public function batchImportAllProductsFromFile($productsToBeInserted){
    foreach ($productsToBeInserted as $key => $customProduct ) {

        $productIDs = $this->getProductIDsByReference($customProduct->MS_CODMAG);
        if (sizeof($productIDs) == 0) {
            $product = new Product();
        } else if (sizeof($productIDs) == 1) {
            $product = new Product($productIDs[0]);
        } else {
            continue;
        }

        $product->reference = $customProduct->MS_CODMAG;
        $product->name = trim($customProduct->MS_DESCRIZIONE);
        $product->price = $customProduct->MS_PREZZO_1;
        $product->out_of_stock = ($customProduct ->MS_ESAURITO === "S" ? true : false);

        $category = null;

        $msGruppoConverted = $this->buildSubGroupCode($customProduct->MS_GRUPPO, $customProduct->MS_SGRUPPO);

        if ($customProduct->MS_GRUPPO !== 0 && $msGruppoConverted !== 0) {
            $product->id_category = [$customProduct->MS_GRUPPO, $msGruppoConverted];
        } else if ($customProduct->MS_GRUPPO === 0 && $msGruppoConverted !== 0) {
            $product->id_category = [$msGruppoConverted];
        } else if ($customProduct ->MS_GRUPPO !== 0 && $msGruppoConverted === 0) {
            $product->id_category = [$customProduct->MS_GRUPPO];
        }
        try {
            if (sizeof($productIDs) == 0) {
                if ($product->add()) {
                    $product->updateCategories($product->category);
                    $product->addFeatureProductImport($product->id, 1, $customProduct->MS_FAM);
                    //StockAvailable::setQuantity((int)$product->id, 0, $product->quantity, Context::getContext()->shop->id);
                }
            } else if (sizeof($productIDs) == 1) {
                if ($product->update()) {
                    $product->updateCategories($product->category);
                    $alreadySavedFeatures = $product->getFeaturesStatic($productIDs[0]);
                    if (sizeof($alreadySavedFeatures) != 1 || $alreadySavedFeatures[0] != $customProduct->MS_FAM) {
                        $product->deleteProductFeatures();
                        $product->addFeatureProductImport($product->id, 1, $customProduct->MS_FAM);
                    }
                }
            }
        } catch (Exception $e) {
            var_dump("Errore: ", $e, $product);
        }
    }
}

<?php

class myProductImporter {
    protected $products;
    protected $products_checksum;

    public function __construct($products) {
        // Your products from the csv file
        $this->products = $products;
        // Here you get an associative array of products references and checksums
        // ex: array('REF01158' => '489f9ze4f4ze9f49ze8', 'REF15616' => '48949844561233132')
        $this->products_checksum = getProductsChecksum();
    }

    public function run() {
        foreach ($this->products as $product) {
            // If the product ref is present in my checksum list, then its an update
            if (isset($this->products_checksum[$product['reference']])) {
                // If the checksum is different, the product needs an update
                if ($this->products_checksum[$product['reference']] != $this->getChecksum($product)) {
                    $this->updateProduct($product);
                }
            // Else it's a new product
            } else {
                $this->addProduct($product);
            }
        }
    }

    protected function updateProduct($product) {
        $PSProduct = getProductByReferebce($product['reference']);
        // Update your product and save its new checksum
    }

    protected function addProduct($product) {
        $PSProduct = new Product();
        // Create the product and save its checksum
    }

    protected function getChecksum($product) {
        // Create a string containing all your product properties
        $checksum = $product['reference'];
        $checksum .= $product['name'];
        $checksum .= $product['description'];
        $checksum .= $product['id_category'];
        return md5($checksum);
    }
}