From b553823dde69405f56ecfbedbe67db8101adac32 Mon Sep 17 00:00:00 2001
From: "A.M. Rowsell" <amrowsell@frozenelectronics.ca>
Date: Thu, 28 Aug 2025 10:28:11 -0400
Subject: [PATCH] FEN: implemented first field of FEN string handling

---
 Board.cpp | 123 ++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 106 insertions(+), 17 deletions(-)

diff --git a/Board.cpp b/Board.cpp
index 77cbd8e..32590ad 100644
--- a/Board.cpp
+++ b/Board.cpp
@@ -30,12 +30,20 @@
  */
 
 Board::Board() {
-    // set up the board grid with smart pointers
-    // initialize each square with a Piece
-    playerTurn = PL_WHITE;
     boardGrid.resize(8);
     for(int i = 0; i < 8; i++) {
         boardGrid[i].resize(8);
+    }
+}
+
+Board::~Board() {
+}
+
+void Board::setupInitialPosition() {
+    // set up the board grid with smart pointers
+    // initialize each square with a Piece
+    playerTurn = PL_WHITE;
+    for(int i = 0; i < 8; i++) {
         switch(i) {
             case 0:
                 // white back rank
@@ -57,7 +65,9 @@ Board::Board() {
             case 3:
             case 4:
             case 5:
-                continue;
+                for(int j = 0; j <= 8; j++)
+                    boardGrid[i][j] = nullptr;
+                break;
             case 6:
                 // black pawn rank
                 for(int j = 0; j <= 8; j++)
@@ -77,27 +87,106 @@ Board::Board() {
                 break;
         }
     }
-}
-
-Board::~Board() {
-}
-
-void Board::setupInitialPosition() {
     return;
 }
 
 int setupFromFEN(std::string strFEN) {
-    std::string field1, field2, field3, field4, field5, field6;
     std::vector<std::string> splitFEN = split(strFEN, ' ');
     if(splitFEN.size() != 6) { // a valid FEN *must* contain 6 fields
         return -1;
     }
-    field1 = splitFEN[0];
-    field2 = splitFEN[1];
-    field3 = splitFEN[2];
-    field4 = splitFEN[3];
-    field5 = splitFEN[4];
-    field6 = splitFEN[5];
+    std::vector<std::string> splitField1 = split(splitFEN[0], '/');
+    int rank = 0, file = 0;
+    int skip = 0;
+    bool wKingPlaced = false, bKingPlaced = false;
+    for(auto &ranks : splitField1) {
+        for(auto &sym : ranks) {
+            if(skip) {
+                boardGrid[rank][file] = nullptr; // remove reference
+                skip--;
+                file++;
+                continue;
+            }
+            switch(sym) {
+            case 'R':
+                // white rook
+                boardGrid[rank][file] = std::make_unique<Rook>(PIECE_WHITE);
+                break;
+            case 'r':
+                // black rook
+                boardGrid[rank][file] = std::make_unique<Rook>(PIECE_BLACK);
+                break;
+            case 'N':
+                // white knight
+                boardGrid[rank][file] = std::make_unique<Knight>(PIECE_WHITE);
+                break;
+            case 'n':
+                // black knight
+                boardGrid[rank][file] = std::make_unique<Knight>(PIECE_BLACK);
+                break;
+            case 'B':
+                // white bishop
+                boardGrid[rank][file] = std::make_unique<Bishop>(PIECE_WHITE);
+                break;
+            case 'b':
+                // black bishop
+                boardGrid[rank][file] = std::make_unique<Bishop>(PIECE_BLACK);
+                break;
+            case 'Q':
+                // white queen
+                boardGrid[rank][file] = std::make_unique<Queen>(PIECE_WHITE);
+                break;
+            case 'q':
+                // black queen;
+                boardGrid[rank][file] = std::make_unique<Queen>(PIECE_BLACK);
+                break;
+            case 'K':
+                // white king
+                if(wKingPlaced) {
+                    // invalid FEN, more than 1 white king
+                    return -1;
+                } else {
+                    boardGrid[rank][file] = std::make_unique<King>(PIECE_WHITE);
+                    wKingPlaced = true;
+                }
+                break;
+            case 'k':
+                // black king
+                if(bKingPlaced) {
+                    // invalid FEN, more than 1 black king
+                    return -1;
+                } else {
+                    boardGrid[rank][file] = std::make_unique<King>(PIECE_BLACK);
+                    bKingPlaced = true;
+                }
+                break;
+            case 'P':
+                // white pawn
+                boardGrid[rank][file] = std::make_unique<Pawn>(PIECE_WHITE);
+                break;
+            case 'p':
+                // black pawn
+                boardGrid[rank][file] = std::make_unique<Pawn>(PIECE_BLACK);
+                break;
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+                skip = atoi(sym);
+                break;
+            default:
+                // invalid character?
+                return -1;
+            }
+            file++;
+        }
+        rank++;
+    }
     return 0;
 }