From c04f179b9902532a8d5db0c2ebd98460a70fc652 Mon Sep 17 00:00:00 2001
From: Adam <adammegarules1@gmail.com>
Date: Sun, 26 Jul 2026 14:10:48 +0200
Subject: making repl work

---
 src/fen.cpp | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 src/fen.cpp

(limited to 'src/fen.cpp')

diff --git a/src/fen.cpp b/src/fen.cpp
new file mode 100644
index 0000000..8244425
--- /dev/null
+++ b/src/fen.cpp
@@ -0,0 +1,138 @@
+#include "board.hpp"
+#include <cctype>
+#include <cstdio>
+#include <print>
+#include <string>
+
+bool WHITE = true;
+bool BLACK = false;
+
+void setBoardFen(std::string fen, board *b) {
+  // example fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
+  int file = 0;
+  int rank = 0;
+
+  std::string castle = "";
+
+  enum parserState {
+    POSITION,
+    TURN,
+    CASTLE,
+    ENPASSANT,
+    CLOCK1,
+    CLOCK2,
+  };
+  parserState state = POSITION;
+
+  for (int i = 0; i < fen.length(); i++) {
+    std::printf("state: %d\n", state);
+    std::printf("doing: %c\n", fen[i]);
+    if (fen[i] == ' ') {
+      if (state == POSITION) {
+        state = TURN;
+        continue;
+      }
+      if (state == TURN) {
+        state = CASTLE;
+        continue;
+      }
+      if (state == CASTLE) {
+        state = ENPASSANT;
+        continue;
+      }
+      if (state == ENPASSANT) {
+        state = CLOCK1;
+        continue;
+      }
+      if (state == CLOCK1) {
+        state = CLOCK2;
+        continue;
+      }
+    }
+    if (state == ENPASSANT) {
+      continue;
+    }
+    if (state == CASTLE) {
+      if (fen[i] == '-') {
+        castle = "-";
+        continue;
+      }
+      if (toupper(fen[i]) == 'K') {
+        castle += fen[i];
+        continue;
+      }
+      if (toupper(fen[i]) == 'Q') {
+        castle += fen[i];
+        continue;
+      }
+    }
+    if (state == TURN) {
+      if (toupper(fen[i]) == 'W') {
+        b->turn = WHITE;
+        continue;
+      }
+      if (toupper(fen[i]) == 'B') {
+        b->turn = BLACK;
+        continue;
+      }
+    }
+    if (state == POSITION) {
+      if (isdigit(fen[i])) {
+        int move = fen[i] - '0';
+        file += move;
+        if (file > 8) {
+          std::println("Fatal: file was to big");
+          return; // malformed rank
+        }
+        continue;
+      }
+      if (fen[i] == '/') {
+        file = 0;
+        rank++;
+        if (rank > 8) {
+          std::println("Fatal: rank was to big");
+          return; // malformed rank
+        }
+        continue;
+      }
+      if (toupper(fen[i]) == 'N') {
+        Piece piece = createPiece(KNIGHT, isupper(fen[i]));
+        b->pieces[rank * 8 + file] = piece;
+        file++;
+        continue;
+      }
+      if (toupper(fen[i]) == 'R') {
+        Piece piece = createPiece(ROOK, isupper(fen[i]));
+        b->pieces[rank * 8 + file] = piece;
+        file++;
+        continue;
+      }
+      if (toupper(fen[i]) == 'Q') {
+        Piece piece = createPiece(QUEEN, isupper(fen[i]));
+        b->pieces[rank * 8 + file] = piece;
+        file++;
+        continue;
+      }
+      if (toupper(fen[i]) == 'B') {
+        Piece piece = createPiece(BISHOP, isupper(fen[i]));
+        b->pieces[rank * 8 + file] = piece;
+        file++;
+        continue;
+      }
+      if (toupper(fen[i]) == 'P') {
+        Piece piece = createPiece(PAWN, isupper(fen[i]));
+        b->pieces[rank * 8 + file] = piece;
+        file++;
+        continue;
+      }
+      if (toupper(fen[i]) == 'K') {
+        Piece piece = createPiece(KING, isupper(fen[i]));
+        b->pieces[rank * 8 + file] = piece;
+        file++;
+        continue;
+      }
+    }
+    break;
+  }
+  b->castle = castle.empty() ? "-" : castle;
+}
-- 
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