let dim_max = 500

let str_dim_max = string_of_int dim_max

type point = {
  x : float;
  y : float;
};;

type rectangle = {
  coord : point;
  long : float;
  larg : float;
};;

type ball = {
  x : float;
  y : float;
  vh : float;
  vv : float;
  rayon : float;
  couleur : Graphics.color;
};;

let b1 = {
  x = 100.;
  y = 100.;
  vh = 0.;
  vv = 0.;
  rayon = 10.;
  couleur = Graphics.red;
};;

let b2 = {
  x = 200.;
  y = 200.;
  vh = (-1.);
  vv = (-1.);
  rayon = 10.;
  couleur = Graphics.green;
};;

let draw_ball b =
  Graphics.set_color b.couleur;
  Graphics.fill_circle (int_of_float b.x) (int_of_float b.y) (int_of_float b.rayon);;

let shift_coord_ball b =
  {
    x = b.x +. b.vh;
    y = b.y +. b.vv;
    vh = b.vh;
    vv = b.vv;
    rayon = b.rayon;
    couleur = b.couleur;
  };;

let collision_ball_board (b : ball) (r : rectangle) : ball =
  if b.x +. b.rayon >= r.coord.x +. r.long then
    { b with vh = -.b.vh } 
  else if b.x -. b.rayon <= r.coord.x then
    { b with vh = -.b.vh } 
  else if b.y +. b.rayon >= r.coord.y +. r.larg then
    { b with vv = -.b.vv } 
  else if b.y -. b.rayon <= r.coord.y then
    { b with vv = -.b.vv }
  else
    b 


type board = {
    rectangle: rectangle;
    balles : ball list;
  };;

let one_turn_ball b (r : rectangle) =
  let bn = collision_ball_board b r in
  shift_coord_ball bn
;;

let one_turn_board (b : board) : board =
  let new_balles = List.map (fun balle -> one_turn_ball balle b.rectangle) b.balles in
 { b with balles = new_balles }


let draw_board (b : board) =
  Graphics.set_line_width 4;

  let rect = b.rectangle in
  let x = int_of_float rect.coord.x in
  let y = int_of_float rect.coord.y  in
  let w = int_of_float rect.long in
  let h = int_of_float rect.larg in

  Graphics.draw_rect x y w h;

 List.iter draw_ball b.balles
;;

let rec turns (p : board) =
  Graphics.clear_graph ();

  let new_p = one_turn_board p in
  draw_board new_p;

  Graphics.synchronize ();
  if Graphics.key_pressed () then
    match Graphics.read_key () with
    | 'q' -> ()
    | ' ' -> 
        while Graphics.key_pressed () do ignore (Graphics.read_key ()) done;
        ignore (Graphics.read_key ()); 
        turns new_p
    | _ -> turns new_p
  else
    turns new_p;;

let main () =
  Random.self_init ();
  Graphics.set_window_title "Press 'q' to quit or __ to Pause";
  Graphics.open_graph (" " ^ str_dim_max ^ "x" ^ str_dim_max);

let initial_board = {
  rectangle = { coord = { x = 0.  ; y =    0.}; long = 500.0; larg = 500.0 };
  balles = [
    { x = 100.0; y = 75.0; rayon = 10.; vh = 0.5; vv = 0.5; couleur = Graphics.red };
    { x = 70.; y = 70.0; rayon = 30.; vh = 0.08; vv = 0.08; couleur = Graphics.yellow };
    { x = 120.0; y = 60.0; rayon = 5.0; vh =0.02 ; vv =0.02; couleur = Graphics.blue };
    { x = 80.0; y = 90.0; rayon =15.0; vh =0.04; vv = 0.04; couleur = Graphics.green };
  ];
} in

turns initial_board;


  Graphics.close_graph ()