Waits until a file is changed

Wait-FileChangeEvent.ps1

<#
.SYNOPSIS
    Waits until a file changes

.EXAMPLE

    .\Wait-FileChangeEvent.ps1 site.scss { taildwindcss site.scss -o output\site.css }

    Waits until site.scss changes and runs a script
#>

[CmdletBinding()]
param (
    $Pattern = ".",
    $Script = $null
)

$item = Get-Item $Pattern
if ($item -is [System.IO.DirectoryInfo])
{
    $Directory = $item.FullName
}
else
{
    $Directory = $item.Directory.FullName
}

Write-Verbose "Directory $directory"
$item | % { Write-Verbose "item: $_" }

$watcher = new-object System.IO.FileSystemWatcher
$watcher.Path = $Directory

Unregister-Event "FileChanged" -ErrorAction SilentlyContinue
Register-ObjectEvent $watcher "Changed" -SourceIdentifier "FileChanged"

If ($null -ne $Script)
{
    While ($true)
    {
        $events = Wait-Event "FileChanged"
        $events | Where-Object  {
            Write-Verbose "FullPath $($_.SourceEventArgs.FullPath)"
            Write-Verbose "Matched Pattern: $( $item -contains (get-item $_.SourceEventArgs.FullPath ) )"
            $item -contains (get-item $_.SourceEventArgs.FullPath )
        } | ForEach-Object  {
            & $script
        }
        $events| Remove-Event
    }

    Unregister-Event "FileChanged"

}