using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Rs.Framework
{
    /// <summary>
    /// 热键管理类
    /// </summary>
    public class HotKeyManager
    {
        private const int MOD_ALT = 0x0001;    // Alt键
        private const int MOD_CTRL = 0x0002;   // Ctrl键
        private const int MOD_SHIFT = 0x0004;  // Shift键
        private const int MOD_WIN = 0x0008;    // Windows键
        private const int WM_HOTKEY = 0x0312;

        private Action<object, EventArgs> hotkeyAction;
        private int id;

        [DllImport("user32.dll")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, Keys vk);

        [DllImport("user32.dll")]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        public HotKeyManager(Keys key, int modifier, Action<object, EventArgs> action)
        {
            hotkeyAction = action;
            id = this.GetHashCode();

            RegisterHotKey(Application.OpenForms[0].Handle, id, modifier, key);
            Application.AddMessageFilter(new MessageFilter(this));
        }

        public void Unregister()
        {
            UnregisterHotKey(Application.OpenForms[0].Handle, id);
        }

        private class MessageFilter : IMessageFilter
        {
            private HotKeyManager hotkey;

            public MessageFilter(HotKeyManager hotkey)
            {
                this.hotkey = hotkey;
            }

            public bool PreFilterMessage(ref Message m)
            {
                if (m.Msg == WM_HOTKEY && (int)m.WParam == hotkey.id)
                {
                    hotkey.hotkeyAction(null, EventArgs.Empty);
                    return true;
                }
                return false;
            }
        }
    }
}