;
                        }
                        break;
                    case 1:
                        switch (buttonAction)
                        {
                            case ButtonAction.Down:
                                mouseEvent = MOUSEEVENTF.MIDDLEDOWN;
                                break;
                            case ButtonAction.Up:
                                mouseEvent = MOUSEEVENTF.MIDDLEUP;
                                break;
                            default:
                                return;
                        }
                        break;
                    case 2:
                        switch (buttonAction)
                        {
                            case ButtonAction.Down:
                                mouseEvent = MOUSEEVENTF.RIGHTDOWN;
                                break;
                            case ButtonAction.Up:
                                mouseEvent = MOUSEEVENTF.RIGHTUP;
                                break;
                            default:
                                return;
                        }
                        break;
                    default:
                        return;
                }
                var xyPercent = GetAbsolutePercentFromRelativePercent(percentX, percentY, viewer.Capturer);
                // Coordinates must be normalized.  The bottom-right coordinate is mapped to 65535.
                var normalizedX = xyPercent.Item1 * 65535D;
                var normalizedY = xyPercent.Item2 * 65535D;
                var union = new InputUnion() { mi = new MOUSEINPUT() { dwFlags = MOUSEEVENTF.ABSOLUTE | mouseEvent | MOUSEEVENTF.VIRTUALDESK, dx = (int)normalizedX, dy = (int)normalizedY, time = 0, mouseData = 0, dwExtraInfo = GetMessageExtraInfo() } };
                var input = new INPUT() { type = InputType.MOUSE, U = union };
                SendInput(1, new INPUT[] { input }, INPUT.Size);
            });
        }

        public void SendMouseMove(double percentX, double percentY, Viewer viewer)
        {
            TryOnInputDesktop(() =>
            {
                var xyPercent = GetAbsolutePercentFromRelativePercent(percentX, percentY, viewer.Capturer);
                // Coordinates must be normalized.  The bottom-right coordinate is mapped to 65535.
                var normalizedX = xyPercent.Item1 * 65535D;
                var normalizedY = xyPercent.Item2 * 65535D;
                var union = new InputUnion() { mi = new MOUSEINPUT() { dwFlags = MOUSEEVENTF.ABSOLUTE | MOUSEEVENTF.MOVE | MOUSEEVENTF.VIRTUALDESK, dx = (int)normalizedX, dy = (int)normalizedY, time = 0, mouseData = 0, dwExtraInfo = GetMessageExtraInfo() } };
                var input = new INPUT() { type = InputType.MOUSE, U = union };
                SendInput(1, new INPUT[] { input }, INPUT.Size);
            });
        }

        public void SendMouseWheel(int deltaY)
        {
            TryOnInputDesktop(() =>
            {
                if (deltaY < 0)
                {
                    deltaY = -120;
                }
                else if (deltaY > 0)
                {
                    deltaY = 120;
                }
                var union = new InputUnion() { mi = new MOUSEINPUT() { dwFlags = MOUSEEVENTF.WHEEL, dx = 0, dy = 0, time = 0, mouseData = deltaY, dwExtraInfo = GetMessageExtraInfo() } };
                var input = new INPUT() { type = InputType.MOUSE, U = union };
                SendInput(1, new INPUT[] { input }, INPUT.Size);
            });
        }

        public void SendText(string transferText)
        {
            TryOnInputDesktop(() =>
            {
                SendKeys.SendWait(transferText);
            });
        }

        public void SetKeyStatesUp()
        {
            TryOnInputDesktop(() =>
            {
                var thread = new Thread(() =>
                {
                    foreach (VirtualKey key in Enum.GetValues(typeof(VirtualKey)))
                    {
                        try
                        {
                            var state = GetKeyState(key);
                            if (state == -127)
                            {
                                var union = new InputUnion()
                                {
                                    ki = new KEYBDINPUT()
                                    {
                                        wVk = key,
                                        wScan = 0,
                                        time = 0,
                                        dwFlags = KEYEVENTF.KEYUP,
                                        dwExtraInfo = GetMessageExtraInfo()
                                    }
                                };
                                var input = new INPUT() { type = InputType.KEYBOARD, U = union };
                                SendInput(1, new INPUT[] { input }, INPUT.Size);
                            }
                        }
                        catch { }
                    }
                });
                thread.SetApartmentState(ApartmentState.STA);
                thread.Start();
            });
        }

        public void ToggleBlockInput(bool toggleOn)
        {
            InputActions.Enqueue(() =>
            {
                inputBlocked = toggleOn;
                var result = BlockInput(toggleOn);
                Logger.Write($"Result of ToggleBlockInput set to {toggleOn}: {result}");
            });
        }

        private void App_Exit(object sender, System.Windows.ExitEventArgs e)
        {
            CancelTokenSource?.Cancel();
        }
        private void CheckQueue(CancellationToken cancelToken)
        {
            while (!cancelToken.IsCancellationRequested)
            {
                try
                {
                    if (InputActions.TryDequeue(out var action))
                    {
                        action();
                    }
                }
                finally
                {
                    Thread.Sleep(1);
                }
            }

            Logger.Write($"Stopping input processing on thread {Thread.CurrentThread.ManagedThreadId}.");
        }

        private VirtualKey ConvertJavaScriptKeyToVirtualKey(string key)
        {
            var keyCode = key switch
            {
                "Down" or "ArrowDown" => VirtualKey.DOWN,
                "Up" or "ArrowUp" => VirtualKey.UP,
                "Left" or "ArrowLeft" => VirtualKey.LEFT,
                "Right" or "ArrowRight" => VirtualKey.RIGHT,
                "Enter" => VirtualKey.RETURN,
                "Esc" or "Escape" => VirtualKey.ESCAPE,
                "Alt" => VirtualKey.MENU,
                "Control" => VirtualKey.CONTROL,
                "Shift" => VirtualKey.SHIFT,
                "PAUSE" => VirtualKey.PAUSE,
                "BREAK" => VirtualKey.PAUSE,
                "Backspace" => VirtualKey.BACK,
                "Tab" => VirtualKey.TAB,
                "CapsLock" => VirtualKey.CAPITAL,
                "Delete" => VirtualKey.DELETE,
                "Home" => VirtualKey.HOME,
                "End" => VirtualKey.END,
                "PageUp" => VirtualKey.PRIOR,
                "PageDown" => VirtualKey.NEXT,
                "NumLock" => VirtualKey.NUMLOCK,
                "Insert" => VirtualKey.INSERT,
                "ScrollLock" => VirtualKey.SCROLL,
                "F1" => VirtualKey.F1,
                "F2" => VirtualKey.F2,
                "F3" => VirtualKey.F3,
                "F4" => VirtualKey.F4,
                "F5" => VirtualKey.F5,
                "F6" => VirtualKey.F6,
                "F7" => VirtualKey.F7,
                "F8" => VirtualKey.F8,
                "F9" => VirtualKey.F9,
                "F10" => VirtualKey.F10,
                "F11" => VirtualKey.F11,
                "F12" => VirtualKey.F12,
                "Meta" => VirtualKey.LWIN,
                "ContextMenu" => VirtualKey.MENU,
                _ => (VirtualKey)VkKeyScan(Convert.ToChar(key)),
            };
            return keyCode;
        }
        private void StartInputProcessingThread()
        {
            CancelTokenSource?.Cancel();
            CancelTokenSource?.Dispose();


            // After BlockInput is enabled, only simulated input coming from the same thread
            // will work.  So we have to start a new thread that runs continuously and
            // processes a queue of input events.
            var newThread = new Thread(() =>
            {
                Logger.Write($"New input processing thread started on thread {Thread.CurrentThread.ManagedThreadId}.");
                CancelTokenSource = new CancellationTokenSource();

                if (inputBlocked)
                {
                    ToggleBlockInput(true);
                }
                CheckQueue(CancelTokenSource.Token);
            });

            newThread.SetApartmentState(ApartmentState.STA);
            newThread.Start();
        }

        private void TryOnInputDesktop(Action inputAction)
        {
            InputActions.Enqueue(() =>
            {
                try
                {
                    if (!Win32Interop.SwitchToInputDesktop())
                    {
                        Logger.Write("Desktop switch failed during input processing.");

                        // Thread likely has hooks in current desktop.  SendKeys will create one with no way to unhook it.
                        // Start a new thread for processing input.
                        StartInputProcessingThread();
                        return;
                    }
                    inputAction();
                }
                catch (Exception ex)
                {
                    Logger.Write(ex);
                }
            });
        }
    }
}