1 files changed, 75 insertions, 1 deletions

diff --git a/src/moves.cpp b/src/moves.cpp
index 0059039..7efd00a 100644
--- a/src/moves.cpp
+++ b/src/moves.cpp
@@ -2,9 +2,38 @@
 #include <cassert>
 #include <cstdint>
 #include <sys/types.h>
+#include <vector>
 
 #include "board.hpp"
 #include "moves.hpp"
+void GenerateKnightMoves(Board *b, int from, std::vector<Move> &moves) {
+
+  Piece knight = b->pieces[from];
+  if (knight.type != KNIGHT) {
+    assert(false && "Calling generate knight moves on non knight");
+    return;
+  }
+  // Knight moves: https://www.chessprogramming.org/Knight_Pattern
+  constexpr std::array<int, 8> knight_moves{-10, 6, 15, 17, 10, -6, -15, -17};
+
+  for (int offset : knight_moves) {
+    int next = from + offset;
+    if (next >= 64 || next < 0) {
+      continue;
+    }
+    const int fileDelta = std::abs((next % 8) - (from % 8));
+    if (fileDelta != 1 && fileDelta != 2) {
+      continue;
+    };
+    if (b->pieces[next].type != NONE) {
+      if (b->pieces[next].color == b->turn) {
+        continue;
+      };
+    }
+
+    moves.push_back({IndexToPosition(from), IndexToPosition(next)});
+  }
+};
 void GeneratePawnMoves(Board *b, int from, std::vector<Move> &moves) {
   Piece pawn = b->pieces[from];
   if (pawn.type != PAWN) {
@@ -49,7 +78,7 @@ void GeneratePawnMoves(Board *b, int from, std::vector<Move> &moves) {
   // the end
 }
 
-std::vector<Move> GetLegalMoves(Board *b) {
+std::vector<Move> GetPseudoLegalMoves(Board *b) {
   std::vector<Move> moves;
   moves.reserve(50); // almost all position dont have that many moves
 
@@ -69,6 +98,9 @@ std::vector<Move> GetLegalMoves(Board *b) {
     if (piece.type == PAWN) {
       GeneratePawnMoves(b, i, moves);
     }
+    if (piece.type == KNIGHT) {
+      GenerateKnightMoves(b, i, moves);
+    };
     if (piece.type == BISHOP) {
       GenerateSlidingMoves(b, i, bishop_Moves, moves);
     }
@@ -86,6 +118,48 @@ std::vector<Move> GetLegalMoves(Board *b) {
 
   return moves;
 }
+std::vector<Move> GetLegalMoves(Board *b) {
+  std::vector<Move> moves = GetPseudoLegalMoves(b);
+  std::vector<Move> legalMove;
+  for (Move move : moves) {
+    bool isLegal = true;
+    Board testBoard = *b;
+    PlayMove(move, &testBoard);
+    testBoard.turn = !testBoard.turn;
+    auto opponentResponse = GetPseudoLegalMoves(&testBoard);
+    for (Move move : opponentResponse) {
+      if (testBoard.pieces[PositionToIndex(move.To)].type == KING) {
+        isLegal = false;
+      }
+    }
+    if (isLegal) {
+      legalMove.push_back(move);
+    };
+  }
+  if (legalMove.size() == 0) {
+    bool isCheck = false;
+
+    Board testBoard = *b;
+    testBoard.turn = !testBoard.turn;
+    auto opponentResponse = GetPseudoLegalMoves(&testBoard);
+    for (Move move : opponentResponse) {
+      if (testBoard.pieces[PositionToIndex(move.To)].type == KING) {
+        isCheck = true;
+      }
+    }
+
+    if (isCheck) {
+      if (b->turn) {
+        b->state = BLACK_WON;
+      } else {
+        b->state = WHITE_WON;
+      };
+    } else {
+      b->state = STALEMATE;
+    }
+  }
+  return legalMove;
+}
 
 Position IndexToPosition(int i) {
   uint8_t rank = i / 8; // 0-7