;;; -*- lexical-binding: t -*-
;;
;; --------------------------------------------------------------------------

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

;; --------------------------------------------------------------------------

(-> 'bad-color)
(-> 'bad-helpers)

;; --------------------------------------------------------------------------

(let* ((p1 (* 9 (** 2 -4)))
       (p2 (- 1 p1))
       c1-last r1 g1 b1 c2-last r2 g2 b2
       r g b res)
  (defun bad-blend (c1 c2)
    (let ((c1-alike (s= c1-last c1))
          (c2-alike (s= c2-last c2)))
      (unless (& c1-alike c2-alike)
        (cl-flet ((clp (c) (min 255 (max 0 c))))
          (unless c1-alike
            (setq c1-last c1)
            (pcase-let ((`(,re ,gr ,bl) (mapcar (L (c) (clp (* c p1))) (bad-color-values c1))))
              (setq r1 re)
              (setq g1 gr)
              (setq b1 bl)))
          (unless c2-alike
            (setq c2-last c2)
            (pcase-let ((`(,re ,gr ,bl) (mapcar (L (c) (clp (* c p2))) (bad-color-values c2))))
              (setq r2 re)
              (setq g2 gr)
              (setq b2 bl)))
          (setq r (clp (+ r1 r2)))
          (setq g (clp (+ g1 g2)))
          (setq b (clp (+ b1 b2)))
          (setq res (@f "#%.2x%.2x%.2x" r g b))))
      res)))

(declare-function bad-blend nil)

;; --------------------------------------------------------------------------

(defun test-bad-blend ()
  (let ((n (** 2 12)))
    (// (bad-timing
         (cl-loop
          repeat n
          for c1 = (bad-bg-random)
          for c2 = (bad-fg-random) do
          (bad-blend c1 c2)))
        n)))

(defun test-bad-80x30 ()
  (bad-timing
   (let ((n (* 80 30)))
     (cl-loop
      repeat n
      for c1 = (bad-bg-random)
      for c2 = (bad-fg-random) do
      (bad-blend c1 c2))))) ; (test-bad-80x30)

;; Worst-case scenario drawing blending for every char in a 80x30 terminal.
;; Note: With byte-compilation on, native-compilation not available on OpenBSD.
;;
;; (@f "%.2f s"        (* 80 30 (test-bad-blend)))  ; 0.13 s
;; (@f "%.2f FPS" (/ 1 (* 80 30 (test-bad-blend)))) ; 7.69 FPS
;;
;; Oh, no! Too slow.
;;
;;   --------------------------------------------
;;    FPS  where
;;   --------------------------------------------
;;     24  cinema movies
;;     30  old games
;;     60  modern consoles (e.g., PS5)
;;    120  eSport competitive players
;;    240  eSport challengers
;;    360  eSport champions
;;   --------------------------------------------
;;    https://www.gpumag.com/good-fps-for-gaming
;;   --------------------------------------------

(<- 'bad-blend)