/// <summary>
/// Retrieve the best chess draw for the given situation (board + previous draw) from the cache. If the situation is not in the cache, null is returned.
/// </summary>
/// <param name="board">The chess board representing the situation.</param>
/// <param name="predecedingDraw">The previous draw made by the enemy.</param>
/// <returns>The best chess draw (if there is one in the cache)</returns>
public ChessDraw?GetBestDraw(IChessBoard board, ChessDraw?predecedingDraw)
{
// get possible draws from database (with win rate)
var drawingSide = predecedingDraw?.DrawingSide.Opponent() ?? ChessColor.White;
string sql =
$"WITH Situation AS( "
+ $" SELECT "
+ $" DrawHash, "
+ $" WinRate, "
+ $" AnalyzedGames, "
+ $" WinRate * AnalyzedGames AS Score "
+ $" FROM WinRateInfo "
+ $" WHERE DrawingSide = '{ char.ToLower(drawingSide.ToChar()) }' AND BoardBeforeHash = '{ board.ToHash() }' "
+ $") "
+ $"SELECT "
+ $" DrawHash, "
+ $" Score "
+ $"FROM Situation "
+ $"WHERE Score = (SELECT MAX(Score) FROM Situation)";
var bestDraws = queryItems(sql).Select(x => new Tuple <ChessDraw, double>(new ChessDraw(int.Parse(x["DrawHash"] as string, NumberStyles.HexNumber)), (double)x["Score"])).ToList();
return(bestDraws?.Count > 0 ? (ChessDraw?)bestDraws.ChooseRandom().Item1 : null);
// query for testing
// ====================================
// WITH Situation AS(
// SELECT
// DrawHashMetadata.*,
// WinRate,
// AnalyzedGames
// FROM WinRateInfo
// INNER JOIN DrawHashMetadata ON WinRateInfo.DrawHash = DrawHashMetadata.DrawHash
// WHERE WinRateInfo.DrawingSide = 'w' AND BoardBeforeHash = '19482090A3318C6318C60000000000000000000000000000000000000000B5AD6B5AD69D6928D2B3'
// )
//
// SELECT
// *,
// WinRate* AnalyzedGames AS Score
// FROM Situation
// ORDER BY Score DESC
}
