Great morning guys!
You helped me out recently and I'm so happy about it. However, today I received some powerbank and because of the circuits preventing over-charge, over-discharge and so on, I decided to rather not touch it.
I made some circuit using logic gates, which, hopefully, should work.I should really explain it (the app doesn't have some features, so...).

 

The switches are there like that, because when I turn the switch on, it should start charging. When switched off, it should discharge. The X is representing the battery. The violet/blue wire is the OUTput, the green one is INput into the battery.