Restrict Page Creation Based on Condition

[Sady_Rifat]

Hello,
I have a requirement to restrict page creation based on some conditions.

For Example,
When an author wants to create a page I need to check some validity from my Java code

As soon as I found anything wrong I need to restrict the author from creating the page and show some error. (This error could be the exception message).

For this, I tried implementing EventListener, but Event is triggered after the page creation.

public JackrabbitEventFilter createPageEvent (String path) {
        JackrabbitEventFilter jackrabbitEventFilterPage = new JackrabbitEventFilter();

        return jackrabbitEventFilterPage.setAbsPath(path)
                .setEventTypes(Event.NODE_ADDED)
                .setIsDeep(true)
                .setNodeTypes(new String[]{NT_PAGE, NT_TAG});
    }

In the OnEvent I throw an exception,

@Override
public void onEvent(EventIterator events) {
    throw new AccessControlException("Restricted");
    // Or any kind of exception
}

But this is not working. 

How I can achieve this?
Note: I also need to get the page properties that are filled up by the author.

[SivakumarKanoori]

@Sady_Rifat :Instead of writing the event listener .Can you try below. 

in the create page wizard, the below validation happens from the below validations.js file . You can write your validation in the below JS file.

JS file location: /libs/cq/gui/components/siteadmin/admin/clientlibs/validations/js/validations.js

SO its better to overlay and customize this js file instead of writing event listener.

[Sady_Rifat]

Using clientlib is possible. But the requirement is to use Java directly. If it's not possible to solve by Java directly then I will go for the clientlib solution.