API should have functions to compare cast time of spells and remaining duration of buffs. about protipper

[emiln]

It seems we prematurely closed this issue. Having tried to use it for Demonology, I have the following remarks:

• GetCastTime throws an error when querying a non-existing spell.
• RemainingDuration throws an error in all of the following cases:
  1. RemainingDuration("Curse of the Elements", "target") – with the target affected by it.
  2. RemainingDuration("Curse of the Elements", "target") – with the target not affected by it.
  3. RemainingDuration("Dark Intent", "player") – with the player not affected by it.

All errors are: (attempt to perform arithmetic on local 'expires' (a nil value))

In other words, it doesn't work at all for debuffs, and asking about a non-present buff or spell will throw an error. A null check will surely avoid the errors, but we may have to divide this into RemainingBuffDuration and RemainingDebuffDuration. I recall making exactly this choice for BuffActive and DebuffActive due to UnitAura acting up.