Save-Download.ps1

function Save-Download {
    <#
    .SYNOPSIS
        Given a the result of WebResponseObject, will download the file to disk without having to specify a name.
    .DESCRIPTION
        Given a the result of WebResponseObject, will download the file to disk without having to specify a name.
    .PARAMETER WebResponse
        A WebResponseObject from running an Invoke-WebRequest on a file to download
    .EXAMPLE
        # Download Microsoft Edge
        $download = Invoke-WebRequest -Uri "https://go.microsoft.com/fwlink/?linkid=2109047&Channel=Stable&language=en&consent=1"
        $download | Save-Download 
    #>
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true, ValueFromPipeline)]
        [Microsoft.PowerShell.Commands.WebResponseObject]
        $WebResponse,

        [Parameter(Mandatory = $false)]
        [string]
        $Directory = '.'
    )

    $errorMessage = 'Cannot determine filename for download.'

    if (!($WebResponse.Headers.ContainsKey('Content-Disposition'))) {
        Write-Error $errorMessage -ErrorAction Stop
    }

    $content = [System.Net.Mime.ContentDisposition]::new($WebResponse.Headers['Content-Disposition'])
    
    $fileName = $content.FileName

    if (!$fileName) {
        Write-Error $errorMessage -ErrorAction Stop
    }

    if (!(Test-Path -Path $Directory)) {
        New-Item -Path $Directory -ItemType Directory
    }
    
    $fullPath = Join-Path -Path $Directory -ChildPath $fileName

    Write-Verbose "Downloading to $fullPath"

    $file = [System.IO.FileStream]::new($fullPath, [System.IO.FileMode]::Create)
    $file.Write($WebResponse.Content, 0, $WebResponse.RawContentLength)
    $file.Close()
}