Different action depending on state of light

I have a "button" like switch in the wall. I also have a Shelly Duo RGBW light bulb. I would like to turn on the light if it is off or turn off the light if it is on - both by the same action (button press). I managed to configure turning on the light, by sending a simple HTTP request, but turning off requires checking the current state of the bulb. I have no clue on how to configure this approach. Can someone please guide me through?