I modeled the chair in Rhino using image references, once I got the curves needed in place, I used network of curves, sweep, and surface from 3,4 curves to creat4e surfaces. Then I offset surfaces to give it a thickness and filleted necessary parts.
Then I used grasshopper to get the following results
Elongate base into a day bed
Extend Sides
Control Angle of the base
GIF s are below click to play!
Parametrics 