How to get Product Name from Opportunity using Groovy

I have a requirement to concatenate Account Name + Product Name as Opportunity Name in Opportunity creation page. I use BeforeInsert object trigger for this. I can get the Account name but I find it hard to get the Product name when I select a product item in the name field.

Please modify my groovy script, as this get the first existing element (product) not the product I selected.

// Set Opportunity Name to Account Name + Product

def voProduct = newView('Product');

def vcProduct = voProduct.createViewCriteria();

def vcrProduct = vcProduct.createRow();

vcProduct.insertRow(vcrProduct);

voProduct.appendViewCriteria(vcProduct);

voProduct.executeQuery();

def prodName = voProduct.first()?.getAttribute('Name');