dev: refactoring things to be more OOP! whoop whoop

Still struggling to understand all these concepts, and I will admit
to using ChatGPT to try and explain where I was going wrong which
did help quite a bit. But if I get this right it will be much
more robust and less "fragile" as they say.

Board.cpp

@@ -7,6 +7,7 @@
 // defined by the Mozilla Public License, v. 2.0.
 
 #include "inc/Board.hpp"
+#include "inc/Piece.hpp"
 #include "inc/strFuncs.hpp"
 
 /*
@@ -241,8 +242,8 @@ int Board::setupFromFEN(std::string strFEN) {
     // ====== START OF FIELD 3 ======
     std::string k = "k", K = "K", q = "q", Q = "Q";
     // yeah this is hacky af but it works... blame SO
-    Piece *baseBKing = getPieceAt(blackKing).get();
+    Piece *baseBKing = getPieceAt(blackKing);
-    Piece *baseWKing = getPieceAt(whiteKing).get();
+    Piece *baseWKing = getPieceAt(whiteKing);
     King *bKing = dynamic_cast<King *>(baseBKing);
     King *wKing = dynamic_cast<King *>(baseWKing);
     if(splitFEN[2] == "-") {
@@ -310,8 +311,4 @@ void Board::deserializeBoard(uint64_t incomingBoard) {
         serialBoard.boardRows[i] = static_cast<uint8_t>((incomingBoard >> (8 * i)) & 0xFF);
     // how do we then figure out what has moved?
     return;
-}
-
-std::unique_ptr<Piece> &Board::getPieceAt(Square square) {
-    return boardGrid[static_cast<int>(square.rank)][static_cast<int>(square.file)];
 }

Piece.cpp

@@ -7,6 +7,7 @@
 // defined by the Mozilla Public License, v. 2.0.
 
 #include "inc/Piece.hpp"
+#include "inc/Board.hpp"
 
 Piece::~Piece() {
     return;
@@ -85,12 +86,10 @@ std::vector<Move> King::getLegalMoves(const Square &from, Board &board) const {
         // establish r/f for square to check
         int r = from.rank + dir[0];
         int f = from.file + dir[1];
-        auto ra = static_cast<Rank>(r);
+        Square targetSquare{static_cast<Rank>(r), static_cast<File>(f)};
-        auto fi = static_cast<File>(f);
-        Square targetSquare = {ra, fi};
         if(targetSquare.isValid()) {
-            const auto &target = board.boardGrid[r][f]; // examine the target square
+            const Piece *target = board.getPieceAt(targetSquare); // examine the target square
-            if(!target) { // if square is empty (NULL)
+            if(!target) { // if square is empty (nullptr)
                 moveList.push_back({from, targetSquare}); // then it's potentially a legal move
             } else if(target && target->getColour() != this->getColour()) { // if it's occupied with a piece of opposite colour
                 moveList.push_back({from, targetSquare}); // then again it's potentially legal
@@ -135,7 +134,8 @@ std::vector<Move> King::getLegalMoves(const Square &from, Board &board) const {
             bool diagonal = (abs(dir[0]) + abs(dir[1]) == 2) ? 1 : 0; // check if diagonal
             bool knight = (abs(dir[0]) + abs(dir[1]) == 3) ? 1 : 0; // check if knight attack
             while(r >= 0 && r < 8 && f >= 0 && f < 8) {
-                auto &target = board.boardGrid[r][f]; // access the square we're examining
+                Square targetSquare{static_cast<Rank>(r), static_cast<File>(f)};
+                const Piece *target = board.getPieceAt(targetSquare); // access the square we're examining
                 if(!target) {
                     // empty square, continue
                     continue;
@@ -204,10 +204,8 @@ std::vector<Move> Rook::getLegalMoves(const Square &from, Board &board) const {
         int r = from.rank + dir[0];
         int f = from.file + dir[1];
         while(r >= 0 && r < 8 && f >= 0 && f < 8) {
-            const auto& target = board.boardGrid[r][f];
+            Square targetSquare{static_cast<Rank>(r), static_cast<File>(f)};
-            auto ra = static_cast<Rank>(r);
+            const Piece *target = board.getPieceAt(targetSquare);
-            auto fi = static_cast<File>(f);
-            Square targetSquare = {ra, fi};
             if(!target) {
                 moveList.push_back({from, targetSquare});
             } else if(target && target->getColour() != this->getColour()) {
@@ -248,11 +246,9 @@ std::vector<Move> Queen::getLegalMoves(const Square &from, Board &board) const {
         // establish r/f for square to check
         int r = from.rank + dir[0];
         int f = from.file + dir[1];
-        auto ra = static_cast<Rank>(r);
-        auto fi = static_cast<File>(f);
-        Square targetSquare = {ra, fi};
         while(r >= 0 && r < 8 && f >= 0 && f < 8) {
-            const auto &target = board.boardGrid[r][f]; // examine the target square
+            Square targetSquare{static_cast<Rank>(r), static_cast<File>(f)};
+            const Piece *target = board.getPieceAt(targetSquare);// examine the target square
             if(!target) { // if square is empty (NULL)
                 moveList.push_back({from, targetSquare}); // then it's potentially a legal move
             } else if(target && target->getColour() != this->getColour()) { // if it's occupied with a piece of opposite colour
@@ -354,13 +350,11 @@ std::vector<Move> Pawn::getLegalMoves(const Square &from, Board &board) const {
             int r = from.rank + dir[0];
             int f = from.file + dir[1];
             if(r >= 0 && r < 8 && f >= 0 && f < 8) { // no need for a while loop as we only have finite moves in limited directions
-                const auto& target = board.boardGrid[r][f];
+                Square targetSquare{static_cast<Rank>(r), static_cast<File>(f)};
-                auto ra = static_cast<Rank>(r);
+                const Piece *target = board.getPieceAt(targetSquare);
-                auto fi = static_cast<File>(f);
-                Square targetSquare = {ra, fi};
                 if(dir[0] == -2 && !this->checkIfMoved()) {
                     // then 2 is potentially legal
-                    if(!target && !(board.boardGrid[r + 1][f])) // check both squares for pieces of any colour
+                    if(!target && board.isSquareEmpty(Square{static_cast<Rank>(r + 1), static_cast<File>(f)})) // check both squares for pieces of any colour
                         moveList.push_back({from, targetSquare});
                     else
                         continue;
@@ -383,13 +377,11 @@ std::vector<Move> Pawn::getLegalMoves(const Square &from, Board &board) const {
             int r = from.rank + dir[0];
             int f = from.file + dir[1];
             if(r >= 0 && r < 8 && f >= 0 && f < 8) { // no need for a while loop as we only have finite moves in limited directions
-                const auto& target = board.boardGrid[r][f];
+                Square targetSquare{static_cast<Rank>(r), static_cast<File>(f)};
-                auto ra = static_cast<Rank>(r);
+                const Piece *target = board.getPieceAt(targetSquare);
-                auto fi = static_cast<File>(f);
-                Square targetSquare = {ra, fi};
                 if(dir[0] == 2 && !this->checkIfMoved()) {
                     // then 2 is potentially legal
-                    if(!target && !(board.boardGrid[r - 1][f]))
+                    if(!target && board.isSquareEmpty(Square{static_cast<Rank>(r + 1), static_cast<File>(f)}))
                         moveList.push_back({from, targetSquare});
                     else
                         continue;

inc/Board.hpp

@@ -13,10 +13,8 @@
 #include <memory>
 #include <string>
 #include <vector>
-
 #include "Piece.hpp"
-
+// suggested to forward declare here, and put include in the .cpp
-// why do I have to forward declare all these?!
 class Piece;
 
 enum Players { PL_WHITE, PL_BLACK };
@@ -25,23 +23,56 @@ struct Square;
 class Board {
   private:
     friend class Piece; // this doesn't seem to do anything
-    Players playerTurn;
-  public:
-    // this should be protected, but even when Piece is declared as a friend,
-    // accessing it in Piece.cpp threw an error
     std::vector<std::vector<std::unique_ptr<Piece>>> boardGrid;
+    Players playerTurn;
+    // let's get super object-oriented, baby
+    // these help the getters and setters access the boardGrid
+    // and also make them shorter and less duplicative
+    std::unique_ptr<Piece>& at(int r, int f) {
+        return boardGrid[r][f];
+    }
+
+    const std::unique_ptr<Piece>& at(int r, int f) const {
+        return boardGrid[r][f];
+    }
+
+    std::unique_ptr<Piece>& at(const Square& sq) {
+        return boardGrid[static_cast<int>(sq.rank)][static_cast<int>(sq.file)];
+    }
+
+    const std::unique_ptr<Piece>& at(const Square& sq) const {
+        return boardGrid[static_cast<int>(sq.rank)][static_cast<int>(sq.file)];
+    }
+  public:
     Board();
     virtual ~Board();
 
+    // These are to allow Piece to access Board in a controlled way
+    // ----- Getters -----
+    Piece* getPieceAt(int r, int f) { return at(r, f).get(); }
+    const Piece* getPieceAt(int r, int f) const { return at(r, f).get(); }
+
+    Piece* getPieceAt(const Square& sq) { return at(sq).get(); }
+    const Piece* getPieceAt(const Square& sq) const { return at(sq).get(); }
+
+    // ----- Setters -----
+    void setPieceAt(int r, int f, std::unique_ptr<Piece> piece) { at(r, f) = std::move(piece); }
+    void setPieceAt(const Square& sq, std::unique_ptr<Piece> piece) { at(sq) = std::move(piece); }
+
+    void clearSquare(int r, int f) { at(r, f).reset(); }
+    void clearSquare(const Square& sq) { at(sq).reset(); }
+
+    // ----- Utility -----
+    bool isSquareEmpty(int r, int f) const { return at(r, f) == nullptr; }
+    bool isSquareEmpty(const Square& sq) const { return at(sq) == nullptr; }
+    
     void setupInitialPosition();
 
     void clearBoard();
-    std::unique_ptr<Piece> &getPieceAt(Square square);
     void movePiece(Square from, Square to);
     void nextTurn();
     int setupFromFEN(std::string strFEN);
     bool isInBounds(Square square) const;
-    bool isEmpty(Square square) const;
     // serial shift register stuff
     uint64_t serialBoard = 0xFFFF00000000FFFF; // opening position
     void deserializeBoard(uint64_t incomingBoard);

inc/Piece.hpp

@@ -28,7 +28,7 @@
 #include <string>
 #include <memory>
 #include <vector>
-#include "Board.hpp"
+
 class Board;
 
 enum PieceType {