public override bool IsLegalMove(Square[][] board, Move move, IEnumerable<Move> pastMoves = null)
{
var defender = GetDestinationPiece(board, move);
if (move.RowChange != LegalDirectionByTeam())
if (!ValidOpeningPushWithNoDefender(board, move))
return false;
if (move.ColumnChange != 0)
{
CheckForMultipleColumnMovement(move);
CheckForLegalDirection(move);
if (defender == null && !IsLegalEnPassant(board, move, pastMoves))
return false;
ValidateNotAttackingSameTeam(board, move);
return true;
}
if (defender != null)
throw new Exception("There is a piece in the way!");
return true;
}
public bool IsLegalCastle(Square[][] board, Move move)
{
var source = board[move.StartRow][move.StartColumn];
var destination = board[move.EndRow][move.EndColumn];
var direction = GetMovementModifier(move.ColumnChange);
var rook = direction > 0
? board[move.EndRow][7].ChessPiece
: board[move.EndRow][0].ChessPiece;
if (move.RowChange != 0)
throw new Exception("Illegal move.");
if (MoveCount > 0)
throw new Exception("You may only castle if your king has not moved yet.");
if (destination.ChessPiece != null)
throw new Exception("You may not castle to an occupied square.");
if (rook == null || rook.PieceType != Data.Enum.PieceType.Rook || rook.MoveCount > 0)
throw new Exception("The rook on that side has already moved.");
if (HasCollision(board, move))
throw new Exception("There is a piece in the way of the castle.");
if (IsInCheck(board))
throw new Exception("You may not castle while in check.");
if (destination.TargetedByTeam(board, GetOppositeTeam()))
throw new Exception("You may not castle into check.");
return true;
}
private static bool IsValidKnightMove(Move move)
{
var possibleMoves = PossibleEndPositions(move.StartColumn, move.StartRow);
var moveIsPossible = possibleMoves.Any(m => m.Row == move.EndRow && m.Column == move.EndColumn);
return moveIsPossible;
}
public override bool IsLegalMove(Square[][] board, Move move, IEnumerable<Move> pastMoves = null)
{
ValidateNotAttackingSameTeam(board, move);
if (move.RowChange != 0 && move.ColumnChange != 0)
throw new Exception("You only move horizontal or vertical with a rook.");
if (HasCollision(board, move))
throw new Exception("There is a piece between you and your destination.");
return true;
}
public override bool IsLegalMove(Square[][] board, Move move, IEnumerable<Move> pastMoves = null)
{
ValidateNotAttackingSameTeam(board, move);
if (Math.Abs(move.RowChange) != Math.Abs(move.ColumnChange))
throw new Exception("You may only move diagonally with a bishop.");
if (HasCollision(board, move))
throw new Exception("There is a piece between your bishop and your destination!");
return true;
}
public override bool IsLegalMove(Square[][] board, Move move, IEnumerable<Move> pastMoves = null)
{
ValidateNotAttackingSameTeam(board, move);
if (!InBounds(move.EndRow, move.EndColumn))
throw new Exception("You have moved out of bounds!");
if (!IsValidKnightMove(move)) //L-movement
throw new Exception("You may only move in a proper 'L' pattern for a knight.");
return true;
}
public override bool IsLegalMove(Square[][] board, Move move, IEnumerable<Move> pastMoves = null)
{
ValidateNotAttackingSameTeam(board, move);
if (!HasLegalMovementModifiers(move))
throw new Exception("You may move diagonal, vertical, or horizontal with a queen.");
if (HasCollision(board, move))
throw new Exception("There is a piece between your queen and your destination!");
return true;
}
private bool HasLegalMovementModifiers(Move move)
{
if (Math.Abs(move.RowChange) == Math.Abs(move.ColumnChange)) //diagonal
return true;
if (move.RowChange != 0 && move.ColumnChange == 0) //vertical
return true;
if (move.RowChange == 0 && move.ColumnChange != 0) //horizontal
return true;
return false;
}
public bool Equals(Move move)
{
if (StartColumn != move.StartColumn)
return false;
if (EndColumn != move.EndColumn)
return false;
if (StartRow != move.StartRow)
return false;
if (EndRow != move.EndRow)
return false;
return true;
}
public bool TargetedByTeam(Square[][] board, Enum.Team team)
{
foreach (var row in board)
foreach (var square in row.Where(square => square.ChessPiece != null && square.ChessPiece.Team == team))
{
var possibleMove = new Move
{
EndColumn = Column,
EndRow = Row,
StartColumn = square.Column,
StartRow = square.Row
};
try
{
if (square.ChessPiece.IsLegalMove(board, possibleMove))
return true;
}
catch
{
}
}
return false;
}
public abstract bool IsLegalMove(Square[][] board, Move move, IEnumerable<Move> pastMoves = null);
private void DestroyOccupant(Square[][] board, Move move)
{
var occupant = GetDestinationPiece(board, move);
if (occupant != null)
{
occupant.Alive = false;
occupant.CurrentColumn = null;
occupant.CurrentRow = null;
}
}
protected void ValidateNotAttackingSameTeam(Square[][] board, Move move)
{
var attacker = GetAttacker(board, move);
var occupant = GetDestinationPiece(board, move);
if (occupant != null && occupant.Team == attacker.Team)
throw new Exception("You may not attack the same team.");
}
protected bool HasCollision(Square[][] board, Move move)
{
var rowModifier = GetMovementModifier(move.RowChange);
var columnModifier = GetMovementModifier(move.ColumnChange);
var row = move.StartRow + rowModifier;
var column = move.StartColumn + columnModifier;
while (row != move.EndRow || column != move.EndColumn)
{
if (!InBounds(row, column))
return true; //out of bounds
if (board[row][column].ChessPiece != null)
return true; //collison
row += rowModifier;
column += columnModifier;
}
return false;
}
protected ChessPiece GetDestinationPiece(Square[][] board, Move move)
{
return board[move.EndRow][move.EndColumn].ChessPiece;
}
private void PerformEnPassant(Move move)
{
var direction = move.RowChange > 0 ? 1 : -1;
var enemySquare = _board.Squares[move.EndRow - direction][move.EndColumn];
enemySquare.ChessPiece.Alive = false;
enemySquare.ChessPiece = null;
}
private static bool FitsCastleCriteria(Move move, ChessPiece piece)
{
return piece.PieceType == PieceType.King && Math.Abs(move.ColumnChange) > 1;
}
public void MovePiece(Move move)
{
var piece = _board.Squares[move.StartRow][move.StartColumn].ChessPiece;
var defender = _board.Squares[move.EndRow][move.EndColumn].ChessPiece;
var currentTeam = TeamToMove();
ValidateActiveGame();
ValidateIsCurrentTeam(piece);
ValidateIsLegalMove(move, piece);
PerformMove(move, defender, piece);
MarkGameProgress(piece, defender);
ValidateKingNotInCheck(currentTeam);
}
private void IncrementMoveData(Move move)
{
Game.Moves.Add(move);
Game.MoveCount++;
Game.MoveCountSinceProgress++;
}
private void ValidateIsLegalMove(Move move, ChessPiece piece)
{
var teamName = Enum.GetName(typeof(Team), piece.Team);
var pieceName = Enum.GetName(typeof(PieceType), piece.PieceType);
var orderedMoves = Game.Moves.OrderBy(i => i.MoveId);
if (!piece.IsLegalMove(_board.Squares, move, orderedMoves))
throw new Exception("This is not a legal move for a " + teamName + " " + pieceName + ".");
}
private bool SavesKing(Move move)
{
var currentTeam = TeamToMove();
var squares = GetMockSquares(_board.Squares);
var piece = squares[move.StartRow][move.StartColumn].ChessPiece;
piece.Move(squares, move);
if (IsKingInCheck(currentTeam, squares))
{
return false;
}
return true;
}
private void PerformMove(Move move, ChessPiece defender, ChessPiece piece)
{
if (FitsEnPassantCriteria(move, defender, piece))
{
PerformEnPassant(move);
}
if (FitsCastleCriteria(move, piece))
{
MoveRookForCastle(move);
}
if (defender != null)
{
if (piece.Team == Team.Dark)
Game.DarkScore += defender.ScoreValue;
if (piece.Team == Team.Light)
Game.LightScore += defender.ScoreValue;
}
piece.Move(_board.Squares, move);
IncrementMoveData(move);
}
public void Move(Square[][] board, Move move)
{
DestroyOccupant(board, move);
board[move.EndRow][move.EndColumn].ChessPiece = this;
board[move.StartRow][move.StartColumn].ChessPiece = null;
CurrentColumn = move.EndColumn;
CurrentRow = move.EndRow;
MoveCount++;
}
public bool ValidOpeningPushWithNoDefender(Square[][] board, Move move)
{
return MoveCount == 0
&& move.RowChange == LegalDirectionByTeam() * 2
&& move.ColumnChange == 0
&& board[move.EndRow - LegalDirectionByTeam()][move.EndColumn].ChessPiece == null
&& board[move.EndRow][move.EndColumn].ChessPiece == null;
}
protected ChessPiece GetAttacker(Square[][] board, Move move)
{
return board[move.StartRow][move.StartColumn].ChessPiece;
}
private static bool FitsEnPassantCriteria(Move move, ChessPiece defender, ChessPiece piece)
{
return defender == null && piece.PieceType == PieceType.Pawn && Math.Abs(move.ColumnChange) == 1;
}
private Exception NewMoveFailureException(Move move, Exception ex)
{
var start = move.StartColumn + ", " + move.StartRow;
var end = move.EndColumn + ", " + move.EndRow;
var reasonForFailure = ex.Message;
return new ArgumentException(String.Format("Moving {0} to {1} is illegal. {2}",
start, end, reasonForFailure));
}
private void MoveRookForCastle(Move move)
{
var direction = move.ColumnChange > 0 ? 1 : -1;
var rook = direction > 0
? _board.Squares[move.EndRow][7].ChessPiece
: _board.Squares[move.EndRow][0].ChessPiece;
var rookMove = new Move()
{
EndColumn = move.EndColumn - direction,
EndRow = move.EndRow,
StartColumn = rook.CurrentColumn ?? 0,
StartRow = move.StartRow,
};
rook.Move(_board.Squares, rookMove);
}
public ActionResult MakeMove(long id, Move move)
{
var game = GetChessGame(id);
var gameManager = new GameManager(game);
if (!IsPlayersMove(game, CurrentUser))
throw new Exception("It is not your turn!");
try
{
var movingTeam = gameManager.TeamToMove();
gameManager.MovePiece(move);
if (gameManager.IsDraw())
gameManager.MarkGameAsDraw();
else if (gameManager.IsCheckmate())
gameManager.MarkWinningTeam(movingTeam);
UnitOfWork.Commit();
var model = GetGameModel(game);
return Json(model, JsonRequestBehavior.AllowGet);
}
catch (Exception ex)
{
throw NewMoveFailureException(move, ex);
}
}
private bool IsPawnsSecondMoveInProperDirection(Move move, Entities.Move lastMove, ChessPiece piece)
{
return piece.PieceType == PieceType.Pawn
&& lastMove.EndRow == move.EndRow - LegalDirectionByTeam()
&& lastMove.EndColumn == move.EndColumn
&& piece.MoveCount == 1;
}