param([ValidateSet(30, 60)][int]$RefreshRate = 60)
$ErrorActionPreference = 'Stop'
Add-Type @'
using System;
using System.Runtime.InteropServices;
public static class VdiDisplayMode {
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct Device {
        public int cb;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)] public string Name;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)] public string Description;
        public int Flags;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)] public string Id;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)] public string Key;
    }
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct Mode {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)] public string name;
        public short spec, driver, size, extra;
        public int fields, x, y, orientation, fixedOutput;
        public short color, duplex, yres, tt, collate;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)] public string form;
        public short logPixels;
        public int bpp, width, height, flags, hz, icmMethod, icmIntent, media, dither,
            reserved1, reserved2, panWidth, panHeight;
    }
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    static extern bool EnumDisplayDevices(string name, uint index, ref Device dev, uint flags);
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    static extern bool EnumDisplaySettings(string name, int index, ref Mode mode);
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    static extern int ChangeDisplaySettingsEx(string name, ref Mode mode, IntPtr window, uint flags, IntPtr param);

    public static string Find() {
        for (uint i = 0; ; i++) {
            var d = new Device();
            d.cb = Marshal.SizeOf(typeof(Device));
            if (!EnumDisplayDevices(null, i, ref d, 0)) return null;
            if ((d.Flags & 1) != 0 && d.Description.IndexOf("Virtual Display Driver", StringComparison.OrdinalIgnoreCase) >= 0)
                return d.Name;
        }
    }
    public static string Current(string name) {
        var m = new Mode();
        m.size = (short)Marshal.SizeOf(typeof(Mode));
        if (!EnumDisplaySettings(name, -1, ref m)) return "unavailable";
        return m.width + "x" + m.height + "@" + m.hz;
    }
    public static int Apply(string name, int refreshRate) {
        for (int i = 0; ; i++) {
            var m = new Mode();
            m.size = (short)Marshal.SizeOf(typeof(Mode));
            if (!EnumDisplaySettings(name, i, ref m)) return -99;
            if (m.width == 2560 && m.height == 1440 && m.hz == refreshRate) {
                m.fields = 0x80000 | 0x100000 | 0x400000;
                int test = ChangeDisplaySettingsEx(name, ref m, IntPtr.Zero, 2, IntPtr.Zero);
                if (test != 0) return test;
                return ChangeDisplaySettingsEx(name, ref m, IntPtr.Zero, 1, IntPtr.Zero);
            }
        }
    }
}
'@
$log = 'C:/ProgramData/VDI/set-2k-result.txt'
$expectedMode = "2560x1440@$RefreshRate"
try {
    for ($i = 0; $i -lt 12; $i++) {
        $dev = [VdiDisplayMode]::Find()
        if ($dev) {
            if ([VdiDisplayMode]::Current($dev) -eq $expectedMode) {
                "$(Get-Date -Format o) device=$dev result=0 mode=$expectedMode (already correct)" | Set-Content $log
                exit 0
            }
            $result = [VdiDisplayMode]::Apply($dev, $RefreshRate)
            $mode = [VdiDisplayMode]::Current($dev)
            if ($result -eq 0 -and $mode -eq $expectedMode) {
                "$(Get-Date -Format o) device=$dev result=0 mode=$mode" | Set-Content $log
                exit 0
            }
        }
        Start-Sleep 5
    }
    throw "2K mode not applied: device=$dev result=$result mode=$mode"
} catch {
    "$(Get-Date -Format o) ERROR $_" | Set-Content $log
    exit 1
}