If you’d like to use an ESP8266 for your project, my ST_Anything library may be of help. It actually supports the ESP01 as a stand-alone controller with 2 digital pins. ST_Anything actually has support already for the photoresistor you showed above, but as an analog illuminance sensor. You should be able to tie it to a digital pin as well, and then use a “contact sensor” device to monitor that pin.