How to instruct a robot to cover the whole mapped 2D area?

Hello experts, I've been searching and trying to figure out how to implement a SLAM based coverage method using ROS on a Turtlebot, that in which the robot builds a map of its workplace and visits every unvisited area of the map (e.g. used floor cleaning applications). You can see what im trying to explain in the following video link:[SLAM based cleaning video](https://www.youtube.com/watch?v=hf1zY8vRC2E "SLAM based cleaning"). In theory, I know that I have to implement a mapping method (gmapping) to build the map and to Transform robot's Pose to /map and save them or assign a higher cost to the visited areas on the map. - I don't know how to instruct or set different dynamically changing goals in the path planner node(s) for the robot to go over unvisited areas in order to give me a complete coverage of the mapped area. (as you could see in the video) Any ideas or pointing me to the correct direction would be highly appreciated. ps: i'm not a pro programmer but i know my way around it. Cheers.