path: root/src/board.cpp

#include "board.hpp"
#include "moves.hpp"
#include "zobrist.hpp"
#include <cassert>

Piece createPiece(PieceType type, bool color) {
  Piece piece;
  piece.type = type;
  piece.color = color;
  return piece;
}

int PositionToIndex(Position i) { return i.rank * 8 + i.file; }

Position FindKing(Game *b, bool white) {
  for (int i = 0; i < 64; i++) {
    Piece piece = b->pieces[i];

    if (piece.type == KING && piece.color == white) {
      return IndexToPosition(i);
    }
  }

  assert(false && "King not found");
  return {0, 0};
}
UndoMove MakeMove(Move move, Game *g) {
  UndoMove undo = {};

  undo.from = move.From;
  undo.to = move.To;

  undo.movedPiece = g->pieces[PositionToIndex(move.From)];
  undo.capturedPiece = g->pieces[PositionToIndex(move.To)];

  undo.oldTurn = g->turn;
  undo.oldCanEnpassant = g->canEnpassant;
  undo.oldEnPassant = g->enPassant;

  undo.oldHalfMoveClock = g->halfMoveClock;
  undo.oldMoveClock = g->MoveClock;

  undo.oldState = g->state;

  undo.OldwhiteCastleKing = g->whiteCastleKing;
  undo.OldwhiteCastleQueen = g->whiteCastleQueen;
  undo.OldblackCastleKing = g->blackCastleKing;
  undo.OldblackCastleQueen = g->blackCastleQueen;

  // play move

  Piece piece = g->pieces[PositionToIndex(move.From)];
  Piece piece2 = g->pieces[PositionToIndex(move.To)];

  if (piece2.type != NONEPIECE) {
    if (piece2.color == g->turn) {
      assert(false && "capturing friendly piece error");
    }
  }

  // clock
  g->MoveClock++;
  if (piece.type == PAWN || piece2.type != NONEPIECE) {
    g->halfMoveClock = 0;
  } else {
    g->halfMoveClock++;
  }

  // Playing enpasstant
  if (piece.type == PAWN && g->canEnpassant && move.To == g->enPassant) {
    Position capturedPawn = move.To;
    capturedPawn.rank += piece.color ? 1 : -1;
    g->pieces[PositionToIndex(capturedPawn)] = {false, NONEPIECE};

    undo.wasEnPassantCapture = true;
    undo.enPassantCapturedSquare = capturedPawn;
    undo.enPassantCapturedPiece = g->pieces[PositionToIndex(capturedPawn)];
  }

  g->canEnpassant = false;

  // Adding enpassant
  if (piece.type == PAWN) {
    Position to = move.To;
    to.rank -= (piece.color ? -2 : 2);
    if (to == move.From) {
      g->canEnpassant = true;
      Position target = move.From;
      target.rank += piece.color ? -1 : 1;
      g->enPassant = target;
    };
  }

  // Promotions
  if (piece.type == PAWN && move.To.rank == (piece.color ? 0 : 7)) {
    // TODO parse the promote type from uci isntead of ignoreting it
    piece.type = move.promotion == NONEPIECE ? QUEEN : move.promotion;
  }

  // caslte
  if (piece.type == KING && move.From.rank == (piece.color ? 0 : 7) &&
      (move.From.file + 2 == move.To.file ||
       move.From.file - 2 == move.To.file)) {

    undo.wasCastle = true;
    undo.CastledSide = (move.To.file > move.From.file);
    if (move.From.file + 2 == move.To.file) {
      Position rook_pos = move.To;
      rook_pos.file += 1;
      Piece rook = g->pieces[PositionToIndex(rook_pos)];
      g->pieces[PositionToIndex(rook_pos)] = {false, NONEPIECE};
      rook_pos = move.From;
      rook_pos.file -= 1;
      g->pieces[PositionToIndex(rook_pos)] = rook;
    }
    if (move.From.file - 2 == move.To.file) {
      Position rook_pos = move.To;
      rook_pos.file -= 1;
      Piece rook = g->pieces[PositionToIndex(rook_pos)];
      g->pieces[PositionToIndex(rook_pos)] = {false, NONEPIECE};
      rook_pos = move.From;
      rook_pos.file += 1;
      g->pieces[PositionToIndex(rook_pos)] = rook;
    }
  };

  // removing caslte rights
  if (piece.type == KING) {
    if (piece.color) {
      g->whiteCastleKing = false;
      g->whiteCastleQueen = false;
    } else {
      g->blackCastleKing = false;
      g->blackCastleQueen = false;
    }
  }

  // this part was written by ai
  if (piece.type == ROOK) {
    if (piece.color) {                                // White
      if (move.From.rank == 7 && move.From.file == 0) // a1
        g->whiteCastleQueen = false;

      if (move.From.rank == 7 && move.From.file == 7) // h1
        g->whiteCastleKing = false;
    } else {                                          // Black
      if (move.From.rank == 0 && move.From.file == 0) // a8
        g->blackCastleQueen = false;

      if (move.From.rank == 0 && move.From.file == 7) // h8
        g->blackCastleKing = false;
    }
  }

  // this part is also written with ai
  if (piece2.type == ROOK) {
    if (piece2.color) {                           // White rook captured
      if (move.To.rank == 7 && move.To.file == 0) // a1
        g->whiteCastleQueen = false;

      if (move.To.rank == 7 && move.To.file == 7) // h1
        g->whiteCastleKing = false;
    } else {                                      // Black rook captured
      if (move.To.rank == 0 && move.To.file == 0) // a8
        g->blackCastleQueen = false;

      if (move.To.rank == 0 && move.To.file == 7) // h8
        g->blackCastleKing = false;
    }
  }

  // playing the moves
  g->pieces[PositionToIndex(move.To)] = piece;
  g->pieces[PositionToIndex(move.From)] = {false, NONEPIECE};

  // changing who turn it is
  g->turn = !g->turn;

  // 3 fold check
  uint64_t key = GenerateZobristKey(g);

  undo.zobristKey = key;

  g->ThreeFoldMap[key]++;

  if (g->ThreeFoldMap[key] >= 3) {
    g->state = DRAW;
  }

  if (g->halfMoveClock >= 50) {
    g->state = DRAW;
  }

  return undo;
};
void UnMakeMove(UndoMove undo, Game *g) {
  g->pieces[PositionToIndex(undo.from)] = undo.movedPiece;

  g->pieces[PositionToIndex(undo.to)] = undo.capturedPiece;

  if (undo.wasEnPassantCapture) {
    g->pieces[PositionToIndex(undo.enPassantCapturedSquare)] =
        undo.enPassantCapturedPiece;
  }

  g->turn = undo.oldTurn;

  g->canEnpassant = undo.oldCanEnpassant;
  g->enPassant = undo.oldEnPassant;

  g->halfMoveClock = undo.oldHalfMoveClock;
  g->MoveClock = undo.oldMoveClock;

  g->state = undo.oldState;

  g->whiteCastleKing = undo.OldwhiteCastleKing;
  g->whiteCastleQueen = undo.OldwhiteCastleQueen;
  g->blackCastleKing = undo.OldblackCastleKing;
  g->blackCastleQueen = undo.OldblackCastleQueen;

  if (undo.wasCastle) {
    if (undo.CastledSide) {
      // rook f-file -> h-file
      Position rookFrom = undo.to;
      rookFrom.file -= 1; // f1/f8

      Position rookTo = undo.to;
      rookTo.file += 1; // h1/h8

      g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
      g->pieces[PositionToIndex(rookFrom)] = {false, NONEPIECE};
    } else {
      // rook d-file -> a-file
      Position rookFrom = undo.to;
      rookFrom.file += 1; // d1/d8

      Position rookTo = undo.to;
      rookTo.file -= 2; // a1/a8

      g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
      g->pieces[PositionToIndex(rookFrom)] = {false, NONEPIECE};
    }
  }
  g->ThreeFoldMap[undo.zobristKey] -= 1;
  if (g->ThreeFoldMap[undo.zobristKey] <= 0) {
    g->ThreeFoldMap.erase(undo.zobristKey);
  };
};