#include "library.h"

struct actor
{ double x, y, spd, reach;
  int size, color;
  bool alive, safe;
  string result; };

struct universe
{ actor boy, bull, tree, dinosaur;
  int fieldw, fieldh, edge; };

universe u;

void set_field(int w, int h, int e)
{ u.fieldw = w;
  u.fieldh = h;
  u.edge = e; }

void set(actor & A, double x, double y, double s, double r)
{ A.x = x;
  A.y = y;
  A.spd = s;
  A.reach = r;
  A.alive = true;
  A.safe = false;
  A.size = 25;
  A.color = color::magenta;
  A.result = "You didn't set me!"; }

void set_sz_color_string(actor & A, int sz, int c, string r)
{ A.size = sz;
  A.color = c;
  A.result = r; }

void draw_to(actor A)
{ draw_to(u.edge+A.x, u.edge+A.y); }

void move_to(actor A)
{ move_to(u.edge+A.x, u.edge+A.y); }

void draw_actor(actor A)
{ set_pen_color(A.color);
  set_pen_width(A.size);
  draw_point(A.x+u.edge, A.y+u.edge); }

void draw_field()
{ set_pen_color(color::green);
  move_to(u.edge, u.edge);
  draw_to(u.edge+u.fieldw, u.edge);
  draw_to(u.edge+u.fieldw, u.edge+u.fieldh);
  draw_to(u.edge, u.edge+u.fieldh);
  draw_to(u.edge, u.edge); }

void draw_actors()
{ draw_actor(u.tree);
  draw_actor(u.boy);
  draw_actor(u.bull);
  draw_actor(u.dinosaur); }

bool close_enough(double ax, double ay, double bx, double by, double reach)
{ double dist = sqrt((ax-bx)*(ax-bx) + (ay-by)*(ay-by));
  return dist < reach; }

bool close_enough(actor mover, actor target)
{ return close_enough(mover.x, mover.y, target.x, target.y, mover.reach); }

// move the mover, draw the line, return whether reached target or not
bool move_towards(actor & mover, actor target, double deltat)
{ if (! mover.alive)
    return false;
  double dir = atan2(target.y-mover.y, target.x-mover.x);
  double dist = mover.spd * deltat;
  double dx = dist * cos(dir);
  double dy = dist * sin(dir);
  move_to(mover);
  set_pen_color(mover.color);
  mover.x += dx;
  mover.y += dy;
  draw_to(mover);
  return close_enough(mover, target); }

bool perform_one_step(actor & mover, actor & target, double deltat)
{ bool reached_target = move_towards(mover, target, deltat);
  if (reached_target && target.alive && ! target.safe)
  { write_string(mover.result);
    target.alive = false; }
  return reached_target; }

void main()
{ set_field(700, 500, 50);
  set(u.tree, 350, 450, 0, 0);
  set(u.bull, 700, 0, 5, 5);
  set(u.boy, 0, u.fieldh, 3, 2);
  set(u.dinosaur, u.fieldw, u.fieldh, 7, 2);
  set_sz_color_string(u.boy, 4, color::blue, "Safe!");
  set_sz_color_string(u.bull, 4, color::red, "Boy Eaten");
  set_sz_color_string(u.tree, 8, color::brown, "Yor program is wrong");
  set_sz_color_string(u.dinosaur, 6, color::dark_green, "Graaaaaaah!");

  double deltat=0.002;
  bool boysafe=false;
  make_window(u.fieldw+2*u.edge, u.fieldh+2*u.edge);
  draw_field();
  draw_actors();

  for (double t=0.0; true; t+=deltat)
  { bool reached = perform_one_step(u.boy, u.tree, deltat);
    if (reached)
      u.boy.safe = true;

    perform_one_step(u.bull, u.boy, deltat);

    if (u.bull.alive)
      perform_one_step(u.dinosaur, u.bull, deltat);
    else
      perform_one_step(u.dinosaur, u.boy, deltat); } }