windows 7 - Automatically open a file when it is added to a directory, with PowerShell

I have a script (.ps1) that is monitoring a directory, and when a file is created it should open that specific file (in this case a .pdf).

There are multiple files in the directory, but it should only open the one that gets detected as it gets created/moved to that directory when the script is running.

A new file will be continuously added so the name changes slightly every time. Example1.pdf, Example2.pdf and so on. This means that i need to open the most recent file, regardless of the name.

Right now it is only monitoring the directory, because i am not sure how to proceed with opening the file when it gets detected.

I would like to keep everything in this single script if possible.

(I am not that experienced with powershell. Howerver, I am experienced with cmd/batch. I am trying to convert to powershell)

Any good methods to make this work?

This is my script:

    $host.UI.RawUI.WindowTitle = "Watcher"
    $watcher = New-Object System.IO.FileSystemWatcher
    $watcher.Path = "C:\top_secret_path\test"
    $watcher.Filter = "*.*"
    $watcher.IncludeSubdirectories = $false
    $watcher.EnableRaisingEvents = $false
    $action = {
        $path = $Event.SourceEventArgs.FullPath
                $changeType = $Event.SourceEventArgs.ChangeType
                $logline = "$(Get-Date), $changeType, $path"
                Add-content "C:\top_secret_path\log.txt" -value $logline
              }
    Register-ObjectEvent $watcher "Created" -Action $action | Format-Table -AutoSize
    while ($true) {sleep 5}