Given its location close to the Middle East and Russia, its size, its shaky commitment to liberal democratic values, and its predominantly Muslim population, Turkey was always going to be both an important and a difficult NATO ally. Today, as a result of Erdogan’s authoritarian leanings, it is particularly so.
There are essentially two ways to deal with Erdogan: give him what he wants; or cut him off at the knees. Donald Trump doesn’t appear to be capable of doing either of those things consistently.
Trump’s enthusiasm for strongmen would suggest that Erdogan should be his friend. That does appear to be his inclination; however, the right-wing base doesn’t much care for Erdogan, so Trump frequently changes course and makes flamboyant public threats upon which he has no real interest in delivering. Erdogan has learned how to play this game; he basically ignores Trump and does whatever he wants.
So where does the blundering end? I don’t know, but it’s nowhere good.