(* This program demonstrates how to build an application
   on top of the CIS 120 GUI library.  It assumes that
   the eventloop.ml*, gctx.ml*, and widget.ml* files
   are all present. *)

(* Create the state affected by the light switch *)
let switched_on : bool ref = ref false

(* Create a lightswitch button, initially labeled "ON " *)
let (on_button_w,l,n) =
   Widget.button "ON "

(* The action associated with clicking the switch. *)
let flip () : unit =
  switched_on := not (!switched_on);
  if !switched_on then
    l.Widget.set_label "OFF"     
  else
    l.Widget.set_label "ON "

(* Add the flip action as a mouseclick_listener *)
;; n.Widget.add_event_listener (Widget.mouseclick_listener flip)

(* Create the "QUIT" button *)
let (quit_button_w,_,n2) =
    Widget.button "QUIT"
    
(* The action associated with the QUIT button *)    
let quit () : unit =
   exit 0

(* Add the quit action as a mouseclick_listener *)
;;  n2.Widget.add_event_listener (Widget.mouseclick_listener quit)


(* Create the "lightbulb" canvas *)
let repaint_light (g:Gctx.t) : unit =
  if !switched_on then
    let g = Gctx.set_color g Gctx.yellow in
    Gctx.fill_rect g (0,100) (100,100)
  else
     ()

let (light,_) = Widget.canvas (100,100) repaint_light


(* Package all the pieces together into a root widget *)
let w : Widget.t =
  Widget.border (Widget.border (Widget.hpair 
    light
    (Widget.hpair (Widget.border on_button_w) 
		              (Widget.border quit_button_w)))) 

(* Start waiting for events *)
;; Eventloop.run w