Refactoring

src/ChessSharp/ChessGame.cs

@@ -14,17 +14,17 @@ public class ChessGame : IDeepCloneable<ChessGame>
         /// <summary>Gets <see cref="Piece"/> in a specific square.</summary>
         /// <param name="file">The <see cref="Linie"/> of the square.</param>
         /// <param name="rank">The <see cref="Rank"/> of the square.</param>
-        public Piece? this[Linie file, Rank rank] => Board[(int)rank][(int)file];
+        public Piece this[Linie file, Rank rank] => Board[(int)rank][(int)file];
 
-        public Piece? this[Square sq] => Board[(int)sq.Rank][(int)sq.File];
+        public Piece this[Square sq] => Board[(int)sq.Rank][(int)sq.File];
 
-        public void SetPiece(Square sq, Piece? p) => Board[(int)sq.Rank][(int)sq.File] = p;
+        public void SetPiece(Square sq, Piece p) => Board[(int)sq.Rank][(int)sq.File] = p;
 
         /// <summary>Gets a list of the game moves.</summary>
         public Li<Move> Moves { get; private set; } // TODO: BAD! Investigate why the class consumer would even need this. Make it a private field if appropriate. And make it some kind of interface (`IEnumerable` for example).
 
         /// <summary>Gets a 2D array of <see cref="Piece"/>s in the board.</summary>
-        public Piece?[][] Board { get; private set; } // TODO: It's bad idea to expose this to public.
+        public Piece[][] Board { get; private set; } // TODO: It's bad idea to expose this to public.
 
         /// <summary>Gets the <see cref="Player"/> who has turn.</summary>
         public Player WhoseTurn { get; private set; } = Player.White;

src/ChessSharp/ChessUtilities.cs

@@ -50,7 +50,6 @@ public static Li<Move> GetValidMoves(ChessGame board)
         /// <param name="source">The source <see cref="Square"/> that you're looking for its valid moves.</param>
         /// <param name="board">The <see cref="ChessGame"/> that you want to get its valid moves from the specified square.</param>
         /// <returns>Returns a list of the valid moves that has the given source square.</returns>
-        /// 
         public static Li<Move> GetValidMovesOfSourceSquare(ChessGame board, Square source)
         {
             if (board == null || source == null)
@@ -76,8 +75,8 @@ public static Li<Move> GetValidMovesOfTargetSquare(ChessGame board, Square targe
                 throw new ArgumentNullException(nameof(board) + " or " + nameof(target));
 
             var validMoves = GetValidMoves(board);
-            validMoves = validMoves.Where(m => m.Destination == target && board[m.Source]?.Owner == board.WhoseTurn 
-                    && board[m.Source]?.GetType() == pieceType).ToLi();
+            validMoves = validMoves.Where(m => m.Destination == target && board[m.Source].Owner == board.WhoseTurn 
+                    && board[m.Source].GetType() == pieceType).ToLi();
             return validMoves;
         }
 
@@ -110,6 +109,5 @@ internal static bool IsPlayerInCheck(Player player, ChessGame board)
                     where piece.IsValidGameMove(move, board)
                     select piece).Any();
         }
-
     }
 }

src/ChessSharp/LichessPuzzle.cs

@@ -105,7 +105,7 @@ private static Move CreateMoveFromSMove(ChessGame game, string sMove, Player fir
                     throw new NotImplementedException();
                     // var possMoves = ChessUtilities.GetValidMovesOfTargetSquare(game, Square.Create(toString), typeof(Pawn));
                 }
-                else if (sMove[sMove.Length - 1].IsContainedIn(piecesChars))
+                else if (sMove[^1].IsContainedIn(piecesChars)) // 1 from end == last char. 
                 {
                     // Bauernumwandlungszug
                     possMoves = possMoves.Where(m => m.Source.File == Parser.ParseFile(sMove[0])).ToLi();

src/ChessSharp/SquareData/Square.cs

@@ -54,10 +54,7 @@ public static Square Parse(ReadOnlySpan<char> square)
     /// <summary>Represents a chess square.</summary>
     public struct Square : IEquatable<Square>
     {
-
-        /// <summary>
-        /// Initializes a new instance of the <c>Square</c>class.
-        /// </summary>
+        /// <summary> Initializes a new instance of the <c>Square</c>class. </summary>
         /// <param name="file">A <see cref="SquareData.Linie"/> enum representing the file of the square.</param>
         /// <param name="rank">A <see cref="SquareData.Rank"/> enum representing the rank of the square.</param>
         public Square(Linie file, Rank rank)

src/ChessUI/PuzzleSet.cs

@@ -56,7 +56,7 @@ public PuzzleGame NextPuzzle()
                     RebasePuzzles();
                 if (Puzzles[currentPuzzleNum + 1].NumCorrect != CurrentRound - 1)
                     RebasePuzzles();
-                game = new PuzzleGame(Puzzles[++currentPuzzleNum].SLichessPuzzle);
+                game = new PuzzleGame(Puzzles[++currentPuzzleNum].SRawPuzzle);
             }
             return game;
         }
@@ -144,7 +144,7 @@ void SearchPuzzles()
                 // for debugging
                 foreach (var f in Filters)
                 {
-                    var num = puzzles.Values.Where(p => f.IsMatching(p.SLichessPuzzle.Split(',').ToLiro())).Count();
+                    var num = puzzles.Values.Where(p => f.IsMatching(p.SRawPuzzle.Split(',').ToLiro())).Count();
                     Debug.WriteLine($"Filter={f} Num={num}");
                 }
                 if (puzzles.Count < NumPuzzlesWanted)
@@ -283,12 +283,12 @@ internal class Puzzle
 {
     public Puzzle(string sLichessPuzzle)
     {
-        this.SLichessPuzzle = sLichessPuzzle;
+        this.SRawPuzzle = sLichessPuzzle;
     }
 
     public Puzzle(string dbString, int dummy) => Read(dbString);
 
-    public string SLichessPuzzle { get; private set; }
+    public string SRawPuzzle { get; private set; }
 
     public int NumCorrect { get; set; }
 
@@ -304,11 +304,11 @@ public Puzzle(string sLichessPuzzle)
 
     public string Rating => SPuzzle.Split(',')[3];
 
-    public override string ToString() => $"TT={NumTriedInRound} C={NumCorrect} E= P={SLichessPuzzle}";
+    public override string ToString() => $"TT={NumTriedInRound} C={NumCorrect} E= P={SRawPuzzle}";
 
-    public string ToDbString() => $"TR={NumTriedInRound};C={NumCorrect};TT={NumTriedTotal};P={SLichessPuzzle}";
+    public string ToDbString() => $"TR={NumTriedInRound};C={NumCorrect};TT={NumTriedTotal};P={SRawPuzzle}";
 
-    private string SPuzzle => SLichessPuzzle.Split(',').Length >= 4 ?  SLichessPuzzle : ",,,,,";
+    private string SPuzzle => SRawPuzzle.Split(',').Length >= 4 ?  SRawPuzzle : ",,,,,";
 
     public void Read(string dbString)
     {
@@ -321,11 +321,11 @@ public void Read(string dbString)
                 case "C": NumCorrect = Helper.ToInt(parts2[1]); break;
                 case "TT": NumTriedTotal = Helper.ToInt(parts2[1]); break;
                 case "TR": NumTriedInRound = Helper.ToInt(parts2[1]); break;
-                case "P": SLichessPuzzle = parts2[1]; break;
+                case "P": SRawPuzzle = parts2[1]; break;
             }
         }
     }
 
-    public override int GetHashCode() => (LichessId + Rating).GetHashCode();
+    public override int GetHashCode() => SRawPuzzle.GetHashCode();
 }