/*
 *  Empire - A multi-player, client/server Internet based war game.
 *  Copyright (C) 1986-2000, Dave Pare, Jeff Bailey, Thomas Ruschak,
 *                           Ken Stevens, Steve McClure
 *
 *  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
 *
 *  ---
 *
 *  See the "LEGAL", "LICENSE", "CREDITS" and "README" files for all the
 *  related information and legal notices. It is expected that any future
 *  projects/authors will amend these files as needed.
 *
 *  ---
 *
 *  nstr.c: Compile and execute the item selections on sectors
 * 
 *  Known contributors to this file:
 *     Dave Pare, 1989
 */

#include <ctype.h>
#include "struct.h"
#include "misc.h"
#include "var.h"
#include "xy.h"
#include "sect.h"
#include "nsc.h"
#include "nat.h"
#include "match.h"
#include "file.h"
#include "player.h"
#include "common.h"
#include "gen.h"

/*
 * return true if the conditions on this item
 * are all true.
 */
int
nstr_exec(struct nscstr *conds, register int ncond, void *ptr, int type)
{
    register struct nscstr *nsc;
    register int op;
    register int lhs;
    register int rhs;
    register int oper;

    for (nsc = conds; --ncond >= 0; nsc++) {
	oper = nsc->oper;
	if (oper > 65535) {
	    oper = oper - 65535;
	    rhs = nsc->fld2;
	} else
	    rhs = decode(player->cnum, nsc->fld2, ptr, type);

	if (oper > 255) {
	    oper = oper - 255;
	    lhs = nsc->fld1;
	} else
	    lhs = decode(player->cnum, nsc->fld1, ptr, type);

	op = oper;
	if ((op == '<' && lhs >= rhs) ||
	    (op == '=' && lhs != rhs) ||
	    (op == '>' && lhs <= rhs) || (op == '#' && lhs == rhs))
	    return 0;
    }
    return 1;
}

int
decode(natid cnum, long int code, void *addr, int type)
{
    register int val;
    register int nsc_code;
    struct natstr *np;
    long code_type = (code & NSC_TMASK);

    val = (code & ~NSC_MASK) & 0xffff;

    /* handle negative numbers properly */
    /* this assumes a binary two's complement number representation */
    if (val >= 0x8000)
	val -= 0x10000;

    nsc_code = code & NSC_CMASK;
    if (nsc_code == NSC_VAR) {
	val = getvar(val, addr, type);
    } else if (nsc_code == NSC_OFF) {
	/*
	 * add offset to value
	 */
	addr = (s_char *)addr + val;
	switch (code_type) {
	case NSC_TIME:
	    val = *((time_t *) addr);
	    break;
	case NSC_CHAR:
	    val = *((s_char *)addr);
	    break;
	case NSC_UCHAR:
	    val = (int)*((unsigned char *)addr);
	    break;
	case NSC_SHORT:
	    val = *((short *)addr);
	    break;
	case NSC_USHORT:
	    val = *((u_short *)addr);
	    break;
	case NSC_INT:
	    val = *((int *)addr);
	    break;
	case NSC_LONG:
	    val = *((long *)addr);
	    break;
	case NSC_XCOORD:
	    val = *((short *)addr);
	    np = getnatp(cnum);
	    val = xrel(np, val);
	    break;
	case NSC_YCOORD:
	    val = *((short *)addr);
	    np = getnatp(cnum);
	    val = yrel(np, val);
	    break;
	default:
	    logerror("bad type in decode: %x!\n", code & NSC_TMASK);
	    val = 0;
	    break;
	}
    }
    if (code & NSC_ROUND)
	val = roundintby(val, 10);
    return val;
}

s_char *
decodep(long int code, void *addr)
{
    addr = (char *)addr + ((code & ~NSC_MASK) & 0xffff);

    if ((code & NSC_TMASK) == NSC_CHARP)
	return *(s_char **)addr ? *((s_char **)addr) : (s_char *)"";
    return addr;
}