private void MovePiece(PieceView piece, SquareView square)
{
//Move the piece
Grid.SetRow(piece, square.Row);
Grid.SetColumn(piece, square.Column);
//Remember that this piece has moved
//PieceView piece = CurrentBoard.Pieces.Single(x => x.Position == square.Position);
piece.HasMoved = true;
//Clear squares showing legal moves
ClearAllSquares();
//Change player turn
Turn = Turn == Players.White ? Players.Black : Players.White;
//TODO:
//Check game over
}
private bool CheckCheck(Players player)
{
PieceView king = CurrentBoard.Pieces.Where(x => x.PieceType == Pieces.King).Single(x => x.Player == player);
SquareView kingSquare = CurrentBoard.Squares.Single(x => x.Position == king.Position);
kingSquare.State = SquareStates.Normal;
foreach (var enemy in CurrentBoard.Pieces.Where(x => x.Player != player))
{
if (CurrentBoard.Pieces.Count(x => x.Position == enemy.Position) == 1)
{
IsCheckingCheck = true;
ShowLegalMoves(enemy);
IsCheckingCheck = false;
}
if (kingSquare.State == SquareStates.ShowingKingInCheck)
{
return(true);
}
}
return(false);
}
internal void StateChanged(bool[] state)
{
CurrentState = state;
//When this method is called for the first time
if (PreviousState == null)
{
PreviousState = CurrentState;
return;
}
//Count the number of state 'changes'
//If only one change occured, remember the 'changePosition'
int changePosition = 0, changes = 0;
for (int position = 0; position < 64; position++)
{
if (PreviousState[position] != CurrentState[position])
{
changes++;
changePosition = position;
}
}
//Indicating Piece-up and Piece-down using Opacity.
foreach (var piece in CurrentBoard.Pieces)
{
piece.State = CurrentState[piece.Position] ? PieceStates.Down : PieceStates.Up;
}
//When the game state was invalid
if (GameState == GameStates.Invalid)
{
//Has the board state been restored?
if (CurrentState.SequenceEqual(PreviousState))
{
GameState = previousGameState;
}
else
{
return;
}
}
//Don't bother going ahead if nothing has changed on the board
if (changes == 0)
{
return;
}
//If we've reached this far, only one state change has happened on the board
//Determine if that change was a Piece-up or Piece-down
bool isPieceUp = PreviousState[changePosition] == true && CurrentState[changePosition] == false;
bool isPieceDown = PreviousState[changePosition] == false && CurrentState[changePosition] == true;
//Get the Square at the position where state changed.
SquareView changedSquare = CurrentBoard.Squares[changePosition];
if (GameState == GameStates.Waiting)
{
if (isPieceUp)
{
var pickedUpPiece = CurrentBoard.Pieces.Single(x => x.Position == changedSquare.Position);
if (pickedUpPiece.Player == Turn)
{
GameState = GameStates.Moving;
changedSquare.State = SquareStates.PieceAboveIsMoving;
CurrentMovingPiece = pickedUpPiece;
ShowLegalMoves(pickedUpPiece);
}
else
{
GameState = GameStates.WrongTurn;
//LastChangeSquare = changedSquare;
//return;
}
}
else
{
GameState = GameStates.Invalid;
return;
}
}
else if (GameState == GameStates.Moving)
{
if (isPieceDown)
{
bool isMoveCanceled = changedSquare.State == SquareStates.PieceAboveIsMoving;
bool isLegalMove =
changedSquare.State == SquareStates.ShowingLegalMove ||
changedSquare.State == SquareStates.ShowingCastling ||
changedSquare.State == SquareStates.ShowingPromotion ||
changedSquare.State == SquareStates.ShowingEnPassant ||
changedSquare.State == SquareStates.ShowingPieceThreatened;
if (isMoveCanceled)
{
GameState = GameStates.Waiting;
ClearAllSquares();
CheckCheck(Turn);
}
else if (isLegalMove)
{
GameState = GameStates.Waiting;
MovePiece(CurrentMovingPiece, changedSquare);
CheckCheck(Turn);
}
else
{
GameState = GameStates.Illegal;
changedSquare.State = SquareStates.ShowingIllegalMove;
}
}
else
{
//Check if player had picked up the piece to capture it
bool isCapturingMove = changedSquare.State == SquareStates.ShowingPieceThreatened;
if (isCapturingMove)
{
//Capture the piece
PieceView capturedPiece = CurrentBoard.Pieces.Single(x => x.Position == changedSquare.Position);
CurrentBoard.Pieces.Remove(capturedPiece);
//Now the capturing piece HAS to take place of the captured piece.
ClearAllSquares();
changedSquare.State = SquareStates.ShowingPieceThreatened;
}
else
{
GameState = GameStates.Invalid;
return;
}
}
}
else if (GameState == GameStates.Illegal)
{
if (isPieceUp)
{
//If the misplaced piece is picked up, change game state back to 'Moving'.
if (LastChangeSquare == changedSquare)
{
GameState = GameStates.Moving;
changedSquare.State = SquareStates.Normal;
}
else
{
GameState = GameStates.Invalid;
return;
}
}
else
{
GameState = GameStates.Invalid;
return;
}
}
else if (GameState == GameStates.WrongTurn)
{
if (isPieceDown)
{
//If the mispicked piece is put back down, change game state back to 'Waiting'
if (LastChangeSquare == changedSquare)
{
GameState = GameStates.Waiting;
}
else
{
GameState = GameStates.Invalid;
return;
}
}
else
{
GameState = GameStates.Invalid;
return;
}
}
LastChangeSquare = changedSquare;
PreviousState = CurrentState;
//Reindicating Piece-up and Piece-down using Opacity.
foreach (var piece in CurrentBoard.Pieces)
{
piece.State = CurrentState[piece.Position] ? PieceStates.Down : PieceStates.Up;
}
}
private void ShowLegalMovesHelper(PieceView piece, int x, int y, bool friendly = false, bool singleStep = false)
{
int far = singleStep ? 2 : 8;
for (int i = 1; i < far; i++)
{
int row = piece.Row + i * y;
int column = piece.Column + i * x;
if (row < 0 || column < 0 || row > 7 || column > 7)
{
break;
}
bool occupied = CurrentBoard.Pieces.Count(p => p.Row == row && p.Column == column) == 1;
SquareView square = CurrentBoard.Squares.Single(p => p.Row == row && p.Column == column);
if (occupied && !friendly)
{
PieceView foreignPiece = CurrentBoard.Pieces.Single(p => p.Position == square.Position);
if (foreignPiece.Player != piece.Player)
{
if (foreignPiece.PieceType == Pieces.King)
{
square.State = SquareStates.ShowingKingInCheck;
}
else if (!IsCheckingCheck)
{
int originalPosition = piece.Position;
MovePieceVirtually(piece, square);
if (CheckCheck(piece.Player) == false)
{
square.State = SquareStates.ShowingPieceThreatened;
}
MovePieceVirtually(piece, CurrentBoard.Squares.Single(p => p.Position == originalPosition));
}
}
return;
}
else if (!occupied)
{
if (piece.PieceType != Pieces.Pawn || piece.PieceType == Pieces.Pawn && friendly)
{
if (!IsCheckingCheck)
{
int originalPosition = piece.Position;
MovePieceVirtually(piece, square);
if (CheckCheck(piece.Player) == false)
{
square.State = SquareStates.ShowingLegalMove;
}
else
{
square.State = SquareStates.ShowingNotPossibleMoves;
}
MovePieceVirtually(piece, CurrentBoard.Squares.Single(p => p.Position == originalPosition));
}
}
}
}
}
private void ShowLegalMoveHelper(PieceView piece, int x, int y, bool friendly = false)
{
ShowLegalMovesHelper(piece, x, y, friendly, true);
}
private void ShowLegalMoves(PieceView piece)
{
switch (piece.PieceType)
{
case Pieces.King:
ShowLegalMoveHelper(piece, -1, -1);
ShowLegalMoveHelper(piece, 0, -1);
ShowLegalMoveHelper(piece, 1, -1);
ShowLegalMoveHelper(piece, -1, 0);
ShowLegalMoveHelper(piece, 1, 0);
ShowLegalMoveHelper(piece, -1, 1);
ShowLegalMoveHelper(piece, 0, 1);
ShowLegalMoveHelper(piece, 1, 1);
break;
case Pieces.Queen:
ShowLegalMovesHelper(piece, -1, -1);
ShowLegalMovesHelper(piece, 0, -1);
ShowLegalMovesHelper(piece, 1, -1);
ShowLegalMovesHelper(piece, -1, 0);
ShowLegalMovesHelper(piece, 1, 0);
ShowLegalMovesHelper(piece, -1, 1);
ShowLegalMovesHelper(piece, 0, 1);
ShowLegalMovesHelper(piece, 1, 1);
break;
case Pieces.Rook:
ShowLegalMovesHelper(piece, 0, -1);
ShowLegalMovesHelper(piece, 0, 1);
ShowLegalMovesHelper(piece, -1, 0);
ShowLegalMovesHelper(piece, 1, 0);
break;
case Pieces.Bishop:
ShowLegalMovesHelper(piece, -1, -1);
ShowLegalMovesHelper(piece, 1, -1);
ShowLegalMovesHelper(piece, -1, 1);
ShowLegalMovesHelper(piece, 1, 1);
break;
case Pieces.Knight:
ShowLegalMoveHelper(piece, -1, -2);
ShowLegalMoveHelper(piece, 2, 1);
ShowLegalMoveHelper(piece, 2, -1);
ShowLegalMoveHelper(piece, -2, 1);
ShowLegalMoveHelper(piece, -2, -1);
ShowLegalMoveHelper(piece, 1, 2);
ShowLegalMoveHelper(piece, -1, 2);
ShowLegalMoveHelper(piece, 1, -2);
ShowLegalMoveHelper(piece, -1, -2);
break;
case Pieces.Pawn:
if (piece.Player == Players.White)
{
if (piece.HasMoved == false)
{
ShowLegalMoveHelper(piece, 0, -2, true);
}
ShowLegalMoveHelper(piece, 0, -1, true);
ShowLegalMoveHelper(piece, -1, -1);
ShowLegalMoveHelper(piece, 1, -1);
}
else
{
if (piece.HasMoved == false)
{
ShowLegalMoveHelper(piece, 0, 2, true);
}
ShowLegalMoveHelper(piece, 0, 1, true);
ShowLegalMoveHelper(piece, -1, 1);
ShowLegalMoveHelper(piece, 1, 1);
}
break;
}
}
private void MovePieceVirtually(PieceView piece, SquareView square)
{
//Move the piece
Grid.SetRow(piece, square.Row);
Grid.SetColumn(piece, square.Column);
}