Can a restaurant tenant with no insurance sue a landlord?

My dad has rented the restaurant for over 10 years, pays $3,600 a month, and the landlord still hasn’t fixed the roof leaks that soak the kitchen every time it rains, causing ongoing business losses and unsafe conditions. The landlord has sent people out before, but the repairs are never complete, and the leaks always return. The place has no insurance, he believes; that's why he's trying to see what can be done by finding him a lawyer and getting this concern answered. Looking to get a response asap.