/* card.c
 *
 * card_t decoding functions.
 *
 * Copyright (C) 2002 Andy Goth <unununium@openverse.com>
 *                    Matt Harang <matt@ioioio.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
 * USA. */

#include <assert.h>
#include "spite.h"

/* Value meaning, there is no card here. */
const card_t card_empty = {0};

/* Returns the card's suit. */
suit_t card_suit(card_t c)
{
	if (!c.exists) return S_NO_CARD;
	if (!c.visible) return S_UNKNOWN;
	if (c.real_value == V_JOKER) return S_JOKER;
	return c.suit;
}

/* Returns the card's real value, the value stamped on the face. */
value_t card_real_value(card_t c)
{
	if (!c.exists) return S_NO_CARD;
	if (!c.visible) return S_UNKNOWN;
	assert(c.real_value >= V_ACE && c.real_value <= V_JOKER);
	return c.real_value;
}

/* Returns the card's effective value, the value the card is being played as. */
value_t card_eff_value(card_t c)
{
	if (!c.exists) return S_NO_CARD;
	if (!c.visible) return S_UNKNOWN;
	if (card_is_wild(c) && card_in_play(c)) {
		assert(c.eff_value >= V_ACE && c.eff_value <= V_QUEEN);
		return c.eff_value;
	}
	assert(c.real_value >= V_ACE && c.real_value <= V_JOKER);
	return c.real_value;
}

/* Returns true if the card is wild. */
bool card_is_wild(card_t c)
{
	value_t v = card_real_value(c);
	return v == V_KING || v == V_JOKER;
}

/* Returns true if the card is on a shared discard pile. */
bool card_in_play(card_t c)
{
	return c.exists && c.visible && c.in_play;
}

/* Can card 'top' be played on card 'bottom'? */
bool card_is_playable(card_t top, card_t bottom)
{
	value_t t_value = card_real_value(top);
	value_t b_value = card_eff_value(bottom);

	assert(card_in_play(bottom));
	assert(!card_in_play(top));
	assert(b_value != V_QUEEN);

	/* Wilds can be played on blank spots and on nonwilds */
	if (card_is_wild(top)) {
		if (b_value == V_QUEEN) return 0;
		if (b_value == V_NO_CARD) return 1;
		return !card_is_wild(bottom);
	}

	/* Ordinary cards can be played only in ascending order (an ace is one
	 * greater than a blank space) */
	return t_value == b_value + 1;
}

/* EOF */