private void PerformChessMove(ChessMove instruction)
{
PlayerSide thisSide = GetThisPlayerSide(instruction);
// chess if there has a chess
if (!HasChess(instruction.From, this.LocationChess))
{
throw new InvalidChessOperation();
}
// check who's turn
if (thisSide != this.WhosTurn)
{
throw new InvalidChessOperation();
}
// check if during promotion
if (this.IsDuringPromotion)
{
// only allow to perform chess change
throw new InvalidChessOperation();
}
// if else:
// basic movement
// if checked after
// update `FreshTwoStepAdvancePawnLocation`
// en passant
// if checked after
// castling
// if checked before
// if checked middle
// if checked after
Chess chess = this.LocationChess[instruction.From];
if (IsReachable(chess, instruction.From, instruction.To, this.LocationChess))
{
if (IsChecked(thisSide, this.LocationChess, instruction))
{
throw new InvalidChessOperation();
}
UpdateFreshTwoStepAdvancePawnLocation(chess, instruction.From, instruction.To);
}
else if (IsEnPassant(chess, instruction.From, instruction.To))
{
if (IsChecked(thisSide, this.LocationChess, instruction))
{
throw new InvalidChessOperation();
}
// remove the killed pawn
switch (chess.Side)
{
case PlayerSide.White:
this.LocationChess.Remove(this.FreshTwoStepAdvanceBlackPawnLocation.Value);
break;
case PlayerSide.Black:
this.LocationChess.Remove(this.FreshTwoStepAdvanceWhitePawnLocation.Value);
break;
}
}
else if (IsCastling(chess, instruction.From, instruction.To))
{
// move rook
Point rookDestination = new Point((instruction.From.X + instruction.To.X) / 2, instruction.From.Y);
Point rookSource = new Point(0, 0);
switch (chess.Side)
{
case PlayerSide.White:
if (instruction.To.X > instruction.From.X)
{
rookSource = new Point(7, 7);
}
else
{
rookSource = new Point(0, 7);
}
break;
case PlayerSide.Black:
if (instruction.To.X > instruction.From.X)
{
rookSource = new Point(7, 0);
}
else
{
rookSource = new Point(0, 0);
}
break;
}
this.LocationChess[rookDestination] = this.LocationChess[rookSource];
this.LocationChess.Remove(rookSource);
}
else
{
throw new InvalidChessOperation();
}
// castling change availability
if (chess.Type == ChessType.King)
{
switch (chess.Side)
{
case PlayerSide.White:
this.CouldWhiteCastlingLeft = false;
this.CouldWhiteCastlingRight = false;
break;
case PlayerSide.Black:
this.CouldBlackCastlingLeft = false;
this.CouldBlackCastlingRight = false;
break;
}
}
else if (chess.Type == ChessType.Rook)
{
switch (instruction.From.Y)
{
case 0:
switch (instruction.From.X)
{
case 0:
this.CouldBlackCastlingLeft = false;
break;
case 7:
this.CouldBlackCastlingRight = false;
break;
}
break;
case 7:
switch (instruction.From.X)
{
case 0:
this.CouldWhiteCastlingLeft = false;
break;
case 7:
this.CouldWhiteCastlingRight = false;
break;
}
break;
}
}
// promotion
if (this.LocationChess[instruction.From].Type == ChessType.Pawn &&
(instruction.To.Y == 7 || instruction.To.Y == 0))
{
this.IsDuringPromotion = true;
}
else
{
this.WhosTurn = GetOppositeSide(GetThisPlayerSide(instruction));
}
// ~~mark check~~
}
private PlayerSide GetThisPlayerSide(ChessMove instruction)
{
return(this.LocationChess[instruction.From].Side);
}
private static bool IsChecked(PlayerSide side, Dictionary <Point, Chess> locationChess, ChessMove after = null)
{
lock (SpinLock_IsChecked)
{
Chess killedChess = null;
bool isChecked = false;
if (after != null)
{
if (locationChess.ContainsKey(after.To))
{
killedChess = locationChess[after.To];
}
locationChess[after.To] = locationChess[after.From];
locationChess.Remove(after.From);
}
Point kingLocation = GetKingLocation(side, locationChess);
foreach ((Point location, Chess chess) in locationChess)
{
if (chess.Side == side)
{
continue;
}
if (IsReachable(chess, location, kingLocation, locationChess))
{
isChecked = true;
break;
}
}
// restore
if (after != null)
{
locationChess[after.From] = locationChess[after.To];
locationChess.Remove(after.To);
if (killedChess != null)
{
locationChess[after.To] = killedChess;
}
}
return(isChecked);
}
}
private static Point GetKingLocation(PlayerSide side, Dictionary <Point, Chess> locationChess, ChessMove after = null)
{
if (after != null && locationChess[after.From].Type == ChessType.King)
{
return(after.To);
}
Point kingLocation = locationChess.Single(xxxx =>
xxxx.Value.Type == ChessType.King &&
xxxx.Value.Side == side).Key;
return(kingLocation);
}
private bool IsCastling(Chess chess, Point from, Point to)
{
if (chess.Type != ChessType.King)
{
return(false);
}
if (Math.Abs(to.X - from.X) == 2 && from.X == 4)
{
// source -> destination: direction
switch (to.X)
{
case 2:
// king goes left
if (!HasChess(new Point(1, from.Y), this.LocationChess) &&
!HasChess(new Point(2, from.Y), this.LocationChess) &&
!HasChess(new Point(3, from.Y), this.LocationChess) &&
(chess.Side == PlayerSide.Black && this.CouldBlackCastlingLeft ||
chess.Side == PlayerSide.White && this.CouldWhiteCastlingLeft
)
)
{
ChessMove moveOneStep = new ChessMove()
{
From = from,
// To = new Point(from.X - 1, from.Y)
To = new Point((from.X + to.X) / 2, from.Y)
};
ChessMove moveTwoSteps = new ChessMove()
{
From = from,
To = to
};
return(!IsChecked(chess.Side, this.LocationChess) &&
!IsChecked(chess.Side, this.LocationChess, moveOneStep) &&
!IsChecked(chess.Side, this.LocationChess, moveTwoSteps));
}
else
{
return(false);
}
case 6:
// king goes right
if (!HasChess(new Point(5, from.Y), this.LocationChess) &&
!HasChess(new Point(6, from.Y), this.LocationChess) &&
(chess.Side == PlayerSide.Black && this.CouldBlackCastlingRight ||
chess.Side == PlayerSide.White && this.CouldWhiteCastlingRight
)
)
{
ChessMove moveOneStep = new ChessMove()
{
From = from,
// To = new Point(from.X + 1, from.Y)
To = new Point((from.X + to.X) / 2, from.Y)
};
ChessMove moveTwoSteps = new ChessMove()
{
From = from,
To = to
};
return(!IsChecked(chess.Side, this.LocationChess) &&
!IsChecked(chess.Side, this.LocationChess, moveOneStep) &&
!IsChecked(chess.Side, this.LocationChess, moveTwoSteps));
}
else
{
return(false);
}
default:
return(false);
}
}
else
{
return(false);
}
}