/*
 * stack.c
 *
 * The move stack for 3Dc.
 */
/*

    3Dc, a game of 3-Dimensional Chess
    Copyright (C) 1995  Paul Hicks

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

    E-Mail: paulh@euristix.ie
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdlib.h>

#include "machine.h"
#include "3Dc.h"
#include "3DcErr.h"

Global stack *
StackNew(void)
{
  stack *s;

  s = (stack *)malloc(sizeof(stack));
  if (!CHECK( s != NULL ))
    return NULL;
  s->top = NULL;
  s->nSize = 0;
  return s;
}

Global void
StackDelete(stack *s)
{
  while(StackPop(s) != NULL)
    nop();

  free(s);
  return;
}

Global void
StackPush(stack *s, const Move *newMove)
{
  struct stack_el *newEl;

  newEl = (struct stack_el *)malloc(sizeof(struct stack_el));
  if (!CHECK( newEl != NULL ))
    return;
  newEl->mvt = (Move *)malloc(sizeof(Move));
  if (!CHECK( newEl->mvt != NULL ))
    return;
  memcpy(newEl->mvt, newMove, sizeof(Move));
  newEl->below = s->top;
  s->top = newEl;
  s->nSize++;
  return;
}

Global Move *
StackPop(stack *s)
{
  Move *oldMove;
  struct stack_el *oldEl;

  if (s->top == NULL)
    return NULL;

  oldMove = s->top->mvt;
  oldEl = s->top;
  s->top = s->top->below;
  s->nSize--;
  free(oldEl);

  return oldMove;
}

/* Don't delete returned value; it's still on the stack! */
Global Move *
StackPeek(stack *s, int numMoves)
{
  struct stack_el *oldEl;

  if (numMoves >= s->nSize)
    return NULL;

  for (oldEl = s->top; numMoves > 0; --numMoves)
    oldEl = oldEl->below;

  return oldEl->mvt;
}

#ifdef DEBUG
Global void
StackDump( stack *s )
{
  int i;
  struct stack_el *el;

  el = s->top;
  for (i=0; i<s->nSize; ++i)
    {
      printf("%i: %s at (%i,%i,%i) to (%i,%i,%i)\n",i,
             Piece2String( Board[el->mvt->xyzBefore.zLevel][el->mvt->xyzBefore.yRank][ el->mvt->xyzBefore.xFile] ),
             el->mvt->xyzBefore.xFile,
             el->mvt->xyzBefore.yRank,
             el->mvt->xyzBefore.zLevel,
             el->mvt->xyzAfter.xFile,
             el->mvt->xyzAfter.yRank,
             el->mvt->xyzAfter.zLevel);
      el = el->below;
    }
}
#endif /* DEBUG */