Is what happened considered a wet dream or masturbation, and does it invalidate the fast?

Istisna' is the act of causing semen to be emitted. Scholars define it as the emission of semen without intercourse, whether by hand or otherwise. Ibn Hajar al-Haytami defined it as the emission of semen without intercourse, whether it is forbidden, such as emitting it with one's hand, or permissible, such as emitting it with one's wife's hand. The Fiqh Encyclopedia mentions that istimna' can occur by hand, or by other forms of direct contact, or by looking, or by thinking. If the emission of semen is caused by touching or friction while you are awake, it is istimna' and invalidates the fast. However, if semen is emitted without any action on your part, but merely by thinking or preoccupation, it does not invalidate the fast. If you are not awake, this is not istimna' but rather a wet dream (ihtilam), and a wet dream does not invalidate the fast.