Villager Happiness System

Lots of people trap villagers so they don't leave their workstations, but it seems kind of broken and kind of wrong, so maybe they could have a happiness system where if you trade with them a lot and help them, you'll get better prices and better trades, and they'll be less likely to leave their workstation? But if you trap them or get them killed by a zombie and cure them over and over they'll be less likely to keep their trades? (I'm not sure how the detection would work for the zombie villager one though)