add_action( 'woocommerce_email_after_order_table', 'add_payment_method_to_admin_new_order', 15, 2 );

/**
 * Add used coupons to the order confirmation email
 *
*/
function add_payment_method_to_admin_new_order( $order, $is_admin_email ) {
	
	if ( $is_admin_email ) {
	
		if( $order->get_used_coupons() ) {
		
			$coupons_count = count( $order->get_used_coupons() );
		
		    echo '<h4>' . __('Coupons used') . ' (' . $coupons_count . ')</h4>';
		     
		    echo '<p><strong>' . __('Coupons used') . ':</strong> ';
		    
		    $i = 1;
		    $coupons_list = '';
		    
		    foreach( $order->get_used_coupons() as $coupon) {
		        $coupons_list .=  $coupon;
		        if( $i < $coupons_count )
		        	$coupons_list .= ', ';
		        $i++;
		    }
		
		    echo '<p><strong>Coupons used (' . $coupons_count . ') :</strong> ' . $coupons_list . '</p>';
		
		} // endif get_used_coupons
	
	} // endif $is_admin_email
}



add_action( 'woocommerce_admin_order_data_after_billing_address', 'custom_checkout_field_display_admin_order_meta', 10, 1 );

/**
 * Add used coupons to the order edit page
 *
*/
function custom_checkout_field_display_admin_order_meta($order){

    if( $order->get_used_coupons() ) {
    
    	$coupons_count = count( $order->get_used_coupons() );
    
        echo '<h4>' . __('Coupons used') . ' (' . $coupons_count . ')</h4>';
         
        echo '<p><strong>' . __('Coupons used') . ':</strong> ';
        
        $i = 1;
        
        foreach( $order->get_used_coupons() as $coupon) {
	        echo $coupon;
	        if( $i < $coupons_count )
	        	echo ', ';
	        $i++;
        }
        
        echo '</p>';
    }

}