I got fired today..help?

here`s my situation im living and working in ireland for 3 years now,paying my taxes and everything...2 months ago my boss informed me that i need a work permit (for being romanian)thing i never knew for sure since i had another job for 2 years where the same i worked with a contract and paying tax..my question is...could i face him in court for hireing me from the begining..he was supposed to know i need that permit ..and in the end fireing me for no reson except the work permit...by the way i was working as deli manager and i worked for this so hard to transform his shitty deli into something really decent and profitable ..and im so angry he just said to me he cant keep me because im romanian.