Is the emission of semen after forbidden thoughts during sleep, and without the usual lustful foreplay, considered a wet dream or masturbation?

If semen is discharged involuntarily and not due to masturbation, there is no sin. However, one must beware of conjuring up sexual fantasies and indulging in them. It is advisable to guard one's thoughts and to ponder upon what benefits one in matters of religion and worldly life.