// Used more specifically to enforce board logic
public bool DoesMoveLeaveUsInCheck(IBoardState <ChessPieceEntity> boardState, BoardMove move)
{
var attackingPlayer = boardState.GetItem(move.From).Item.Player;
var clone = (IBoardState <ChessPieceEntity>)boardState.Clone();
_moveService.Move(clone, move);
var king = clone.GetItems((int)attackingPlayer, (int)ChessPieceName.King).Single();
return(_playerStateService.IsLocationUnderCheck(clone, king.Location, king.Item.Player).result);
}
private PlayerState CheckForCheckMate(IBoardState <ChessPieceEntity> boardState,
LocatedItem <ChessPieceEntity> king, LocatedItem <ChessPieceEntity> attacker)
{
var state = PlayerState.Check;
var clone = (IBoardState <ChessPieceEntity>)boardState.Clone();
// Find the attacking piece
// Not sure why we need to refresh its piece paths here but I get problems with out it
RefreshPiecePaths(clone, attacker);
// find the path it's attacking on
var attackPath = attacker.Paths.FirstOrDefault(p => p.ContainsTo(king.Location));
// Remove the king from the board so as to not have it's location block
// attack paths from the new location
clone.Remove(king.Location);
var kingCannotMove = !king.Paths.Any() || king.Paths.FlattenMoves()
.ToList()
.All(m
=> IsLocationUnderCheck(clone, m.To, king.Item.Player).result);
//
// get all friendly pieces except king
// refresh there paths
var friendlyPieces = clone.GetItems(king.Item.Owner)
.Where(p => p.Item.Piece != ChessPieceName.King)
.OrderBy(p => p.Item.EntityType);
// check if any friendly paths intersect the attackPath or attack the attacker
var canBlock = friendlyPieces.Where(fp
=> fp.Paths.FlattenMoves()
.Any(fm => attackPath
.Any(am => am.To.Equals(fm.To) || am.From.Equals(fm.To)
)
)
);
if (kingCannotMove && !canBlock.Any())
{
return(PlayerState.Checkmate);
}
return(PlayerState.Check);
}
// Typically only used to produce correct san notation on output
public bool DoesMoveCauseCheck(IBoardState <ChessPieceEntity> boardState, BoardMove move)
{
// TODO: Would it be quicker to
var attackingPlayer = boardState.GetItem(move.From).Item.Player;
var defender = boardState.GetItem(move.To);
if (defender != null && defender.Item.Is(attackingPlayer.Enemy(), ChessPieceName.King))
{
return(true);
}
var clone = (IBoardState <ChessPieceEntity>)boardState.Clone();
_moveService.Move(clone, move);
var king = clone.GetItems((int)attackingPlayer.Enemy(), (int)ChessPieceName.King).Single();
return(_playerStateService.IsLocationUnderCheck(clone, king.Location, king.Item.Player).result);
}
