(* Js_of_ocaml example
 * http://www.ocsigen.org/js_of_ocaml/
 * Copyright (C) 2010 Jérôme Vouillon
 * Laboratoire PPS - CNRS Université Paris Diderot
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *)
open Js_of_ocaml
open Js_of_ocaml_lwt

let n = 12

let h = 20.

let w = floor ((h *. sqrt 3. /. 2.) +. 0.5)

(****)

let _ = Random.self_init ()

let create_cubes v = Array.init n (fun _ -> Array.init n (fun _ -> Array.make n v))

let get a i j k = i < 0 || j < 0 || k < 0 || (i < n && j < n && k < n && a.(i).(j).(k))

let update a =
  let i = Random.int n in
  let j = Random.int n in
  let k = Random.int n in
  if a.(i).(j).(k)
  then
    if not (get a (i + 1) j k || get a i (j + 1) k || get a i j (k + 1))
    then (
      a.(i).(j).(k) <- false;
      true)
    else false
  else if get a (i - 1) j k && get a i (j - 1) k && get a i j (k - 1)
  then (
    a.(i).(j).(k) <- true;
    true)
  else false

(****)

module Html = Dom_html

let top = Js.string "#a8a8f6"

let left = Js.string "#d9d9d9"

let right = Js.string "#767676"

let edge = Js.string "#000000"

let on_cube c i j k f =
  let x = float (i - k + n - 1) *. w in
  let y = (float (n - 1 - j) *. h) +. (float (i + k) *. h /. 2.) in
  c##save;
  c##translate x y;
  f c;
  c##restore

let draw_top c =
  c##.fillStyle := top;
  c##beginPath;
  c##moveTo w 0.;
  c##lineTo (2. *. w) (h /. 2.);
  c##lineTo w h;
  c##lineTo 0. (h /. 2.);
  c##fill

let top_edges c =
  c##beginPath;
  c##moveTo 0. (h /. 2.);
  c##lineTo w 0.;
  c##lineTo (2. *. w) (h /. 2.);
  c##stroke

let draw_right c =
  c##.fillStyle := right;
  c##beginPath;
  c##moveTo w h;
  c##lineTo w (2. *. h);
  c##lineTo (2. *. w) (1.5 *. h);
  c##lineTo (2. *. w) (h /. 2.);
  c##fill

let right_edges c =
  c##beginPath;
  c##moveTo w (2. *. h);
  c##lineTo w h;
  c##lineTo (2. *. w) (h /. 2.);
  c##stroke

let draw_left c =
  c##.fillStyle := left;
  c##beginPath;
  c##moveTo w h;
  c##lineTo w (2. *. h);
  c##lineTo 0. (1.5 *. h);
  c##lineTo 0. (h /. 2.);
  c##fill

let left_edges c =
  c##beginPath;
  c##moveTo w h;
  c##lineTo 0. (h /. 2.);
  c##lineTo 0. (1.5 *. h);
  c##stroke

let remaining_edges c =
  c##beginPath;
  c##moveTo 0. (float n *. 1.5 *. h);
  c##lineTo (float n *. w) (float n *. 2. *. h);
  c##lineTo (float n *. 2. *. w) (float n *. 1.5 *. h);
  c##lineTo (float n *. 2. *. w) (float n *. 0.5 *. h);
  c##stroke

let tile c a (top, right, left) =
  for i = 0 to n - 1 do
    let j = ref (n - 1) in
    for k = 0 to n - 1 do
      while !j >= 0 && not a.(i).(!j).(k) do
        decr j
      done;
      on_cube c i !j k top
    done
  done;
  for j = 0 to n - 1 do
    let i = ref (n - 1) in
    for k = 0 to n - 1 do
      while !i >= 0 && not a.(!i).(j).(k) do
        decr i
      done;
      on_cube c !i j k right
    done
  done;
  for i = 0 to n - 1 do
    let k = ref (n - 1) in
    for j = 0 to n - 1 do
      while !k >= 0 && not a.(i).(j).(!k) do
        decr k
      done;
      on_cube c i j !k left
    done
  done

let create_canvas () =
  let d = Html.window##.document in
  let c = Html.createCanvas d in
  c##.width := (n * 2 * truncate w) + 1;
  c##.height := (n * 2 * truncate h) + 1;
  c

let redraw ctx canvas a =
  let c = canvas##getContext Html._2d_ in
  c##setTransform 1. 0. 0. 1. 0. 0.;
  c##clearRect 0. 0. (float canvas##.width) (float canvas##.height);
  c##setTransform 1. 0. 0. 1. 0.5 0.5;
  c##.globalCompositeOperation := Js.string "lighter";
  tile c a (draw_top, draw_right, draw_left);
  c##.globalCompositeOperation := Js.string "source-over";
  tile c a (top_edges, right_edges, left_edges);
  remaining_edges c;
  ctx##drawImage_fromCanvas canvas 0. 0.

let ( >>= ) = Lwt.bind

let rec loop c c' a =
  Lwt_js.sleep 0.2
  >>= fun () ->
  let need_redraw = ref false in
  for _i = 0 to 99 do
    need_redraw := update a || !need_redraw
  done;
  if !need_redraw then redraw c c' a;
  loop c c' a

let start _ =
  let c = create_canvas () in
  let c' = create_canvas () in
  Dom.appendChild Html.window##.document##.body c;
  let c = c##getContext Html._2d_ in
  c##.globalCompositeOperation := Js.string "copy";
  let a = create_cubes true in
  redraw c c' a;
  ignore (loop c c' a);
  Js._false

let _ = Html.window##.onload := Html.handler start
