5 files changed, 33 insertions, 2 deletions
diff --git a/src/bot.cpp b/src/bot.cpp
index 03636f9..02dfd22 100644
--- a/src/bot.cpp
+++ b/src/bot.cpp
@@ -14,7 +14,7 @@
 #include <iterator>
 #include <vector>
 
-constexpr int MAXIMUM_DEPTH = 10;
+constexpr int MAXIMUM_DEPTH = 6;
 constexpr int MAXIMUM_TIME_PER_MOVE = 7;
 constexpr int Q_DEPTH_LIMIT = 4;
 
diff --git a/src/bot.hpp b/src/bot.hpp
index 821eb28..c271882 100644
--- a/src/bot.hpp
+++ b/src/bot.hpp
@@ -5,4 +5,4 @@
 
 Move GetBestMove(Game *b, int depth);
 
-#endif /* SRC_EVALUATE_H_ */
+#endif /* SRC_BOT_H_ */
diff --git a/src/moves.cpp b/src/moves.cpp
index 163bb8c..803538b 100644
--- a/src/moves.cpp
+++ b/src/moves.cpp
@@ -417,6 +417,13 @@ void GenerateCastlingMoves(int from, Game *g, std::vector<Move> &moves) {
   bool oneToLeft = g->PieceBitboard & (1ULL << (from - 1));
   bool twoToLeft = g->PieceBitboard & (1ULL << (from - 2));
   bool threeToLeft = g->PieceBitboard & (1ULL << (from - 3));
+
+  Position kingPosition = FindKing(g, g->turn);
+
+  bool check = IsSquareAttacked(g, kingPosition, !g->turn);
+  if (check) {
+    return;
+  }
   if (g->turn) {
     // white
     if (!oneToRight && !twoToRight && g->whiteCastleKing) {
diff --git a/src/opening_book.cpp b/src/opening_book.cpp
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/opening_book.cpp
diff --git a/src/opening_book.hpp b/src/opening_book.hpp
new file mode 100644
index 0000000..e37e8b3
--- /dev/null
+++ b/src/opening_book.hpp
@@ -0,0 +1,24 @@
+#ifndef SRC_OPENING_BOOK_H_
+#define SRC_OPENING_BOOK_H_
+
+#include "board/board.hpp"
+#include <cstdint>
+#include <string>
+#include <vector>
+struct Polygot_Entry {
+  uint64_t key;
+  uint16_t move;
+  uint16_t weight;
+  uint32_t learn;
+};
+
+class Polyglot_Book {
+public:
+  bool Load(const std::string &filename);
+  bool HasMove(const Game &board) const;
+  Move GetMove(const Game &board) const;
+
+private:
+  std::vector<Polygot_Entry> entries;
+};
+#endif /* SRC_OPENING_BOOK_H_ */