Control Moisture and Temperature inside an outdoor security camera housing

I am building a security camera setup for mostly evening use. I have a weatherproof case to mount a camera inside. The camera has a clear plastic dome to see out of. The entire unit is to be placed outdoors. I want to heat and cool the inside of the housing to prevent the dome from steaming up and creating blurry images. Most security out door housings have built in fans and heaters in an attempt to control moisture.

I want you to design something that would turn the fan on at a predetermined temperature and the heat on when it becomes cold using available electronics? Lastly, can we make all of this adjustable?

Only experienced bidders please.