private static bool TryFindMove(IEnumerable <LocatedItem <ChessPieceEntity> > items, BoardLocation destination,
StandardAlgebraicNotation san,
out BoardMove findMoveTo)
{
findMoveTo = null;
var locatedItems = items as LocatedItem <ChessPieceEntity>[] ?? items.ToArray();
if (!locatedItems.Any())
{
return(true);
}
if (locatedItems.Count() == 1)
{
var item = locatedItems.Single();
if (san.PromotionPiece.HasValue)
{
findMoveTo = item.Paths.FlattenMoves().FindMove(item.Location, destination,
ChessFactory.MoveExtraData(item.Item.Player, san.PromotionPiece.Value));
}
else
{
findMoveTo = item.FindMoveTo(destination);
}
return(findMoveTo != null);
}
return(false);
}
public BoardMove Find(StandardAlgebraicNotation san, Colours forPlayer)
{
var t = san.ToNotation();
if (san.CastleMove != StandardAlgebraicNotation.CastleSide.None)
{
return(FindCastleMove(san, forPlayer));
}
var destination = BoardLocation.At(san.ToFileX, san.ToRankY);
if (san.HaveFrom)
{
var exact = FindExactMove(san, destination);
if (exact == null)
{
Throw.MoveNotFound($"Move not found: {san.ToNotation()}");
}
return(exact);
}
var items = _boardState
.GetItems((int)forPlayer, (int)san.Piece)
.ThatCanMoveTo(destination);
if (TryFindMove(items, destination, san, out var move))
{
return(move);
}
if (san.FromFileX.HasValue)
{
items = items.Where(i => i.Paths.FlattenMoves().Any(m => m.From.X == san.FromFileX.Value));
if (TryFindMove(items, destination, san, out move))
{
return(move);
}
}
if (san.FromRankY.HasValue)
{
items = items.Where(i => i.Paths.FlattenMoves().Any(m => m.From.Y == san.FromRankY.Value));
if (TryFindMove(items, destination, san, out move))
{
return(move);
}
}
Throw.MoveNotFound($"Couldn't disambiguate move: {san.ToNotation()}");
return(null);
}
private BoardMove FindExactMove(StandardAlgebraicNotation san, BoardLocation destination)
{
var from = BoardLocation.At(san.FromFileX.Value, san.FromRankY.Value);
var item = _boardState.GetItem(@from);
var mv = item.Paths.FindMove(@from, destination);
var moveList = item.Paths.FlattenMoves().Select(m => m.ToChessCoords()).Aggregate((s, v) => s += $"{v},");
if (mv == null)
{
Throw.MoveNotFound($"Cannot find move matching '{san.ToNotation()}', destination '{destination.ToChessCoord()}', moveList '{moveList}");
}
return(mv);
}
public static bool TryParse(string notation, out StandardAlgebraicNotation an)
{
an = null;
if (string.IsNullOrEmpty(notation))
{
return(false);
}
try
{
an = Parse(notation);
}
catch
{
return(false);
}
return(true);
}
private BoardMove FindCastleMove(StandardAlgebraicNotation san, Colours forPlayer)
{
var king = _boardState.GetItem(King.StartPositionFor(forPlayer));
if (king == null)
{
Throw.MoveNotFound($"King not found: {san.ToNotation()}");
}
var y = forPlayer == Colours.White ? 1 : 8;
var from = BoardLocation.At(san.FromFileX.Value, y);
var to = BoardLocation.At(san.ToFileX, y);
var move = king.Paths.FindMove(@from, to);
if (move == null)
{
Throw.MoveNotFound($"No valid castle move found: {from}{to}");
}
return(move);
}