private IEnumerator GetEngineMove()
{
// This prevents the player from making a move during the calculation.
isReady = false;
ChangeText("Thinking...", "");
// This checks if it is stalemate for the engine.
if (position.IsStalemate(color.Flip()))
{
StartCoroutine(HandleStrike("You lose!", "Stalemate!"));
yield break;
}
// This checks if there are only kings on the board, which is always a draw.
if (position.All(c => c == '_' || c.ToLower() == 'k'))
{
StartCoroutine(HandleStrike("You lose!", "Kings only!"));
yield break;
}
yield return(_bestMove.Start(position, (MovesLeft * 2) + 1, color == PieceColor.Black));
// This looks convoluted, but it's only asking if the player has made a blunder, to the point of an unwinnable position.
if (isWinning &&
((color == PieceColor.White && _bestMove.Result.Evaluation != sbyte.MaxValue - (MovesLeft * 2)) ||
(color == PieceColor.Black && _bestMove.Result.Evaluation != (MovesLeft * 2) + sbyte.MinValue)))
{
isWinning = false;
Log("Rustmate has evaluated that this position is now unwinnable for you. Congratulations.");
}
ChangeText("Mate in", "", MovesLeft.ToString());
PlaySound(Sounds._1dch.Opponent);
// This indicates if the game has ended.
if (_bestMove.Result.IsEqual(Position.finishedGame))
{
isReady = false;
PlaySound(Sounds._1dch.Check);
// Stalemate.
if (_bestMove.Result.Evaluation == 0)
{
StartCoroutine(HandleStrike("You lose!", "Stalemate!"));
}
// Checkmate against the player.
else if (color == PieceColor.White ^ _bestMove.Result.Evaluation > 0)
{
StartCoroutine(HandleStrike("You lose!", "Checkmate!"));
}
// Checkmate for the player.
else
{
PlaySound(Sounds._1dch.GameEnd, Sounds._1dch.Solve);
string message = new[] { "Good game!", "Well played!" }.PickRandom();
Solve(message);
ChangeText("Solved!", message);
}
}
else
{
// This allows the player to make a move again.
isReady = true;
position = _bestMove
.Result
.Move(position, this);
Log("Rustmate plays {0}, the position is now {1}.", ToLog(_bestMove.Result), position);
souvenirPositions.Add(ToLog(_bestMove.Result));
// Having the game end after an engine move always means a loss for the player.
if (position.IsGameEnd(color))
{
StartCoroutine(HandleStrike("You lose!", position.IsStalemate(color) ? "Stalemate!" : "Checkmate!"));
}
// This checks if there are only kings on the board, which is always a draw.
else if (position.All(c => c == '_' || c.ToLower() == 'k'))
{
StartCoroutine(HandleStrike("You lose!", "Kings only!"));
}
else if (MovesLeft == 0)
{
StartCoroutine(HandleStrike("You lose!", "Out of moves!"));
}
}
RenderPosition(position);
}