/* This may look like c to you, but it's really -*-c++-*- */

/*   GMA or "The Go-moku Apprentice" is a go-moku implementation that
 *   learns the game from its own (and its opponents') mistakes.
 *   Copyright (C) 1998 Johan Walles (d92-jwa@nada.kth.se)
 *
 *   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 "pattern.h"

int Pattern::winner() const
{
  // If I can win by making this move, return 0
  // If my opponent can win here, return 1
  // Otherwise return -1

  int direction, position, offset;
  unsigned char first_sign[2];
  int n_signs[2];
  bool you_win = false;
  // bool i_win = false;

  for (direction = 0; direction < 8; direction += 2)
    {
      // Go through all four directions

      for (offset = 0; offset < 2; offset++)
	{
	  // Go through each direction both this way and that

	  n_signs[offset] = 0;
	  first_sign[offset] = (chars[direction + offset] >> 6) & 0x03;

	  if ((first_sign[offset] != PATTERN_MINE) &&
	      (first_sign[offset] != PATTERN_YOURS))
	    continue;

	  for (position = 6; position >= 0; position -= 2)
	    {
	      if (((chars[direction + offset] >> position) & 0x03) ==
		  first_sign[offset])
		n_signs[offset]++;
	      else
		break;
	    }
	}

      // Check both directions by themselves
      for (offset = 0; offset < 2; offset++)
	{
	  if (n_signs[offset] == 4)
	    if (first_sign[offset] == PATTERN_MINE)
	      return 0; // i_win = true;
	    else if (first_sign[offset] == PATTERN_YOURS)
	      you_win = true;
	}
      
      // Check both directions together
      if ((first_sign[0] == first_sign[1]) &&
	  ((n_signs[0] + n_signs[1]) >= 4))
	{
	  if (first_sign[0] == PATTERN_MINE)
	    return 0; // i_win = true;
	  else if (first_sign[0] == PATTERN_YOURS)
	    you_win = true;
	}
    }

  return you_win ? 1 : -1;
}