#include <cmath>
#include "visionary.h"
using namespace std;

static double dist(const wabbit *w1, const wabbit *w2)
	throw (wabbit::cross_game)
{
	int dx;
	int dy;

	difference(w1, w2, &dx, &dy);
	return sqrt(static_cast<double>(dx * dx + dy * dy));
}

inline int signum(int i) throw () {return i < 0 ? -1 : i > 0;}

static void step(const wabbit *w1, const wabbit *w2, int *dx, int *dy)
	throw (wabbit::cross_game)
{
	difference(w1, w2, dx, dy);
	*dx = signum(*dx);
	*dy = signum(*dy);
}

void visionary::decide(int *dx, int *dy) const
{
	static const unsigned radius = 3;   //of vision

	//Move one step away from a wabbit that could eat me.

	for (const_iterator it = begin(); it != end(); ++it) {

		const wabbit *const other = *it;

		if (other != static_cast<const wabbit *>(this) &&
			dist(this, other) <= radius &&
			other->hungry() > this->bitter()) {

			step(other, this, dx, dy);
			return;
		}
	}

	/*
	Arrive here if there were no enemies within the visual radius.
	Now see if there's any food I could eat within the visual radius.
	If so, take one step towards it.
	*/

	for (const_iterator it = begin(); it != end(); ++it) {

		const wabbit *const other = *it;

		if (other != static_cast<const wabbit *>(this) &&
			dist(this, other) <= radius &&
			this->hungry() > other->bitter()) {

			step(this, other, dx, dy);
			return;
		}
	}

	//Arrive here if there were neither enemies nor food nearby:
	//lethargic in the absence of stimulation.
	*dx = *dy = 0;
}