;;; -*- lexical-binding: t -*-
;;
;; -----------------------------------------------------------------------------
;; this file: https://dataswamp.org/~incal/bad-el/src/bad-sdl2/bad-sdl2.el
;; -----------------------------------------------------------------------------

(require 'cl-lib)
(cl-pushnew "."  load-path :test #'string=)
(cl-pushnew ".." load-path :test #'string=)
(require 'luki-lisp)

(-> 'bad-ecs)

(let ((dm "bad-sdl2.so"))
  (load dm nil t)
  (declare-function draw_init  dm)
  (declare-function draw_quit  dm)
  (declare-function draw_frame dm))

(defun bad-grid-string ()
  (cl-loop
   for s across-ref ecs-grid
   concat (concat s "\n") into str
   finally return str))

(defun bad-grid-string-set-to-buffer ()
  (cl-loop
   with lines   = (--- ecs-grid)
   with buf-str = (take lines
                        (split-string
                         (buffer-substring-no-properties (point-min) (point-max))
                         "\n"))
   for b in buf-str
   for s across-ref ecs-grid
   do (setf s b)))

;; (bad-grid-string-set-to-buffer) ecs-grid

(defun bad-grid-string-hash ()
  (benchmark (secure-hash 'sha256 (or (bad-grid-string) ""))))

(defun hz ()
  (let ((current-time-list nil))
    (cdr (time-convert nil nil))))

(defun time-now ()
  (let ((current-time-list nil))
    (1st (time-convert nil nil))))

(defun sdl2-fps ()
  (ecs-init)
  (about-emacs)
  (draw_init)
  (cl-loop
   with fps     = 60
   with hz      = (hz)
   with ticks   = (/ hz fps)
   with frames  = (** 2 12)
   with beg     = (time-now)
   with hline   = (make-string 80 46)
   with slp     = 0
   with tslp    = 0
   for  lne     = 0
   for f from 0 to frames
   for next = (+ beg (* (1+ f) ticks)) do
     (ecs-grid-clear)
     (bad-grid-string-set-to-buffer)
     (setf (aref ecs-grid     lne)  (@f "GNU Emacs %d.%d" emacs-major-version emacs-minor-version))
     (setf (aref ecs-grid (++ lne))     "dynamic module SDL2")
     (setf (aref ecs-grid (++ lne))     hline)
     (setf (aref ecs-grid (++ lne)) (@f "frame %d / %d (%d%%)" f frames (round (* 100 (// f frames)))))
     (setf (aref ecs-grid (++ lne))     hline)
     (setf (aref ecs-grid (++ lne)) (@f "fps (set to) %d" fps))
     (setf (aref ecs-grid (++ lne)) (@f "fps (actual) %.3f" (// (* hz f) (- (time-now) beg))))
     (setf (aref ecs-grid (++ lne))     hline)
     (setf (aref ecs-grid (++ lne)) (@f "surplus time / frame: %.3f seconds" (// tslp (1+ f))))
     (draw_frame)
     (setf slp (// (- next (time-now)) hz))
     (incf tslp slp)
     (sleep-for slp)
   finally (sleep-for 4) (draw_quit)))

(defun sdl2-solar ()
  (cl-loop
   with emacs  = (selected-frame)
   with run    = t
   with fps    = 60
   with hz     = (hz)
   with ticks  = (/ hz fps)
   with frames = (** 2 12)
   with beg    = (time-now)
   initially
     (ecs-solar-init)
     (draw_init)
     ;; BEG ugly hack to maintain keys
     ;; (set-frame-parameter nil 'alpha-background 0.0)
       (setq mode-line-format nil)
       (discard-input)
       (select-frame-set-input-focus emacs)
     ;; END
   for f from 0 to frames
   for next = (+ beg (* (1+ f) ticks))
   while run do
     (pcase (& (input-pending-p) (read-event))
       ((or ?q 13)  (setf run    nil))
       ((or ?d ?l)  (ecs-solar-camera-move-right))
       ((or ?a ?j)  (ecs-solar-camera-move-left))
       ((or ?r ?p)  (ecs-solar-camera-move-up))
       ((or ?f ?\;) (ecs-solar-camera-move-down))
       ((or ?w ?i)  (ecs-solar-camera-move-forward))
       ((or ?s ?k)  (ecs-solar-camera-move-backward)))
     (ecs-solar-update-and-render)
     (draw_frame)
     (sit-for (// (- next (time-now)) hz))
   finally
     ;; (set-frame-parameter nil 'alpha-background 1.0)
     (draw_quit)))

(<- 'bad-sdl2)