Powershell Computer Keepalive (Anti-Idle)

keepalive.ps1

<# 
  This script will prevent GPOs from enabling the screensaver, shutting off your screen, or force-locking your workstation
  It works by sending an F15 keystroke every minute (only if there have been no keystrokes or mouse movement for 30 seconds)
  Be green - if you want to use this, power off your monitor(s)!
#>

Add-Type @'
    using System;
    using System.Diagnostics;
    using System.Runtime.InteropServices;
    namespace PInvoke.Win32 {
        public static class UserInput {
            [DllImport("user32.dll", SetLastError=false)]
            private static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);
            [StructLayout(LayoutKind.Sequential)]
            private struct LASTINPUTINFO {
                public uint cbSize;
                public int dwTime;
            }
            public static DateTime LastInput {
                get {
                    DateTime bootTime = DateTime.UtcNow.AddMilliseconds(-Environment.TickCount);
                    DateTime lastInput = bootTime.AddMilliseconds(LastInputTicks);
                    return lastInput;
                }
            }
            public static TimeSpan IdleTime {
                get {
                    return DateTime.UtcNow.Subtract(LastInput);
                }
            }
            public static int LastInputTicks {
                get {
                    LASTINPUTINFO lii = new LASTINPUTINFO();
                    lii.cbSize = (uint)Marshal.SizeOf(typeof(LASTINPUTINFO));
                    GetLastInputInfo(ref lii);
                    return lii.dwTime;
                }
            }
        }
    }
'@  # https://stackoverflow.com/questions/39312540/how-to-detect-user-activity-input-or-lack-thereof-on-a-pc

$host.ui.RawUI.WindowTitle = "Idle Keepalive"

$myshell = New-Object -com "Wscript.Shell"

While($true) { 
    $i++

    Start-Sleep -Seconds 60

    #Calculate idle time
    $idleTime = [PInvoke.Win32.UserInput]::IdleTime
    $TimeSpan = New-TimeSpan -Seconds 30

    #Only send keystroke if Windows API reports idle for more than 30 seconds. This should limit sending keystrokes when not idle, in case they mess up apps
    if ($idleTime -gt $TimeSpan) { 
        $myshell.sendkeys("{SCROLLLOCK}")
        Start-Sleep -Milliseconds 100
        $myshell.sendkeys("{SCROLLLOCK}")
        Write-Output "Keepalive script has been running for $i minutes [F15 key sent]"
    }else {
        Write-Output "Keepalive script has been running for $i minutes"
    }

}