You will have to build up some complex expressions and the Calculator UI is not your friend.
For such things I do a lot of cut, try, copy, paste using an external text editor window, saving the "chunks" that worked. And to that, if you can't Print an expression you aren't done with that "chunk" or ready to integrate into the full expression.
You will need "cross" (to get time from v(t)) and "value" to get I(t) from time arg you just pulled. Then rack 'em up.
If you have working Calculator expressions then you are getting close to being able to Ocean-script a more effective solution but I managed to resist learning anything about Ocean except that I wanted to know nothing about it, for a couple of decades.