Well i guess you can do wait 0.0 set oldx and oldy to current x and current y
then trigger on player overlap wall, if oldx is less than the wall's x, it means the player came from the left so set the player'S position to like wall.x - ( wall.width/2 + payer.width/2 ) to put the player at the edge of the wall on the left or seomthing
You can do anything you want