From d69c731bde5cf2c958c794f505684365072ab64a Mon Sep 17 00:00:00 2001
From: Adam <adammegarules1@gmail.com>
Date: Tue, 28 Jul 2026 13:52:49 +0200
Subject: adding make move and unmake move

---
 src/board.cpp | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

(limited to 'src/board.cpp')

diff --git a/src/board.cpp b/src/board.cpp
index 5107a0f..f78d429 100644
--- a/src/board.cpp
+++ b/src/board.cpp
@@ -156,3 +156,126 @@ void PlayMove(Move move, Game *b) {
   }
 };
 int PositionToIndex(Position i) { return i.rank * 8 + i.file; }
+
+UndoMove MakeMove(Move move, Game *g) {
+  UndoMove undo = {};
+
+  undo.from = move.From;
+  undo.to = move.To;
+
+  undo.movedPiece = g->pieces[PositionToIndex(move.From)];
+  undo.capturedPiece = g->pieces[PositionToIndex(move.To)];
+
+  undo.oldTurn = g->turn;
+  undo.oldCanEnpassant = g->canEnpassant;
+  undo.oldEnPassant = g->enPassant;
+
+  undo.oldHalfMoveClock = g->halfMoveClock;
+  undo.oldMoveClock = g->MoveClock;
+
+  undo.oldState = g->state;
+  undo.oldCaslte = g->castle;
+
+  // play move
+
+  Piece piece = g->pieces[PositionToIndex(move.From)];
+  Piece piece2 = g->pieces[PositionToIndex(move.To)];
+
+  if (piece2.type != NONE) {
+    if (piece2.color == g->turn) {
+      assert(false && "capturing friendly piece error");
+    }
+  }
+  piece.moved = true;
+
+  // clock
+  g->MoveClock++;
+  if (piece.type == PAWN || piece2.type != NONE) {
+    g->halfMoveClock = 0;
+  } else {
+    g->halfMoveClock++;
+  }
+
+  // Playing enpasstant
+  if (piece.type == PAWN && g->canEnpassant && move.To == g->enPassant) {
+    Position capturedPawn = move.To;
+    capturedPawn.rank += piece.color ? 1 : -1;
+    g->pieces[PositionToIndex(capturedPawn)] = {false, NONE, false};
+
+    undo.wasEnPassantCapture = true;
+    undo.enPassantCapturedSquare = capturedPawn;
+    undo.enPassantCapturedPiece = g->pieces[PositionToIndex(capturedPawn)];
+  }
+
+  g->canEnpassant = false;
+
+  // Adding enpassant
+  if (piece.type == PAWN) {
+    Position to = move.To;
+    to.rank -= (piece.color ? -2 : 2);
+    if (to == move.From) {
+      g->canEnpassant = true;
+      Position target = move.From;
+      target.rank += piece.color ? -1 : 1;
+      g->enPassant = target;
+    };
+  }
+
+  // Promotions
+  if (piece.type == PAWN && move.To.rank == (piece.color ? 0 : 7)) {
+    // TODO parse the promote type from uci isntead of ignoreting it
+    piece.type = move.promotion == NONE ? QUEEN : move.promotion;
+  }
+
+  // setting the moves
+  g->pieces[PositionToIndex(move.To)] = piece;
+  g->pieces[PositionToIndex(move.From)] = {false, NONE, false};
+
+  // post move change
+
+  // changing who turn it is
+  g->turn = !g->turn;
+
+  // 3 fold check
+  uint64_t key = GenerateZobristKey(g);
+
+  undo.zobristKey = key;
+
+  g->ThreeFoldMap[key]++;
+
+  if (g->ThreeFoldMap[key] >= 3) {
+    g->state = DRAW;
+  }
+
+  if (g->halfMoveClock >= 50) {
+    g->state = DRAW;
+  }
+
+  return undo;
+};
+void UnMake(UndoMove undo, Game *g) {
+  g->pieces[PositionToIndex(undo.from)] = undo.movedPiece;
+
+  g->pieces[PositionToIndex(undo.to)] = undo.capturedPiece;
+
+  if (undo.wasEnPassantCapture) {
+    g->pieces[PositionToIndex(undo.enPassantCapturedSquare)] =
+        undo.enPassantCapturedPiece;
+  }
+
+  g->turn = undo.oldTurn;
+
+  g->canEnpassant = undo.oldCanEnpassant;
+  g->enPassant = undo.oldEnPassant;
+
+  g->halfMoveClock = undo.oldHalfMoveClock;
+  g->MoveClock = undo.oldMoveClock;
+
+  g->state = undo.oldState;
+
+  g->castle = undo.oldCaslte;
+
+  if (--g->ThreeFoldMap[undo.zobristKey] <= 0) {
+    g->ThreeFoldMap.erase(undo.zobristKey);
+  }
+};
-- 
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