#include "library.h"

struct Actor
{ string name, saying;
  double xpos, ypos, size, speed;
  int colour, target;

  Actor()
  { }

  Actor(string n, double xp, double yp, double sz, double sp, int c, int t, string s)
  { name = n;
    xpos = xp; ypos = yp;
    size = sz; speed = sp;
    colour = c; target = t;
    saying = s; } };

double Distance(Actor a, Actor b)
{ return sqrt(pow(a.xpos-b.xpos, 2) + pow(a.ypos-b.ypos, 2)); }

bool can_reach(Actor a, Actor b)
{ const bool r = Distance(a, b) < a.size/2 + b.size/2;
  if (r)
    cout << "distance= " << Distance(a, b) << ", sizeA=" << a.size << ", sizeB=" << b.size << "\n";
  return r; }

const int treeidx = 0, bullidx = 1, boyidx = 2, dinoidx = 3, nactors = 4;

struct universe
{ int fieldw, fieldh;
  Actor A[nactors]; };

void report(Actor a)
{ cout << a.name << " is at " << a.xpos << ", " << a.ypos << "\n"; }

void draw(universe u)
{ set_pen_color(color::green);
  move_to(0, 0);
  draw_to(u.fieldw, 0);
  draw_to(u.fieldw, u.fieldh);
  draw_to(0, u.fieldh);
  draw_to(0, 0);
  for (int i = 0; i < nactors; i += 1)
  { report(u.A[i]);
    set_pen_color(u.A[i].colour);
    set_pen_width(u.A[i].size);
    draw_point(u.A[i].xpos, u.A[i].ypos); } }

void update(Actor & a, Actor t)
{ double dir = atan2(t.xpos-a.xpos, t.ypos-a.ypos);
  double dx = a.speed * sin(dir);
  double dy = a.speed * cos(dir);
  a.xpos += dx;
  a.ypos += dy; }

bool update(universe & u)     // returns true if someone wins
{ for (int i = 0; i < nactors; i += 1)
  { update(u.A[i], u.A[u.A[i].target]);
    if (can_reach(u.A[i], u.A[u.A[i].target]))
    { write_string(u.A[i].saying);
      return true; } }
  return false; }

void main()
{ make_window(850, 650);
  universe U;
  U.fieldw = 800; U.fieldh = 600;
  U.A[treeidx] = Actor("tree", 600, 300, 50, 0, color::green, boyidx, "Tree wins");
  U.A[bullidx] = Actor("bull",  50,  50,  7, 8, color::red,  boyidx,  "Boy Eaten!");
  U.A[boyidx]  = Actor("boy",  100, 550,  4, 6, color::blue, treeidx, "Boy Safe");
  U.A[dinoidx] = Actor("dinosaur",  500, 50,  4, 6, color::brown, bullidx, "Graaaaaaaah!");
  draw(U);
  while (true)
  { wait(0.1);
    if (update(U))
      break;
    draw(U); } }