Transform absolute "external" links in internal links between pages, based on a base URL

This issue is about automatically detecting links to the current wiki that have been added in the wiki as regular "web" links (by copy-pasting from the URL bar of the browser), and transforming these in internal links.
Currently, upon import, these links remain external links that point to the ancient confluence wiki that is the source of the data that was imported.

The 2 types of external links that I identified so far are:

http(s)://<wiki domain>/display/<spacename>/<pagename>
http(s)://<wiki domain>/pages/viewpage.action?pageId=<pageId>

Of course, the base URL should be passed as a parameter to the import process.