Is ghusl obligatory and the fast to be completed, or is the fast to be completed without ghusl, or is it permissible to break the fast, if a fasting person has a wet dream but sees no discharge?

If a fasting person experiences a wet dream but does not see traces of semen, ghusl is not obligatory for him, nor is his fast invalidated. This is because a wet dream occurs without the fasting person's choice. Ghusl becomes obligatory if semen is discharged, and his fast remains valid.