Powershell, split large XML files on node name, with offset support

SplitXml.ps1

param(  [string]$file = $(throw "file is required"), $matchesPerSplit = 50, $maxFiles = [Int32]::MaxValue, $splitOnNode = $(throw "splitOnNode is required"), $offset = 0 )
# with a little help of https://gist.github.com/awayken/5861923
$ErrorActionPreference = "Stop";

trap {
    $ErrorActionPreference = "Continue"
    write-error "Script failed: $_ \r\n $($_.ScriptStackTrace)"
    exit (1);
}

$file = (resolve-path $file).path

$fileNameExt = [IO.Path]::GetExtension($file)
$fileNameWithoutExt = [IO.Path]::GetFileNameWithoutExtension($file)
$fileNameDirectory = [IO.Path]::GetDirectoryName($file)


$reader = [System.Xml.XmlReader]::Create($file) 
 
$matchesCount = $idx = 0

try {
    "Splitting $from on node name='$splitOnNode', with a max of $matchesPerSplit matches per file. Max of $maxFiles files will be generated."
    $result = $reader.ReadToFollowing($splitOnNode)
    $hasNextSibling = $true
    while (-not($reader.EOF) -and $result -and $hasNextSibling -and ($idx -lt $maxFiles + $offset)) {
        if ($matchesCount -lt $matchesPerSplit) {
            if($offset -gt $idx) {
               $idx++
               continue
            }
        
            $to = [IO.Path]::Combine($fileNameDirectory, "$fileNameWithoutExt.$($idx -$offset)$fileNameExt")
            "Writing to $to"
            $toXml = New-Object System.Xml.XmlTextWriter($to, $null)
            $toXml.Formatting = 'Indented'
            $toXml.Indentation = 2
            try {
               $toXml.WriteStartElement("split")
               $toXml.WriteAttributeString("cnt", $null, "$idx")
               
               do {
                  $toXml.WriteRaw($reader.ReadOuterXml())
                  $matchesCount++;
                  $hasNextSibling = $reader.ReadToNextSibling($splitOnNode)
               } while($hasNextSibling -and ($matchesCount -lt $matchesPerSplit))
               $toXml.WriteEndElement();
            } 
            finally {
               $toXml.Flush()
               $toXml.Close()
            }
            $idx++
            $matchesCount = 0;
        }
    }
}
finally {
    $reader.Close()
}

Hi, many thanks for this code, brilliant!
Could you help me with code line that I can extract the node's id of the used node and use that node's id on the file name rather than incremental $idx, please?
Many thanks!

I dont have time to test right now but the node should be in hear,
$reader.ReadOuterXml())

Not sure if you can extract it directly or if you need to load the content in another object first . It needs to be done without moving the readers position