Simple PowerShell function that allows to split a CSV by parts or by size using `StreamReader` and `StreamWriter`

Split-Csv.ps1

function Split-Csv {
    [CmdletBinding(DefaultParameterSetName = 'ByParts')]
    param(
        [Parameter(Mandatory, ValueFromPipelineByPropertyName)]
        [alias('FullName')]
        [string] $Path,

        [parameter(Mandatory)]
        [string] $DestinationFolder,

        [parameter(ParameterSetName = 'BySize')]
        [int] $BySize = 1kb,

        [parameter(ParameterSetName = 'ByParts')]
        [int] $ByParts = 3
    )

    process {
        try {
            [IO.FileInfo] $Path = $PSCmdlet.GetUnresolvedProviderPathFromPSPath($Path)
            $Destination = $PSCmdlet.GetUnresolvedProviderPathFromPSPath($DestinationFolder)
            if(-not (Test-Path $Destination)) {
                $null = New-Item $Destination -ItemType Directory
            }
            $reader  = [IO.StreamReader] $Path.FullName
            $headers = $reader.ReadLine()
            $Index   = 0

            if($PSCmdlet.ParameterSetName -eq 'ByParts') {
                $ChunkSize = [math]::Ceiling($Path.Length / $ByParts) + $headers.Length
            }
            else {
                $ChunkSize = $BySize - $headers.Length
            }

            $newWriter = {
                $name     = $Path.BaseName + " - Part $Index" + $Path.Extension
                $newChunk = Join-Path $Destination -ChildPath $name
                $writer   = [IO.StreamWriter] $newChunk
                $writer.AutoFlush = $true
                $writer.WriteLine($headers)
                $writer
            }

            $writer = & $newWriter

            while(-not $reader.EndOfStream) {
                if($writer.BaseStream.Length -ge $ChunkSize) {
                    $Index++
                    $writer.Dispose()
                    $writer = & $newWriter
                }
                $writer.WriteLine($reader.ReadLine())
            }
        }
        catch {
            $PSCmdlet.ThrowTerminatingError($_)
        }
        finally {
            $writer, $reader | ForEach-Object Dispose
        }
    }
}