#include "library.h"

struct actor
{ double xpos, ypos;
  double speed, reach;
  int hue;
  bool alive;
  string yay; };

actor create(double x, double y, double spd, double rch, int col, string s)
{ actor a;
  a.xpos = x;
  a.ypos = y;
  a.speed = spd;
  a.reach = rch;
  a.hue = col;
  a.yay = s;
  a.alive = true;
  return a; }


bool update(actor & runner, actor target, double ti)
      // return = has runner reached target?
{ if (! runner.alive)
    return false;
  move_to(runner.xpos, runner.ypos);
  double a = direction_from_to_in_radians(runner.xpos, runner.ypos,
                                          target.xpos, target.ypos);
  double d = runner.speed * ti;
  runner.xpos += d * sin(a);
  runner.ypos -= d * cos(a);

  set_pen_color(runner.hue);
  draw_to(runner.xpos, runner.ypos);

  double farness = distance_to(target.xpos, target.ypos);
  return farness < runner.reach; }

  
void main()
{ const int fieldw = 500, fieldl = 800;
  const double timeint = 0.001;

  actor boy = create(400, fieldw, 8, 2, color::blue, "Boy gets apple and is safe");
  actor bull = create(fieldl, 0, 10, 4, color::red, "Moooooo! Bull eats boy!");
  actor dinosaur = create(0, 0, 20, 4, color::violet, "Grrrrraaaah!");
  actor tree = create(fieldl/4*3, fieldw/2, 1, 0, color::green, "");
  actor anchor = create(fieldl, fieldw, 0, 0, color::green, "");

  make_window(fieldl+3, fieldw+3);
  fill_rectangle(0, 0, fieldl, fieldw, color::green);
  fill_rectangle(1, 1, fieldl-2, fieldw-2, color::white);
  set_pen_width(3);

  while (true)
  { bool boysafe = update(boy, tree, timeint);
    if (boysafe) 
      write_string(boy.yay);

    bool bullarrives = update(bull, boy, timeint);
    if (bullarrives)
    { if (! boysafe)
      { write_string(bull.yay);
        boy.alive = false; }
      break; }

    bool dinoarrives = update(dinosaur, bull, timeint);
    if (dinoarrives)
    { write_string(dinosaur.yay);
      bull.alive = false; }

    update(tree, anchor, timeint); } }