<#
.Synopsis
   Clears GPO Cache on remote computer
.DESCRIPTION
   This function clears the GPO Cache on a remote computer by creating Scheduled Task to remove, using System user context
.PARAMETER COMPUTERS
   A single computer name or array of computer names
.EXAMPLE
   Clear-GPOCache PC1
   Clears the GPO cache on PC1
.EXAMPLE
   "PC1","PC2" |Clear-GPOCache
   Clears the GPO cache on PC1 and PC2
.NOTES
Alan Kaplan
5/22/2017
7/11/2017  Added test for temp dir, ch

#>
function Clear-GPOCache
{
    [CmdletBinding( SupportsShouldProcess=$true) ]
    Param
    (
        # Single Computer name or an array
        [Parameter(Mandatory=$true,
                   ValueFromPipeline=$true,
                   ValueFromPipelineByPropertyName=$true, 
                   Position=0)]
        $Computers
    )

Begin
{
$batchFileLocal = "c:\temp\ClearGPO.cmd"
$batchTxt = @"
@echo off
REM This 
c:
DEL /S /F /Q "%ALLUSERSPROFILE%\Application Data\Microsoft\Group Policy\History\*.*"
REG DELETE HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies /f

[HKUDeletes]
esentutl /r edb /l %windir%\security /s %windir%\security
klist purge
gpupdate /force
echo GPO cache cleared by $env:USERDOMAIN\$env:USERNAME at %date% %time% >> c:\GPOCacheClearedLog.txt
del $batchFileLocal
"@


} #End Begin
Process
{
    Foreach ($Computer in $Computers) {
        if ($pscmdlet.ShouldProcess($computer) ){ $bTest = $False}Else{$bTest = $true}
        Write-Verbose "Pinging $computer"
    if (
        ((Test-Connection -Count 1 -Computer $computer -Quiet) -eq $False) -and ($Computer -notlike $env:COMPUTERNAME)
        )
    {
        [PSCustomObject]@{
        Computer = $Computer
        Result = "Offline"
        }
        Continue
    }
    ELSE
    {
    try{
        Write-Verbose "Getting local time from $computer"
        $WMITime = Get-WMIObject -ComputerName $computer Win32_Localtime -Property Hour, Minute -ErrorAction Stop
        $t= [datetime]::Parse($($WMITime).Hour.ToString() + ':'+ $($WMITime).Minute.ToString())
        $t = $t.AddMinutes(3).GetDateTimeFormats()[109]

        Write-Verbose "Getting local user SIDS from $computer"
        $SidList = Get-WmiObject  -ComputerName $computer -query "SELECT SID FROM Win32_UserProfile where special = 'False'" 
        $DelList = ''
        foreach ($sid in $SidList.Sid){
            $DelList += "REG DELETE HKU\$sid\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies /f`n"
        }

        if ((test-path "\\$computer\c$\temp") -eq $false ){new-item -path "\\$computer\c$\temp" -ItemType Directory}


        $batchText = $batchTxt.Replace('[HKUDeletes]',$DelList)
        $batchFileUNC = "\\$computer\c$\temp\ClearGPO.cmd"
        Set-content -Value $batchText -Path $batchFileUNC -Force -Whatif:$bTest
        $cmd = "Schtasks /Create /s $computer /st $t /tr $batchFileLocal /RU System /TN ClearGPOCache /sc ONCE /f /v1 /z"
        Write-Verbose "Running Clear GPO Cache as scheduled job on $computer starting at $t with command`:`n`"$cmd`""
        if ($bTest){
            #Do nothing
            Write "What if: Performing the operation `"Create Scheduled Task`" on target `"$computer`""
            $testMsg = ' (Test Mode)'
        }ELSE{
            Invoke-Expression $cmd
            #Note in event log
            write-eventlog -computername $Computer -logname Application -Source 'Windows PowerShell' -eventID 9001 -message "Clear GPO Cache run by $env:UserDomain`\$env:username from $env:computername"
        }

        [PSCustomObject]@{
        Computer = $Computer
        Result = "Success" + $testMsg
        }
    
    }
    Catch
    {
        $errmsg = $Error[0].exception.message + $testMsg
        [PSCustomObject]@{
        Computer = $Computer
        Result = "Error: $errmsg"
        }
        Continue
    }
    
    }
  }
} #End Process
End
{
} #End End
} #End Function