Why is Turkey Taking in so Many Syrian refugees?

The UN can´t stop praising the Turkish government for hosting around 2 million Syrians. The Turks have indeed been generous, more than any other country in the region. Actually, too generous. Why is Ankara so keen to help the Syrians fleeing into Turkey?
This “generosity” is actually not that generous. The Turkish government has strong reasons to want the Syrians in.