PowerShellでgigignore.ioから.gitignoreを作る & いい感じに補完する

gitignore_io.ps1

function gig() {
    param(
        [Parameter(Mandatory=$true)]
        [string[]]$list
    )
    $params = ($list | ForEach-Object { [uri]::EscapeDataString($_) }) -join ","
    Invoke-WebRequest -Uri "https://www.toptal.com/developers/gitignore/api/$params" | select -ExpandProperty content | Out-File -FilePath $(Join-Path -path $pwd -ChildPath ".gitignore") -Encoding ascii
}
Register-ArgumentCompleter -CommandName "gig" `
    -ParameterName "list" `
    -ScriptBlock {
        param($commandName, $parameterName, $wordToComplete, $commandAst, $fakeBoundParameter)
        $url = "https://www.toptal.com/developers/gitignore/api/list"
        $res = Invoke-WebRequest -Uri $url
        $list = $res.Content.Split(",`n".ToCharArray())
        $decidedIndex = $wordToComplete.LastIndexOf(",")
        if ($decidedIndex -gt 0) {
            $decided = $wordToComplete.Substring(0, $decidedIndex)
        } else {
            $decided = ""
        }
        foreach($item in $list)
        {
            if($item -notmatch $wordToComplete)
            {
                continue;
            }
            $completionText = $decided + $item
            [System.Management.Automation.CompletionResult]::new(
                $completionText, $item, 
                [System.Management.Automation.CompletionResultType]::ParameterValue,
                $item
            ); 
        }
    }