Magento – Email Notification On Low stock, Out of stock , Back to stock Magento 1.9

I want to create a stock alert where user can subscribe

product_alert_stock table in the database store details when user click on subscribe link.

Currently it sends on two conditions : On stock change and Price change.

I want to send email if stock goes below a fixed quantity.

For this i created an custom attribute namely send_mail_qty

It must send an email to the customer when a product is below a fixed quantity

i created a custom module and using event “
in config.xml

  <events>
      <cataloginventory_stock_item_save_after> <!-- identifier of the event we want to catch -->
        <observers>
          <cataloginventory_stock_item_save_after_handler> <!-- identifier of the event handler -->
            <type>model</type> <!-- class method call type; valid are model, object and singleton -->
            <class>customalert/observer</class> <!-- observers class alias -->
            <method>stockChange</method>  <!-- observer's method to be called -->
            <args></args> <!-- additional arguments passed to observer -->
          </cataloginventory_stock_item_save_after_handler>
        </observers>
      </cataloginventory_stock_item_save_after>
    </events>

In observer.php

        public function stockChange(Varien_Event_Observer $observer)
        {

             $arg_attribute          = 'send_mail_qty';
$attribute_model        = Mage::getModel('eav/entity_attribute');
$attribute_options_model= Mage::getModel('eav/entity_attribute_source_table') ;

$attribute_code         = $attribute_model->getIdByCode('catalog_product', $arg_attribute);
$attribute              = $attribute_model->load($attribute_code);

$attribute_table        = $attribute_options_model->setAttribute($attribute);
$options                = $attribute_options_model->getAllOptions();

            Mage::log( 'start');
            Mage::log( $options );
            // Mage::log( print_r($val) );

            Mage::log( 'end');


        }

}

But it gives me

2017-10-13T06:26:42+00:00 DEBUG (7): start
2017-10-13T06:26:42+00:00 DEBUG (7): Array
(
    [0] => Array
        (
            [label] => 
            [value] => 
        )

)

2017-10-13T06:26:42+00:00 DEBUG (7): end