#include <iostream>
#include <cstdlib>   //for exit function
#include "wolf.h"
using namespace std;

wolf::wolf(const terminal& initial_t, unsigned initial_x, unsigned initial_y)
	: t(&initial_t), x(initial_x), y(initial_y)
{
	if (!t->in_range(x, y)) {
		cerr << "Initial wolf position (" << x << ", " << y
			<< ") off " << t->xmax() << " by " << t->ymax()
			<< " terminal.\n";
		exit(EXIT_FAILURE);
	}

	const char other = t->get(x, y);
	const char background = t->background();

	if (other != background) {
		cerr << "Initial wolf position (" << x << ", " << y
			<< ") already occupied by '" << other << "'.\n";
		exit(EXIT_FAILURE);
	}

	if (c == background) {
		cerr << "Wolf character '" << c << "' can't be the same as "
			"the terminal's background character.\n";
		exit(EXIT_FAILURE);
	}

	t->put(x, y, c);
}

wolf::~wolf()
{
	t->beep();
	t->wait(1000);

	if (t->get(x, y) == c) {
		t->put(x, y);
	}
}

//Return false if this wolf ate another animal, true otherwise.

bool wolf::move()
{
	struct keystroke {
		char c;
		int dx;   //horizontal difference
		int dy;   //vertical difference
	};

	static const keystroke a[] = {
		{'h',   -1,    0},   //left
		{'j',    0,    1},   //down
		{'k',    0,   -1},   //up
		{'l',    1,    0}    //right
	};
	static const size_t n = sizeof a / sizeof a[0];

	if (const char k = t->key()) {
		for (const keystroke *p = a; p < a + n; ++p) {
			if (k == p->c) {
				const unsigned newx = x + p->dx;
				const unsigned newy = y + p->dy;

				if (!t->in_range(newx, newy)) {
					break;         //Go to line 57.
				}

				const bool I_ate_him =
					t->get(newx, newy) != t->background();

				t->put(x, y);      //Erase this wolf from its old location.
				x = newx;
				y = newy;
				t->put(x, y, c);   //Redraw this wolf at its new location.

				return !I_ate_him;
			}
		}

		//Punish user who pressed an illegal key or tried to move off screen.
		t->beep();
	}

	return true;
}