public Move(Piece piece, Location from, Location to)
{
if (piece == null) throw new ArgumentNullException(nameof(piece));
if (@from == null) throw new ArgumentNullException(nameof(@from));
if (to == null) throw new ArgumentNullException(nameof(to));
From = from;
To = to;
Piece = piece;
}
public Piece GetPiece( Location location )
{
var file = location.File - 'a';
var rank = location.Rank - 1;
return _board[file][rank];
}
private void SetPiece( Location location, Piece piece )
{
var file = location.File - 'a';
var rank = location.Rank - 1;
_board[file][rank] = piece;
}
public static Location FromOffset(Location location, int fileOffset, int rankOffset)
{
var rank = location.Rank + rankOffset;
var file = (char) (location.File + fileOffset);
if (rank < 1 || rank > 8)
return null;
if (file < 'a' || file > 'h')
return null;
return new Location(file, rank);
}
private bool Equals( Location other )
{
return _rank == other._rank && _file == other._file;
}
public static bool TryParse(string locationString, out Location location)
{
location = null;
if (locationString?.Length != 2) return false;
int rank;
if (int.TryParse(locationString[1].ToString(), out rank))
{
location = new Location(locationString[0], rank);
return true;
}
return false;
}
private Location GetSourceLocation(Piece piece, Location destinationLocation, string fromLocationHint)
{
if (piece == null) throw new ArgumentNullException(nameof(piece));
if (destinationLocation == null) throw new ArgumentNullException(nameof(destinationLocation));
switch (piece.Type)
{
case PieceType.Pawn:
return GetPawnSourceLocation(piece, destinationLocation, fromLocationHint);
case PieceType.Rook:
return GetRookSourceLocation(piece, destinationLocation, fromLocationHint);
case PieceType.Knight:
return GetKnightSourceLocation(piece, destinationLocation, fromLocationHint);
case PieceType.Bishop:
return GetBishopSourceLocation(piece, destinationLocation, fromLocationHint);
case PieceType.King:
return GetKingSourceLocation(piece, destinationLocation);
case PieceType.Queen:
return GetQueenSourceLocation(piece, destinationLocation, fromLocationHint);
}
throw new InvalidOperationException();
}
private Location GetRookSourceLocation(Piece rook, Location destinationLocation, string fromLocationHint)
{
return
FindSourceLocationForPieceWithStrategy(rook, destinationLocation, l => Location.FromOffset(l, 0, -1), fromLocationHint) ??
FindSourceLocationForPieceWithStrategy(rook, destinationLocation, l => Location.FromOffset(l, 0, 1), fromLocationHint) ??
FindSourceLocationForPieceWithStrategy(rook, destinationLocation, l => Location.FromOffset(l, -1, 0), fromLocationHint) ??
FindSourceLocationForPieceWithStrategy(rook, destinationLocation, l => Location.FromOffset(l, 1, 0), fromLocationHint);
}
private Location GetPawnSourceLocation(Piece pawn, Location destinationLocation, string fromLocationHint)
{
//Check if the space was occupied
var previousPiece = GetPiece(destinationLocation);
if (previousPiece != null)
{
//It was a capture check the diagonals
//TODO: Validate that both locations do not contain a valid pawn
var leftLocation = Location.FromOffset(destinationLocation, -1, pawn.Color == PieceColor.White ? -1 : 1);
if (leftLocation != null && pawn.Equals(GetPiece(leftLocation)) && leftLocation.MatchesHint(fromLocationHint))
{
return leftLocation;
}
var rightLocation = Location.FromOffset(destinationLocation, 1, pawn.Color == PieceColor.White ? -1 : 1);
if (rightLocation != null && pawn.Equals(GetPiece(rightLocation)) && rightLocation.MatchesHint(fromLocationHint))
{
return rightLocation;
}
}
else
{
//Not a capture look for a pawn in the same file
var oneBackLocation = Location.FromOffset(destinationLocation, 0, pawn.Color == PieceColor.White ? -1 : 1);
if (pawn.Equals(GetPiece(oneBackLocation)))
return oneBackLocation;
//Check if the pawn moved two spaces on its first move
if (pawn.Color == PieceColor.White && destinationLocation.Rank == 4)
{
var startingLocation = Location.FromOffset(destinationLocation, 0, -2);
if (pawn.Equals(GetPiece(startingLocation)))
return startingLocation;
}
else if (pawn.Color == PieceColor.Black && destinationLocation.Rank == 5)
{
var startingLocation = Location.FromOffset(destinationLocation, 0, 2);
if (pawn.Equals(GetPiece(startingLocation)))
return startingLocation;
}
}
return null;
}
private Location GetKnightSourceLocation(Piece knight, Location destinationLocation, string fromLocationHint)
{
var location = Location.FromOffset(destinationLocation, 2, 1);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, 2, -1);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, 1, -2);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, -1, -2);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, -2, -1);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, -2, 1);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, -1, 2);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
location = Location.FromOffset(destinationLocation, 1, 2);
if (location != null && knight.Equals(GetPiece(location)) && location.MatchesHint(fromLocationHint))
return location;
return null;
}
private Location GetKingSourceLocation(Piece king, Location destinationLocation)
{
var locations = new[]
{
Location.FromOffset(destinationLocation, 0, 1),
Location.FromOffset(destinationLocation, 1, 1),
Location.FromOffset(destinationLocation, 1, 0),
Location.FromOffset(destinationLocation, 1, -1),
Location.FromOffset(destinationLocation, 0, -1),
Location.FromOffset(destinationLocation, -1, -1),
Location.FromOffset(destinationLocation, -1, 0),
Location.FromOffset(destinationLocation, -1, 1)
};
return locations.FirstOrDefault(location => king.Equals(GetPiece(location)));
}
private Location GetBishopSourceLocation(Piece bishop, Location destinationLocation, string fromLocationHint)
{
return
FindSourceLocationForPieceWithStrategy(bishop, destinationLocation, l => Location.FromOffset(l, -1, -1), fromLocationHint) ??
FindSourceLocationForPieceWithStrategy(bishop, destinationLocation, l => Location.FromOffset(l, -1, 1), fromLocationHint) ??
FindSourceLocationForPieceWithStrategy(bishop, destinationLocation, l => Location.FromOffset(l, 1, 1), fromLocationHint) ??
FindSourceLocationForPieceWithStrategy(bishop, destinationLocation, l => Location.FromOffset(l, 1, -1), fromLocationHint);
}
private Location FindSourceLocationForPieceWithStrategy(Piece piece, Location destinationLocation, Func<Location, Location> strategy, string locationHint)
{
for (Location location = strategy(destinationLocation);
location != null;
location = strategy(location))
{
var foundPiece = GetPiece(location);
if (foundPiece != null)
{
if (piece.Equals(foundPiece) && location.MatchesHint(locationHint))
return location;
break;
}
}
return null;
}
public Piece GetPiece(Location location)
{
//For now it is just the initial starting locations since we have not implemented moving
return _board.GetPiece(location);
}