implemented en passant

src/logic/board.py

@@ -172,9 +172,6 @@ class Board:
 
         piece = move.piece
 
-        # -- Set en passant target if needed
-        ret._en_passant_target = self._en_passant_target
-
         # -- Actually make the move
         pieces_moving, other_pieces = (ret._white, ret._black) if piece.colour == Colour.WHITE else (ret._black, ret._white)
 
@@ -183,6 +180,16 @@ class Board:
         if move.pos in other_pieces:
             del other_pieces[move.pos]
 
+        if move.en_passant:
+            pos_to_remove = Position(move.pos.x, move.pos.y + (1 if self._turn == Colour.BLACK else -1))
+            del other_pieces[pos_to_remove]
+
+        # -- Set en passant target if needed
+        if move.becomes_en_passant_target:
+            ret._en_passant_target = pieces_moving[move.pos]
+        else:
+            ret._en_passant_target = None
+
         # -- Handle castling (just move the rook over)
         if move.castle_side == CastleSide.King:
             rook_pos = Position(7, piece.pos.y)

src/logic/move.py

@@ -8,11 +8,13 @@ class CastleSide(Enum):
     Queen = "O-O-O"
 
 class Move:
-    def __init__(self, piece: "Piece", pos: Position,/, is_capturing: bool = False, castle_side: CastleSide = CastleSide.Neither) -> None:
+    def __init__(self, piece: "Piece", pos: Position,/, is_capturing: bool = False, castle_side: CastleSide = CastleSide.Neither, en_passant: bool = False, becomes_en_passant_target: bool = False) -> None:
         self.piece = piece
         self.pos = pos
         self.is_capturing = is_capturing
         self.castle_side = castle_side
+        self.becomes_en_passant_target = becomes_en_passant_target
+        self.en_passant = en_passant
 
     def to_algebraic(self) -> str:
         raise NotImplementedError("The move can't be translated to algbraic notation, as it was not implemented")

src/logic/pieces/pawn.py

@@ -24,18 +24,30 @@ class Pawn(Piece):
             if capturable_piece.colour != self.colour:
                 ret.append(Move(self, capturable_piece.pos, is_capturing = True))
 
+        # -- Can we capture en passant?
+        if board._en_passant_target is not None and \
+            board._en_passant_target.pos.y == self.pos.y and (
+                board._en_passant_target.pos.x == self.pos.x - 1
+                or board._en_passant_target.pos.x == self.pos.x + 1
+        ):
+            if board._en_passant_target.colour != self.colour:
+                old_pos = board._en_passant_target.pos
+                new_pos = Position(old_pos.x, old_pos.y + (1 if self.colour == Colour.WHITE else -1))
+                ret.append(Move(self, new_pos, is_capturing = True, en_passant = True))
+
+        # -- Normal moves
         if self.colour == Colour.WHITE:
             for dy in range(1, 3 if self.pos.y == 1 else 2):
                 if self.pos.y + dy > 7 or board.piece_at(self.pos.x, self.pos.y + dy):
                     break
                 pos = Position(self.pos.x, self.pos.y + dy)
-                ret.append(Move(self, pos))
+                ret.append(Move(self, pos, becomes_en_passant_target=dy==2))
         else:
             for dy in range(1, 3 if self.pos.y == 6 else 2):
                 if self.pos.y - dy < 0 or board.piece_at(self.pos.x, self.pos.y - dy):
                     break
                 pos = Position(self.pos.x, self.pos.y - dy)
-                ret.append(Move(self, pos))
+                ret.append(Move(self, pos, becomes_en_passant_target=dy==2))
 
         if not looking_for_check and board.is_check_for(self.colour):
             return self.keep_only_blocking(ret, board)