(ns glimmer-gfx.raster
  "Software rasterizer over an int-array of 0xRRGGBB. Nothing here knows what
   a window is -- and nothing here calls into Java. aget/aset/int-array/abs are
   all clojure.core; the ^ints/^long hints are hints, not calls."
  (:require [clojure.string :as str]))

(defrecord Buf [^ints px ^long w ^long h])

(defn buf [w h] (->Buf (int-array (* w h)) w h))

(defn clear [{:keys [^ints px]} ^long c]
  (let [c (int c)] (dotimes [i (alength px)] (aset px i c))))

(defn px!
  [{:keys [^ints px ^long w ^long h]} ^long x ^long y ^long c]
  (when (and (>= x 0) (< x w) (>= y 0) (< y h))
    (aset px (unchecked-add (unchecked-multiply y w) x) (int c))))

(defn rect!
  "Filled, clipped."
  [{:keys [^ints px ^long w ^long h]} x0 y0 rw rh c]
  (let [x1 (min w (+ x0 rw)) y1 (min h (+ y0 rh))
        c (int c)]
    (loop [y (max 0 y0)]
      (when (< y y1)
        (let [row (unchecked-multiply y w)]
          (loop [x (max 0 x0)]
            (when (< x x1)
              (aset px (unchecked-add row x) c)
              (recur (inc x)))))
        (recur (inc y))))))

(defn line!
  "Bresenham. ponytail: no AA -- add Wu's if the jaggies bother you."
  [b x0 y0 x1 y1 c]
  (let [dx (abs (- x1 x0)) dy (- (abs (- y1 y0)))
        sx (if (< x0 x1) 1 -1) sy (if (< y0 y1) 1 -1)]
    (loop [x x0 y y0 err (+ dx dy)]
      (px! b x y c)
      (when-not (and (= x x1) (= y y1))
        (let [e2 (* 2 err)]
          (recur (if (>= e2 dy) (+ x sx) x)
                 (if (<= e2 dx) (+ y sy) y)
                 (cond-> err (>= e2 dy) (+ dy) (<= e2 dx) (+ dx))))))))

(defn poly!
  "Closed wireframe through [x y] points. Vector art is lines, so this is the
   whole of it. ponytail: outline only -- a filled polygon needs a scanline
   pass, add one when something actually has to be solid."
  [b pts c]
  (doseq [[[x0 y0] [x1 y1]] (map vector pts (concat (rest pts) [(first pts)]))]
    (line! b (int x0) (int y0) (int x1) (int y1) c)))

;; ------------------------------------------------------------------ 3x5 font
;; Authored as strings so a glyph is readable and fixable in place.

(def ^:private glyphs
  (->> ["A.#.|#.#|###|#.#|#.#"  "B##.|#.#|##.|#.#|##."  "C.##|#..|#..|#..|.##"
        "D##.|#.#|#.#|#.#|##."  "E###|#..|##.|#..|###"  "F###|#..|##.|#..|#.."
        "G.##|#..|#.#|#.#|.##"  "H#.#|#.#|###|#.#|#.#"  "I###|.#.|.#.|.#.|###"
        "J..#|..#|..#|#.#|.#."  "K#.#|#.#|##.|#.#|#.#"  "L#..|#..|#..|#..|###"
        "M#.#|###|###|#.#|#.#"  "N##.|#.#|#.#|#.#|#.#"  "O.#.|#.#|#.#|#.#|.#."
        "P##.|#.#|##.|#..|#.."  "Q.#.|#.#|#.#|###|.##"  "R##.|#.#|##.|#.#|#.#"
        "S.##|#..|.#.|..#|##."  "T###|.#.|.#.|.#.|.#."  "U#.#|#.#|#.#|#.#|.##"
        "V#.#|#.#|#.#|#.#|.#."  "W#.#|#.#|###|###|#.#"  "X#.#|#.#|.#.|#.#|#.#"
        "Y#.#|#.#|.#.|.#.|.#."  "Z###|..#|.#.|#..|###"
        "0###|#.#|#.#|#.#|###"  "1.#.|##.|.#.|.#.|###"  "2##.|..#|.#.|#..|###"
        "3##.|..#|.#.|..#|##."  "4#.#|#.#|###|..#|..#"  "5###|#..|##.|..#|##."
        "6.##|#..|###|#.#|###"  "7###|..#|.#.|.#.|.#."  "8###|#.#|###|#.#|###"
        "9###|#.#|###|..#|##."
        " ...|...|...|...|..."  "....|...|...|...|.#."  ":...|.#.|...|.#.|..."
        "-...|...|###|...|..."  "/..#|..#|.#.|#..|#.."  "%#.#|..#|.#.|#..|#.#"
        "(.#.|#..|#..|#..|.#."  ")#..|.#.|.#.|.#.|#.."]
       (map (fn [s] [(first s) (->> (subs s 1) (remove #{\|}) (partition 3)
                                    (mapv str/join))]))
       (into {})))

(def ^:const glyph-w 4)                                  ; 3px + 1px gap

(defn text!
  "Draws s at (x,y), scaled. Unknown chars render blank."
  ([b x y s c] (text! b x y s c 2))
  ([b x y s c k]
   (let [s (str/upper-case (str s))]
     (dotimes [i (count s)]
       (when-let [g (glyphs (nth s i))]
         (dotimes [row 5]
           (dotimes [col 3]
             (when (= \# (nth (g row) col))
               (rect! b (+ x (* k (+ (* i glyph-w) col))) (+ y (* k row)) k k c)))))))))

(defn text-w ^long [s ^long k] (* k glyph-w (count s)))