How can I use the XP bar as a mana bar in a datapack?

I'm making a magic-themed datapack in Minecraft Java Edition (1.21.1),
and I want to use the XP bar as a mana bar.
I’m not sure how to control the XP bar correctly or how to link it with a scoreboard.
If anyone knows a reliable way to:
use XP levels or XP progress as a mana value
update the XP bar based on a scoreboard
reduce or increase mana during skills
set a maximum mana value
please tell me how to do it.
Any examples or command snippets would be extremely helpful.
Thanks in advance!