Register-AwsCompletion.ps1

# This idea was inspired by  https://github.com/aws/aws-cli/issues/5309#issuecomment-693941619
$awsCompleter = Get-Command -Name aws_completer -ErrorAction SilentlyContinue
if ($awsCompleter) {
    # for PyPI installation.
    if ($awsCompleter.Name -notlike '*.exe' ) {
        $f = { python $awsCompleter.Source }
    }
    else {
        $f = { & $awsCompleter.Name }
    }
    Register-ArgumentCompleter -Native -CommandName aws -ScriptBlock {
        param($wordToComplete, $commandAst, $cursorPosition)
        if ("$commandAst" -eq 'aws') {
            # complement the deleted space so that aws_completer lists all services.
            $compLine = "$commandAst "
        }
        else {
            $compLine = $commandAst
        }
        $env:COMP_LINE = $compLine
        $env:COMP_POINT = $cursorPosition
        & $f | ForEach-Object {
            [System.Management.Automation.CompletionResult]::new($_, $_, 'ParameterValue', $_)
        }
        Remove-Item env:\COMP_LINE
        Remove-Item env:\COMP_POINT
    }
}