Garrison Invasion check?

[siweia]

I am currently working on an infobar that may tell someone has already earned the invasion rewards and killed the dreanor world bosses or not.
I got the idea from the "World Boss Status", used the "IsQuestFlaggedCompleted(xxx)" to check the status. But the problem for now, I do not know how to find the right quest id for the rewards.
What would be the right way to do so?

[Lombra]

I'm guessing these.