// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
// Description: Provides mouse and keyboard input functionality
 
using System.Windows.Input;
using System.Runtime.InteropServices;
using MS.Win32;
 
using System;
 
namespace MS.Internal.Automation
{
    // 
    // Provides internal methods for sending keyboard input
    // 
    internal sealed class Input
    {
        //------------------------------------------------------
        //
        //  Constructors
        //
        //------------------------------------------------------
 
        #region Constructors
 
        // Static class - Private to prevent creation
        private Input() { }
 
        #endregion Constructors
 
        //------------------------------------------------------
        //
        //  Internal Methods
        //
        //------------------------------------------------------
 
        #region Internal Methods
 
        // 
        // Inject keyboard input into the system
        // 
        internal static void SendKeyboardInput( Key key, bool press )
        {
            UnsafeNativeMethods.INPUT ki = new UnsafeNativeMethods.INPUT
            {
                type = UnsafeNativeMethods.INPUT_KEYBOARD
            };
            ki.union.keyboardInput.wVk = (short) KeyInterop.VirtualKeyFromKey( key );
            ki.union.keyboardInput.wScan = (short) UnsafeNativeMethods.MapVirtualKey( ki.union.keyboardInput.wVk, 0 );
            int dwFlags = 0;
            if( ki.union.keyboardInput.wScan > 0 )
                dwFlags |= UnsafeNativeMethods.KEYEVENTF_SCANCODE;
            if( !press )
                dwFlags |= UnsafeNativeMethods.KEYEVENTF_KEYUP;
            ki.union.keyboardInput.dwFlags = dwFlags;
            if( IsExtendedKey( key ) )
            {
                ki.union.keyboardInput.dwFlags |= UnsafeNativeMethods.KEYEVENTF_EXTENDEDKEY;
            }
            ki.union.keyboardInput.time = 0;
            ki.union.keyboardInput.dwExtraInfo = new IntPtr( 0 );
 
            Misc.SendInput(1, ref ki, Marshal.SizeOf(ki));
        }
 
        // Used internally by the HWND SetFocus code - it sends a hotkey to
        // itself - because it uses a VK that's not on the keyboard, it needs
        // to send the VK directly, not the scan code, which regular
        // SendKeyboardInput does.
        internal static void SendKeyboardInputVK( byte vk, bool press )
        {
            UnsafeNativeMethods.INPUT ki = new UnsafeNativeMethods.INPUT
            {
                type = UnsafeNativeMethods.INPUT_KEYBOARD
            };
            ki.union.keyboardInput.wVk = vk;
            ki.union.keyboardInput.wScan = 0;
            ki.union.keyboardInput.dwFlags = press ? 0 : UnsafeNativeMethods.KEYEVENTF_KEYUP;
            ki.union.keyboardInput.time = 0;
            ki.union.keyboardInput.dwExtraInfo = new IntPtr( 0 );
 
            Misc.SendInput(1, ref ki, Marshal.SizeOf(ki));
        }
 
 
        #endregion Internal Methods
 
        //------------------------------------------------------
        //
        //  Private Methods
        //
        //------------------------------------------------------
 
        #region Private Methods
 
 
        private static bool IsExtendedKey( Key key )
        {
            // From the SDK:
            // The extended-key flag indicates whether the keystroke message originated from one of
            // the additional keys on the enhanced keyboard. The extended keys consist of the ALT and
            // CTRL keys on the right-hand side of the keyboard; the INS, DEL, HOME, END, PAGE UP,
            // PAGE DOWN, and arrow keys in the clusters to the left of the numeric keypad; the NUM LOCK
            // key; the BREAK (CTRL+PAUSE) key; the PRINT SCRN key; and the divide (/) and ENTER keys in
            // the numeric keypad. The extended-key flag is set if the key is an extended key. 
            //
            // - docs appear to be incorrect. Use of Spy++ indicates that break is not an extended key.
            // Also, menu key and windows keys also appear to be extended.
            return key == Key.RightAlt
                || key == Key.RightCtrl
                || key == Key.NumLock
                || key == Key.Insert
                || key == Key.Delete
                || key == Key.Home
                || key == Key.End
                || key == Key.Prior
                || key == Key.Next
                || key == Key.Up
                || key == Key.Down
                || key == Key.Left
                || key == Key.Right
                || key == Key.Apps
                || key == Key.RWin
                || key == Key.LWin;
 
            // Note that there are no distinct values for the following keys:
            // numpad divide
            // numpad enter
        }
 
        #endregion Private Methods
 
        //------------------------------------------------------
        //
        //  Private Fields
        //
        //------------------------------------------------------
 
        #region Private Fields
 
        // Stateless object, has no private fields
 
        #endregion Private Fields
    }
}