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

wolf::wolf(const terminal& init_t, unsigned init_x, unsigned init_y):
	t {&init_t}, x {init_x}, y {init_y}, c {'W'}
{

	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);
}

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

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

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

	if (const char k {t->key()}) {   //If a key was pressed,
		for (const auto& stroke: a) {
			if (k == stroke.c) {
				const unsigned newx {x + stroke.dx};
				const unsigned newy {y + stroke.dy};

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

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

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

				return !I_ate_him;
			}
		}

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

	return true; //Arrive here to keep the game going if wolf didn't move. 
}