How can custom field modified in CREATE ISSUE page in JIRA via a pluggin

Jira Development
1

Here is my requirement -

In the create issue page i have created some CUSTOM DATE fields (END-DATE)and a duration field.I want to calculate the end-date custom field based on the start date and duration field provided by user while creating the issue.

Is there any way i can do this via a plugin.I am able to do this in the EDIT of an issue usinga plugin , but dont know how to get control over the CREATE-ISSUE PAGE and do the calculation via a plugin.

Any possible solution as much appreciated…Thanks in Advance.
Please help on this.