param( 
    [string]$url
)

function Add-Custom-Action($web)
{
    Write-Host "Add custom action on" $web.Url -foregroundcolor green
    $actions = $web.UserCustomActions
    $contains = $false
    foreach ($a in $actions)
    {
        if ($a.ScriptSrc.ToLower() -eq "/_layouts/15/taloyhtio/scripts/freshchat.js")
        {
            $contains = $true
            break
        }
    }

    if ($contains)
    {
        Write-Host "    Custom action is already added" -foregroundcolor yellow
        return
    }

    $action = $web.UserCustomActions.Add()
    $action.Location = "ScriptLink"
    $action.ScriptSrc = "/_layouts/15/taloyhtio/scripts/freshchat.js";
    $action.Sequence = 10010
    #$action.ScriptBlock = null
    $action.Update();
}

if (-not $url)
{
    Write-Host "Specify web url in url parameter" -foregroundcolor red
    return
}

$web = Get-SPWeb $url
Add-Custom-Action $web