woocommerce test coupon code in a specific function

Inside my plugin specific function, i would like to test the ID of my coupon code.

If the coupon used by the customer is this ID do this ... else do this ...

I never develop with the woocommerce set-up and this need is realy simple.

Could you help me ?

Here is my function :

Note : sg_enable_order_approval == enable means All order is need admin approval sg_enable_order_approval == disable means enable plugin for per product

function sgitsoa_paymentgatways_disable_manager( $available_gateways )
    {
        global $woocommerce;
        $allowed_gateways  = array();  
        $sg_product_enable = false;
        
        
        if(is_admin()) {
            return $available_gateways;
        }
            

        // check cart for any product which enable product approval
        
        if(get_option('sg_enable_order_approval')=='disable' ) { // plugin activate for per product
                        
                     
            $items = $woocommerce->cart->get_cart();

            foreach($items as $item => $values) { 
                $_product =  wc_get_product($values['data']->get_id()); 
                                    
                                    
                if(get_post_meta($values['product_id'], 'sg_product_enable', true)=='yes') {
                    $sg_product_enable = true;
                }
                                    
            } 
        }                

                  

    // Check all products in cart. If any of the product require confirmation please make order approval.



        if(get_option('sg_enable_order_approval')=='enable' || $sg_product_enable==true ) {

            if(is_checkout() && isset($available_gateways['sgitsoa_gateway']) && !is_wc_endpoint_url('order-pay') ) {
                     
                $allowed_gateways['sgitsoa_gateway'] = $available_gateways['sgitsoa_gateway'];
                return $allowed_gateways;
            }
            
            if(is_wc_endpoint_url('order-pay') && isset($available_gateways['sgitsoa_gateway']) ) {     
                
                unset($available_gateways['sgitsoa_gateway']);
                return $available_gateways;
            }
        }
                    //
                    
                if($sg_product_enable==false) {
                    unset($available_gateways['sgitsoa_gateway']);
                }          

                     return $available_gateways;
   
    }

}

'''