<?php

    include_once('C:/xampp/htdocs/magento/app/Mage.php');

    Mage::app();
    $rootMagento = mage::getBaseDir();
    $files = scandir($rootMagento);
    $count = sizeof($files);
    for ($i =0; $i< $count; $i++) {
        if ($files[$i]=='productData.txt'){
            $fileAperto = fopen($files[$i], "r");
            $buffer = fread($fileAperto,filesize("productData.txt"));
            list($sku, $name, $description, $shortDescription, $price) = split("[n]", $buffer);
            if ($sku == '' || $name == '' || $description == ''
                || $shortDescription == '' || $price == '') {
                mage::log('esportazione non corretta: manca uno dei dati');
            }
            fclose($fileAperto);
        }
    }

    //// prodotto ////

    $product_model = mage::getModel('catalog/product');

    $productId = $product_model->getIdBySku($sku);
    if (!$productId){
        //inserimento
        $productData = array ('sku' => $sku,
                              'name' => $name,
                              'description' => $description,
                              'short_description' => $shortDescription,
                              'status' => 0,
                              'visibility' => 0
                              );

        $product_model->setData($productData);
        try{
            $productId = $product_model->save()->getId();
            $product = $product_model->load($productId);
            $product->setQty($qty);
            $product->setIsInStock(1); //->isInStock(1)
            $product->save();
        }catch(Exception $e){
            mage::log($e->getMessage());
        }

    }else{
        //aggiornamento
        $product = $product_model->load($productId);
        // $productData... ... ..
        $product->setData($productData); // + codice x stock
    }