How can I make an entity shoot a projectile at it's target ONLY if the target is not reachable?

I'm trying to make a boss that both has a melee attack and also shoots projectiles when the target is far away enough, but when I enable projectiles, it just shoots them regardless of how close or far away it is. The target can literally be 2 block away and it will still shoot projectiles. Is there a way to achieve this?