namespace System.Windows
{
    using System;
    using System.Security;
    using System.Security.Permissions;
    using System.Windows.Input;
    using System.Windows.Interop;
    using Standard;
 
    public static class SystemCommands
    {
        public static RoutedCommand CloseWindowCommand { get; private set; }
        public static RoutedCommand MaximizeWindowCommand { get; private set; }
        public static RoutedCommand MinimizeWindowCommand { get; private set; }
        public static RoutedCommand RestoreWindowCommand { get; private set; }
        public static RoutedCommand ShowSystemMenuCommand { get; private set; }
 
        static SystemCommands()
        {
            CloseWindowCommand = new RoutedCommand("CloseWindow", typeof(SystemCommands));
            MaximizeWindowCommand = new RoutedCommand("MaximizeWindow", typeof(SystemCommands));
            MinimizeWindowCommand = new RoutedCommand("MinimizeWindow", typeof(SystemCommands));
            RestoreWindowCommand = new RoutedCommand("RestoreWindow", typeof(SystemCommands));
            ShowSystemMenuCommand = new RoutedCommand("ShowSystemMenu", typeof(SystemCommands));                 
        }
 
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        /// <SecurityNote>
        [SecurityCritical]
        private static void _PostSystemCommand(Window window, SC command)
        {
            IntPtr hwnd = new WindowInteropHelper(window).Handle;
            if (hwnd == IntPtr.Zero || !NativeMethods.IsWindow(hwnd))
            {
                return;
            }
 
            NativeMethods.PostMessage(hwnd, WM.SYSCOMMAND, new IntPtr((int)command), IntPtr.Zero);
        }
 
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        ///   Safe     : Demands full trust permissions
        /// <SecurityNote>
        [SecuritySafeCritical]
        [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
        public static void CloseWindow(Window window)
        {
            Verify.IsNotNull(window, "window");
            _PostSystemCommand(window, SC.CLOSE);
        }
 
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        ///   Safe     : Demands full trust permissions
        /// <SecurityNote>
        [SecuritySafeCritical]
        [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
        public static void MaximizeWindow(Window window)
        {
            Verify.IsNotNull(window, "window");
            _PostSystemCommand(window, SC.MAXIMIZE);
        }
 
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        ///   Safe     : Demands full trust permissions
        /// <SecurityNote>
        [SecuritySafeCritical]
        [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
        public static void MinimizeWindow(Window window)
        {
            Verify.IsNotNull(window, "window");
            _PostSystemCommand(window, SC.MINIMIZE);
        }
 
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        ///   Safe     : Demands full trust permissions
        /// <SecurityNote>
        [SecuritySafeCritical]
        [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
        public static void RestoreWindow(Window window)
        {
            Verify.IsNotNull(window, "window");
            _PostSystemCommand(window, SC.RESTORE);
        }
 
        /// <summary>Display the system menu at a specified location.</summary>
        /// <param name="screenLocation">The location to display the system menu, in logical screen coordinates.</param>
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        ///   Safe     : Demands full trust permissions
        /// <SecurityNote>
        [SecuritySafeCritical]
        [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
        public static void ShowSystemMenu(Window window, Point screenLocation)
        {
            Verify.IsNotNull(window, "window");
            DpiScale dpi = window.GetDpi();
            ShowSystemMenuPhysicalCoordinates(window, DpiHelper.LogicalPixelsToDevice(screenLocation, dpi.DpiScaleX, dpi.DpiScaleY));
        }
 
        /// <SecurityNote>
        ///   Critical : Calls critical methods
        /// <SecurityNote>
        [SecurityCritical]
        internal static void ShowSystemMenuPhysicalCoordinates(Window window, Point physicalScreenLocation)
        {
            const uint TPM_RETURNCMD = 0x0100;
            const uint TPM_LEFTBUTTON = 0x0;
 
            Verify.IsNotNull(window, "window");
            IntPtr hwnd = new WindowInteropHelper(window).Handle;
            if (hwnd == IntPtr.Zero || !NativeMethods.IsWindow(hwnd))
            {
                return;
            }
 
            IntPtr hmenu = NativeMethods.GetSystemMenu(hwnd, false);
 
            uint cmd = NativeMethods.TrackPopupMenuEx(hmenu, TPM_LEFTBUTTON | TPM_RETURNCMD, (int)physicalScreenLocation.X, (int)physicalScreenLocation.Y, hwnd, IntPtr.Zero);
            if (0 != cmd)
            {
                NativeMethods.PostMessage(hwnd, WM.SYSCOMMAND, new IntPtr(cmd), IntPtr.Zero);
            }
        }
    }
}