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// san.cpp

#include "common.h"

// handy definitions

#define WCHAR_TO_COLUMN(a) ((a) == L'a' ? 0 : ((a) == L'b' ? 1 : ((a) == L'c' ? 2 : ((a) == L'd' ? 3 : ((a) == L'e' ? 4 : ((a) == L'f' ? 5 : ((a) == L'g' ? 6 : ((a) == L'h' ? 7 : -1))))))))

#define WCHAR_TO_LINE(a) ((a) == L'1' ? 0 : ((a) == L'2' ? 1 : ((a) == L'3' ? 2 : ((a) == L'4' ? 3 : ((a) == L'5' ? 4 : ((a) == L'6' ? 5 : ((a) == L'7' ? 6 : ((a) == L'8' ? 7 : -1))))))))

#define COLUMN_TO_WSTRING(c) ((c) == 0 ? L"a" : ((c) == 1 ? L"b" : ((c) == 2 ? L"c" : ((c) == 3 ? L"d" : ((c) == 4 ? L"e" : ((c) == 5 ? L"f" : ((c) == 6 ? L"g" : ((c) == 7 ? L"h" : L"_"))))))))

#define LINE_TO_WSTRING(l) ((l) == 0 ? L"1" : ((l) == 1 ? L"2" : ((l) == 2 ? L"3" : ((l) == 3 ? L"4" : ((l) == 4 ? L"5" : ((l) == 5 ? L"6" : ((l) == 6 ? L"7" : ((l) == 7 ? L"8" : L"_"))))))))

// prototypes of local functions

static bool SAN_DisambiguateMove (boardmove_t *move, boardmove_t *new_move);

bool Move_SetupFromSAN (boardmove_t *move, boardmove_t *new_move, int move_color)

{

   // helper function to translate a SAN move into numeric from and to positions on the specified board

   // WARNING: THIS FUNCTION DOES NOT RETURN WITH A FULLY CONSTRUCTED MOVE!

   // FIXME: accelerate this function by reducing the number of towupper()/towlower() calls

   int fieldstart;

   int fieldstop;

   int length;

   // first, get move string length

   length = wcslen (new_move->pgntext);

   // parse it from the beginning

   fieldstart = 0;

   fieldstop = 0;

   // find where it stops

   while ((fieldstop < length) && !iswspace (new_move->pgntext[fieldstop]))

      fieldstop++; // reach the first space

   fieldstop--; // ignore the space

   // does it finish with a move value estimation ?

   while ((fieldstop >= fieldstart) && ((new_move->pgntext[fieldstop] == L'?') || (new_move->pgntext[fieldstop] == L'!')))

      fieldstop--; // ignore these signs, they are redundant

   // does it finish with a check or a checkmate sign ?

   if ((fieldstop >= fieldstart) && ((new_move->pgntext[fieldstop] == L'+') || (new_move->pgntext[fieldstop] == L'#')))

      fieldstop--; // chop off these signs, they are redundant

   // reset relevant parts of the move we're about to build

   new_move->color = move_color; // save its color

   new_move->part = PART_NONE;

   new_move->promotion_type = PART_NONE;

   new_move->source[0] = -1;

   new_move->source[1] = -1;

   new_move->target[0] = -1;

   new_move->target[1] = -1;

   // is it a long castle ?

   if ((_wcsnicmp (&new_move->pgntext[fieldstart], L"O-O-O", 5) == 0) || (wcsncmp (&new_move->pgntext[fieldstart], L"0-0-0", 5) == 0))

   {

      new_move->source[0] = (move_color == COLOR_WHITE ? 0 : 7);

      new_move->source[1] = 4;

      new_move->target[0] = (move_color == COLOR_WHITE ? 0 : 7);

      new_move->target[1] = 2;

      new_move->part = PART_KING; // it's a king's move

   }

   // else is it a short castle ?

   else if ((_wcsnicmp (&new_move->pgntext[fieldstart], L"O-O", 3) == 0) || (wcsncmp (&new_move->pgntext[fieldstart], L"0-0", 3) == 0))

   {

      new_move->source[0] = (move_color == COLOR_WHITE ? 0 : 7);

      new_move->source[1] = 4;

      new_move->target[0] = (move_color == COLOR_WHITE ? 0 : 7);

      new_move->target[1] = 6;

      new_move->part = PART_KING; // it's a king's move

   }

   // else it's a normal move

   else

   {

      // does it end with the optional "en passant" prefix ?

      if ((fieldstop >= fieldstart + 4) && (wcsncmp (&new_move->pgntext[fieldstop - 3], L"e.p.", 4) == 0))

         fieldstop -= 4; // if so, chop it off

      // is the last character a part type ? (WARNING: PART TYPES ARE MANDATORILY IN UPPERCASE)

      if ((fieldstop >= fieldstart) && (new_move->pgntext[fieldstop] == L'R'))

      {

         new_move->promotion_type = PART_ROOK; // there's a promotion to rook

         fieldstop--; // proceed to previous character

      }

      else if ((fieldstop >= fieldstart) && (new_move->pgntext[fieldstop] == L'N'))

      {

         new_move->promotion_type = PART_KNIGHT; // there's a promotion to knight

         fieldstop--; // proceed to previous character

      }

      else if ((fieldstop >= fieldstart) && (new_move->pgntext[fieldstop] == L'B'))

      {

         new_move->promotion_type = PART_BISHOP; // there's a promotion to bishop

         fieldstop--; // proceed to previous character

      }

      else if ((fieldstop >= fieldstart) && (new_move->pgntext[fieldstop] == L'Q'))

      {

         new_move->promotion_type = PART_QUEEN; // there's a promotion to queen

         fieldstop--; // proceed to previous character

      }

      // is there the promotion's equal sign ?

      if ((fieldstop >= fieldstart) && (new_move->pgntext[fieldstop] == L'='))

         fieldstop--; // skip it, it's redundant

      // read the target line and column

      if (fieldstop >= fieldstart)

      {

         new_move->target[0] = WCHAR_TO_LINE (new_move->pgntext[fieldstop]); // read the target line

         fieldstop--; // proceed to previous character

      }

      if (fieldstop >= fieldstart)

      {

         new_move->target[1] = WCHAR_TO_COLUMN (new_move->pgntext[fieldstop]); // read the target column (WARNING: ONLY IF LOWERCASE)

         fieldstop--; // proceed to previous character

      }

      if ((fieldstop >= fieldstart) && (new_move->pgntext[fieldstop] == L'x'))

         fieldstop--; // if there's a taking piece indication, it's superfluous, so skip it

      // read the optional source line and column

      if ((fieldstop >= fieldstart) && (WCHAR_TO_LINE (new_move->pgntext[fieldstop]) != -1))

      {

         new_move->source[0] = WCHAR_TO_LINE (new_move->pgntext[fieldstop]); // read the source line

         fieldstop--; // proceed to previous character

      }

      if ((fieldstop >= fieldstart) && (WCHAR_TO_COLUMN (new_move->pgntext[fieldstop]) != -1))

      {

         new_move->source[1] = WCHAR_TO_COLUMN (new_move->pgntext[fieldstop]); // read the source column (WARNING: ONLY IF LOWERCASE)

         fieldstop--; // proceed to previous character

      }

      // read the part's type (WARNING: PART TYPES ARE MANDATORILY IN UPPERCASE)

      if (fieldstop >= fieldstart)

      {

         if      (new_move->pgntext[fieldstop] == L'R') new_move->part = PART_ROOK; // it's a rook

         else if (new_move->pgntext[fieldstop] == L'N') new_move->part = PART_KNIGHT; // it's a knight

         else if (new_move->pgntext[fieldstop] == L'B') new_move->part = PART_BISHOP; // it's a bishop

         else if (new_move->pgntext[fieldstop] == L'Q') new_move->part = PART_QUEEN; // it's a queen

         else if (new_move->pgntext[fieldstop] == L'K') new_move->part = PART_KING; // it's a king

         else if (new_move->pgntext[fieldstop] == L'P') new_move->part = PART_PAWN; // it's a pawn (Wikipedia says "P" is a valid part type in PGN texts...)

         else return (false); // on error, cancel

      }

      else

         new_move->part = PART_PAWN; // if not specified, it's a pawn

   }

   // now, disambiguate.

   return (SAN_DisambiguateMove (move, new_move));

}

bool Move_DescribeInSAN (boardmove_t *move)

{

   // convert a board and its part placements into a SAN notation, writing in the pgntext buffer

   int line;

   int column;

   boardslot_t *slot;

   bool needs_line;

   bool needs_column;

   // build move string in abbreviated algebraic notation

   move->pgntext[0] = 0;

   // is it a king castling or a normal move ?

   if ((move->part == PART_KING) && (move->source[1] == 4) && (move->target[1] == 2))

      wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"O-O-O"); // long castle

   else if ((move->part == PART_KING) && (move->source[1] == 4) && (move->target[1] == 6))

      wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"O-O"); // short castle

   else

   {

      // part identifier (omit it if pawn)

      if (move->part == PART_ROOK)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"R");

      else if (move->part == PART_KNIGHT)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"N");

      else if (move->part == PART_BISHOP)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"B");

      else if (move->part == PART_QUEEN)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"Q");

      else if (move->part == PART_KING)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"K");

      // is it a pawn taking ?

      if ((move->part == PART_PAWN) && (move->has_captured))

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), COLUMN_TO_WSTRING (move->source[1]));

      // else is there a possible ambiguity ? (not for pawns)

      if ((move->part != PART_PAWN) && (Move_CountPartsByColorAndType (move, move->color, move->part) > 1))

      {

         // assume we don't need to disambiguate neither by column nor by line

         needs_column = false;

         needs_line = false;

         // cycle through the board and find all this part's siblings (be sure to parse them all)

         for (line = 0; line < 8; line++)

            for (column = 0; column < 8; column++)

            {

               slot = &move->slots[line][column]; // quick access to slot

               // is this slot occupied by one of our siblings that is not the one doing the move AND its movement is valid ?

               if ((slot->part == move->part) && (slot->color == move->color) && ((line != move->source[0]) || (column != move->source[1]))

                   && Move_IsMoveValid (move, line, column, move->target[0], move->target[1]))

               {

                  if (column != move->source[1])

                     needs_column = true; // if columns differ, remember to write start column

                  else

                     needs_line = true; // else if lines differ, remember to write start line

               }

            }

         // do we need to write start column or start line ?

         if (needs_column)

            wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), COLUMN_TO_WSTRING (move->source[1])); // if so, write start column

         if (needs_line)

            wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), LINE_TO_WSTRING (move->source[0])); // if so, write start line

      }

      // does it capture something ?

      if (move->has_captured)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"x");

      // target column, target line

      wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), COLUMN_TO_WSTRING (move->target[1]));

      wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), LINE_TO_WSTRING (move->target[0]));

      // is there a promotion ?

      if (move->promotion_type == PART_ROOK)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"=R");

      else if (move->promotion_type == PART_KNIGHT)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"=N");

      else if (move->promotion_type == PART_BISHOP)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"=B");

      else if (move->promotion_type == PART_QUEEN)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"=Q");

      else if (move->promotion_type == PART_KING)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"=K");

      // is there a check or a checkmate ?

      if (move->is_check)

      {

         if (move->is_stalemate)

            wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"#"); // checkmate

         else

            wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"+"); // normal check

      }

      // is it an en passant coup ?

      if (move->is_enpassant)

         wcscat_s (move->pgntext, WCHAR_SIZEOF (move->pgntext), L"e.p.");

   }

   return (true); // finished

}

static bool SAN_DisambiguateMove (boardmove_t *move, boardmove_t *new_move)

{

   // handy helper to disambiguate a move literal of which we don't know the source,

   // but for which we know the part type and the target slot

   int index_line;

   int index_column;

   // are both source line and column known ?

   if ((new_move->source[0] != -1) && (new_move->source[1] != -1))

      return (true); // no need to disambiguate anything

   // else is source line known ?

   else if (new_move->source[0] != -1)

   {

      // cycle through all the columns and find the part of the same type that has the right to move there

      for (index_column = 0; index_column < 8; index_column++)

         if ((move->slots[new_move->source[0]][index_column].color == new_move->color)

             && (move->slots[new_move->source[0]][index_column].part == new_move->part)

             && Move_IsMoveValid (move, new_move->source[0], index_column, new_move->target[0], new_move->target[1]))

         {

            new_move->source[1] = index_column; // save column

            return (true); // we've found it, stop searching

         }

   }

   // else is source column known ?

   else if (new_move->source[1] != -1)

   {

      // cycle through all the lines and find the part of the same type that has the right to move there

      for (index_line = 0; index_line < 8; index_line++)

         if ((move->slots[index_line][new_move->source[1]].color == new_move->color)

             && (move->slots[index_line][new_move->source[1]].part == new_move->part)

             && Move_IsMoveValid (move, index_line, new_move->source[1], new_move->target[0], new_move->target[1]))

         {

            new_move->source[0] = index_line; // save line

            return (true); // we've found it, stop searching

         }

   }

   // else neither source line nor column is known

   else

   {

      // cycle through all the board and find the part of the same type that has the right to move there

      for (index_line = 0; index_line < 8; index_line++)

         for (index_column = 0; index_column < 8; index_column++)

            if ((move->slots[index_line][index_column].color == new_move->color)

                && (move->slots[index_line][index_column].part == new_move->part)

                && Move_IsMoveValid (move, index_line, index_column, new_move->target[0], new_move->target[1]))

            {

               new_move->source[0] = index_line; // save line and column

               new_move->source[1] = index_column;

               return (true); // we've found it, stop searching

            }

   }

   return (false); // no possibility found

}