Key.cs

namespace Ignite {
    public static class Key {
        [System.Runtime.InteropServices.DllImport ("user32.dll")]
        private static extern short GetAsyncKeyState (int vKey);

        [System.Runtime.InteropServices.DllImport ("user32.dll")]
        private static extern void keybd_event (byte bVk, byte bScan, uint dwFlags, nuint dwExtraInfo);

        [System.Runtime.InteropServices.DllImport ("user32.dll")]
        private static extern uint SendInput (uint nInputs, [System.Runtime.InteropServices.MarshalAs (System.Runtime.InteropServices.UnmanagedType.LPArray)] INPUT[] pInputs, int cbSize);

        [System.Runtime.InteropServices.StructLayout (System.Runtime.InteropServices.LayoutKind.Sequential)]
        public struct INPUT {
            public uint type;
            public InputUnion U;
        }

        [System.Runtime.InteropServices.StructLayout (System.Runtime.InteropServices.LayoutKind.Explicit)]
        public struct InputUnion {
            [System.Runtime.InteropServices.FieldOffset (0)] public MOUSEINPUT mi;
            [System.Runtime.InteropServices.FieldOffset (0)] public KEYBDINPUT ki;
            [System.Runtime.InteropServices.FieldOffset (0)] public HARDWAREINPUT hi;
        }

        [System.Runtime.InteropServices.StructLayout (System.Runtime.InteropServices.LayoutKind.Sequential)]
        public struct KEYBDINPUT {
            public ushort wVk;
            public ushort wScan;
            public uint dwFlags;
            public uint time;
            public nuint dwExtraInfo;
        }

        [System.Runtime.InteropServices.StructLayout (System.Runtime.InteropServices.LayoutKind.Sequential)]
        public struct MOUSEINPUT {
            public int dx;
            public int dy;
            public uint mouseData;
            public uint dwFlags;
            public uint time;
            public nuint dwExtraInfo;
        }

        [System.Runtime.InteropServices.StructLayout (System.Runtime.InteropServices.LayoutKind.Sequential)]
        public struct HARDWAREINPUT {
            public uint uMsg;
            public ushort wParamL;
            public ushort wParamH;
        }

        public const byte BACKSPACE = 0x08;
        public const byte TAB = 0x09;
        public const byte CLEAR = 0x0C;
        public const byte ENTER = 0x0D;
        public const byte SHIFT = 0x10;
        public const byte CTRL = 0x11;
        public const byte ALT = 0x12;
        public const byte PAUSE = 0x13;
        public const byte CAPITAL = 0x14;
        public const byte ESC = 0x1B;
        public const byte SPACE = 0x20;
        public const byte END = 0x23;
        public const byte HOME = 0x24;
        public const byte SELECT = 0x29;
        public const byte PRINT = 0x2A;
        public const byte EXECUTE = 0x2B;
        public const byte SNAPSHOT = 0x2C;
        public const byte INSERT = 0x2D;
        public const byte DELETE = 0x2E;
        public const byte HELP = 0x2F;

        public const byte ZERO = 0x30;
        public const byte ONE = 0x31;
        public const byte TWO = 0x32;
        public const byte THREE = 0x33;
        public const byte FOUR = 0x34;
        public const byte FIVE = 0x35;
        public const byte SIX = 0x36;
        public const byte SEVEN = 0x37;
        public const byte EIGHT = 0x38;
        public const byte NINE = 0x39;

        public const byte A = 0x41;
        public const byte B = 0x42;
        public const byte C = 0x43;
        public const byte D = 0x44;
        public const byte E = 0x45;
        public const byte F = 0x46;
        public const byte G = 0x47;
        public const byte H = 0x48;
        public const byte I = 0x49;
        public const byte J = 0x4A;
        public const byte K = 0x4B;
        public const byte L = 0x4C;
        public const byte M = 0x4D;
        public const byte N = 0x4E;
        public const byte O = 0x4F;
        public const byte P = 0x50;
        public const byte Q = 0x51;
        public const byte R = 0x52;
        public const byte S = 0x53;
        public const byte T = 0x54;
        public const byte U = 0x55;
        public const byte V = 0x56;
        public const byte W = 0x57;
        public const byte X = 0x58;
        public const byte Y = 0x59;
        public const byte Z = 0x5A;

        public const byte APPS = 0x5D;
        public const byte SLEEP = 0x5F;
        public const byte MULTIPLY = 0x6A;
        public const byte ADD = 0x6B;
        public const byte SEPARATOR = 0x6C;
        public const byte SUBTRACT = 0x6D;
        public const byte DECIMAL = 0x6E;
        public const byte DIVIDE = 0x6F;

        public const byte F1 = 0x70;
        public const byte F2 = 0x71;
        public const byte F3 = 0x72;
        public const byte F4 = 0x73;
        public const byte F5 = 0x74;
        public const byte F6 = 0x75;
        public const byte F7 = 0x76;
        public const byte F8 = 0x77;
        public const byte F9 = 0x78;
        public const byte F10 = 0x79;
        public const byte F11 = 0x7A;
        public const byte F12 = 0x7B;
        public const byte F13 = 0x7C;
        public const byte F14 = 0x7D;
        public const byte F15 = 0x7E;
        public const byte F16 = 0x7F;
        public const byte F17 = 0x80;
        public const byte F18 = 0x81;
        public const byte F19 = 0x82;
        public const byte F20 = 0x83;
        public const byte F21 = 0x84;
        public const byte F22 = 0x85;
        public const byte F23 = 0x86;
        public const byte F24 = 0x87;

        public const byte NUMLOCK = 0x90;
        public const byte SCROLL = 0x91;
        public const byte PROCESS = 0xE5;
        public const byte PACKET = 0xE7;
        public const byte ATTENTION = 0xF6;
        public const byte CRSEL = 0xF7;
        public const byte EXSEL = 0xF8;
        public const byte EREOF = 0xF9;
        public const byte PLAY = 0xFA;
        public const byte ZOOM = 0xFB;
        public const byte PA1 = 0xFD;

        public class Mouse {
            public const byte LEFT = 0x01;
            public const byte RIGHT = 0x02;
            public const byte CANCEL = 0x03;
            public const byte MIDDLE = 0x04;
            public const byte BACKWARD = 0x05;
            public const byte FORWARD = 0x06;
        }

        public class Page {
            public const byte UP = 0x21;
            public const byte DOWN = 0x22;
        }

        public class Arrow {
            public const byte LEFT = 0x25;
            public const byte UP = 0x26;
            public const byte RIGHT = 0x27;
            public const byte DOWN = 0x28;
        }

        public class Windows {
            public const byte LEFT = 0x5B;
            public const byte RIGHT = 0x5C;
        }

        public class Numpad {
            public const byte ZERO = 0x60;
            public const byte ONE = 0x61;
            public const byte TWO = 0x62;
            public const byte THREE = 0x63;
            public const byte FOUR = 0x64;
            public const byte FIVE = 0x65;
            public const byte SIX = 0x66;
            public const byte SEVEN = 0x67;
            public const byte EIGHT = 0x68;
            public const byte NINE = 0x69;
        }

        public class Shift {
            public const byte LEFT = 0xA0;
            public const byte RIGHT = 0xA1;
        }

        public class Ctrl {
            public const byte LEFT = 0xA2;
            public const byte RIGHT = 0xA3;
        }

        public class Alt {
            public const byte LEFT = 0xA4;
            public const byte RIGHT = 0xA5;
        }

        public class Browser {
            public const byte BACK = 0xA6;
            public const byte FORWARD = 0xA7;
            public const byte REFRESH = 0xA8;
            public const byte STOP = 0xA9;
            public const byte SEARCH = 0xAA;
            public const byte FAVORITES = 0xAB;
            public const byte HOME = 0xAC;
        }

        public class Volume {
            public const byte MUTE = 0xAD;
            public const byte DOWN = 0xAE;
            public const byte UP = 0xAF;
        }

        public class Media {
            public const byte NEXT = 0xB0;
            public const byte PREVIOUS = 0xB1;
            public const byte STOP = 0xB2;
            public const byte PLAY = 0xB3;
            public const byte PAUSE = 0xB3;
        }

        public class Launch {
            public const byte MAIL = 0xB4;
            public const byte MEDIA = 0xB5;
            public const byte APP1 = 0xB6;
            public const byte APP2 = 0xB7;
        }

        public class OEM {
            public const byte ONE = 0xBA;
            public const byte PLUS = 0xBB;
            public const byte COMMA = 0xBC;
            public const byte MINUS = 0xBD;
            public const byte PERIOD = 0xBE;
            public const byte TWO = 0xBF;
            public const byte THREE = 0xC0;
            public const byte FOUR = 0xDB;
            public const byte FIVE = 0xDC;
            public const byte SIX = 0xDD;
            public const byte SEVEN = 0xDE;
            public const byte EIGHT = 0xDF;
            public const byte NINE = 0xE2;
            public const byte CLEAR = 0xFE;
        }

        public class Subscribe {
            private bool Running;

            public Mode Option { get; }
            public byte[] Keys { get; }
            public System.Action Action { get; }
            public int Delay { get; }

            public Subscribe (in System.Action action, in byte[] keys, in Mode mode = Mode.Down, in int delay = 15) {
                this.Keys = keys;
                this.Delay = delay;
                this.Option = mode;
                this.Action = action;

                Running = true;
                _ = this.Monitor ();
            }

            public Subscribe (in System.Action action, in byte key, in Mode mode = Mode.Down, in int delay = 15) : this (in action, [key], in mode, in delay) { }

            public void Unsubscribe () => this.Running = false;

            private async System.Threading.Tasks.Task Monitor () {
                var previous = new bool[this.Keys.Length];

                while (Running) {
                    var current = new bool[this.Keys.Length];

                    for (var i = 0; i < this.Keys.Length; i++)
                        current[i] = Pressed (this.Keys[i]);

                    if ((this.Option == Mode.Pressed && All (current)) ||
                        (this.Option == Mode.Down && All (current) && !Equal (previous, current)) ||
                        (this.Option == Mode.Up && !All (current) && Any (previous))) {
                        this.Action ();
                    }

                    System.Array.Copy (current, previous, current.Length);
                    await System.Threading.Tasks.Task.Delay (this.Delay);
                }
            }

            private static bool All(bool[] keys) {
                foreach (var key in keys)
                    if (!key)
                        return false;

                return true;
            }

            private static bool Any (bool[] keys) {
                foreach (var key in keys)
                    if (key)
                        return true;

                return false;
            }

            private static bool Equal (bool[] a, bool[] b) {
                if (a.Length != b.Length)
                    return false;

                for (var i = 0; i < a.Length; i++)
                    if (a[i] != b[i])
                        return false;

                return true;
            }

            public enum Mode {
                Up,
                Down,
                Pressed
            }
        }

        public static bool Pressed (in int key)
            => (GetAsyncKeyState (key) & 0x8000) != 0;

        public static void Send (params byte[] keys) {
            foreach (var key in keys) {
                switch (key) {
                    case Mouse.LEFT:
                        Click (0x0002, 0x0004);
                        break;
                    case Mouse.RIGHT:
                        Click (0x0008, 0x0010);
                        break;
                    default:
                        keybd_event (key, 0, 0, nuint.Zero);
                        System.Threading.Thread.Sleep (1);
                        keybd_event (key, 0, 2, nuint.Zero);
                        break;
                }
            }
        }
        public static void Send (in byte[] keys) {
            foreach (var key in keys) {
                switch (key) {
                    case Mouse.LEFT:
                        Click (0x0002, 0x0004);
                        break;
                    case Mouse.RIGHT:
                        Click (0x0008, 0x0010);
                        break;
                    default:
                        keybd_event (key, 0, 0, nuint.Zero);
                        System.Threading.Thread.Sleep (1);
                        keybd_event (key, 0, 2, nuint.Zero);
                        break;
                }
            }
        }
        public static void Send (in string value) {
            foreach (var key in value) {
                var inputs = new INPUT[2];
                    inputs[0] = new INPUT {
                        type = 1,
                        U = new InputUnion {
                            ki = new KEYBDINPUT {
                                wScan = key,
                                dwFlags = 4
                            }
                        }
                    };

                    inputs[1] = new INPUT {
                        type = 1,
                        U = new InputUnion {
                            ki = new KEYBDINPUT {
                                wScan = key,
                                dwFlags = 6
                            }
                        }
                    };

                _ = SendInput (2, inputs, System.Runtime.InteropServices.Marshal.SizeOf<INPUT> ());

                System.Threading.Thread.Sleep (1);
            }
        }
        private static void Click (in uint down, in uint up) {
            var inputs = new INPUT[2];
                inputs[0] = new INPUT {
                    type = 0,
                    U = new InputUnion {
                        mi = new MOUSEINPUT {
                            dwFlags = down
                        }
                    }
                };

                inputs[1] = new INPUT {
                    type = 0,
                    U = new InputUnion {
                        mi = new MOUSEINPUT {
                            dwFlags = up
                        }
                    }
                };

            _ = SendInput (2, inputs, System.Runtime.InteropServices.Marshal.SizeOf<INPUT> ());

            System.Threading.Thread.Sleep (1);
        }
    }
}