+ let pieces = { "w": new Array(8), "b": new Array(8) };
+ // Shuffle pieces on first and last rank
+ for (let c of ["w","b"])
+ {
+ let positions = _.range(8);
+
+ // Get random squares for bishops
+ let randIndex = 2 * _.random(3);
+ let bishop1Pos = positions[randIndex];
+ // The second bishop must be on a square of different color
+ let randIndex_tmp = 2 * _.random(3) + 1;
+ let bishop2Pos = positions[randIndex_tmp];
+ // Remove chosen squares
+ positions.splice(Math.max(randIndex,randIndex_tmp), 1);
+ positions.splice(Math.min(randIndex,randIndex_tmp), 1);
+
+ // Get random squares for knights
+ randIndex = _.random(5);
+ let knight1Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+ randIndex = _.random(4);
+ let knight2Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Get random square for queen
+ randIndex = _.random(3);
+ let queenPos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Rooks and king positions are now fixed, because of the ordering rook-king-rook
+ let rook1Pos = positions[0];
+ let kingPos = positions[1];
+ let rook2Pos = positions[2];
+
+ // Finally put the shuffled pieces in the board array
+ pieces[c][rook1Pos] = 'r';
+ pieces[c][knight1Pos] = 'n';
+ pieces[c][bishop1Pos] = 'b';
+ pieces[c][queenPos] = 'q';
+ pieces[c][kingPos] = 'k';
+ pieces[c][bishop2Pos] = 'b';
+ pieces[c][knight2Pos] = 'n';
+ pieces[c][rook2Pos] = 'r';
+ }
+ return pieces["b"].join("") +
+ "/pppppppp/8/8/8/8/PPPPPPPP/" +
+ pieces["w"].join("").toUpperCase() +
+ " w 1111 -"; //add turn + flags + enpassant
+ }
+
+ // "Parse" FEN: just return untransformed string data
+ static ParseFen(fen)
+ {
+ const fenParts = fen.split(" ");
+ let res =
+ {
+ position: fenParts[0],
+ turn: fenParts[1],
+ };
+ let nextIdx = 2;
+ if (V.HasFlags)
+ Object.assign(res, {flags: fenParts[nextIdx++]});
+ if (V.HasEnpassant)
+ Object.assign(res, {enpassant: fenParts[nextIdx]});
+ return res;
+ }
+
+ // Return current fen (game state)
+ getFen()
+ {
+ return this.getBaseFen() + " " + this.turn +
+ (V.HasFlags ? (" " + this.getFlagsFen()) : "") +
+ (V.HasEnpassant ? (" " + this.getEnpassantFen()) : "");
+ }
+
+ // Position part of the FEN string
+ getBaseFen()
+ {
+ let position = "";
+ for (let i=0; i<V.size.x; i++)
+ {
+ let emptyCount = 0;
+ for (let j=0; j<V.size.y; j++)
+ {
+ if (this.board[i][j] == V.EMPTY)
+ emptyCount++;
+ else
+ {
+ if (emptyCount > 0)
+ {
+ // Add empty squares in-between
+ position += emptyCount;
+ emptyCount = 0;
+ }
+ position += V.board2fen(this.board[i][j]);
+ }
+ }
+ if (emptyCount > 0)
+ {
+ // "Flush remainder"
+ position += emptyCount;
+ }
+ if (i < V.size.x - 1)
+ position += "/"; //separate rows
+ }
+ return position;
+ }
+
+ // Flags part of the FEN string
+ getFlagsFen()
+ {
+ let flags = "";
+ // Add castling flags
+ for (let i of ['w','b'])
+ {
+ for (let j=0; j<2; j++)
+ flags += (this.castleFlags[i][j] ? '1' : '0');
+ }
+ return flags;
+ }
+
+ // Enpassant part of the FEN string
+ getEnpassantFen()
+ {
+ const L = this.epSquares.length;
+ if (!this.epSquares[L-1])
+ return "-"; //no en-passant
+ return V.CoordsToSquare(this.epSquares[L-1]);
+ }
+
+ // Turn position fen into double array ["wb","wp","bk",...]
+ static GetBoard(position)
+ {
+ const rows = position.split("/");