Prestashop 1.7 check available stock at final order step - prestashop

Question

I had something working on Prestashop 1.6 to check cart quantities before the customer can buy. Here is my problem on Prestashop 1.7 :
If a customer put an item in his cart today, he comes back in 2 days and he is still logged in. The cart is still available while the product, in reality, became out of stock.
The customer can make the order and the quantity in my stock is -1. Since I upgraded to prestashop 1.7 it's a disaster, I have quantities at -5, -10...because if this non-checked scenario.
abstract class PaymentModule extends PaymentModuleCore
{
public function validateOrder($id_cart, $id_order_state, $amount_paid, $payment_method = 'Unknown',
$message = null, $extra_vars = array(), $currency_special = null, $dont_touch_amount = false,
$secure_key = false, Shop $shop = null)
{
if (!isset($this->context))
$this->context = Context::getContext();
$this->context->cart = new Cart($id_cart);
if (!$this->context->cart->checkQuantities()){
Tools::redirect(__PS_BASE_URI__.'order.php?step=0');
}
return parent::validateOrder($id_cart, $id_order_state, $amount_paid, $payment_method, $message,
$extra_vars, $currency_special, $dont_touch_amount, $secure_key, $shop);
}
}

Answer 1

Actually the best solution is to use this addons : https://addons.prestashop.com/en/stock-supplier-management/21707-temporary-product-reservation-lonely-stock.html
Prestashop handles really bad cart stocks.
Anyway if you want to do it yourself and check stock available it's pretty simple :
<?php
$cart = $this->context->cart;
$cart_products = $cart->getProducts();
if (!empty($cart_products)) {
$db = Db::getInstance();
foreach ($cart_products as $key => $cart_product) {
$real_quantity = StockAvailable::getQuantityAvailableByProduct($cart_product['id_product'], $cart_product['id_product_attribute']);
if ( (int) $real_quantity < (int) $cart_product['quantity'] ) {
// If negative
$real_quantity = (int) $real_quantity < 0 ? 0 : $real_quantity;
$sql = '
UPDATE `'._DB_PREFIX_.'cart_product`
SET quantity = '.(int) $real_quantity.',`date_add` = NOW()
WHERE `id_product` = '.(int) $cart_product['id_product'].
(!empty($cart_product['id_product_attribute']) ? ' AND `id_product_attribute` = '.(int) $cart_product['id_product_attribute'] : '').'
AND `id_cart` = '.(int) $cart->id;
$db->execute($sql);
}
}
// Garbage collector
$db->execute('DELETE FROM '._DB_PREFIX_.'cart_product WHERE quantity < 1 ');
}