private IEnumerable <Move[]> FindMoves(Side side, BoardSquare pos, Direction dir, HashSet <BoardSquare> visited = null, bool capture = false)
{
visited ??= new HashSet <BoardSquare>();
var square = pos.Shift(dir);
if (!square.IsValid || visited.Contains(square))
{
return(Array.Empty <Move[]>());
}
var piece = GetPiece(square);
if (piece is null)
{
return(capture ? Array.Empty <Move[]>() : new[] { new [] { new Move(pos, square, null) } });
}
if (piece.Side != side)
{
var jump = square.Shift(dir);
if (jump.IsValid && GetPiece(jump) is null)
{
var move = new Move(pos, jump, piece);
visited.Add(square);
var paths = new List <Move[]>();
paths.AddRange(FindMoves(side, jump, Direction.UpperLeft, visited, true));
paths.AddRange(FindMoves(side, jump, Direction.UpperRight, visited, true));
paths.AddRange(FindMoves(side, jump, Direction.LowerLeft, visited, true));
paths.AddRange(FindMoves(side, jump, Direction.LowerRight, visited, true));
visited.Remove(square);
if (!paths.Any())
{
return(new[] { new[] { move } });
}
var maxLength = paths.Max(x => x.Length);
return(paths.Where(x => x.Length == maxLength).Select(path =>
{
var moves = new List <Move> {
move
};
moves.AddRange(path);
return moves.ToArray();
}));
}
}
return(Array.Empty <Move[]>());
}
