Upgrade Block powershell function

function upgrade()
{
    $global:n = $n + 1;
    $blockName = $args[0];
    $uItem = $args[1][0];
    $uCount = $args[1][1];
    $uHits = $args[1][2];
    $uNext = $args[1][3];
    $blockPath = "/blocks/block[@name='"+$blockName+"']";
    $upgrdPath = $blockPath+"/property[@class='UpgradeBlock']";
    $block = $xml.SelectSingleNode($blockPath);

    if($block)
    {
        $upgradeClass = $xml.SelectSingleNode($upgrdPath);
        if($upgradeClass -eq $null)
        {
            $upgradeClass = $block.AppendChild($xml.CreateElement("property"));
            $upgradeClass.SetAttribute("class", "UpgradeBlock");
        }
        if($uNext -ne 0)
        {
            $ToBlock = $xml.SelectSingleNode($upgrdPath+"/property[@name='ToBlock']");
            if($ToBlock -eq $null){ $ToBlock = $upgradeClass.AppendChild($xml.CreateElement("property"));}
            $ToBlock.SetAttribute("name", "ToBlock");
            $ToBlock.SetAttribute("value", $uNext);
        }
        if($uItem -ne 0)
        {
            $Item = $xml.SelectSingleNode($upgrdPath+"/property[@name='Item']");
            if($Item -eq $null){ $Item = $upgradeClass.AppendChild($xml.CreateElement("property")); }
            $Item.SetAttribute("name", "Item");
            $Item.SetAttribute("value", $uItem);
        }
        if($uCount -ne 0)
        {
            $ItemCount = $xml.SelectSingleNode($upgrdPath+"/property[@name='ItemCount']");
            if($ItemCount -eq $null){ $ItemCount = $upgradeClass.AppendChild($xml.CreateElement("property")); }
            $ItemCount.SetAttribute("name", "ItemCount");
            $ItemCount.SetAttribute("value", $uCount);
        }
        if($uHits -ne 0)
        {
            $UpgradeHitCount = $xml.SelectSingleNode($upgrdPath+"/property[@name='UpgradeHitCount']");
            if($UpgradeHitCount -eq $null){ $UpgradeHitCount = $upgradeClass.AppendChild($xml.CreateElement("property")); }
            $UpgradeHitCount.SetAttribute("name", "UpgradeHitCount");
            $UpgradeHitCount.SetAttribute("value", $uHits);
        }
    }
}