adding enpassant

6 files changed, 52 insertions, 14 deletions

diff --git a/src/board.cpp b/src/board.cpp
index 877e8c7..a74c5dc 100644
--- a/src/board.cpp
+++ b/src/board.cpp
@@ -35,7 +35,7 @@ Piece createPiece(PieceType type, bool color, bool moved) {
   piece.color = color;
   piece.moved = moved;
   return piece;
-};
+}
 void printBoard(Board *b) {
   std::string line = "  +-----------------+\n";
   std::string whiteLetters = "    a b c d e f g h\n";
@@ -87,6 +87,9 @@ void printBoard(Board *b) {
   assert(b->castle != "");
 
   std::println("Castling: {}", b->castle);
+  std::println("Can enpassant: {}", b->canEnpassant ? "Yes" : "No");
+  std::println("Where enpassant: {}{}", (char)((int)b->enPassant.file + 'A'),
+               8 - (int)b->enPassant.rank);
 }
 
 void PlayMove(Move move, Board *b) {
@@ -98,8 +101,34 @@ void PlayMove(Move move, Board *b) {
       assert(false && "capturing friendly piece error");
     }
   }
-  b->pieces[PositionToIndex(move.To)] = piece;
-  b->pieces[PositionToIndex(move.From)] = {false, NONE, false};
-  return;
-}
+  piece.moved = true;
+  if (piece.type == PAWN || piece2.type == NONE) {
+    b->halfMoveClock = 0;
+  } else {
+    b->halfMoveClock++;
+  }
+  if (piece.type == PAWN && b->canEnpassant && move.To == b->enPassant) {
+    Position capturedPawn = move.To;
+    capturedPawn.rank += piece.color ? 1 : -1;
+    b->pieces[PositionToIndex(capturedPawn)] = {false, NONE, false};
+  }
+
+  b->canEnpassant = false;
+  b->MoveClock++;
+
+  if (piece.type == PAWN) {
+    Position to = move.To;
+    to.rank -= (piece.color ? -2 : 2);
+    if (to == move.From) {
+      b->canEnpassant = true;
+      Position target = move.From;
+      target.rank += piece.color ? -1 : 1;
+      b->enPassant = target;
+    };
+
+    b->pieces[PositionToIndex(move.To)] = piece;
+    b->pieces[PositionToIndex(move.From)] = {false, NONE, false};
+    return;
+  }
+};
 int PositionToIndex(Position i) { return i.rank * 8 + i.file; }
diff --git a/src/board.hpp b/src/board.hpp
index 05706ff..44d32ee 100644
--- a/src/board.hpp
+++ b/src/board.hpp
@@ -28,22 +28,24 @@ struct Piece {
   bool moved;
 };
 
+struct Position {
+  uint8_t rank;
+  uint8_t file;
+
+  bool operator==(const Position &) const = default;
+};
+
 struct Board {
   Piece pieces[64];
   bool turn; // 1 white; 0 black
   std::string castle;
   uint8_t halfMoveClock;
   uint16_t MoveClock;
+  Position enPassant;
+  bool canEnpassant;
   GameState state;
 };
 
-struct Position {
-  uint8_t rank;
-  uint8_t file;
-
-  bool operator==(const Position &) const = default;
-};
-
 struct Move {
   Position From;
   Position To;
diff --git a/src/fen.cpp b/src/fen.cpp
index 2808a4c..fa8f289 100644
--- a/src/fen.cpp
+++ b/src/fen.cpp
@@ -82,7 +82,7 @@ void setBoardFen(std::string fen, Board *b) {
       if (isdigit(fen[i])) {
         int move = fen[i] - '0';
         file += move;
-        if (file >= 8) {
+        if (file > 8) {
           std::println("Fatal: file was to big");
           exit(1);
           return; // malformed rank
diff --git a/src/main.cpp b/src/main.cpp
index b8dd297..706ca28 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,6 @@
 #include "board.hpp"
 #include "fen.hpp"
+#include "moves.hpp"
 #include "repl.hpp"
 #include <cstdio>
 #include <string>
@@ -23,6 +24,8 @@ void setAllPiecesToEmpty(Board *b) {
 };
 Board initBoard(string startingFEN) {
   Board b;
+  b.enPassant = IndexToPosition(0); // default value
+  b.canEnpassant = false;
   b.state = TURN;
   b.turn = true;
   b.castle = "";
diff --git a/src/moves.cpp b/src/moves.cpp
index 7efd00a..81ea1df 100644
--- a/src/moves.cpp
+++ b/src/moves.cpp
@@ -70,6 +70,11 @@ void GeneratePawnMoves(Board *b, int from, std::vector<Move> &moves) {
     }
 
     int target = (position.rank + (pawn.color ? -1 : 1)) * 8 + targetFile;
+
+    if (IndexToPosition(target) == b->enPassant && b->canEnpassant) {
+      // enpasstant!!!!!!!
+      moves.push_back({position, IndexToPosition(target)});
+    }
     if (b->pieces[target].type != NONE &&
         b->pieces[target].color != pawn.color) {
       moves.push_back({position, IndexToPosition(target)});
diff --git a/src/repl.cpp b/src/repl.cpp
index ffa52b6..2ffa59b 100644
--- a/src/repl.cpp
+++ b/src/repl.cpp
@@ -121,7 +121,6 @@ int startREPL(Board *b) {
       }
       std::println();
       PlayMove(move, b);
-      b->MoveClock++;
       b->turn = !b->turn;
       printBoard(b);
     }