private MoveNode GetMoveNodeMaxDepth(Color color, ChessBoard board, Move move, float baseValue)
{
var node = new MoveNode
{
Children = null,
Move = move
};
var boardCopy = board.CopyWithMove(move);
var cacheKey = new EvalCacheKey(boardCopy.GetFenString());
if (boardEvalCache.ContainsKey(cacheKey))
{
node.Score = boardEvalCache[cacheKey];
}
else
{
var score = boardEvaluator.EvaluateBoard(boardCopy, color) - baseValue;
if (!boardEvalCache.ContainsKey(cacheKey))
{
boardEvalCache.TryAdd(cacheKey, score);
cacheChanged = true;
}
node.Score = score;
}
return(node);
}
private MoveNode CreateRootMoveNode(Color color, ChessBoard board, Move baseMove)
{
float baseValue = boardEvaluator.EvaluateBoard(board, color);
var node = new MoveNode
{
Move = baseMove
};
var boardWithMove = board.CopyWithMove(node.Move);
var cacheKey = new EvalCacheKey(boardWithMove.GetFenString());
if (boardWithMove.Winner.HasWinner)
{
float score = boardEvaluator.EvaluateBoard(board.CopyWithMove(node.Move), color);
boardEvalCache.TryAdd(cacheKey, score);
node.Score = score;
winFoundOnRoot = true;
return(node);
}
if (boardEvalCache.ContainsKey(cacheKey))
{
node.Score = boardEvalCache[cacheKey];
}
else
{
node.Children = BuildMoveTreeForColor(ChessBoard.InvertColor(color), color, board.CopyWithMove(baseMove), 2, baseValue);
}
if (node.Children == null || !node.Children.Any())
{
cacheKey = new EvalCacheKey(board.CopyWithMove(node.Move).GetFenString());
if (boardEvalCache.ContainsKey(cacheKey))
{
node.Score = boardEvalCache[cacheKey];
}
else
{
float score = boardEvaluator.EvaluateBoard(board.CopyWithMove(node.Move), color);
boardEvalCache.TryAdd(cacheKey, score);
cacheChanged = true;
node.Score = score;
}
}
else
{
node.Score = node.GetWorstChild();
}
return(node);
}
private List <MoveNode> BuildMoveTreeForColor(Color color, Color originalColor, ChessBoard board, int currentLevel, float baseValue)
{
if (winFoundOnRoot)
{
return(new List <MoveNode>());
}
if (currentLevel > maxDepth)
{
return(null);
}
var nodes = new List <MoveNode>();
var cacheKey = new EvalCacheKey(board.GetFenString());
var initScore = boardEvaluator.EvaluateBoard(board, originalColor);
if (initScore - baseValue <= -4)
{
nodes.Add(new MoveNode
{
Score = initScore - baseValue,
Children = null
});
return(nodes);
}
if (boardEvalCache.ContainsKey(cacheKey))
{
return(new List <MoveNode>
{
new MoveNode
{
Score = boardEvalCache[cacheKey] - baseValue,
Children = null
}
});
}
foreach (var move in board.GetAllAvailableMoves(color))
{
if (winFoundOnRoot)
{
return(new List <MoveNode>());
}
if (currentLevel == maxDepth)
{
var node = GetMoveNodeMaxDepth(color, board, move, baseValue);
nodes.Add(node);
}
else
{
var chessBoard = board.CopyWithMove(move);
float testScore = boardEvaluator.EvaluateBoard(board.CopyWithMove(move), originalColor);
boardEvalCache.TryAdd(cacheKey, testScore);
var node = new MoveNode
{
Children = BuildMoveTreeForColor(ChessBoard.InvertColor(color), originalColor, chessBoard, currentLevel + 1, baseValue),
Move = move
};
if (node.Children.Any())
{
node.Score = color == originalColor?node.GetWorstChild() : node.GetBestChild();
}
else
{
cacheKey = new EvalCacheKey(board.GetFenString());
if (boardEvalCache.ContainsKey(cacheKey))
{
node.Score = boardEvalCache[cacheKey] - baseValue;
}
else
{
var score = boardEvaluator.EvaluateBoard(chessBoard.CopyWithMove(move), originalColor);
if (!boardEvalCache.ContainsKey(cacheKey))
{
boardEvalCache.TryAdd(cacheKey, score);
cacheChanged = true;
}
node.Score = score - baseValue;
}
}
nodes.Add(node);
}
}
return(nodes);
}