;;;; raylib [core] example - window should close
;;;;
;;;; examples/core/core_window_should_close.c. Needed set-exit-key, and one
;;;; enum member to go with it: raylib.flan's `Key` now has `null 0`, read off
;;;; KEY_NULL in raylib.h. The binding is hand-written rather than taken from
;;;; the generated half because the Flan face differs — raylib declares
;;;; `void SetExitKey(int key)` and the generated line therefore takes an i32,
;;;; where this one takes a Key, so `(rl/set-exit-key :null)` is checked
;;;; against the enum and `:nul` is a compile error instead of a 0.
;;;;
;;;; The whole example is about what window-should-close? means. It is not a
;;;; flag raylib latches: it is "the close button was clicked, or the exit key
;;;; is down", recomputed each frame, and it goes back to false on its own.
;;;; That is what lets this program ask for confirmation and then carry on —
;;;; and it is also why the loop is driven by a `defvar` of its own rather
;;;; than by the predicate, which is the one structural difference from every
;;;; other example in this directory.
;;;;
;;;; `(set-exit-key :null)` takes ESC away from raylib so the program can read
;;;; it itself. The window's X button still works and is still what
;;;; window-should-close? reports.

(import rl "vendor:raylib")

(defconst screen-width  800)
(defconst screen-height 450)

(defvar exit-requested bool)
(defvar exiting bool)

(defn main [] ()
  (rl/init-window screen-width screen-height
                  "raylib [core] example - window should close")
  (defer (rl/close-window))

  ;; No key closes the window any more. ESC is an ordinary key from here on.
  (rl/set-exit-key :null)

  (rl/set-target-fps 60)

  (until exiting
    ;; Update. Either way of asking to leave raises the question; only Y and N
    ;; answer it. window-should-close? is false again on the next frame, so
    ;; the request has to be remembered in a variable.
    (when (or (rl/window-should-close?) (rl/key-pressed? :escape))
      (set exit-requested true))

    ;; The C's `if (Y) ... else if (N) ...`, which is an `if` with a `when`
    ;; in its else and not a `cond`: a `cond` needs an `:else` arm and there
    ;; is nothing to do when neither key was pressed.
    (when exit-requested
      (if (rl/key-pressed? :y)
        (set exiting true)
        (when (rl/key-pressed? :n) (set exit-requested false))))

    ;; Draw
    (rl/begin-drawing)
    (rl/clear-background rl/raywhite)

    (if exit-requested
      (do
        (rl/draw-rectangle 0 100 screen-width 200 rl/black)
        (rl/draw-text "Are you sure you want to exit program? [Y/N]" 40 180 30
                      rl/white))
      (rl/draw-text "Try to close the window to get confirmation message!"
                    120 200 20 rl/lightgray))

    (rl/end-drawing)))