Prune episodes from a daily series in Sonarr

[CmdletBinding()]
Param(
    [Parameter(Mandatory=$True)]
        [string]$filePath,

    [Parameter(Mandatory=$True)]
        [int]$daysToKeep
)

# Store the folder timestamp, because deleting files will modify it.
$FolderTimestamp = (Get-Item $filePath).LastWriteTime

$showNFO = "$filePath\tvshow.nfo"
Write-Verbose -Message "NFO File: $showNFO"

if (Test-Path "$filePath\tvshow.nfo")
    { [xml]$showXML = Get-Content $showNFO }
else
    {
    Write-Error -Message "Unable to locate $showNFO"
    Exit
    }

$validFiles = Get-ChildItem $filePath | Where-Object Name -Like ($showXML.tvshow.title + "*")

Write-Verbose -Message ("Found " + $validFiles.Count + " files")


$filesToDelete = $validFiles | Where-Object LastWriteTime -LT (Get-Date | ForEach-Object {$_.AddDays(-$daysToKeep)})

Write-Verbose -Message ("Eligible files " + $filesToDelete.Count)

$filesToDelete | ForEach-Object { Remove-Item $_.FullName }

Write-Output ("FINISH: Removed " + $filesToDelete.Count + " files.")

# Restore the folder Timestamp
(Get-Item $filePath).LastWriteTime = $FolderTimestamp