How is (%of Xdmg as extra Ydmg) calculated

So..

Thing is, I am using lightning strike with physical to lightning gem, which means I have 100% dmg converted to lightning. Then I use hatred aura.. it adds a bunch of dmg.. and now, the question is.. why?

Is hatred aura calculated before - so my base physical damage which is then calculated for lightning strike itself is higher? If so.. is it then true, that when I use Atziris promise flask, Im also getting bonus chaos damage to base dmg before calculation for lightning strike begins? (in this case, it adds physical dmg to my LS, but elemental conversion is almost nonexistant, because I have almost no elemental dmg from other sources...)

Can someone shed some light and tell me how exacty this thing works? Ty

Added damage gets calculated before conversion happens. As far as I know that would mean that you get the bonus chaos damage from the physical base damage, but no % of elemental damage as extra chaos damage. Not entirely sure though, only about 70% sure.

Its intresting tho its probably answered alredy.
I think that suport gems on same link all effect the base skill, now for other sorces i suspect only final product is calculated.