How to sent email notification when customer subscribed to the out of stock product?

[trace]

How to do email notification after customer subscribed to the out of stock product?
 
File: https://github.com/PrestaShop/mailalerts/blob/master/controllers/front/actions.php
 
Why this code is not work?
 

if ($mail_alert->add() !== false) {
        die('1');

            $product_name = Product::getProductName($id_customer);
            $shop_email = '[email protected]';
            $shop_name = Configuration::get('PS_SHOP_NAME');
            $dir_mail = dirname(__FILE__).'/../../mails/';
            $template_vars = array(
                '{customer_email}' => $customer_email,
                '{product_name}' => $product_name
            );

            Mail::Send(
                $id_lang,
                'new_oos',
                Mail::l('New request of product', $id_lang),
                $template_vars,
                (string)$shop_email,
                null,
                (string)$shop_email,
                (string)Configuration::get('PS_SHOP_NAME', null, null, $id_shop),
                null,
                null,
                $dir_mail,
                false,
                $id_shop
            );

    } else {
        die('0');
    }
}

P.S: Email templates (new_oos.html and new_oos.txt) added to the mailalerts/mails/en/ folder.

Edited July 26, 2017 by trace (see edit history)

[trace]

Up. Please! Can anybody help?

[trace]

up

[DataKick]

 

you prematurely terminate the first if branch by die(1) - your code is equivalent to this

if ($mail_alert->add() !== false) {
  die('1');
} else {
  die('0');
}

Edited August 6, 2017 by DataKick (see edit history)

[trace]

you prematurely terminate the first if branch by die(1).

OMG...   

Thank you!