open Caml_xss

let dims = ref (180, 80)

let mk_color (r, g, b) =
  (r * 257,
   g * 257,
   b * 257)

let _color_bg =
  mk_color (0, 0, 0)

let _color0 =
  mk_color (255, 255, 255)

let _color1 =
  mk_color (120, 80, 255)

let _color2 =
  mk_color (255, 160, 26)

let _color3 =
  mk_color (20, 250, 62)

type shape =
  | Losange of (int * int * int * int) list (* four lines *)
  | Square of (int * int) * int  (* ((x, y), size) *)
  | Circle of (int * int) * int  (* ((x, y), radius) *)

let coords_losange (x, y) =
  [ (10 + x,  0 + y, 16 + x, 10 + y);
    (16 + x, 10 + y, 10 + x, 20 + y);
    (10 + x, 20 + y,  4 + x, 10 + y);
    ( 4 + x, 10 + y, 10 + x,  0 + y); ]

module UserSaver = struct
  type _state = {
    colormap: Caml_xss.colormap;
    color_bg: pixel;
    color0: pixel;
    color1: pixel;
    color2: pixel;
    color3: pixel;
    shapes: shape list;
  }
  type state = _state ref
  let update_shapes shapes =
    List.map (fun shape ->
      match shape with
      | Losange (losange_coords) -> Losange (losange_coords)
      | Square ((x, y), s) -> Square ((x + 1, y), s)
      | Circle ((x, y), r) -> Circle ((x - 1, y), r)
    ) shapes
  let update_state state =
    { state with shapes = update_shapes state.shapes }
  type user_calls = {
    saver_init: x_elems -> state;
    saver_draw: x_elems -> state -> int;
    saver_reshape: x_elems -> state -> int -> int -> unit;
    saver_free: x_elems -> state -> unit;
  }
  let user_saver = {
    saver_init = (fun xelms ->
      let colormap = X.default_colormap xelms in
      let color_bg = X.alloc_color xelms colormap _color_bg in
      let color0 = X.alloc_color xelms colormap _color0 in
      let color1 = X.alloc_color xelms colormap _color1 in
      let color2 = X.alloc_color xelms colormap _color2 in
      let color3 = X.alloc_color xelms colormap _color3 in
      ref {
        colormap;
        color_bg;
        color0;
        color1;
        color2;
        color3;
        shapes = [
          Losange (coords_losange (20, 30));
          Losange (coords_losange (36, 32));
          Square ((60, 50), 10);
          Square ((80, 60), 10);
          Square ((100, 80), 20);
          Circle ((100, 80), 20)
        ];
      }
    );
    saver_reshape = (fun xelms state w h ->
      dims := (w, h);
    );
    saver_free = (fun xelms state -> print_newline ());
    saver_draw = (fun xelms _state ->
      let state = !_state in
      _state := update_state state;
      let w, h = !dims in
      X.set_foreground xelms state.color_bg;
      X.fill_rectangle xelms (0, 0, w, h);
      X.set_foreground xelms state.color0;
      List.iter (X.draw_point xelms) [
        (20, 20); (22, 20); (24, 20)];
      begin
        List.iter (fun shape ->
          match shape with
          | Losange (losange_coords) ->
              X.set_foreground xelms state.color1;
              List.iter (X.draw_line xelms) losange_coords;
          | Square ((x, y), s) ->
              X.set_foreground xelms state.color2;
              List.iter (X.draw_rectangle xelms) [(x, y, s, s)];
              List.iter (X.draw_point xelms) [(x + s, y + s)];
          | Circle ((x, y), r) ->
              X.set_foreground xelms state.color3;
              X.draw_arc xelms (x - r/2, y - r/2, r, r, 0, 360*64);
        ) state.shapes;
      end;
      X.set_foreground xelms state.color3;
      X.draw_arc xelms (40, 60, 20, 20, 0, 360*64);
      X.draw_arc xelms (0, 0, 30, 30, 0, 360*64);
      (80_000)
    );
  }
end

module SomeSaver = MakeSaver(UserSaver)