Get-WebFile.ps1

function Get-WebFile {
    param(
        [Parameter(Mandatory=$true)]
        $Uri,
        [string] $OutFile,
        [string] $Hash,
        [string] $HashAlgorithm = 'SHA256'
    )

    if (-not $OutFile) {
        $OutFile = Split-Path -Leaf $Uri
    }

    $meta = Get-Item $OutFile -ErrorAction SilentlyContinue
    if ($meta -and $meta.PSIsContainer) {
        throw '$OutFile may not be a directory'
    }

    $container = Split-Path $OutFile
    if (-not $container) {
        $container = '.'
    }

    $tempFile = Join-Path $container "$(New-Guid).part"
    Invoke-WebRequest $Uri -OutFile $tempFile -ErrorAction Stop

    if ($Hash) {
        $actual = Get-FileHash $tempFile -Algorithm $HashAlgorithm
        if ($Hash -ne $actual.Hash) {
            throw "Downloaded file does not have the expected $HashAlgorithm hash: $Hash"
        }
    }

    Move-Item $tempFile $OutFile -Force
    
    Get-Item $OutFile
}