So I spent about 18 - 20 hours making this farm. I am also pretty sure there is no other auto huge tree farm on the internet, which was part of my inspiration to make it in the first place. Anyway, the whole system is powered by one lever labeled "Start", and the player has to place and grow the spruce saplings (works with normal sized trees, not sure about other large trees such as dark oak or jungle), everything else it automatic. All you have to do to turn it off is flick the lever again. I didn't add a collection system because I find those boring, but I did add a command block that teleports items to a hopper for collection